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      1 // Copyright 2012 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 (function(global, utils) {
      6 "use strict";
      7 
      8 %CheckIsBootstrapping();
      9 
     10 // -------------------------------------------------------------------
     11 // Imports
     12 
     13 define kRandomBatchSize = 64;
     14 // The first two slots are reserved to persist PRNG state.
     15 define kRandomNumberStart = 2;
     16 
     17 var GlobalFloat64Array = global.Float64Array;
     18 var GlobalMath = global.Math;
     19 var GlobalObject = global.Object;
     20 var InternalArray = utils.InternalArray;
     21 var NaN = %GetRootNaN();
     22 var nextRandomIndex = kRandomBatchSize;
     23 var randomNumbers = UNDEFINED;
     24 var toStringTagSymbol = utils.ImportNow("to_string_tag_symbol");
     25 
     26 //-------------------------------------------------------------------
     27 
     28 // ECMA 262 - 15.8.2.1
     29 function MathAbs(x) {
     30   x = +x;
     31   return (x > 0) ? x : 0 - x;
     32 }
     33 
     34 // ECMA 262 - 15.8.2.2
     35 function MathAcosJS(x) {
     36   return %_MathAcos(+x);
     37 }
     38 
     39 // ECMA 262 - 15.8.2.3
     40 function MathAsinJS(x) {
     41   return %_MathAsin(+x);
     42 }
     43 
     44 // ECMA 262 - 15.8.2.4
     45 function MathAtanJS(x) {
     46   return %_MathAtan(+x);
     47 }
     48 
     49 // ECMA 262 - 15.8.2.5
     50 // The naming of y and x matches the spec, as does the order in which
     51 // ToNumber (valueOf) is called.
     52 function MathAtan2JS(y, x) {
     53   y = +y;
     54   x = +x;
     55   return %_MathAtan2(y, x);
     56 }
     57 
     58 // ECMA 262 - 15.8.2.6
     59 function MathCeil(x) {
     60   return -%_MathFloor(-x);
     61 }
     62 
     63 // ECMA 262 - 15.8.2.8
     64 function MathExp(x) {
     65   return %MathExpRT(TO_NUMBER(x));
     66 }
     67 
     68 // ECMA 262 - 15.8.2.9
     69 function MathFloorJS(x) {
     70   return %_MathFloor(+x);
     71 }
     72 
     73 // ECMA 262 - 15.8.2.10
     74 function MathLog(x) {
     75   return %_MathLogRT(TO_NUMBER(x));
     76 }
     77 
     78 // ECMA 262 - 15.8.2.11
     79 function MathMax(arg1, arg2) {  // length == 2
     80   var length = %_ArgumentsLength();
     81   if (length == 2) {
     82     arg1 = TO_NUMBER(arg1);
     83     arg2 = TO_NUMBER(arg2);
     84     if (arg2 > arg1) return arg2;
     85     if (arg1 > arg2) return arg1;
     86     if (arg1 == arg2) {
     87       // Make sure -0 is considered less than +0.
     88       return (arg1 === 0 && %_IsMinusZero(arg1)) ? arg2 : arg1;
     89     }
     90     // All comparisons failed, one of the arguments must be NaN.
     91     return NaN;
     92   }
     93   var r = -INFINITY;
     94   for (var i = 0; i < length; i++) {
     95     var n = %_Arguments(i);
     96     n = TO_NUMBER(n);
     97     // Make sure +0 is considered greater than -0.
     98     if (NUMBER_IS_NAN(n) || n > r || (r === 0 && n === 0 && %_IsMinusZero(r))) {
     99       r = n;
    100     }
    101   }
    102   return r;
    103 }
    104 
    105 // ECMA 262 - 15.8.2.12
    106 function MathMin(arg1, arg2) {  // length == 2
    107   var length = %_ArgumentsLength();
    108   if (length == 2) {
    109     arg1 = TO_NUMBER(arg1);
    110     arg2 = TO_NUMBER(arg2);
    111     if (arg2 > arg1) return arg1;
    112     if (arg1 > arg2) return arg2;
    113     if (arg1 == arg2) {
    114       // Make sure -0 is considered less than +0.
    115       return (arg1 === 0 && %_IsMinusZero(arg1)) ? arg1 : arg2;
    116     }
    117     // All comparisons failed, one of the arguments must be NaN.
    118     return NaN;
    119   }
    120   var r = INFINITY;
    121   for (var i = 0; i < length; i++) {
    122     var n = %_Arguments(i);
    123     n = TO_NUMBER(n);
    124     // Make sure -0 is considered less than +0.
    125     if (NUMBER_IS_NAN(n) || n < r || (r === 0 && n === 0 && %_IsMinusZero(n))) {
    126       r = n;
    127     }
    128   }
    129   return r;
    130 }
    131 
    132 // ECMA 262 - 15.8.2.13
    133 function MathPowJS(x, y) {
    134   return %_MathPow(TO_NUMBER(x), TO_NUMBER(y));
    135 }
    136 
    137 // ECMA 262 - 15.8.2.14
    138 function MathRandom() {
    139   if (nextRandomIndex >= kRandomBatchSize) {
    140     randomNumbers = %GenerateRandomNumbers(randomNumbers);
    141     nextRandomIndex = kRandomNumberStart;
    142   }
    143   return randomNumbers[nextRandomIndex++];
    144 }
    145 
    146 function MathRandomRaw() {
    147   if (nextRandomIndex >= kRandomBatchSize) {
    148     randomNumbers = %GenerateRandomNumbers(randomNumbers);
    149     nextRandomIndex = kRandomNumberStart;
    150   }
    151   return %_DoubleLo(randomNumbers[nextRandomIndex++]) & 0x3FFFFFFF;
    152 }
    153 
    154 // ECMA 262 - 15.8.2.15
    155 function MathRound(x) {
    156   return %RoundNumber(TO_NUMBER(x));
    157 }
    158 
    159 // ECMA 262 - 15.8.2.17
    160 function MathSqrtJS(x) {
    161   return %_MathSqrt(+x);
    162 }
    163 
    164 // Non-standard extension.
    165 function MathImul(x, y) {
    166   return %NumberImul(TO_NUMBER(x), TO_NUMBER(y));
    167 }
    168 
    169 // ES6 draft 09-27-13, section 20.2.2.28.
    170 function MathSign(x) {
    171   x = +x;
    172   if (x > 0) return 1;
    173   if (x < 0) return -1;
    174   // -0, 0 or NaN.
    175   return x;
    176 }
    177 
    178 // ES6 draft 09-27-13, section 20.2.2.34.
    179 function MathTrunc(x) {
    180   x = +x;
    181   if (x > 0) return %_MathFloor(x);
    182   if (x < 0) return -%_MathFloor(-x);
    183   // -0, 0 or NaN.
    184   return x;
    185 }
    186 
    187 // ES6 draft 09-27-13, section 20.2.2.5.
    188 function MathAsinh(x) {
    189   x = TO_NUMBER(x);
    190   // Idempotent for NaN, +/-0 and +/-Infinity.
    191   if (x === 0 || !NUMBER_IS_FINITE(x)) return x;
    192   if (x > 0) return MathLog(x + %_MathSqrt(x * x + 1));
    193   // This is to prevent numerical errors caused by large negative x.
    194   return -MathLog(-x + %_MathSqrt(x * x + 1));
    195 }
    196 
    197 // ES6 draft 09-27-13, section 20.2.2.3.
    198 function MathAcosh(x) {
    199   x = TO_NUMBER(x);
    200   if (x < 1) return NaN;
    201   // Idempotent for NaN and +Infinity.
    202   if (!NUMBER_IS_FINITE(x)) return x;
    203   return MathLog(x + %_MathSqrt(x + 1) * %_MathSqrt(x - 1));
    204 }
    205 
    206 // ES6 draft 09-27-13, section 20.2.2.7.
    207 function MathAtanh(x) {
    208   x = TO_NUMBER(x);
    209   // Idempotent for +/-0.
    210   if (x === 0) return x;
    211   // Returns NaN for NaN and +/- Infinity.
    212   if (!NUMBER_IS_FINITE(x)) return NaN;
    213   return 0.5 * MathLog((1 + x) / (1 - x));
    214 }
    215 
    216 // ES6 draft 09-27-13, section 20.2.2.17.
    217 function MathHypot(x, y) {  // Function length is 2.
    218   // We may want to introduce fast paths for two arguments and when
    219   // normalization to avoid overflow is not necessary.  For now, we
    220   // simply assume the general case.
    221   var length = %_ArgumentsLength();
    222   var args = new InternalArray(length);
    223   var max = 0;
    224   for (var i = 0; i < length; i++) {
    225     var n = %_Arguments(i);
    226     n = TO_NUMBER(n);
    227     if (n === INFINITY || n === -INFINITY) return INFINITY;
    228     n = MathAbs(n);
    229     if (n > max) max = n;
    230     args[i] = n;
    231   }
    232 
    233   // Kahan summation to avoid rounding errors.
    234   // Normalize the numbers to the largest one to avoid overflow.
    235   if (max === 0) max = 1;
    236   var sum = 0;
    237   var compensation = 0;
    238   for (var i = 0; i < length; i++) {
    239     var n = args[i] / max;
    240     var summand = n * n - compensation;
    241     var preliminary = sum + summand;
    242     compensation = (preliminary - sum) - summand;
    243     sum = preliminary;
    244   }
    245   return %_MathSqrt(sum) * max;
    246 }
    247 
    248 // ES6 draft 09-27-13, section 20.2.2.16.
    249 function MathFroundJS(x) {
    250   return %MathFround(TO_NUMBER(x));
    251 }
    252 
    253 // ES6 draft 07-18-14, section 20.2.2.11
    254 function MathClz32JS(x) {
    255   return %_MathClz32(x >>> 0);
    256 }
    257 
    258 // ES6 draft 09-27-13, section 20.2.2.9.
    259 // Cube root approximation, refer to: http://metamerist.com/cbrt/cbrt.htm
    260 // Using initial approximation adapted from Kahan's cbrt and 4 iterations
    261 // of Newton's method.
    262 function MathCbrt(x) {
    263   x = TO_NUMBER(x);
    264   if (x == 0 || !NUMBER_IS_FINITE(x)) return x;
    265   return x >= 0 ? CubeRoot(x) : -CubeRoot(-x);
    266 }
    267 
    268 macro NEWTON_ITERATION_CBRT(x, approx)
    269   (1.0 / 3.0) * (x / (approx * approx) + 2 * approx);
    270 endmacro
    271 
    272 function CubeRoot(x) {
    273   var approx_hi = MathFloorJS(%_DoubleHi(x) / 3) + 0x2A9F7893;
    274   var approx = %_ConstructDouble(approx_hi | 0, 0);
    275   approx = NEWTON_ITERATION_CBRT(x, approx);
    276   approx = NEWTON_ITERATION_CBRT(x, approx);
    277   approx = NEWTON_ITERATION_CBRT(x, approx);
    278   return NEWTON_ITERATION_CBRT(x, approx);
    279 }
    280 
    281 // -------------------------------------------------------------------
    282 
    283 %AddNamedProperty(GlobalMath, toStringTagSymbol, "Math", READ_ONLY | DONT_ENUM);
    284 
    285 // Set up math constants.
    286 utils.InstallConstants(GlobalMath, [
    287   // ECMA-262, section 15.8.1.1.
    288   "E", 2.7182818284590452354,
    289   // ECMA-262, section 15.8.1.2.
    290   "LN10", 2.302585092994046,
    291   // ECMA-262, section 15.8.1.3.
    292   "LN2", 0.6931471805599453,
    293   // ECMA-262, section 15.8.1.4.
    294   "LOG2E", 1.4426950408889634,
    295   "LOG10E", 0.4342944819032518,
    296   "PI", 3.1415926535897932,
    297   "SQRT1_2", 0.7071067811865476,
    298   "SQRT2", 1.4142135623730951
    299 ]);
    300 
    301 // Set up non-enumerable functions of the Math object and
    302 // set their names.
    303 utils.InstallFunctions(GlobalMath, DONT_ENUM, [
    304   "random", MathRandom,
    305   "abs", MathAbs,
    306   "acos", MathAcosJS,
    307   "asin", MathAsinJS,
    308   "atan", MathAtanJS,
    309   "ceil", MathCeil,
    310   "exp", MathExp,
    311   "floor", MathFloorJS,
    312   "log", MathLog,
    313   "round", MathRound,
    314   "sqrt", MathSqrtJS,
    315   "atan2", MathAtan2JS,
    316   "pow", MathPowJS,
    317   "max", MathMax,
    318   "min", MathMin,
    319   "imul", MathImul,
    320   "sign", MathSign,
    321   "trunc", MathTrunc,
    322   "asinh", MathAsinh,
    323   "acosh", MathAcosh,
    324   "atanh", MathAtanh,
    325   "hypot", MathHypot,
    326   "fround", MathFroundJS,
    327   "clz32", MathClz32JS,
    328   "cbrt", MathCbrt
    329 ]);
    330 
    331 %SetForceInlineFlag(MathAbs);
    332 %SetForceInlineFlag(MathAcosJS);
    333 %SetForceInlineFlag(MathAsinJS);
    334 %SetForceInlineFlag(MathAtanJS);
    335 %SetForceInlineFlag(MathAtan2JS);
    336 %SetForceInlineFlag(MathCeil);
    337 %SetForceInlineFlag(MathClz32JS);
    338 %SetForceInlineFlag(MathFloorJS);
    339 %SetForceInlineFlag(MathRandom);
    340 %SetForceInlineFlag(MathSign);
    341 %SetForceInlineFlag(MathSqrtJS);
    342 %SetForceInlineFlag(MathTrunc);
    343 
    344 // -------------------------------------------------------------------
    345 // Exports
    346 
    347 utils.Export(function(to) {
    348   to.MathAbs = MathAbs;
    349   to.MathExp = MathExp;
    350   to.MathFloor = MathFloorJS;
    351   to.IntRandom = MathRandomRaw;
    352   to.MathMax = MathMax;
    353   to.MathMin = MathMin;
    354 });
    355 
    356 })
    357