The Tor Browser / file comparison
comparison: js/src/tests/ecma_6/Math/fround.js
js/src/tests/ecma_6/Math/fround.js
- branch
- TOR_BUG_3246
- changeset 7
- 129ffea94266
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| -1:000000000000 | 0:9bdce46c716b |
|---|---|
| 1 /* | |
| 2 * Any copyright is dedicated to the Public Domain. | |
| 3 * http://creativecommons.org/licenses/publicdomain/ | |
| 4 */ | |
| 5 | |
| 6 // Some tests regarding conversion to Float32 | |
| 7 assertEq(Math.fround(), NaN); | |
| 8 | |
| 9 // Special values | |
| 10 assertEq(Math.fround(NaN), NaN); | |
| 11 assertEq(Math.fround(-Infinity), -Infinity); | |
| 12 assertEq(Math.fround(Infinity), Infinity); | |
| 13 assertEq(Math.fround(-0), -0); | |
| 14 assertEq(Math.fround(+0), +0); | |
| 15 | |
| 16 // Polyfill function for Float32 conversion | |
| 17 var toFloat32 = (function() { | |
| 18 var f32 = new Float32Array(1); | |
| 19 function f(x) { | |
| 20 f32[0] = x; | |
| 21 return f32[0]; | |
| 22 } | |
| 23 return f; | |
| 24 })(); | |
| 25 | |
| 26 // A test on a certain range of numbers, including big numbers, so that | |
| 27 // we get a loss in precision for some of them. | |
| 28 for (var i = 0; i < 64; ++i) { | |
| 29 var p = Math.pow(2, i) + 1; | |
| 30 assertEq(Math.fround(p), toFloat32(p)); | |
| 31 assertEq(Math.fround(-p), toFloat32(-p)); | |
| 32 } | |
| 33 | |
| 34 /******************************************** | |
| 35 /* Tests on maximal Float32 / Double values * | |
| 36 /*******************************************/ | |
| 37 function maxValue(exponentWidth, significandWidth) { | |
| 38 var n = 0; | |
| 39 var maxExp = Math.pow(2, exponentWidth - 1) - 1; | |
| 40 for (var i = significandWidth; i >= 0; i--) | |
| 41 n += Math.pow(2, maxExp - i); | |
| 42 return n; | |
| 43 } | |
| 44 | |
| 45 var DBL_MAX = maxValue(11, 52); | |
| 46 assertEq(DBL_MAX, Number.MAX_VALUE); // sanity check | |
| 47 | |
| 48 // Finite as a double, too big for a float | |
| 49 assertEq(Math.fround(DBL_MAX), Infinity); | |
| 50 | |
| 51 var FLT_MAX = maxValue(8, 23); | |
| 52 assertEq(Math.fround(FLT_MAX), FLT_MAX); | |
| 53 assertEq(Math.fround(FLT_MAX + Math.pow(2, Math.pow(2, 8 - 1) - 1 - 23 - 2)), FLT_MAX); // round-nearest rounds down to FLT_MAX | |
| 54 assertEq(Math.fround(FLT_MAX + Math.pow(2, Math.pow(2, 8 - 1) - 1 - 23 - 1)), Infinity); // no longer rounds down to FLT_MAX | |
| 55 | |
| 56 /********************************************************* | |
| 57 /******* Tests on denormalizations and roundings ********* | |
| 58 /********************************************************/ | |
| 59 | |
| 60 function minValue(exponentWidth, significandWidth) { | |
| 61 return Math.pow(2, -(Math.pow(2, exponentWidth - 1) - 2) - significandWidth); | |
| 62 } | |
| 63 | |
| 64 var DBL_MIN = Math.pow(2, -1074); | |
| 65 assertEq(DBL_MIN, Number.MIN_VALUE); // sanity check | |
| 66 | |
| 67 // Too small for a float | |
| 68 assertEq(Math.fround(DBL_MIN), 0); | |
| 69 | |
| 70 var FLT_MIN = minValue(8, 23); | |
| 71 assertEq(Math.fround(FLT_MIN), FLT_MIN); | |
| 72 | |
| 73 assertEq(Math.fround(FLT_MIN / 2), 0); // halfway, round-nearest rounds down to 0 (even) | |
| 74 assertEq(Math.fround(FLT_MIN / 2 + Math.pow(2, -202)), FLT_MIN); // first double > FLT_MIN / 2, rounds up to FLT_MIN | |
| 75 | |
| 76 assertEq(Math.fround(-FLT_MIN), -FLT_MIN); | |
| 77 | |
| 78 assertEq(Math.fround(-FLT_MIN / 2), -0); // halfway, round-nearest rounds up to -0 (even) | |
| 79 assertEq(Math.fround(-FLT_MIN / 2 - Math.pow(2, -202)), -FLT_MIN); // first double < -FLT_MIN / 2, rounds down to -FLT_MIN | |
| 80 | |
| 81 reportCompare(0, 0, "ok"); |
