| // picoChip ASM file |
| // |
| // Support for 16-bit unsigned division/modulus. |
| // |
| // Copyright (C) 2003-2014 Free Software Foundation, Inc. |
| // Contributed by Picochip Ltd. |
| // Maintained by Daniel Towner (daniel.towner@picochip.com) |
| // |
| // This file is free software; you can redistribute it and/or modify it |
| // under the terms of the GNU General Public License as published by the |
| // Free Software Foundation; either version 3, or (at your option) any |
| // later version. |
| // |
| // This file is distributed in the hope that it will be useful, but |
| // WITHOUT ANY WARRANTY; without even the implied warranty of |
| // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| // General Public License for more details. |
| // |
| // Under Section 7 of GPL version 3, you are granted additional |
| // permissions described in the GCC Runtime Library Exception, version |
| // 3.1, as published by the Free Software Foundation. |
| // |
| // You should have received a copy of the GNU General Public License and |
| // a copy of the GCC Runtime Library Exception along with this program; |
| // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see |
| // <http://www.gnu.org/licenses/>. |
| |
| .section .text |
| |
| .global __udivmodhi4 |
| __udivmodhi4: |
| _picoMark_FUNCTION_BEGIN= |
| |
| // picoChip Function Prologue : &__udivmodhi4 = 6 bytes |
| |
| // 16-bit unsigned division. The divstep function is only capable of |
| // handling 15-bit division (plus a sign to give 16-bits). It is not |
| // capable of handling unsigned division directly. Instead, take |
| // advantage of the special property that |
| // ((divisor / 2) / dividend) * 2 will be almost good enough. The |
| // error in the result is only 0 or 1, and this can be easily |
| // tested and corrected. A full description of the algorithm can |
| // be found in `Hacker's Delight', by Henry Warren, page 146. |
| |
| // Input: |
| // r0 - dividend |
| // r1 - divisor |
| // Output: |
| // r0 - quotient |
| // r1 - remainder |
| |
| // Note that the lr, and original inputs are speculatively saved. They |
| // will only be restored if the 15-bit division function is called. |
| |
| sub.0 r1,0,r15 \ stl r[0:1],(fp)-1 |
| bge divisorIs15bit |
| =-> sub.0 r0,r1,r2 \ stw lr,(fp)-3 |
| |
| // The divisor is >= 2^15. |
| bhs quotientIs1 |
| |
| // The dividend < divisor. The quotient is thus 0, and the |
| // remainder is the dividend. |
| copy.0 r0,r1 \ jr (lr) |
| =-> copy.0 0,r0 |
| |
| quotientIs1: |
| // The dividend >= divisor. The quotient is thus 1, and the |
| // remainder can be computed directly by subtraction (i.e., the |
| // result of the comparison already performed to branch here). |
| jr (lr) \ copy.0 r2,r1 |
| =-> copy.0 1,r0 |
| |
| divisorIs15bit: |
| // The divisor is < 2^15. |
| |
| // Divide the original dividend by 2, and call the 15-bit division. |
| // Note that the original dividend is stored in r5, which is |
| // known to be unused by the called function, so that |
| // a memory stall isn't introduced immediately after the |
| // function returns, to reload this value from memory. |
| |
| jl (&__divmod15) \ copy.0 r0,r5 // fn_call &__divmod15 |
| =-> lsr.0 r0,1,r0 |
| |
| // Compute the new quotient and remainder by multiplying them by 2. |
| // The remainder will be 1 out, if the original dividend was odd. |
| and.0 r5,1,r5 \ ldl (fp)-1,r[2:3] |
| add.0 [lsl r1,1],r5,r1 \ lsl.1 r0,1,r0 |
| |
| // The error in the quotient is 0 or 1. The error can be determined |
| // by comparing the remainder to the original divisor. If the |
| // remainder is bigger, then an error of 1 has been introduced. |
| sub.0 r1,r3,r15 \ ldw (fp)-3,lr |
| blo noCompensation |
| =-> nop |
| add.0 r0,1,r0 \ sub.1 r1,r3,r1 |
| noCompensation: |
| jr (lr) |
| |
| _picoMark_FUNCTION_END= |
| // picoChip Function Epilogue : udivmodhi4 |
| |
| |
| //============================================================================ |
| // All DWARF information between this marker, and the END OF DWARF |
| // marker should be included in the source file. Search for |
| // FUNCTION_STACK_SIZE_GOES_HERE and FUNCTION NAME GOES HERE, and |
| // provide the relevant information. Add markers called |
| // _picoMark_FUNCTION_BEGIN and _picoMark_FUNCTION_END around the |
| // function in question. |
| //============================================================================ |
| |
| //============================================================================ |
| // Frame information. |
| //============================================================================ |
| |
| .section .debug_frame |
| _picoMark_DebugFrame= |
| |
| // Common CIE header. |
| .unalignedInitLong _picoMark_CieEnd-_picoMark_CieBegin |
| _picoMark_CieBegin= |
| .unalignedInitLong 0xffffffff |
| .initByte 0x1 // CIE Version |
| .ascii 16#0# // CIE Augmentation |
| .uleb128 0x1 // CIE Code Alignment Factor |
| .sleb128 2 // CIE Data Alignment Factor |
| .initByte 0xc // CIE RA Column |
| .initByte 0xc // DW_CFA_def_cfa |
| .uleb128 0xd |
| .uleb128 0x0 |
| .align 2 |
| _picoMark_CieEnd= |
| |
| // FDE |
| _picoMark_LSFDE0I900821033007563= |
| .unalignedInitLong _picoMark_FdeEnd-_picoMark_FdeBegin |
| _picoMark_FdeBegin= |
| .unalignedInitLong _picoMark_DebugFrame // FDE CIE offset |
| .unalignedInitWord _picoMark_FUNCTION_BEGIN // FDE initial location |
| .unalignedInitWord _picoMark_FUNCTION_END-_picoMark_FUNCTION_BEGIN |
| .initByte 0xe // DW_CFA_def_cfa_offset |
| .uleb128 0x6 // <-- FUNCTION_STACK_SIZE_GOES_HERE |
| .initByte 0x4 // DW_CFA_advance_loc4 |
| .unalignedInitLong _picoMark_FUNCTION_END-_picoMark_FUNCTION_BEGIN |
| .initByte 0xe // DW_CFA_def_cfa_offset |
| .uleb128 0x0 |
| .align 2 |
| _picoMark_FdeEnd= |
| |
| //============================================================================ |
| // Abbrevation information. |
| //============================================================================ |
| |
| .section .debug_abbrev |
| _picoMark_ABBREVIATIONS= |
| |
| .section .debug_abbrev |
| .uleb128 0x1 // (abbrev code) |
| .uleb128 0x11 // (TAG: DW_TAG_compile_unit) |
| .initByte 0x1 // DW_children_yes |
| .uleb128 0x10 // (DW_AT_stmt_list) |
| .uleb128 0x6 // (DW_FORM_data4) |
| .uleb128 0x12 // (DW_AT_high_pc) |
| .uleb128 0x1 // (DW_FORM_addr) |
| .uleb128 0x11 // (DW_AT_low_pc) |
| .uleb128 0x1 // (DW_FORM_addr) |
| .uleb128 0x25 // (DW_AT_producer) |
| .uleb128 0x8 // (DW_FORM_string) |
| .uleb128 0x13 // (DW_AT_language) |
| .uleb128 0x5 // (DW_FORM_data2) |
| .uleb128 0x3 // (DW_AT_name) |
| .uleb128 0x8 // (DW_FORM_string) |
| .initByte 0x0 |
| .initByte 0x0 |
| |
| .uleb128 0x2 ;# (abbrev code) |
| .uleb128 0x2e ;# (TAG: DW_TAG_subprogram) |
| .initByte 0x0 ;# DW_children_no |
| .uleb128 0x3 ;# (DW_AT_name) |
| .uleb128 0x8 ;# (DW_FORM_string) |
| .uleb128 0x11 ;# (DW_AT_low_pc) |
| .uleb128 0x1 ;# (DW_FORM_addr) |
| .uleb128 0x12 ;# (DW_AT_high_pc) |
| .uleb128 0x1 ;# (DW_FORM_addr) |
| .initByte 0x0 |
| .initByte 0x0 |
| |
| .initByte 0x0 |
| |
| //============================================================================ |
| // Line information. DwarfLib requires this to be present, but it can |
| // be empty. |
| //============================================================================ |
| |
| .section .debug_line |
| _picoMark_LINES= |
| |
| //============================================================================ |
| // Debug Information |
| //============================================================================ |
| .section .debug_info |
| |
| //Fixed header. |
| .unalignedInitLong _picoMark_DEBUG_INFO_END-_picoMark_DEBUG_INFO_BEGIN |
| _picoMark_DEBUG_INFO_BEGIN= |
| .unalignedInitWord 0x2 |
| .unalignedInitLong _picoMark_ABBREVIATIONS |
| .initByte 0x2 |
| |
| // Compile unit information. |
| .uleb128 0x1 // (DIE 0xb) DW_TAG_compile_unit) |
| .unalignedInitLong _picoMark_LINES |
| .unalignedInitWord _picoMark_FUNCTION_END |
| .unalignedInitWord _picoMark_FUNCTION_BEGIN |
| // Producer is `picoChip' |
| .ascii 16#70# 16#69# 16#63# 16#6f# 16#43# 16#68# 16#69# 16#70# 16#00# |
| .unalignedInitWord 0xcafe // ASM language |
| .ascii 16#0# // Name. DwarfLib expects this to be present. |
| |
| .uleb128 0x2 ;# (DIE DW_TAG_subprogram) |
| |
| // FUNCTION NAME GOES HERE. Use `echo name | od -t x1' to get the hex. Each hex |
| // digit is specified using the format 16#XX# |
| .ascii 16#5f# 16#75# 16#64# 16#69# 16#76# 16#6d# 16#6f# 16#64# 16#68# 16#69# 16#34# 16#0# // Function name `_udivmodhi4' |
| .unalignedInitWord _picoMark_FUNCTION_BEGIN // DW_AT_low_pc |
| .unalignedInitWord _picoMark_FUNCTION_END // DW_AT_high_pc |
| |
| .initByte 0x0 // end of compile unit children. |
| |
| _picoMark_DEBUG_INFO_END= |
| |
| //============================================================================ |
| // END OF DWARF |
| //============================================================================ |
| .section .endFile |
| // End of picoChip ASM file |
