test/js-api/wasm-module-builder.js - external/github.com/WebAssembly/spec - Git at Google


            
            // Copyright 2016 the V8 project authors. All rights reserved.

            
            // Use of this source code is governed by a BSD-style license that can be

            
            // found in the LICENSE file.


            // Used for encoding f32 and double constants to bits.

            
            let byte_view = new Uint8Array(8);

            
            let data_view = new DataView(byte_view.buffer);


            // The bytes function receives one of

            
            //  - several arguments, each of which is either a number or a string of length

            
            //    1; if it's a string, the charcode of the contained character is used.

            
            //  - a single array argument containing the actual arguments

            
            //  - a single string; the returned buffer will contain the char codes of all

            
            //    contained characters.

            
            function bytes(...input) {

            
              if (input.length == 1 && typeof input[0] == 'array') input = input[0];

            
              if (input.length == 1 && typeof input[0] == 'string') {

            
                let len = input[0].length;

            
                let view = new Uint8Array(len);

            
                for (let i = 0; i < len; i++) view[i] = input[0].charCodeAt(i);

            
                return view.buffer;

            
              }

            
              let view = new Uint8Array(input.length);

            
              for (let i = 0; i < input.length; i++) {

            
                let val = input[i];

            
                if (typeof val == 'string') {

            
                  assertEquals(1, val.length, 'string inputs must have length 1');

            
                  val = val.charCodeAt(0);

            
                }

            
                view[i] = val | 0;

            
              }

            
              return view.buffer;

            
            }


            // Header declaration constants

            
            var kWasmH0 = 0;

            
            var kWasmH1 = 0x61;

            
            var kWasmH2 = 0x73;

            
            var kWasmH3 = 0x6d;


            var kWasmV0 = 0x1;

            
            var kWasmV1 = 0;

            
            var kWasmV2 = 0;

            
            var kWasmV3 = 0;


            var kHeaderSize = 8;

            
            var kPageSize = 65536;

            
            var kSpecMaxPages = 65535;

            
            var kMaxVarInt32Size = 5;

            
            var kMaxVarInt64Size = 10;


            let kDeclNoLocals = 0;


            // Section declaration constants

            
            let kUnknownSectionCode = 0;

            
            let kTypeSectionCode = 1;        // Function signature declarations

            
            let kImportSectionCode = 2;      // Import declarations

            
            let kFunctionSectionCode = 3;    // Function declarations

            
            let kTableSectionCode = 4;       // Indirect function table and other tables

            
            let kMemorySectionCode = 5;      // Memory attributes

            
            let kGlobalSectionCode = 6;      // Global declarations

            
            let kExportSectionCode = 7;      // Exports

            
            let kStartSectionCode = 8;       // Start function declaration

            
            let kElementSectionCode = 9;     // Elements section

            
            let kCodeSectionCode = 10;       // Function code

            
            let kDataSectionCode = 11;       // Data segments

            
            let kDataCountSectionCode = 12;  // Data segment count (between Element & Code)

            
            let kTagSectionCode = 13;        // Tag section (between Memory & Global)


            // Name section types

            
            let kModuleNameCode = 0;

            
            let kFunctionNamesCode = 1;

            
            let kLocalNamesCode = 2;


            let kWasmFunctionTypeForm = 0x60;

            
            let kWasmAnyFunctionTypeForm = 0x70;

            
            let kWasmStructTypeForm = 0x5f;

            
            let kWasmArrayTypeForm = 0x5e;

            
            let kWasmSubtypeForm = 0x50;

            
            let kWasmSubtypeFinalForm = 0x4f;

            
            let kWasmRecursiveTypeGroupForm = 0x4e;


            let kNoSuperType = 0xFFFFFFFF;


            let kHasMaximumFlag = 1;

            
            let kSharedHasMaximumFlag = 3;


            // Segment flags

            
            let kActiveNoIndex = 0;

            
            let kPassive = 1;

            
            let kActiveWithIndex = 2;

            
            let kPassiveWithElements = 5;


            // Function declaration flags

            
            let kDeclFunctionName   = 0x01;

            
            let kDeclFunctionImport = 0x02;

            
            let kDeclFunctionLocals = 0x04;

            
            let kDeclFunctionExport = 0x08;


            // Value types and related

            
            let kWasmVoid = 0x40;

            
            let kWasmI32 = 0x7f;

            
            let kWasmI64 = 0x7e;

            
            let kWasmF32 = 0x7d;

            
            let kWasmF64 = 0x7c;

            
            let kWasmS128 = 0x7b;


            // These are defined as negative integers to distinguish them from positive type

            
            // indices.

            
            let kWasmNullFuncRef = -0x0d;

            
            let kWasmNullExternRef = -0x0e;

            
            let kWasmNullRef = -0x0f;

            
            let kWasmFuncRef = -0x10;

            
            let kWasmAnyFunc = kWasmFuncRef;  // Alias named as in the JS API spec

            
            let kWasmExternRef = -0x11;

            
            let kWasmAnyRef = -0x12;

            
            let kWasmEqRef = -0x13;

            
            let kWasmI31Ref = -0x14;

            
            let kWasmStructRef = -0x15;

            
            let kWasmArrayRef = -0x16;

            
            let kWasmExnRef = -0x17;

            
            let kWasmNullExnRef = -0x0c;


            // Use the positive-byte versions inside function bodies.

            
            let kLeb128Mask = 0x7f;

            
            let kFuncRefCode = kWasmFuncRef & kLeb128Mask;

            
            let kAnyFuncCode = kFuncRefCode;  // Alias named as in the JS API spec

            
            let kExternRefCode = kWasmExternRef & kLeb128Mask;

            
            let kExnRefCode = kWasmExnRef & kLeb128Mask;

            
            let kAnyRefCode = kWasmAnyRef & kLeb128Mask;

            
            let kEqRefCode = kWasmEqRef & kLeb128Mask;

            
            let kI31RefCode = kWasmI31Ref & kLeb128Mask;

            
            let kNullExternRefCode = kWasmNullExternRef & kLeb128Mask;

            
            let kNullFuncRefCode = kWasmNullFuncRef & kLeb128Mask;

            
            let kNullExnRefCode = kWasmNullExnRef & kLeb128Mask;

            
            let kStructRefCode = kWasmStructRef & kLeb128Mask;

            
            let kArrayRefCode = kWasmArrayRef & kLeb128Mask;

            
            let kNullRefCode = kWasmNullRef & kLeb128Mask;


            let kWasmRefNull = 0x63;

            
            let kWasmRef = 0x64;

            
            function wasmRefNullType(heap_type, is_shared = false) {

            
              return {opcode: kWasmRefNull, heap_type: heap_type, is_shared: is_shared};

            
            }

            
            function wasmRefType(heap_type, is_shared = false) {

            
              return {opcode: kWasmRef, heap_type: heap_type, is_shared: is_shared};

            
            }


            // Packed storage types

            
            let kWasmI8 = 0x78;

            
            let kWasmI16 = 0x77;


            let kExternalFunction = 0;

            
            let kExternalTable = 1;

            
            let kExternalMemory = 2;

            
            let kExternalGlobal = 3;

            
            let kExternalTag = 4;


            let kTableZero = 0;

            
            let kMemoryZero = 0;

            
            let kSegmentZero = 0;


            let kExceptionAttribute = 0;


            // Useful signatures

            
            let kSig_i_i = makeSig([kWasmI32], [kWasmI32]);

            
            let kSig_l_l = makeSig([kWasmI64], [kWasmI64]);

            
            let kSig_i_l = makeSig([kWasmI64], [kWasmI32]);

            
            let kSig_i_ii = makeSig([kWasmI32, kWasmI32], [kWasmI32]);

            
            let kSig_i_iii = makeSig([kWasmI32, kWasmI32, kWasmI32], [kWasmI32]);

            
            let kSig_v_iiii = makeSig([kWasmI32, kWasmI32, kWasmI32, kWasmI32], []);

            
            let kSig_f_ff = makeSig([kWasmF32, kWasmF32], [kWasmF32]);

            
            let kSig_d_dd = makeSig([kWasmF64, kWasmF64], [kWasmF64]);

            
            let kSig_l_ll = makeSig([kWasmI64, kWasmI64], [kWasmI64]);

            
            let kSig_i_dd = makeSig([kWasmF64, kWasmF64], [kWasmI32]);

            
            let kSig_v_v = makeSig([], []);

            
            let kSig_i_v = makeSig([], [kWasmI32]);

            
            let kSig_l_v = makeSig([], [kWasmI64]);

            
            let kSig_f_v = makeSig([], [kWasmF32]);

            
            let kSig_d_v = makeSig([], [kWasmF64]);

            
            let kSig_v_i = makeSig([kWasmI32], []);

            
            let kSig_v_ii = makeSig([kWasmI32, kWasmI32], []);

            
            let kSig_v_iii = makeSig([kWasmI32, kWasmI32, kWasmI32], []);

            
            let kSig_v_l = makeSig([kWasmI64], []);

            
            let kSig_v_d = makeSig([kWasmF64], []);

            
            let kSig_v_dd = makeSig([kWasmF64, kWasmF64], []);

            
            let kSig_v_ddi = makeSig([kWasmF64, kWasmF64, kWasmI32], []);

            
            let kSig_ii_v = makeSig([], [kWasmI32, kWasmI32]);

            
            let kSig_iii_v = makeSig([], [kWasmI32, kWasmI32, kWasmI32]);

            
            let kSig_ii_i = makeSig([kWasmI32], [kWasmI32, kWasmI32]);

            
            let kSig_iii_i = makeSig([kWasmI32], [kWasmI32, kWasmI32, kWasmI32]);

            
            let kSig_ii_ii = makeSig([kWasmI32, kWasmI32], [kWasmI32, kWasmI32]);

            
            let kSig_iii_ii = makeSig([kWasmI32, kWasmI32], [kWasmI32, kWasmI32, kWasmI32]);


            let kSig_v_f = makeSig([kWasmF32], []);

            
            let kSig_f_f = makeSig([kWasmF32], [kWasmF32]);

            
            let kSig_f_d = makeSig([kWasmF64], [kWasmF32]);

            
            let kSig_d_d = makeSig([kWasmF64], [kWasmF64]);

            
            let kSig_r_r = makeSig([kWasmExternRef], [kWasmExternRef]);

            
            let kSig_a_a = makeSig([kWasmAnyFunc], [kWasmAnyFunc]);

            
            let kSig_i_r = makeSig([kWasmExternRef], [kWasmI32]);

            
            let kSig_v_r = makeSig([kWasmExternRef], []);

            
            let kSig_v_a = makeSig([kWasmAnyFunc], []);

            
            let kSig_v_rr = makeSig([kWasmExternRef, kWasmExternRef], []);

            
            let kSig_v_aa = makeSig([kWasmAnyFunc, kWasmAnyFunc], []);

            
            let kSig_r_v = makeSig([], [kWasmExternRef]);

            
            let kSig_a_v = makeSig([], [kWasmAnyFunc]);

            
            let kSig_a_i = makeSig([kWasmI32], [kWasmAnyFunc]);


            function makeSig(params, results) {

            
              return {params: params, results: results};

            
            }


            function makeSig_v_x(x) {

            
              return makeSig([x], []);

            
            }


            function makeSig_v_xx(x) {

            
              return makeSig([x, x], []);

            
            }


            function makeSig_r_v(r) {

            
              return makeSig([], [r]);

            
            }


            function makeSig_r_x(r, x) {

            
              return makeSig([x], [r]);

            
            }


            function makeSig_r_xx(r, x) {

            
              return makeSig([x, x], [r]);

            
            }


            // Opcodes

            
            let kExprUnreachable = 0x00;

            
            let kExprNop = 0x01;

            
            let kExprBlock = 0x02;

            
            let kExprLoop = 0x03;

            
            let kExprIf = 0x04;

            
            let kExprElse = 0x05;

            
            let kExprTry = 0x06;

            
            let kExprCatch = 0x07;

            
            let kExprThrow = 0x08;

            
            let kExprRethrow = 0x09;

            
            let kExprThrowRef = 0x0a;

            
            let kExprEnd = 0x0b;

            
            let kExprBr = 0x0c;

            
            let kExprBrIf = 0x0d;

            
            let kExprBrTable = 0x0e;

            
            let kExprReturn = 0x0f;

            
            let kExprCallFunction = 0x10;

            
            let kExprCallIndirect = 0x11;

            
            let kExprReturnCall = 0x12;

            
            let kExprReturnCallIndirect = 0x13;

            
            let kExprCatchAll = 0x19;

            
            let kExprDrop = 0x1a;

            
            let kExprSelect = 0x1b;

            
            let kExprTryTable = 0x1f;

            
            let kExprLocalGet = 0x20;

            
            let kExprLocalSet = 0x21;

            
            let kExprLocalTee = 0x22;

            
            let kExprGlobalGet = 0x23;

            
            let kExprGlobalSet = 0x24;

            
            let kExprTableGet = 0x25;

            
            let kExprTableSet = 0x26;

            
            let kExprI32LoadMem = 0x28;

            
            let kExprI64LoadMem = 0x29;

            
            let kExprF32LoadMem = 0x2a;

            
            let kExprF64LoadMem = 0x2b;

            
            let kExprI32LoadMem8S = 0x2c;

            
            let kExprI32LoadMem8U = 0x2d;

            
            let kExprI32LoadMem16S = 0x2e;

            
            let kExprI32LoadMem16U = 0x2f;

            
            let kExprI64LoadMem8S = 0x30;

            
            let kExprI64LoadMem8U = 0x31;

            
            let kExprI64LoadMem16S = 0x32;

            
            let kExprI64LoadMem16U = 0x33;

            
            let kExprI64LoadMem32S = 0x34;

            
            let kExprI64LoadMem32U = 0x35;

            
            let kExprI32StoreMem = 0x36;

            
            let kExprI64StoreMem = 0x37;

            
            let kExprF32StoreMem = 0x38;

            
            let kExprF64StoreMem = 0x39;

            
            let kExprI32StoreMem8 = 0x3a;

            
            let kExprI32StoreMem16 = 0x3b;

            
            let kExprI64StoreMem8 = 0x3c;

            
            let kExprI64StoreMem16 = 0x3d;

            
            let kExprI64StoreMem32 = 0x3e;

            
            let kExprMemorySize = 0x3f;

            
            let kExprMemoryGrow = 0x40;

            
            let kExprI32Const = 0x41;

            
            let kExprI64Const = 0x42;

            
            let kExprF32Const = 0x43;

            
            let kExprF64Const = 0x44;

            
            let kExprI32Eqz = 0x45;

            
            let kExprI32Eq = 0x46;

            
            let kExprI32Ne = 0x47;

            
            let kExprI32LtS = 0x48;

            
            let kExprI32LtU = 0x49;

            
            let kExprI32GtS = 0x4a;

            
            let kExprI32GtU = 0x4b;

            
            let kExprI32LeS = 0x4c;

            
            let kExprI32LeU = 0x4d;

            
            let kExprI32GeS = 0x4e;

            
            let kExprI32GeU = 0x4f;

            
            let kExprI64Eqz = 0x50;

            
            let kExprI64Eq = 0x51;

            
            let kExprI64Ne = 0x52;

            
            let kExprI64LtS = 0x53;

            
            let kExprI64LtU = 0x54;

            
            let kExprI64GtS = 0x55;

            
            let kExprI64GtU = 0x56;

            
            let kExprI64LeS = 0x57;

            
            let kExprI64LeU = 0x58;

            
            let kExprI64GeS = 0x59;

            
            let kExprI64GeU = 0x5a;

            
            let kExprF32Eq = 0x5b;

            
            let kExprF32Ne = 0x5c;

            
            let kExprF32Lt = 0x5d;

            
            let kExprF32Gt = 0x5e;

            
            let kExprF32Le = 0x5f;

            
            let kExprF32Ge = 0x60;

            
            let kExprF64Eq = 0x61;

            
            let kExprF64Ne = 0x62;

            
            let kExprF64Lt = 0x63;

            
            let kExprF64Gt = 0x64;

            
            let kExprF64Le = 0x65;

            
            let kExprF64Ge = 0x66;

            
            let kExprI32Clz = 0x67;

            
            let kExprI32Ctz = 0x68;

            
            let kExprI32Popcnt = 0x69;

            
            let kExprI32Add = 0x6a;

            
            let kExprI32Sub = 0x6b;

            
            let kExprI32Mul = 0x6c;

            
            let kExprI32DivS = 0x6d;

            
            let kExprI32DivU = 0x6e;

            
            let kExprI32RemS = 0x6f;

            
            let kExprI32RemU = 0x70;

            
            let kExprI32And = 0x71;

            
            let kExprI32Ior = 0x72;

            
            let kExprI32Xor = 0x73;

            
            let kExprI32Shl = 0x74;

            
            let kExprI32ShrS = 0x75;

            
            let kExprI32ShrU = 0x76;

            
            let kExprI32Rol = 0x77;

            
            let kExprI32Ror = 0x78;

            
            let kExprI64Clz = 0x79;

            
            let kExprI64Ctz = 0x7a;

            
            let kExprI64Popcnt = 0x7b;

            
            let kExprI64Add = 0x7c;

            
            let kExprI64Sub = 0x7d;

            
            let kExprI64Mul = 0x7e;

            
            let kExprI64DivS = 0x7f;

            
            let kExprI64DivU = 0x80;

            
            let kExprI64RemS = 0x81;

            
            let kExprI64RemU = 0x82;

            
            let kExprI64And = 0x83;

            
            let kExprI64Ior = 0x84;

            
            let kExprI64Xor = 0x85;

            
            let kExprI64Shl = 0x86;

            
            let kExprI64ShrS = 0x87;

            
            let kExprI64ShrU = 0x88;

            
            let kExprI64Rol = 0x89;

            
            let kExprI64Ror = 0x8a;

            
            let kExprF32Abs = 0x8b;

            
            let kExprF32Neg = 0x8c;

            
            let kExprF32Ceil = 0x8d;

            
            let kExprF32Floor = 0x8e;

            
            let kExprF32Trunc = 0x8f;

            
            let kExprF32NearestInt = 0x90;

            
            let kExprF32Sqrt = 0x91;

            
            let kExprF32Add = 0x92;

            
            let kExprF32Sub = 0x93;

            
            let kExprF32Mul = 0x94;

            
            let kExprF32Div = 0x95;

            
            let kExprF32Min = 0x96;

            
            let kExprF32Max = 0x97;

            
            let kExprF32CopySign = 0x98;

            
            let kExprF64Abs = 0x99;

            
            let kExprF64Neg = 0x9a;

            
            let kExprF64Ceil = 0x9b;

            
            let kExprF64Floor = 0x9c;

            
            let kExprF64Trunc = 0x9d;

            
            let kExprF64NearestInt = 0x9e;

            
            let kExprF64Sqrt = 0x9f;

            
            let kExprF64Add = 0xa0;

            
            let kExprF64Sub = 0xa1;

            
            let kExprF64Mul = 0xa2;

            
            let kExprF64Div = 0xa3;

            
            let kExprF64Min = 0xa4;

            
            let kExprF64Max = 0xa5;

            
            let kExprF64CopySign = 0xa6;

            
            let kExprI32ConvertI64 = 0xa7;

            
            let kExprI32SConvertF32 = 0xa8;

            
            let kExprI32UConvertF32 = 0xa9;

            
            let kExprI32SConvertF64 = 0xaa;

            
            let kExprI32UConvertF64 = 0xab;

            
            let kExprI64SConvertI32 = 0xac;

            
            let kExprI64UConvertI32 = 0xad;

            
            let kExprI64SConvertF32 = 0xae;

            
            let kExprI64UConvertF32 = 0xaf;

            
            let kExprI64SConvertF64 = 0xb0;

            
            let kExprI64UConvertF64 = 0xb1;

            
            let kExprF32SConvertI32 = 0xb2;

            
            let kExprF32UConvertI32 = 0xb3;

            
            let kExprF32SConvertI64 = 0xb4;

            
            let kExprF32UConvertI64 = 0xb5;

            
            let kExprF32ConvertF64 = 0xb6;

            
            let kExprF64SConvertI32 = 0xb7;

            
            let kExprF64UConvertI32 = 0xb8;

            
            let kExprF64SConvertI64 = 0xb9;

            
            let kExprF64UConvertI64 = 0xba;

            
            let kExprF64ConvertF32 = 0xbb;

            
            let kExprI32ReinterpretF32 = 0xbc;

            
            let kExprI64ReinterpretF64 = 0xbd;

            
            let kExprF32ReinterpretI32 = 0xbe;

            
            let kExprF64ReinterpretI64 = 0xbf;

            
            let kExprI32SExtendI8 = 0xc0;

            
            let kExprI32SExtendI16 = 0xc1;

            
            let kExprI64SExtendI8 = 0xc2;

            
            let kExprI64SExtendI16 = 0xc3;

            
            let kExprI64SExtendI32 = 0xc4;

            
            let kExprRefNull = 0xd0;

            
            let kExprRefIsNull = 0xd1;

            
            let kExprRefFunc = 0xd2;


            // Prefix opcodes

            
            let kGCPrefix = 0xfb;

            
            let kNumericPrefix = 0xfc;

            
            let kSimdPrefix = 0xfd;

            
            let kAtomicPrefix = 0xfe;


            // Use these for multi-byte instructions (opcode > 0x7F needing two LEB bytes):

            
            function GCInstr(opcode) {

            
              if (opcode <= 0x7F) return [kGCPrefix, opcode];

            
              return [kGCPrefix, 0x80 | (opcode & 0x7F), opcode >> 7];

            
            }


            // GC opcodes

            
            let kExprStructNew = 0x00;

            
            let kExprStructNewDefault = 0x01;

            
            let kExprStructGet = 0x02;

            
            let kExprStructGetS = 0x03;

            
            let kExprStructGetU = 0x04;

            
            let kExprStructSet = 0x05;

            
            let kExprArrayNew = 0x06;

            
            let kExprArrayNewDefault = 0x07;

            
            let kExprArrayNewFixed = 0x08;

            
            let kExprArrayNewData = 0x09;

            
            let kExprArrayNewElem = 0x0a;

            
            let kExprArrayGet = 0x0b;

            
            let kExprArrayGetS = 0x0c;

            
            let kExprArrayGetU = 0x0d;

            
            let kExprArraySet = 0x0e;

            
            let kExprArrayLen = 0x0f;

            
            let kExprArrayFill = 0x10;

            
            let kExprArrayCopy = 0x11;

            
            let kExprArrayInitData = 0x12;

            
            let kExprArrayInitElem = 0x13;

            
            let kExprRefTest = 0x14;

            
            let kExprRefTestNull = 0x15;

            
            let kExprRefCast = 0x16;

            
            let kExprRefCastNull = 0x17;

            
            let kExprBrOnCast = 0x18;

            
            let kExprBrOnCastFail = 0x19;

            
            let kExprExternInternalize = 0x1a;

            
            let kExprExternExternalize = 0x1b;

            
            let kExprRefI31 = 0x1c;

            
            let kExprI31GetS = 0x1d;

            
            let kExprI31GetU = 0x1e;


            // Numeric opcodes.

            
            let kExprMemoryInit = 0x08;

            
            let kExprDataDrop = 0x09;

            
            let kExprMemoryCopy = 0x0a;

            
            let kExprMemoryFill = 0x0b;

            
            let kExprTableInit = 0x0c;

            
            let kExprElemDrop = 0x0d;

            
            let kExprTableCopy = 0x0e;

            
            let kExprTableGrow = 0x0f;

            
            let kExprTableSize = 0x10;

            
            let kExprTableFill = 0x11;


            // Atomic opcodes.

            
            let kExprAtomicNotify = 0x00;

            
            let kExprI32AtomicWait = 0x01;

            
            let kExprI64AtomicWait = 0x02;

            
            let kExprI32AtomicLoad = 0x10;

            
            let kExprI32AtomicLoad8U = 0x12;

            
            let kExprI32AtomicLoad16U = 0x13;

            
            let kExprI32AtomicStore = 0x17;

            
            let kExprI32AtomicStore8U = 0x19;

            
            let kExprI32AtomicStore16U = 0x1a;

            
            let kExprI32AtomicAdd = 0x1e;

            
            let kExprI32AtomicAdd8U = 0x20;

            
            let kExprI32AtomicAdd16U = 0x21;

            
            let kExprI32AtomicSub = 0x25;

            
            let kExprI32AtomicSub8U = 0x27;

            
            let kExprI32AtomicSub16U = 0x28;

            
            let kExprI32AtomicAnd = 0x2c;

            
            let kExprI32AtomicAnd8U = 0x2e;

            
            let kExprI32AtomicAnd16U = 0x2f;

            
            let kExprI32AtomicOr = 0x33;

            
            let kExprI32AtomicOr8U = 0x35;

            
            let kExprI32AtomicOr16U = 0x36;

            
            let kExprI32AtomicXor = 0x3a;

            
            let kExprI32AtomicXor8U = 0x3c;

            
            let kExprI32AtomicXor16U = 0x3d;

            
            let kExprI32AtomicExchange = 0x41;

            
            let kExprI32AtomicExchange8U = 0x43;

            
            let kExprI32AtomicExchange16U = 0x44;

            
            let kExprI32AtomicCompareExchange = 0x48;

            
            let kExprI32AtomicCompareExchange8U = 0x4a;

            
            let kExprI32AtomicCompareExchange16U = 0x4b;


            let kExprI64AtomicLoad = 0x11;

            
            let kExprI64AtomicLoad8U = 0x14;

            
            let kExprI64AtomicLoad16U = 0x15;

            
            let kExprI64AtomicLoad32U = 0x16;

            
            let kExprI64AtomicStore = 0x18;

            
            let kExprI64AtomicStore8U = 0x1b;

            
            let kExprI64AtomicStore16U = 0x1c;

            
            let kExprI64AtomicStore32U = 0x1d;

            
            let kExprI64AtomicAdd = 0x1f;

            
            let kExprI64AtomicAdd8U = 0x22;

            
            let kExprI64AtomicAdd16U = 0x23;

            
            let kExprI64AtomicAdd32U = 0x24;

            
            let kExprI64AtomicSub = 0x26;

            
            let kExprI64AtomicSub8U = 0x29;

            
            let kExprI64AtomicSub16U = 0x2a;

            
            let kExprI64AtomicSub32U = 0x2b;

            
            let kExprI64AtomicAnd = 0x2d;

            
            let kExprI64AtomicAnd8U = 0x30;

            
            let kExprI64AtomicAnd16U = 0x31;

            
            let kExprI64AtomicAnd32U = 0x32;

            
            let kExprI64AtomicOr = 0x34;

            
            let kExprI64AtomicOr8U = 0x37;

            
            let kExprI64AtomicOr16U = 0x38;

            
            let kExprI64AtomicOr32U = 0x39;

            
            let kExprI64AtomicXor = 0x3b;

            
            let kExprI64AtomicXor8U = 0x3e;

            
            let kExprI64AtomicXor16U = 0x3f;

            
            let kExprI64AtomicXor32U = 0x40;

            
            let kExprI64AtomicExchange = 0x42;

            
            let kExprI64AtomicExchange8U = 0x45;

            
            let kExprI64AtomicExchange16U = 0x46;

            
            let kExprI64AtomicExchange32U = 0x47;

            
            let kExprI64AtomicCompareExchange = 0x49

            
            let kExprI64AtomicCompareExchange8U = 0x4c;

            
            let kExprI64AtomicCompareExchange16U = 0x4d;

            
            let kExprI64AtomicCompareExchange32U = 0x4e;


            // Simd opcodes.

            
            let kExprS128LoadMem = 0x00;

            
            let kExprS128StoreMem = 0x01;

            
            let kExprI32x4Splat = 0x0c;

            
            let kExprI32x4Eq = 0x2c;

            
            let kExprS1x4AllTrue = 0x75;

            
            let kExprF32x4Min = 0x9e;


            // Exception handling with exnref.

            
            let kCatchNoRef = 0x0;

            
            let kCatchRef = 0x1;

            
            let kCatchAllNoRef = 0x2;

            
            let kCatchAllRef = 0x3;


            class Binary {

            
              constructor() {

            
                this.length = 0;

            
                this.buffer = new Uint8Array(8192);

            
              }


              ensure_space(needed) {

            
                if (this.buffer.length - this.length >= needed) return;

            
                let new_capacity = this.buffer.length * 2;

            
                while (new_capacity - this.length < needed) new_capacity *= 2;

            
                let new_buffer = new Uint8Array(new_capacity);

            
                new_buffer.set(this.buffer);

            
                this.buffer = new_buffer;

            
              }


              trunc_buffer() {

            
                return new Uint8Array(this.buffer.buffer, 0, this.length);

            
              }


              reset() {

            
                this.length = 0;

            
              }


              emit_u8(val) {

            
                this.ensure_space(1);

            
                this.buffer[this.length++] = val;

            
              }


              emit_u16(val) {

            
                this.ensure_space(2);

            
                this.buffer[this.length++] = val;

            
                this.buffer[this.length++] = val >> 8;

            
              }


              emit_u32(val) {

            
                this.ensure_space(4);

            
                this.buffer[this.length++] = val;

            
                this.buffer[this.length++] = val >> 8;

            
                this.buffer[this.length++] = val >> 16;

            
                this.buffer[this.length++] = val >> 24;

            
              }


              emit_leb_u(val, max_len) {

            
                this.ensure_space(max_len);

            
                for (let i = 0; i < max_len; ++i) {

            
                  let v = val & 0xff;

            
                  val = val >>> 7;

            
                  if (val == 0) {

            
                    this.buffer[this.length++] = v;

            
                    return;

            
                  }

            
                  this.buffer[this.length++] = v | 0x80;

            
                }

            
                throw new Error("Leb value exceeds maximum length of " + max_len);

            
              }


              emit_u32v(val) {

            
                this.emit_leb_u(val, kMaxVarInt32Size);

            
              }


              emit_u64v(val) {

            
                this.emit_leb_u(val, kMaxVarInt64Size);

            
              }


              emit_bytes(data) {

            
                this.ensure_space(data.length);

            
                this.buffer.set(data, this.length);

            
                this.length += data.length;

            
              }


              emit_string(string) {

            
                // When testing illegal names, we pass a byte array directly.

            
                if (string instanceof Array) {

            
                  this.emit_u32v(string.length);

            
                  this.emit_bytes(string);

            
                  return;

            
                }


                // This is the hacky way to convert a JavaScript string to a UTF8 encoded

            
                // string only containing single-byte characters.

            
                let string_utf8 = unescape(encodeURIComponent(string));

            
                this.emit_u32v(string_utf8.length);

            
                for (let i = 0; i < string_utf8.length; i++) {

            
                  this.emit_u8(string_utf8.charCodeAt(i));

            
                }

            
              }


              emit_heap_type(heap_type) {

            
                this.emit_bytes(wasmSignedLeb(heap_type, kMaxVarInt32Size));

            
              }


              emit_type(type) {

            
                if ((typeof type) == 'number') {

            
                  this.emit_u8(type >= 0 ? type : type & kLeb128Mask);

            
                } else {

            
                  this.emit_u8(type.opcode);

            
                  if ('depth' in type) this.emit_u8(type.depth);

            
                  this.emit_heap_type(type.heap_type);

            
                }

            
              }


              emit_init_expr(expr) {

            
                this.emit_bytes(expr);

            
                this.emit_u8(kExprEnd);

            
              }


              emit_header() {

            
                this.emit_bytes([

            
                  kWasmH0, kWasmH1, kWasmH2, kWasmH3, kWasmV0, kWasmV1, kWasmV2, kWasmV3

            
                ]);

            
              }


              emit_section(section_code, content_generator) {

            
                // Emit section name.

            
                this.emit_u8(section_code);

            
                // Emit the section to a temporary buffer: its full length isn't know yet.

            
                const section = new Binary;

            
                content_generator(section);

            
                // Emit section length.

            
                this.emit_u32v(section.length);

            
                // Copy the temporary buffer.

            
                // Avoid spread because {section} can be huge.

            
                this.emit_bytes(section.trunc_buffer());

            
              }

            
            }


            class WasmFunctionBuilder {

            
              constructor(module, name, type_index) {

            
                this.module = module;

            
                this.name = name;

            
                this.type_index = type_index;

            
                this.body = [];

            
                this.locals = [];

            
                this.local_names = [];

            
              }


              numLocalNames() {

            
                let num_local_names = 0;

            
                for (let loc_name of this.local_names) {

            
                  if (loc_name !== undefined) ++num_local_names;

            
                }

            
                return num_local_names;

            
              }


              exportAs(name) {

            
                this.module.addExport(name, this.index);

            
                return this;

            
              }


              exportFunc() {

            
                this.exportAs(this.name);

            
                return this;

            
              }


              addBody(body) {

            
                for (let b of body) {

            
                  if (typeof b !== 'number' || (b & (~0xFF)) !== 0 )

            
                    throw new Error('invalid body (entries must be 8 bit numbers): ' + body);

            
                }

            
                this.body = body.slice();

            
                // Automatically add the end for the function block to the body.

            
                this.body.push(kExprEnd);

            
                return this;

            
              }


              addBodyWithEnd(body) {

            
                this.body = body;

            
                return this;

            
              }


              getNumLocals() {

            
                let total_locals = 0;

            
                for (let l of this.locals) {

            
                  for (let type of ["i32", "i64", "f32", "f64", "s128"]) {

            
                    total_locals += l[type + "_count"] || 0;

            
                  }

            
                }

            
                return total_locals;

            
              }


              addLocals(locals, names) {

            
                const old_num_locals = this.getNumLocals();

            
                this.locals.push(locals);

            
                if (names) {

            
                  const missing_names = old_num_locals - this.local_names.length;

            
                  this.local_names.push(...new Array(missing_names), ...names);

            
                }

            
                return this;

            
              }


              end() {

            
                return this.module;

            
              }

            
            }


            class WasmGlobalBuilder {

            
              constructor(module, type, mutable, init) {

            
                this.module = module;

            
                this.type = type;

            
                this.mutable = mutable;

            
                this.init = init;

            
              }


              exportAs(name) {

            
                this.module.exports.push({name: name, kind: kExternalGlobal,

            
                                          index: this.index});

            
                return this;

            
              }

            
            }


            function checkExpr(expr) {

            
              for (let b of expr) {

            
                if (typeof b !== 'number' || (b & (~0xFF)) !== 0) {

            
                  throw new Error(

            
                      'invalid body (entries must be 8 bit numbers): ' + expr);

            
                }

            
              }

            
            }


            class WasmTableBuilder {

            
              constructor(module, type, initial_size, max_size, init_expr) {

            
                this.module = module;

            
                this.type = type;

            
                this.initial_size = initial_size;

            
                this.has_max = max_size != undefined;

            
                this.max_size = max_size;

            
                this.init_expr = init_expr;

            
                this.has_init = init_expr !== undefined;

            
              }


              exportAs(name) {

            
                this.module.exports.push({name: name, kind: kExternalTable,

            
                                          index: this.index});

            
                return this;

            
              }

            
            }


            function makeField(type, mutability) {

            
              if ((typeof mutability) != 'boolean') {

            
                throw new Error('field mutability must be boolean');

            
              }

            
              return {type: type, mutability: mutability};

            
            }


            class WasmStruct {

            
              constructor(fields, is_final, supertype_idx) {

            
                if (!Array.isArray(fields)) {

            
                  throw new Error('struct fields must be an array');

            
                }

            
                this.fields = fields;

            
                this.type_form = kWasmStructTypeForm;

            
                this.is_final = is_final;

            
                this.supertype = supertype_idx;

            
              }

            
            }


            class WasmArray {

            
              constructor(type, mutability, is_final, supertype_idx) {

            
                this.type = type;

            
                this.mutability = mutability;

            
                this.type_form = kWasmArrayTypeForm;

            
                this.is_final = is_final;

            
                this.supertype = supertype_idx;

            
              }

            
            }


            class WasmModuleBuilder {

            
              constructor() {

            
                this.types = [];

            
                this.imports = [];

            
                this.exports = [];

            
                this.globals = [];

            
                this.tables = [];

            
                this.tags = [];

            
                this.functions = [];

            
                this.element_segments = [];

            
                this.data_segments = [];

            
                this.explicit = [];

            
                this.rec_groups = [];

            
                this.num_imported_funcs = 0;

            
                this.num_imported_globals = 0;

            
                this.num_imported_tables = 0;

            
                this.num_imported_tags = 0;

            
                return this;

            
              }


              addStart(start_index) {

            
                this.start_index = start_index;

            
                return this;

            
              }


              addMemory(min, max, exp, shared) {

            
                this.memory = {min: min, max: max, exp: exp, shared: shared};

            
                return this;

            
              }


              addExplicitSection(bytes) {

            
                this.explicit.push(bytes);

            
                return this;

            
              }


              stringToBytes(name) {

            
                var result = new Binary();

            
                result.emit_string(name);

            
                return result.trunc_buffer()

            
              }


              createCustomSection(name, bytes) {

            
                name = this.stringToBytes(name);

            
                var section = new Binary();

            
                section.emit_u8(kUnknownSectionCode);

            
                section.emit_u32v(name.length + bytes.length);

            
                section.emit_bytes(name);

            
                section.emit_bytes(bytes);

            
                return section.trunc_buffer();

            
              }


              addCustomSection(name, bytes) {

            
                this.explicit.push(this.createCustomSection(name, bytes));

            
              }


              // We use {is_final = true} so that the MVP syntax is generated for

            
              // signatures.

            
              addType(type, supertype_idx = kNoSuperType, is_final = true) {

            
                var pl = type.params.length;   // should have params

            
                var rl = type.results.length;  // should have results

            
                var type_copy = {params: type.params, results: type.results,

            
                                 is_final: is_final, supertype: supertype_idx};

            
                this.types.push(type_copy);

            
                return this.types.length - 1;

            
              }


              addStruct(fields, supertype_idx = kNoSuperType, is_final = false) {

            
                this.types.push(new WasmStruct(fields, is_final, supertype_idx));

            
                return this.types.length - 1;

            
              }


              addArray(type, mutability, supertype_idx = kNoSuperType, is_final = false) {

            
                this.types.push(new WasmArray(type, mutability, is_final, supertype_idx));

            
                return this.types.length - 1;

            
              }


              nextTypeIndex() { return this.types.length; }


              static defaultFor(type) {

            
                switch (type) {

            
                  case kWasmI32:

            
                    return wasmI32Const(0);

            
                  case kWasmI64:

            
                    return wasmI64Const(0);

            
                  case kWasmF32:

            
                    return wasmF32Const(0.0);

            
                  case kWasmF64:

            
                    return wasmF64Const(0.0);

            
                  case kWasmS128:

            
                    return [kSimdPrefix, kExprS128Const, ...(new Array(16).fill(0))];

            
                  default:

            
                    if ((typeof type) != 'number' && type.opcode != kWasmRefNull) {

            
                      throw new Error("Non-defaultable type");

            
                    }

            
                    let heap_type = (typeof type) == 'number' ? type : type.heap_type;

            
                    return [kExprRefNull, ...wasmSignedLeb(heap_type, kMaxVarInt32Size)];

            
                }

            
              }


              addGlobal(type, mutable, init) {

            
                if (init === undefined) init = WasmModuleBuilder.defaultFor(type);

            
                checkExpr(init);

            
                let glob = new WasmGlobalBuilder(this, type, mutable, init);

            
                glob.index = this.globals.length + this.num_imported_globals;

            
                this.globals.push(glob);

            
                return glob;

            
              }


              addTable(type, initial_size, max_size = undefined, init_expr = undefined) {

            
                if (type == kWasmI32 || type == kWasmI64 || type == kWasmF32 ||

            
                    type == kWasmF64 || type == kWasmS128 || type == kWasmVoid) {

            
                  throw new Error('Tables must be of a reference type');

            
                }

            
                if (init_expr != undefined) checkExpr(init_expr);

            
                let table = new WasmTableBuilder(

            
                    this, type, initial_size, max_size, init_expr);

            
                table.index = this.tables.length + this.num_imported_tables;

            
                this.tables.push(table);

            
                return table;

            
              }


              addTag(type) {

            
                let type_index = (typeof type) == "number" ? type : this.addType(type);

            
                let tag_index = this.tags.length + this.num_imported_tags;

            
                this.tags.push(type_index);

            
                return tag_index;

            
              }


              addFunction(name, type) {

            
                let type_index = (typeof type) == "number" ? type : this.addType(type);

            
                let func = new WasmFunctionBuilder(this, name, type_index);

            
                func.index = this.functions.length + this.num_imported_funcs;

            
                this.functions.push(func);

            
                return func;

            
              }


              addImport(module, name, type) {

            
                if (this.functions.length != 0) {

            
                  throw new Error('Imported functions must be declared before local ones');

            
                }

            
                let type_index = (typeof type) == "number" ? type : this.addType(type);

            
                this.imports.push({module: module, name: name, kind: kExternalFunction,

            
                                   type_index: type_index});

            
                return this.num_imported_funcs++;

            
              }


              addImportedGlobal(module, name, type, mutable = false) {

            
                if (this.globals.length != 0) {

            
                  throw new Error('Imported globals must be declared before local ones');

            
                }

            
                let o = {module: module, name: name, kind: kExternalGlobal, type: type,

            
                         mutable: mutable};

            
                this.imports.push(o);

            
                return this.num_imported_globals++;

            
              }


              addImportedMemory(module, name, initial = 0, maximum, shared) {

            
                let o = {module: module, name: name, kind: kExternalMemory,

            
                         initial: initial, maximum: maximum, shared: shared};

            
                this.imports.push(o);

            
                return this;

            
              }


              addImportedTable(module, name, initial, maximum, type) {

            
                if (this.tables.length != 0) {

            
                  throw new Error('Imported tables must be declared before local ones');

            
                }

            
                let o = {module: module, name: name, kind: kExternalTable, initial: initial,

            
                         maximum: maximum, type: type || kWasmAnyFunctionTypeForm};

            
                this.imports.push(o);

            
                return this.num_imported_tables++;

            
              }


              addImportedTag(module, name, type) {

            
                if (this.tags.length != 0) {

            
                  throw new Error('Imported tags must be declared before local ones');

            
                }

            
                let type_index = (typeof type) == "number" ? type : this.addType(type);

            
                let o = {module: module, name: name, kind: kExternalTag, type: type_index};

            
                this.imports.push(o);

            
                return this.num_imported_tags++;

            
              }


              addExport(name, index) {

            
                this.exports.push({name: name, kind: kExternalFunction, index: index});

            
                return this;

            
              }


              addExportOfKind(name, kind, index) {

            
                this.exports.push({name: name, kind: kind, index: index});

            
                return this;

            
              }


              addDataSegment(addr, data, is_global = false) {

            
                this.data_segments.push(

            
                    {addr: addr, data: data, is_global: is_global, is_active: true});

            
                return this.data_segments.length - 1;

            
              }


              addPassiveDataSegment(data) {

            
                this.data_segments.push({data: data, is_active: false});

            
                return this.data_segments.length - 1;

            
              }


              exportMemoryAs(name) {

            
                this.exports.push({name: name, kind: kExternalMemory, index: 0});

            
              }


              addElementSegment(table, base, is_global, array) {

            
                this.element_segments.push({table: table, base: base, is_global: is_global,

            
                                                array: array, is_active: true});

            
                return this;

            
              }


              addPassiveElementSegment(array, is_import = false) {

            
                this.element_segments.push({array: array, is_active: false});

            
                return this;

            
              }


              appendToTable(array) {

            
                for (let n of array) {

            
                  if (typeof n != 'number')

            
                    throw new Error('invalid table (entries have to be numbers): ' + array);

            
                }

            
                if (this.tables.length == 0) {

            
                  this.addTable(kWasmAnyFunc, 0);

            
                }

            
                // Adjust the table to the correct size.

            
                let table = this.tables[0];

            
                const base = table.initial_size;

            
                const table_size = base + array.length;

            
                table.initial_size = table_size;

            
                if (table.has_max && table_size > table.max_size) {

            
                  table.max_size = table_size;

            
                }

            
                return this.addElementSegment(0, base, false, array);

            
              }


              setTableBounds(min, max = undefined) {

            
                if (this.tables.length != 0) {

            
                  throw new Error("The table bounds of table '0' have already been set.");

            
                }

            
                this.addTable(kWasmAnyFunc, min, max);

            
                return this;

            
              }


              startRecGroup() {

            
                this.rec_groups.push({start: this.types.length, size: 0});

            
              }


              endRecGroup() {

            
                if (this.rec_groups.length == 0) {

            
                  throw new Error("Did not start a recursive group before ending one")

            
                }

            
                let last_element = this.rec_groups[this.rec_groups.length - 1]

            
                if (last_element.size != 0) {

            
                  throw new Error("Did not start a recursive group before ending one")

            
                }

            
                last_element.size = this.types.length - last_element.start;

            
              }


              setName(name) {

            
                this.name = name;

            
                return this;

            
              }


              toBuffer(debug = false) {

            
                let binary = new Binary;

            
                let wasm = this;


                // Add header

            
                binary.emit_header();


                // Add type section

            
                if (wasm.types.length > 0) {

            
                  if (debug) print('emitting types @ ' + binary.length);

            
                  binary.emit_section(kTypeSectionCode, section => {

            
                    let length_with_groups = wasm.types.length;

            
                    for (let group of wasm.rec_groups) {

            
                      length_with_groups -= group.size - 1;

            
                    }

            
                    section.emit_u32v(length_with_groups);


                    let rec_group_index = 0;


                    for (let i = 0; i < wasm.types.length; i++) {

            
                      if (rec_group_index < wasm.rec_groups.length &&

            
                          wasm.rec_groups[rec_group_index].start == i) {

            
                        section.emit_u8(kWasmRecursiveTypeGroupForm);

            
                        section.emit_u32v(wasm.rec_groups[rec_group_index].size);

            
                        rec_group_index++;

            
                      }


                      let type = wasm.types[i];

            
                      if (type.supertype != kNoSuperType) {

            
                        section.emit_u8(type.is_final ? kWasmSubtypeFinalForm

            
                                                      : kWasmSubtypeForm);

            
                        section.emit_u8(1);  // supertype count

            
                        section.emit_u32v(type.supertype);

            
                      } else if (!type.is_final) {

            
                        section.emit_u8(kWasmSubtypeForm);

            
                        section.emit_u8(0);  // no supertypes

            
                      }

            
                      if (type instanceof WasmStruct) {

            
                        section.emit_u8(kWasmStructTypeForm);

            
                        section.emit_u32v(type.fields.length);

            
                        for (let field of type.fields) {

            
                          section.emit_type(field.type);

            
                          section.emit_u8(field.mutability ? 1 : 0);

            
                        }

            
                      } else if (type instanceof WasmArray) {

            
                        section.emit_u8(kWasmArrayTypeForm);

            
                        section.emit_type(type.type);

            
                        section.emit_u8(type.mutability ? 1 : 0);

            
                      } else {

            
                        section.emit_u8(kWasmFunctionTypeForm);

            
                        section.emit_u32v(type.params.length);

            
                        for (let param of type.params) {

            
                          section.emit_type(param);

            
                        }

            
                        section.emit_u32v(type.results.length);

            
                        for (let result of type.results) {

            
                          section.emit_type(result);

            
                        }

            
                      }

            
                    }

            
                  });

            
                }


                // Add imports section

            
                if (wasm.imports.length > 0) {

            
                  if (debug) print("emitting imports @ " + binary.length);

            
                  binary.emit_section(kImportSectionCode, section => {

            
                    section.emit_u32v(wasm.imports.length);

            
                    for (let imp of wasm.imports) {

            
                      section.emit_string(imp.module);

            
                      section.emit_string(imp.name || '');

            
                      section.emit_u8(imp.kind);

            
                      if (imp.kind == kExternalFunction) {

            
                        section.emit_u32v(imp.type_index);

            
                      } else if (imp.kind == kExternalGlobal) {

            
                        section.emit_type(imp.type);

            
                        section.emit_u8(imp.mutable);

            
                      } else if (imp.kind == kExternalMemory) {

            
                        var has_max = (typeof imp.maximum) != "undefined";

            
                        var is_shared = (typeof imp.shared) != "undefined";

            
                        if (is_shared) {

            
                          section.emit_u8(has_max ? 3 : 2); // flags

            
                        } else {

            
                          section.emit_u8(has_max ? 1 : 0); // flags

            
                        }

            
                        section.emit_u32v(imp.initial); // initial

            
                        if (has_max) section.emit_u32v(imp.maximum); // maximum

            
                      } else if (imp.kind == kExternalTable) {

            
                        section.emit_type(imp.type);

            
                        var has_max = (typeof imp.maximum) != "undefined";

            
                        section.emit_u8(has_max ? 1 : 0); // flags

            
                        section.emit_u32v(imp.initial); // initial

            
                        if (has_max) section.emit_u32v(imp.maximum); // maximum

            
                      } else if (imp.kind == kExternalTag) {

            
                        section.emit_u32v(kExceptionAttribute);

            
                        section.emit_u32v(imp.type);

            
                      } else {

            
                        throw new Error("unknown/unsupported import kind " + imp.kind);

            
                      }

            
                    }

            
                  });

            
                }


                // Add functions declarations

            
                if (wasm.functions.length > 0) {

            
                  if (debug) print("emitting function decls @ " + binary.length);

            
                  binary.emit_section(kFunctionSectionCode, section => {

            
                    section.emit_u32v(wasm.functions.length);

            
                    for (let func of wasm.functions) {

            
                      section.emit_u32v(func.type_index);

            
                    }

            
                  });

            
                }


                // Add table section

            
                if (wasm.tables.length > 0) {

            
                  if (debug) print ("emitting tables @ " + binary.length);

            
                  binary.emit_section(kTableSectionCode, section => {

            
                    section.emit_u32v(wasm.tables.length);

            
                    for (let table of wasm.tables) {

            
                      if (table.has_init) {

            
                        section.emit_u8(0x40);  // "has initializer"

            
                        section.emit_u8(0x00);  // Reserved byte.

            
                      }

            
                      section.emit_type(table.type);

            
                      section.emit_u8(table.has_max);

            
                      section.emit_u32v(table.initial_size);

            
                      if (table.has_max) section.emit_u32v(table.max_size);

            
                      if (table.has_init) section.emit_init_expr(table.init_expr);

            
                    }

            
                  });

            
                }


                // Add memory section

            
                if (wasm.memory !== undefined) {

            
                  if (debug) print("emitting memory @ " + binary.length);

            
                  binary.emit_section(kMemorySectionCode, section => {

            
                    section.emit_u8(1);  // one memory entry

            
                    const has_max = wasm.memory.max !== undefined;

            
                    const is_shared = wasm.memory.shared !== undefined;

            
                    // Emit flags (bit 0: reszeable max, bit 1: shared memory)

            
                    if (is_shared) {

            
                      section.emit_u8(has_max ? kSharedHasMaximumFlag : 2);

            
                    } else {

            
                      section.emit_u8(has_max ? kHasMaximumFlag : 0);

            
                    }

            
                    section.emit_u32v(wasm.memory.min);

            
                    if (has_max) section.emit_u32v(wasm.memory.max);

            
                  });

            
                }


                // Add global section.

            
                if (wasm.globals.length > 0) {

            
                  if (debug) print ("emitting globals @ " + binary.length);

            
                  binary.emit_section(kGlobalSectionCode, section => {

            
                    section.emit_u32v(wasm.globals.length);

            
                    for (let global of wasm.globals) {

            
                      section.emit_type(global.type);

            
                      section.emit_u8(global.mutable);

            
                      section.emit_init_expr(global.init);

            
                    }

            
                  });

            
                }


                // Add tags.

            
                if (wasm.tags.length > 0) {

            
                  if (debug) print("emitting tags @ " + binary.length);

            
                  binary.emit_section(kTagSectionCode, section => {

            
                    section.emit_u32v(wasm.tags.length);

            
                    for (let type of wasm.tags) {

            
                      section.emit_u32v(kExceptionAttribute);

            
                      section.emit_u32v(type);

            
                    }

            
                  });

            
                }


                // Add export table.

            
                var mem_export = (wasm.memory !== undefined && wasm.memory.exp);

            
                var exports_count = wasm.exports.length + (mem_export ? 1 : 0);

            
                if (exports_count > 0) {

            
                  if (debug) print("emitting exports @ " + binary.length);

            
                  binary.emit_section(kExportSectionCode, section => {

            
                    section.emit_u32v(exports_count);

            
                    for (let exp of wasm.exports) {

            
                      section.emit_string(exp.name);

            
                      section.emit_u8(exp.kind);

            
                      section.emit_u32v(exp.index);

            
                    }

            
                    if (mem_export) {

            
                      section.emit_string("memory");

            
                      section.emit_u8(kExternalMemory);

            
                      section.emit_u8(0);

            
                    }

            
                  });

            
                }


                // Add start function section.

            
                if (wasm.start_index !== undefined) {

            
                  if (debug) print("emitting start function @ " + binary.length);

            
                  binary.emit_section(kStartSectionCode, section => {

            
                    section.emit_u32v(wasm.start_index);

            
                  });

            
                }


                // Add element segments

            
                if (wasm.element_segments.length > 0) {

            
                  if (debug) print("emitting element segments @ " + binary.length);

            
                  binary.emit_section(kElementSectionCode, section => {

            
                    var inits = wasm.element_segments;

            
                    section.emit_u32v(inits.length);


                    for (let init of inits) {

            
                      if (init.is_active) {

            
                        // Active segment.

            
                        if (init.table == 0) {

            
                          section.emit_u32v(kActiveNoIndex);

            
                        } else {

            
                          section.emit_u32v(kActiveWithIndex);

            
                          section.emit_u32v(init.table);

            
                        }

            
                        if (init.is_global) {

            
                          section.emit_u8(kExprGlobalGet);

            
                        } else {

            
                          section.emit_u8(kExprI32Const);

            
                        }

            
                        section.emit_u32v(init.base);

            
                        section.emit_u8(kExprEnd);

            
                        if (init.table != 0) {

            
                          section.emit_u8(kExternalFunction);

            
                        }

            
                        section.emit_u32v(init.array.length);

            
                        for (let index of init.array) {

            
                          section.emit_u32v(index);

            
                        }

            
                      } else {

            
                        // Passive segment.

            
                        section.emit_u8(kPassiveWithElements);  // flags

            
                        section.emit_u8(kWasmAnyFunc);

            
                        section.emit_u32v(init.array.length);

            
                        for (let index of init.array) {

            
                          if (index === null) {

            
                            section.emit_u8(kExprRefNull);

            
                            section.emit_u8(kExprEnd);

            
                          } else {

            
                            section.emit_u8(kExprRefFunc);

            
                            section.emit_u32v(index);

            
                            section.emit_u8(kExprEnd);

            
                          }

            
                        }

            
                      }

            
                    }

            
                  });

            
                }


                // If there are any passive data segments, add the DataCount section.

            
                if (wasm.data_segments.some(seg => !seg.is_active)) {

            
                  binary.emit_section(kDataCountSectionCode, section => {

            
                    section.emit_u32v(wasm.data_segments.length);

            
                  });

            
                }


                // Add function bodies.

            
                if (wasm.functions.length > 0) {

            
                  // emit function bodies

            
                  if (debug) print("emitting code @ " + binary.length);

            
                  binary.emit_section(kCodeSectionCode, section => {

            
                    section.emit_u32v(wasm.functions.length);

            
                    let header = new Binary;

            
                    for (let func of wasm.functions) {

            
                      header.reset();

            
                      // Function body length will be patched later.

            
                      let local_decls = [];

            
                      for (let l of func.locals || []) {

            
                        if (l.i32_count > 0) {

            
                          local_decls.push({count: l.i32_count, type: kWasmI32});

            
                        }

            
                        if (l.i64_count > 0) {

            
                          local_decls.push({count: l.i64_count, type: kWasmI64});

            
                        }

            
                        if (l.f32_count > 0) {

            
                          local_decls.push({count: l.f32_count, type: kWasmF32});

            
                        }

            
                        if (l.f64_count > 0) {

            
                          local_decls.push({count: l.f64_count, type: kWasmF64});

            
                        }

            
                        if (l.s128_count > 0) {

            
                          local_decls.push({count: l.s128_count, type: kWasmS128});

            
                        }

            
                        if (l.anyref_count > 0) {

            
                          local_decls.push({count: l.anyref_count, type: kWasmExternRef});

            
                        }

            
                        if (l.anyfunc_count > 0) {

            
                          local_decls.push({count: l.anyfunc_count, type: kWasmAnyFunc});

            
                        }

            
                      }


                      header.emit_u32v(local_decls.length);

            
                      for (let decl of local_decls) {

            
                        header.emit_u32v(decl.count);

            
                        header.emit_type(decl.type);

            
                      }


                      section.emit_u32v(header.length + func.body.length);

            
                      section.emit_bytes(header.trunc_buffer());

            
                      section.emit_bytes(func.body);

            
                    }

            
                  });

            
                }


                // Add data segments.

            
                if (wasm.data_segments.length > 0) {

            
                  if (debug) print("emitting data segments @ " + binary.length);

            
                  binary.emit_section(kDataSectionCode, section => {

            
                    section.emit_u32v(wasm.data_segments.length);

            
                    for (let seg of wasm.data_segments) {

            
                      if (seg.is_active) {

            
                        section.emit_u8(0);  // linear memory index 0 / flags

            
                        if (seg.is_global) {

            
                          // initializer is a global variable

            
                          section.emit_u8(kExprGlobalGet);

            
                          section.emit_u32v(seg.addr);

            
                        } else {

            
                          // initializer is a constant

            
                          section.emit_u8(kExprI32Const);

            
                          section.emit_u32v(seg.addr);

            
                        }

            
                        section.emit_u8(kExprEnd);

            
                      } else {

            
                        section.emit_u8(kPassive);  // flags

            
                      }

            
                      section.emit_u32v(seg.data.length);

            
                      section.emit_bytes(seg.data);

            
                    }

            
                  });

            
                }


                // Add any explicitly added sections

            
                for (let exp of wasm.explicit) {

            
                  if (debug) print("emitting explicit @ " + binary.length);

            
                  binary.emit_bytes(exp);

            
                }


                // Add names.

            
                let num_function_names = 0;

            
                let num_functions_with_local_names = 0;

            
                for (let func of wasm.functions) {

            
                  if (func.name !== undefined) ++num_function_names;

            
                  if (func.numLocalNames() > 0) ++num_functions_with_local_names;

            
                }

            
                if (num_function_names > 0 || num_functions_with_local_names > 0 ||

            
                    wasm.name !== undefined) {

            
                  if (debug) print('emitting names @ ' + binary.length);

            
                  binary.emit_section(kUnknownSectionCode, section => {

            
                    section.emit_string('name');

            
                    // Emit module name.

            
                    if (wasm.name !== undefined) {

            
                      section.emit_section(kModuleNameCode, name_section => {

            
                        name_section.emit_string(wasm.name);

            
                      });

            
                    }

            
                    // Emit function names.

            
                    if (num_function_names > 0) {

            
                      section.emit_section(kFunctionNamesCode, name_section => {

            
                        name_section.emit_u32v(num_function_names);

            
                        for (let func of wasm.functions) {

            
                          if (func.name === undefined) continue;

            
                          name_section.emit_u32v(func.index);

            
                          name_section.emit_string(func.name);

            
                        }

            
                      });

            
                    }

            
                    // Emit local names.

            
                    if (num_functions_with_local_names > 0) {

            
                      section.emit_section(kLocalNamesCode, name_section => {

            
                        name_section.emit_u32v(num_functions_with_local_names);

            
                        for (let func of wasm.functions) {

            
                          if (func.numLocalNames() == 0) continue;

            
                          name_section.emit_u32v(func.index);

            
                          name_section.emit_u32v(func.numLocalNames());

            
                          for (let i = 0; i < func.local_names.length; ++i) {

            
                            if (func.local_names[i] === undefined) continue;

            
                            name_section.emit_u32v(i);

            
                            name_section.emit_string(func.local_names[i]);

            
                          }

            
                        }

            
                      });

            
                    }

            
                  });

            
                }


                return binary.trunc_buffer();

            
              }


              toArray(debug = false) {

            
                return Array.from(this.toBuffer(debug));

            
              }


              instantiate(ffi) {

            
                let module = this.toModule();

            
                let instance = new WebAssembly.Instance(module, ffi);

            
                return instance;

            
              }


              asyncInstantiate(ffi) {

            
                return WebAssembly.instantiate(this.toBuffer(), ffi)

            
                    .then(({module, instance}) => instance);

            
              }


              toModule(debug = false) {

            
                return new WebAssembly.Module(this.toBuffer(debug));

            
              }

            
            }


            function wasmSignedLeb(val, max_len = 5) {

            
              let res = [];

            
              for (let i = 0; i < max_len; ++i) {

            
                let v = val & 0x7f;

            
                // If {v} sign-extended from 7 to 32 bits is equal to val, we are done.

            
                if (((v << 25) >> 25) == val) {

            
                  res.push(v);

            
                  return res;

            
                }

            
                res.push(v | 0x80);

            
                val = val >> 7;

            
              }

            
              throw new Error(

            
                  'Leb value <' + val + '> exceeds maximum length of ' + max_len);

            
            }


            function wasmI32Const(val) {

            
              return [kExprI32Const, ...wasmSignedLeb(val, 5)];

            
            }


            function wasmF32Const(f) {

            
              // Write in little-endian order at offset 0.

            
              data_view.setFloat32(0, f, true);

            
              return [

            
                kExprF32Const, byte_view[0], byte_view[1], byte_view[2], byte_view[3]

            
              ];

            
            }


            function wasmF64Const(f) {

            
              // Write in little-endian order at offset 0.

            
              data_view.setFloat64(0, f, true);

            
              return [

            
                kExprF64Const, byte_view[0], byte_view[1], byte_view[2],

            
                byte_view[3], byte_view[4], byte_view[5], byte_view[6], byte_view[7]

            
              ];

            
            }