*/
static void seedMT(php_uint32 seed TSRMLS_DC)
{
- /*
- We initialize state[0..(N-1)] via the generator
-
- x_new = (69069 * x_old) mod 2^32
-
- from Line 15 of Table 1, p. 106, Sec. 3.3.4 of Knuth's
- _The Art of Computer Programming_, Volume 2, 3rd ed.
-
- Notes (SJC): I do not know what the initial state requirements
- of the Mersenne Twister are, but it seems this seeding generator
- could be better. It achieves the maximum period for its modulus
- (2^30) iff x_initial is odd (p. 20-21, Sec. 3.2.1.2, Knuth); if
- x_initial can be even, you have sequences like 0, 0, 0, ...;
- 2^31, 2^31, 2^31, ...; 2^30, 2^30, 2^30, ...; 2^29, 2^29 + 2^31,
- 2^29, 2^29 + 2^31, ..., etc. so I force seed to be odd below.
-
- Even if x_initial is odd, if x_initial is 1 mod 4 then
-
- the lowest bit of x is always 1,
- the next-to-lowest bit of x is always 0,
- the 2nd-from-lowest bit of x alternates ... 0 1 0 1 0 1 0 1 ... ,
- the 3rd-from-lowest bit of x 4-cycles ... 0 1 1 0 0 1 1 0 ... ,
- the 4th-from-lowest bit of x has the 8-cycle ... 0 0 0 1 1 1 1 0 ... ,
- ...
-
- and if x_initial is 3 mod 4 then
+ /*
+ We initialize state[0..(N-1)] via the generator
+
+ x_new = (69069 * x_old) mod 2^32
+
+ from Line 15 of Table 1, p. 106, Sec. 3.3.4 of Knuth's
+ _The Art of Computer Programming_, Volume 2, 3rd ed.
+
+ Notes (SJC): I do not know what the initial state requirements
+ of the Mersenne Twister are, but it seems this seeding generator
+ could be better. It achieves the maximum period for its modulus
+ (2^30) iff x_initial is odd (p. 20-21, Sec. 3.2.1.2, Knuth); if
+ x_initial can be even, you have sequences like 0, 0, 0, ...;
+ 2^31, 2^31, 2^31, ...; 2^30, 2^30, 2^30, ...; 2^29, 2^29 + 2^31,
+ 2^29, 2^29 + 2^31, ..., etc. so I force seed to be odd below.
+
+ Even if x_initial is odd, if x_initial is 1 mod 4 then
- the lowest bit of x is always 1,
- the next-to-lowest bit of x is always 1,
- the 2nd-from-lowest bit of x alternates ... 0 1 0 1 0 1 0 1 ... ,
- the 3rd-from-lowest bit of x 4-cycles ... 0 0 1 1 0 0 1 1 ... ,
- the 4th-from-lowest bit of x has the 8-cycle ... 0 0 1 1 1 1 0 0 ... ,
- ...
+ the lowest bit of x is always 1,
+ the next-to-lowest bit of x is always 0,
+ the 2nd-from-lowest bit of x alternates ... 0 1 0 1 0 1 0 1 ... ,
+ the 3rd-from-lowest bit of x 4-cycles ... 0 1 1 0 0 1 1 0 ... ,
+ the 4th-from-lowest bit of x has the 8-cycle ... 0 0 0 1 1 1 1 0 ... ,
+ ...
+
+ and if x_initial is 3 mod 4 then
- The generator's potency (min. s>=0 with (69069-1)^s = 0 mod 2^32) is
- 16, which seems to be alright by p. 25, Sec. 3.2.1.3 of Knuth. It
- also does well in the dimension 2..5 spectral tests, but it could be
- better in dimension 6 (Line 15, Table 1, p. 106, Sec. 3.3.4, Knuth).
+ the lowest bit of x is always 1,
+ the next-to-lowest bit of x is always 1,
+ the 2nd-from-lowest bit of x alternates ... 0 1 0 1 0 1 0 1 ... ,
+ the 3rd-from-lowest bit of x 4-cycles ... 0 0 1 1 0 0 1 1 ... ,
+ the 4th-from-lowest bit of x has the 8-cycle ... 0 0 1 1 1 1 0 0 ... ,
+ ...
+
+ The generator's potency (min. s>=0 with (69069-1)^s = 0 mod 2^32) is
+ 16, which seems to be alright by p. 25, Sec. 3.2.1.3 of Knuth. It
+ also does well in the dimension 2..5 spectral tests, but it could be
+ better in dimension 6 (Line 15, Table 1, p. 106, Sec. 3.3.4, Knuth).
- Note that the random number user does not see the values generated
- here directly since reloadMT() will always munge them first, so maybe
- none of all of this matters. In fact, the seed values made here could
- even be extra-special desirable if the Mersenne Twister theory says
- so-- that's why the only change I made is to restrict to odd seeds.
- */
-
- register php_uint32 x = (seed | 1U) & 0xFFFFFFFFU, *s = BG(state);
- register int j;
-
- for(BG(left)=0, *s++=x, j=N; --j;
- *s++ = (x*=69069U) & 0xFFFFFFFFU);
+ Note that the random number user does not see the values generated
+ here directly since reloadMT() will always munge them first, so maybe
+ none of all of this matters. In fact, the seed values made here could
+ even be extra-special desirable if the Mersenne Twister theory says
+ so-- that's why the only change I made is to restrict to odd seeds.
+ */
+
+ register php_uint32 x = (seed | 1U) & 0xFFFFFFFFU, *s = BG(state);
+ register int j;
+
+ for (BG(left) = 0, *s++ = x, j = N; --j;
+ *s++ = (x *= 69069U) & 0xFFFFFFFFU);
}
/* }}} */
static php_uint32 reloadMT(TSRMLS_D)
{
- register php_uint32 *p0=BG(state), *p2=BG(state)+2, *pM=BG(state)+M, s0, s1;
- register int j;
+ register php_uint32 *p0 = BG(state), *p2 = BG(state) + 2, *pM = BG(state) + M, s0, s1;
+ register int j;
- if(BG(left) < -1)
- seedMT(4357U TSRMLS_CC);
+ if (BG(left) < -1)
+ seedMT(4357U TSRMLS_CC);
- BG(left)=N-1, BG(next)=BG(state)+1;
+ BG(left) = N - 1, BG(next) = BG(state) + 1;
- for(s0=BG(state)[0], s1=BG(state)[1], j=N-M+1; --j; s0=s1, s1=*p2++)
- *p0++ = *pM++ ^ (mixBits(s0, s1) >> 1) ^ (loBit(s1) ? K : 0U);
+ for (s0 = BG(state)[0], s1 = BG(state)[1], j = N - M + 1; --j; s0 = s1, s1 = *p2++)
+ *p0++ = *pM++ ^ (mixBits(s0, s1) >> 1) ^ (loBit(s1) ? K : 0U);
- for(pM=BG(state), j=M; --j; s0=s1, s1=*p2++)
- *p0++ = *pM++ ^ (mixBits(s0, s1) >> 1) ^ (loBit(s1) ? K : 0U);
+ for (pM = BG(state), j = M; --j; s0 = s1, s1 = *p2++)
+ *p0++ = *pM++ ^ (mixBits(s0, s1) >> 1) ^ (loBit(s1) ? K : 0U);
- s1=BG(state)[0], *p0 = *pM ^ (mixBits(s0, s1) >> 1) ^ (loBit(s1) ? K : 0U);
- s1 ^= (s1 >> 11);
- s1 ^= (s1 << 7) & 0x9D2C5680U;
- s1 ^= (s1 << 15) & 0xEFC60000U;
- return(s1 ^ (s1 >> 18));
+ s1 = BG(state)[0], *p0 = *pM ^ (mixBits(s0, s1) >> 1) ^ (loBit(s1) ? K : 0U);
+ s1 ^= (s1 >> 11);
+ s1 ^= (s1 << 7) & 0x9D2C5680U;
+ s1 ^= (s1 << 15) & 0xEFC60000U;
+
+ return s1 ^ (s1 >> 18);
}
static php_uint32 randomMT(TSRMLS_D)
{
- php_uint32 y;
+ php_uint32 y;
+
+ if (--BG(left) < 0)
+ return reloadMT(TSRMLS_C);
- if(--BG(left) < 0)
- return(reloadMT(TSRMLS_C));
+ y = *BG(next)++;
+ y ^= (y >> 11);
+ y ^= (y << 7) & 0x9D2C5680U;
+ y ^= (y << 15) & 0xEFC60000U;
- y = *BG(next)++;
- y ^= (y >> 11);
- y ^= (y << 7) & 0x9D2C5680U;
- y ^= (y << 15) & 0xEFC60000U;
- return(y ^ (y >> 18));
+ return y ^ (y >> 18);
}
/* {{{ proto void srand(int seed)
projects / php / commitdiff