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1
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'use strict';
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2
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3
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// NOTE: This could be potentionally used to generate loop-less multiplications
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4
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function genCombMulTo (alen, blen) {
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5
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var len = alen + blen - 1;
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6
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var src = [
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7
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'var a = self.words;',
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8
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'var b = num.words;',
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9
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'var o = out.words;',
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10
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'var c = 0;',
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11
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'var lo;',
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12
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'var mid;',
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13
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'var hi;'
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14
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];
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15
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for (var i = 0; i < alen; i++) {
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16
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src.push('var a' + i + ' = a[' + i + '] | 0;');
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17
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src.push('var al' + i + ' = a' + i + ' & 0x1fff;');
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18
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src.push('var ah' + i + ' = a' + i + ' >>> 13;');
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19
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}
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20
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for (i = 0; i < blen; i++) {
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21
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src.push('var b' + i + ' = b[' + i + '] | 0;');
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22
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src.push('var bl' + i + ' = b' + i + ' & 0x1fff;');
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23
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src.push('var bh' + i + ' = b' + i + ' >>> 13;');
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24
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}
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25
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src.push('');
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26
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src.push('out.negative = self.negative ^ num.negative;');
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27
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src.push('out.length = ' + len + ';');
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28
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29
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for (var k = 0; k < len; k++) {
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30
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var minJ = Math.max(0, k - alen + 1);
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31
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var maxJ = Math.min(k, blen - 1);
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32
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33
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src.push('\/* k = ' + k + ' *\/');
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34
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src.push('var w' + k + ' = c;');
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35
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src.push('c = 0;');
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36
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for (var j = minJ; j <= maxJ; j++) {
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37
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i = k - j;
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38
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39
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src.push('lo = Math.imul(al' + i + ', bl' + j + ');');
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40
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src.push('mid = Math.imul(al' + i + ', bh' + j + ');');
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41
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src.push('mid = (mid + Math.imul(ah' + i + ', bl' + j + ')) | 0;');
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42
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src.push('hi = Math.imul(ah' + i + ', bh' + j + ');');
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43
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44
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src.push('w' + k + ' = (w' + k + ' + lo) | 0;');
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45
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src.push('w' + k + ' = (w' + k + ' + ((mid & 0x1fff) << 13)) | 0;');
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46
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src.push('c = (c + hi) | 0;');
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47
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src.push('c = (c + (mid >>> 13)) | 0;');
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48
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src.push('c = (c + (w' + k + ' >>> 26)) | 0;');
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49
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src.push('w' + k + ' &= 0x3ffffff;');
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50
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}
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51
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}
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52
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// Store in separate step for better memory access
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53
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for (k = 0; k < len; k++) {
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54
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src.push('o[' + k + '] = w' + k + ';');
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55
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}
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56
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src.push('if (c !== 0) {',
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57
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' o[' + k + '] = c;',
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58
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' out.length++;',
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59
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'}',
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60
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'return out;');
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61
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62
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return src.join('\n');
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63
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}
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64
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65
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console.log(genCombMulTo(10, 10));
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