ref: e6624da5efc4a98942a3620dae59c0610331a812
dir: /libstd/rand.myr/
use "die.use" use "types.use" use "alloc.use" /* Translated from C by Ori Bernstein */ /* A C-program for MT19937, with initialization improved 2002/1/26. Coded by Takuji Nishimura and Makoto Matsumoto. Copyright (C) 1997 - 2002, Makoto Matsumoto and Takuji Nishimura, All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. 3. The names of its contributors may not be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. Any feedback is very welcome. http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html email: m-mat @ math.sci.hiroshima-u.ac.jp (remove space) */ pkg std = type rng const mksrng : (seed : uint32 -> rng#) const delrng : (rng : rng# -> void) generic rand : (rng : rng#, lo : @a::(numeric,integral), hi : @a::(numeric,integral) -> @a::(numeric,integral)) generic randN : (rng : rng# -> @a::(numeric,integral)) const randbytes : (rng : rng#, buf : byte[:] -> size) const rand32 : (rng : rng# -> uint32) ;; type rng = struct state : uint32[624] i : uint32 ;; /* allocates and initializes a random number generator */ const mksrng = {seed var rng rng = alloc() init(rng, seed) -> rng } const delrng = {rng free(rng) } /* initializes a random number generator from the seed `seed`. */ const init = {rng, seed var i for i = 0; i < 624; i++ rng.state[i] = seed seed = 1812433253 * (seed ^ (seed >> 30)) + i + 1 ;; rng.i = i } /* Generates a random integer from `rng` in the range [lo, hi), returning the value. The range [lo, hi) must be positive, nonempty, and the difference between hi and lo must be less then 2^(type_bits - 1) */ generic rand = {rng, lo, hi -> @a::(integral,numeric) var span, lim var maxrand var val assert(hi - lo > 0, "rand.myr: range for random values must be >= 1") span = hi - lo maxrand = (1 << (8*sizeof(@a))) - 1 /* max for signed value */ if maxrand < 0 /* signed */ maxrand = (1 << (8*sizeof(@a)-1)) - 1 /* max for signed value */ ;; lim = (maxrand/span)*span val = (randN(rng) & maxrand) while val > lim val = (randN(rng) & maxrand) ;; -> val % span + lo } /* Generates a random integer of any size from the random number generator `rng`. The returned value may be negative, if the type is signed. */ generic randN = {rng -> @a::(integral,numeric) var i, val val = 0 for i = 0; i < sizeof(@a)/4; i++ val <<= 8*sizeof(@a) val |= rand32(rng) castto(@a::(integral,numeric)) ;; -> val } /* generates a 32 bit unsigned random number from the random number generator `rng`. */ const rand32 = {rng var x if rng.i == 624 next(rng) ;; x = rng.state[rng.i] rng.i++ x ^= x >> 11 x ^= (x << 7) & 0x9D2C5680 x ^= (x << 15) & 0xEFC60000 -> x ^ (x >> 18) } const randbytes = {rng, buf var i, n, r n = 0 for i = 0; i < buf.len/4; i++ r = rand32(rng) buf[n++] = (r >> 0 & 0xff) castto(byte) buf[n++] = (r >> 8 & 0xff) castto(byte) buf[n++] = (r >> 16 & 0xff) castto(byte) buf[n++] = (r >> 32 & 0xff) castto(byte) ;; r = rand32(rng) for ; n != buf.len; n++ buf[n++] = (r & 0xff) castto(byte) r >>= 8 ;; -> n } /* updates random number generator state when we tick over. */ const next = {rng var k var y for k = 0; k < 227; k++ y = (rng.state[k] & 0x80000000) | (rng.state[k + 1] & 0x7FFFFFFF) rng.state[k] = rng.state[k + 397] ^ (y >> 1) ^ ((y & 1) * 0x9908B0DF) ;; for ; k < 623; k++ y = (rng.state[k] & 0x80000000) | (rng.state[k + 1] & 0x7FFFFFFF) rng.state[k] = rng.state[k - 227] ^ (y >> 1) ^ ((y & 1) * 0x9908B0DF); ;; y = (rng.state[623] & 0x80000000) | (rng.state[0] & 0x7FFFFFFF) rng.state[623] = rng.state[396] ^ (y >> 1) ^ ((y & 1) * 0x9908B0DF); rng.i = 0 }