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| 1 // Copyright 2014 the V8 project authors. All rights reserved. |
| 2 // Use of this source code is governed by a BSD-style license that can be |
| 3 // found in the LICENSE file. |
| 4 |
| 5 // Flags: --harmony-maths |
| 6 |
| 7 // Monkey-patch Float32Array. |
| 8 Float32Array = function(x) { this[0] = 0; }; |
| 9 |
| 10 assertTrue(isNaN(Math.fround(NaN))); |
| 11 assertTrue(isNaN(Math.fround(function() {}))); |
| 12 assertTrue(isNaN(Math.fround({ toString: function() { return NaN; } }))); |
| 13 assertTrue(isNaN(Math.fround({ valueOf: function() { return "abc"; } }))); |
| 14 assertEquals("Infinity", String(1/Math.fround(0))); |
| 15 assertEquals("-Infinity", String(1/Math.fround(-0))); |
| 16 assertEquals("Infinity", String(Math.fround(Infinity))); |
| 17 assertEquals("-Infinity", String(Math.fround(-Infinity))); |
| 18 |
| 19 assertEquals("Infinity", String(Math.fround(1E200))); |
| 20 assertEquals("-Infinity", String(Math.fround(-1E200))); |
| 21 assertEquals("Infinity", String(1/Math.fround(1E-300))); |
| 22 assertEquals("-Infinity", String(1/Math.fround(-1E-300))); |
| 23 |
| 24 mantissa_23_shift = Math.pow(2, -23); |
| 25 mantissa_29_shift = Math.pow(2, -23-29); |
| 26 |
| 27 // Javascript implementation of IEEE 754 to test double to single conversion. |
| 28 function ieee754float(sign_bit, |
| 29 exponent_bits, |
| 30 mantissa_23_bits, |
| 31 mantissa_29_bits) { |
| 32 this.sign_bit = sign_bit & 1; |
| 33 this.exponent_bits = exponent_bits & ((1 << 11) - 1); |
| 34 this.mantissa_23_bits = mantissa_23_bits & ((1 << 23) - 1); |
| 35 this.mantissa_29_bits = mantissa_29_bits & ((1 << 29) - 1); |
| 36 } |
| 37 |
| 38 ieee754float.prototype.returnSpecial = function() { |
| 39 if (mantissa_23_bits == 0 && mantissa_29_bits == 0) return sign * Infinity; |
| 40 return NaN; |
| 41 } |
| 42 |
| 43 ieee754float.prototype.toDouble = function() { |
| 44 var sign = this.sign_bit ? -1 : 1; |
| 45 var exponent = this.exponent_bits - 1023; |
| 46 if (exponent == -1023) returnSpecial(); |
| 47 var mantissa = 1 + this.mantissa_23_bits * mantissa_23_shift + |
| 48 this.mantissa_29_bits * mantissa_29_shift; |
| 49 return sign * Math.pow(2, exponent) * mantissa; |
| 50 } |
| 51 |
| 52 ieee754float.prototype.toSingle = function() { |
| 53 var sign = this.sign_bit ? -1 : 1; |
| 54 var exponent = this.exponent_bits - 1023; |
| 55 if (exponent == -1023) returnSpecial(); |
| 56 if (exponent > 127) return sign * Infinity; |
| 57 if (exponent < -126) return this.toSingleSubnormal(sign, exponent); |
| 58 var round = this.mantissa_29_bits >> 28; |
| 59 var mantissa = 1 + (this.mantissa_23_bits + round) * mantissa_23_shift; |
| 60 return sign * Math.pow(2, exponent) * mantissa; |
| 61 } |
| 62 |
| 63 ieee754float.prototype.toSingleSubnormal = function(sign, exponent) { |
| 64 var shift = -126 - exponent; |
| 65 if (shift > 24) return sign * 0; |
| 66 var round_mask = 1 << (shift - 1); |
| 67 var mantissa_23_bits = this.mantissa_23_bits + (1 << 23); |
| 68 var round = ((mantissa_23_bits & round_mask) != 0) | 0; |
| 69 if (round) { // Round to even if tied. |
| 70 var tied_mask = round_mask - 1; |
| 71 var result_last_bit_mask = 1 << shift; |
| 72 var tied = this.mantissa_29_bits == 0 && |
| 73 (mantissa_23_bits & tied_mask ) == 0; |
| 74 var result_already_even = (mantissa_23_bits & result_last_bit_mask) == 0; |
| 75 if (tied && result_already_even) round = 0; |
| 76 } |
| 77 mantissa_23_bits >>= shift; |
| 78 var mantissa = (mantissa_23_bits + round) * mantissa_23_shift; |
| 79 return sign * Math.pow(2, -126) * mantissa; |
| 80 } |
| 81 |
| 82 |
| 83 var pi = new ieee754float(0, 0x400, 0x490fda, 0x14442d18); |
| 84 assertEquals(pi.toSingle(), Math.fround(pi.toDouble())); |
| 85 |
| 86 function fuzz_mantissa(sign, exp, m1inc, m2inc) { |
| 87 for (var m1 = 0; m1 < (1 << 23); m1 += m1inc) { |
| 88 for (var m2 = 0; m2 < (1 << 29); m2 += m2inc) { |
| 89 var float = new ieee754float(sign, exp, m1, m2); |
| 90 assertEquals(float.toSingle(), Math.fround(float.toDouble())); |
| 91 } |
| 92 } |
| 93 } |
| 94 |
| 95 for (var sign = 0; sign < 2; sign++) { |
| 96 for (var exp = 1024 - 170; exp < 1024 + 170; exp++) { |
| 97 fuzz_mantissa(sign, exp, 1337 * exp - sign, 127913 * exp - sign); |
| 98 } |
| 99 } |
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