| 1 | //----------------------------------------------------------------------------- |
| 2 | //----------------------------------------------------------------------------- |
| 3 | // Burtle Prng - Modified. 42iterations instead of 20. |
| 4 | // ref: http://burtleburtle.net/bob/rand/smallprng.html |
| 5 | //----------------------------------------------------------------------------- |
| 6 | #include "prng.h" |
| 7 | |
| 8 | #define rot(x,k) (((x)<<(k))|((x)>>(32-(k)))) |
| 9 | uint32_t burtle_get_mod( prng_ctx *x ) { |
| 10 | uint32_t e = x->a - rot(x->b, 21); |
| 11 | x->a = x->b ^ rot(x->c, 19); |
| 12 | x->b = x->c + rot(x->d, 6); |
| 13 | x->c = x->d + e; |
| 14 | x->d = e + x->a; |
| 15 | return x->d; |
| 16 | } |
| 17 | |
| 18 | void burtle_init_mod(prng_ctx *x, uint32_t seed ) { |
| 19 | x->a = 0xf1ea5eed; |
| 20 | x->b = x->c = x->d = seed; |
| 21 | for (uint8_t i=0; i < 42; ++i) { |
| 22 | (void)burtle_get_mod(x); |
| 23 | } |
| 24 | } |
| 25 | |
| 26 | void burtle_init(prng_ctx *x, uint32_t seed ) { |
| 27 | uint32_t i; |
| 28 | x->a = 0xf1ea5eed, x->b = x->c = x->d = seed; |
| 29 | for (i=0; i < 20; ++i) { |
| 30 | (void)burtle_get_mod(x); |
| 31 | } |
| 32 | } |
| 33 | |
| 34 | |
| 35 | uint32_t GetSimplePrng( uint32_t seed ){ |
| 36 | seed *= 0x19660D; |
| 37 | seed += 0x3C6EF35F; |
| 38 | return seed; |
| 39 | } |