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      1 // Copyright 2009 the V8 project authors. All rights reserved.
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      3 // modification, are permitted provided that the following conditions are
      4 // met:
      5 //
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     26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     27 
     28 // Test fast div and mod.
     29 
     30 function divmod(div_func, mod_func, x, y) {
     31   var div_answer = (div_func)(x);
     32   assertEquals(x / y, div_answer, x + "/" + y);
     33   var mod_answer = (mod_func)(x);
     34   assertEquals(x % y, mod_answer, x + "%" + y);
     35   var minus_div_answer = (div_func)(-x);
     36   assertEquals(-x / y, minus_div_answer, "-" + x + "/" + y);
     37   var minus_mod_answer = (mod_func)(-x);
     38   assertEquals(-x % y, minus_mod_answer, "-" + x + "%" + y);
     39 }
     40 
     41 
     42 function run_tests_for(divisor) {
     43   print("(function(left) { return left / " + divisor + "; })");
     44   var div_func = this.eval("(function(left) { return left / " + divisor + "; })");
     45   var mod_func = this.eval("(function(left) { return left % " + divisor + "; })");
     46   var exp;
     47   // Strange number test.
     48   divmod(div_func, mod_func, 0, divisor);
     49   divmod(div_func, mod_func, 1 / 0, divisor);
     50   // Floating point number test.
     51   for (exp = -1024; exp <= 1024; exp += 8) {
     52     divmod(div_func, mod_func, Math.pow(2, exp), divisor);
     53     divmod(div_func, mod_func, 0.9999999 * Math.pow(2, exp), divisor);
     54     divmod(div_func, mod_func, 1.0000001 * Math.pow(2, exp), divisor);
     55   }
     56   // Integer number test.
     57   for (exp = 0; exp <= 32; exp++) {
     58     divmod(div_func, mod_func, 1 << exp, divisor);
     59     divmod(div_func, mod_func, (1 << exp) + 1, divisor);
     60     divmod(div_func, mod_func, (1 << exp) - 1, divisor);
     61   }
     62   divmod(div_func, mod_func, Math.floor(0x1fffffff / 3), divisor);
     63   divmod(div_func, mod_func, Math.floor(-0x20000000 / 3), divisor);
     64 }
     65 
     66 
     67 var divisors = [
     68   0,
     69   1,
     70   2,
     71   3,
     72   4,
     73   5,
     74   6,
     75   7,
     76   8,
     77   9,
     78   10,
     79   0x1000000,
     80   0x40000000,
     81   12,
     82   60,
     83   100,
     84   1000 * 60 * 60 * 24];
     85 
     86 for (var i = 0; i < divisors.length; i++) {
     87   run_tests_for(divisors[i]);
     88 }
     89 
     90 // Test extreme corner cases of modulo.
     91 
     92 // Computes the modulo by slow but lossless operations.
     93 function compute_mod(dividend, divisor) {
     94   // Return NaN if either operand is NaN, if divisor is 0 or
     95   // dividend is an infinity. Return dividend if divisor is an infinity.
     96   if (isNaN(dividend) || isNaN(divisor) || divisor == 0) { return NaN; }
     97   var sign = 1;
     98   if (dividend < 0) { dividend = -dividend; sign = -1; }
     99   if (dividend == Infinity) { return NaN; }
    100   if (divisor < 0) { divisor = -divisor; }
    101   if (divisor == Infinity) { return sign * dividend; }
    102   function rec_mod(a, b) {
    103     // Subtracts maximal possible multiplum of b from a.
    104     if (a >= b) {
    105       a = rec_mod(a, 2 * b);
    106       if (a >= b) { a -= b; }
    107     }
    108     return a;
    109   }
    110   return sign * rec_mod(dividend, divisor);
    111 }
    112 
    113 (function () {
    114   var large_non_smi = 1234567891234.12245;
    115   var small_non_smi = 43.2367243;
    116   var repeating_decimal = 0.3;
    117   var finite_decimal = 0.5;
    118   var smi = 43;
    119   var power_of_two = 64;
    120   var min_normal = Number.MIN_VALUE * Math.pow(2, 52);
    121   var max_denormal = Number.MIN_VALUE * (Math.pow(2, 52) - 1);
    122 
    123   // All combinations of NaN, Infinity, normal, denormal and zero.
    124   var example_numbers = [
    125     NaN,
    126     0,
    127     Number.MIN_VALUE,
    128     3 * Number.MIN_VALUE,
    129     max_denormal,
    130     min_normal,
    131     repeating_decimal,
    132     finite_decimal,
    133     smi,
    134     power_of_two,
    135     small_non_smi,
    136     large_non_smi,
    137     Number.MAX_VALUE,
    138     Infinity
    139   ];
    140 
    141   function doTest(a, b) {
    142     var exp = compute_mod(a, b);
    143     var act = a % b;
    144     assertEquals(exp, act, a + " % " + b);
    145   }
    146 
    147   for (var i = 0; i < example_numbers.length; i++) {
    148     for (var j = 0; j < example_numbers.length; j++) {
    149       var a = example_numbers[i];
    150       var b = example_numbers[j];
    151       doTest(a,b);
    152       doTest(-a,b);
    153       doTest(a,-b);
    154       doTest(-a,-b);
    155     }
    156   }
    157 })();
    158 
    159 
    160 (function () {
    161   // Edge cases
    162   var zero = 0;
    163   var minsmi32 = -0x40000000;
    164   var minsmi64 = -0x80000000;
    165   var somenum = 3532;
    166   assertEquals(-0, zero / -1, "0 / -1");
    167   assertEquals(1, minsmi32 / -0x40000000, "minsmi/minsmi-32");
    168   assertEquals(1, minsmi64 / -0x80000000, "minsmi/minsmi-64");
    169   assertEquals(somenum, somenum % -0x40000000, "%minsmi-32");
    170   assertEquals(somenum, somenum % -0x80000000, "%minsmi-64");
    171 })();
    172 
    173 
    174 // Side-effect-free expressions containing bit operations use
    175 // an optimized compiler with int32 values.   Ensure that modulus
    176 // produces negative zeros correctly.
    177 function negative_zero_modulus_test() {
    178   var x = 4;
    179   var y = -4;
    180   x = x + x - x;
    181   y = y + y - y;
    182   var z = (y | y | y | y) % x;
    183   assertEquals(-1 / 0, 1 / z);
    184   z = (x | x | x | x) % x;
    185   assertEquals(1 / 0, 1 / z);
    186   z = (y | y | y | y) % y;
    187   assertEquals(-1 / 0, 1 / z);
    188   z = (x | x | x | x) % y;
    189   assertEquals(1 / 0, 1 / z);
    190 }
    191 
    192 negative_zero_modulus_test();
    193