| 'use strict'; |
| |
| var $pow = require('math-intrinsics/pow'); |
| |
| module.exports = function bytesAsFloat32(rawBytes) { |
| // return new $Float32Array(new $Uint8Array(rawBytes).buffer)[0]; |
| |
| /* |
| Let value be the byte elements of rawBytes concatenated and interpreted as a little-endian bit string encoding of an IEEE 754-2008 binary32 value. |
| If value is an IEEE 754-2008 binary32 NaN value, return the NaN Number value. |
| Return the Number value that corresponds to value. |
| */ |
| var sign = rawBytes[3] & 0x80 ? -1 : 1; // Check the sign bit |
| var exponent = ((rawBytes[3] & 0x7F) << 1) |
| | (rawBytes[2] >> 7); // Combine bits for exponent |
| var mantissa = ((rawBytes[2] & 0x7F) << 16) |
| | (rawBytes[1] << 8) |
| | rawBytes[0]; // Combine bits for mantissa |
| |
| if (exponent === 0 && mantissa === 0) { |
| return sign === 1 ? 0 : -0; |
| } |
| if (exponent === 0xFF && mantissa === 0) { |
| return sign === 1 ? Infinity : -Infinity; |
| } |
| if (exponent === 0xFF && mantissa !== 0) { |
| return NaN; |
| } |
| |
| exponent -= 127; // subtract the bias |
| |
| if (exponent === -127) { |
| return sign * mantissa * $pow(2, -126 - 23); |
| } |
| return sign * (1 + (mantissa * $pow(2, -23))) * $pow(2, exponent); |
| }; |