| 'use strict'; |
| |
| // NOTE: This could be potentionally used to generate loop-less multiplications |
| function genCombMulTo (alen, blen) { |
| var len = alen + blen - 1; |
| var src = [ |
| 'var a = self.words;', |
| 'var b = num.words;', |
| 'var o = out.words;', |
| 'var c = 0;', |
| 'var lo;', |
| 'var mid;', |
| 'var hi;' |
| ]; |
| for (var i = 0; i < alen; i++) { |
| src.push('var a' + i + ' = a[' + i + '] | 0;'); |
| src.push('var al' + i + ' = a' + i + ' & 0x1fff;'); |
| src.push('var ah' + i + ' = a' + i + ' >>> 13;'); |
| } |
| for (i = 0; i < blen; i++) { |
| src.push('var b' + i + ' = b[' + i + '] | 0;'); |
| src.push('var bl' + i + ' = b' + i + ' & 0x1fff;'); |
| src.push('var bh' + i + ' = b' + i + ' >>> 13;'); |
| } |
| src.push(''); |
| src.push('out.negative = self.negative ^ num.negative;'); |
| src.push('out.length = ' + len + ';'); |
| |
| for (var k = 0; k < len; k++) { |
| var minJ = Math.max(0, k - alen + 1); |
| var maxJ = Math.min(k, blen - 1); |
| |
| src.push('\/* k = ' + k + ' *\/'); |
| src.push('var w' + k + ' = c;'); |
| src.push('c = 0;'); |
| for (var j = minJ; j <= maxJ; j++) { |
| i = k - j; |
| |
| src.push('lo = Math.imul(al' + i + ', bl' + j + ');'); |
| src.push('mid = Math.imul(al' + i + ', bh' + j + ');'); |
| src.push('mid = (mid + Math.imul(ah' + i + ', bl' + j + ')) | 0;'); |
| src.push('hi = Math.imul(ah' + i + ', bh' + j + ');'); |
| |
| src.push('w' + k + ' = (w' + k + ' + lo) | 0;'); |
| src.push('w' + k + ' = (w' + k + ' + ((mid & 0x1fff) << 13)) | 0;'); |
| src.push('c = (c + hi) | 0;'); |
| src.push('c = (c + (mid >>> 13)) | 0;'); |
| src.push('c = (c + (w' + k + ' >>> 26)) | 0;'); |
| src.push('w' + k + ' &= 0x3ffffff;'); |
| } |
| } |
| // Store in separate step for better memory access |
| for (k = 0; k < len; k++) { |
| src.push('o[' + k + '] = w' + k + ';'); |
| } |
| src.push('if (c !== 0) {', |
| ' o[' + k + '] = c;', |
| ' out.length++;', |
| '}', |
| 'return out;'); |
| |
| return src.join('\n'); |
| } |
| |
| console.log(genCombMulTo(10, 10)); |
