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random.c: optimize int_pair_to_real_inclusive

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* random.c (int_pair_to_real_inclusive): optimize to multiply
  without Bignum.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@54938 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
nobu 2016-05-07 07:22:14 +00:00
parent 091d88ab4b
commit ed5b985650
2 changed files with 19 additions and 32 deletions
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5
ChangeLog
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@ -1,3 +1,8 @@
Sat May 7 16:22:13 2016 Nobuyoshi Nakada <nobu@ruby-lang.org>
* random.c (int_pair_to_real_inclusive): optimize to multiply
without Bignum.
Sat May 7 07:58:02 2016 Nobuyoshi Nakada <nobu@ruby-lang.org>
* process.c (rb_exec_getargs): honor the expected argument types

46
random.c
View file

@ -279,41 +279,23 @@ rb_genrand_real(void)
static double
int_pair_to_real_inclusive(uint32_t a, uint32_t b)
{
VALUE x;
VALUE m;
uint32_t xary[2], mary[2];
double r;
/* (a << 32) | b */
xary[0] = a;
xary[1] = b;
x = rb_integer_unpack(xary, 2, sizeof(uint32_t), 0,
INTEGER_PACK_MSWORD_FIRST|INTEGER_PACK_NATIVE_BYTE_ORDER|
INTEGER_PACK_FORCE_BIGNUM);
/* (1 << 53) | 1 */
mary[0] = 0x00200000;
mary[1] = 0x00000001;
m = rb_integer_unpack(mary, 2, sizeof(uint32_t), 0,
INTEGER_PACK_MSWORD_FIRST|INTEGER_PACK_NATIVE_BYTE_ORDER|
INTEGER_PACK_FORCE_BIGNUM);
x = rb_big_mul(x, m);
if (FIXNUM_P(x)) {
#if CHAR_BIT * SIZEOF_LONG > 64
r = (double)(FIX2ULONG(x) >> 64);
enum {dig = 53};
enum {dig_u = dig-32, dig_r64 = 64-dig, bmask = ~(~0u<<(dig_r64))};
#if defined HAVE_UINT128_T
const uint128_t m = ((uint128_t)1 << dig) | 1;
uint128_t x = ((uint128_t)a << 32) | b;
r = (double)(uint64_t)((x * m) >> 64);
#elif defined HAVE_UINT64_T
uint64_t x = ((uint64_t)a << dig_u) +
(((uint64_t)b + (a >> dig_u)) >> dig_r64);
r = (double)x;
#else
return 0.0;
/* shift then add to get rid of overflow */
b = (b >> dig_r64) + (((a >> dig_u) + (b & bmask)) >> dig_r64);
r = (double)a * (1 << dig_u) + b;
#endif
}
else {
uint32_t uary[4];
rb_integer_pack(x, uary, numberof(uary), sizeof(uint32_t), 0,
INTEGER_PACK_MSWORD_FIRST|INTEGER_PACK_NATIVE_BYTE_ORDER);
/* r = x >> 64 */
r = (double)uary[0] * (0x10000 * (double)0x10000) + (double)uary[1];
}
return ldexp(r, -53);
return ldexp(r, -dig);
}
VALUE rb_cRandom;