diff --git a/lib/libc/gen/_rand48.c b/lib/libc/gen/_rand48.c index 990e2c86949b..114c1595b33d 100644 --- a/lib/libc/gen/_rand48.c +++ b/lib/libc/gen/_rand48.c @@ -1,46 +1,18 @@ /* * Copyright (c) 1993 Martin Birgmeier * All rights reserved. * * You may redistribute unmodified or modified versions of this source * code provided that the above copyright notice and this and the * following conditions are retained. * * This software is provided ``as is'', and comes with no warranties * of any kind. I shall in no event be liable for anything that happens * to anyone/anything when using this software. */ #include "rand48.h" -unsigned short _rand48_seed[3] = { - RAND48_SEED_0, - RAND48_SEED_1, - RAND48_SEED_2 -}; -unsigned short _rand48_mult[3] = { - RAND48_MULT_0, - RAND48_MULT_1, - RAND48_MULT_2 -}; -unsigned short _rand48_add = RAND48_ADD; - -void -_dorand48(unsigned short xseed[3]) -{ - unsigned long accu; - unsigned short temp[2]; - - accu = (unsigned long) _rand48_mult[0] * (unsigned long) xseed[0] + - (unsigned long) _rand48_add; - temp[0] = (unsigned short) accu; /* lower 16 bits */ - accu >>= sizeof(unsigned short) * 8; - accu += (unsigned long) _rand48_mult[0] * (unsigned long) xseed[1] + - (unsigned long) _rand48_mult[1] * (unsigned long) xseed[0]; - temp[1] = (unsigned short) accu; /* middle 16 bits */ - accu >>= sizeof(unsigned short) * 8; - accu += _rand48_mult[0] * xseed[2] + _rand48_mult[1] * xseed[1] + _rand48_mult[2] * xseed[0]; - xseed[0] = temp[0]; - xseed[1] = temp[1]; - xseed[2] = (unsigned short) accu; -} +uint48 _rand48_seed = RAND48_SEED; +uint48 _rand48_mult = RAND48_MULT; +uint48 _rand48_add = RAND48_ADD; diff --git a/lib/libc/gen/drand48.c b/lib/libc/gen/drand48.c index cec04a6a2425..f7f43ff20468 100644 --- a/lib/libc/gen/drand48.c +++ b/lib/libc/gen/drand48.c @@ -1,22 +1,22 @@ /* * Copyright (c) 1993 Martin Birgmeier * All rights reserved. * * You may redistribute unmodified or modified versions of this source * code provided that the above copyright notice and this and the * following conditions are retained. * * This software is provided ``as is'', and comes with no warranties * of any kind. I shall in no event be liable for anything that happens * to anyone/anything when using this software. */ #include "rand48.h" -extern unsigned short _rand48_seed[3]; - double drand48(void) { - return erand48(_rand48_seed); + ERAND48_BEGIN; + _DORAND48(_rand48_seed); + ERAND48_END(_rand48_seed); } diff --git a/lib/libc/gen/erand48.c b/lib/libc/gen/erand48.c index 286904c27839..38d4774a9fe6 100644 --- a/lib/libc/gen/erand48.c +++ b/lib/libc/gen/erand48.c @@ -1,23 +1,24 @@ /* * Copyright (c) 1993 Martin Birgmeier * All rights reserved. * * You may redistribute unmodified or modified versions of this source * code provided that the above copyright notice and this and the * following conditions are retained. * * This software is provided ``as is'', and comes with no warranties * of any kind. I shall in no event be liable for anything that happens * to anyone/anything when using this software. */ #include "rand48.h" double erand48(unsigned short xseed[3]) { - _dorand48(xseed); - return ldexp((double) xseed[0], -48) + - ldexp((double) xseed[1], -32) + - ldexp((double) xseed[2], -16); + uint48 tmp; + + ERAND48_BEGIN; + DORAND48(tmp, xseed); + ERAND48_END(tmp); } diff --git a/lib/libc/gen/jrand48.c b/lib/libc/gen/jrand48.c index 0a9f780a9e5c..93442439d49e 100644 --- a/lib/libc/gen/jrand48.c +++ b/lib/libc/gen/jrand48.c @@ -1,24 +1,23 @@ /* * Copyright (c) 1993 Martin Birgmeier * All rights reserved. * * You may redistribute unmodified or modified versions of this source * code provided that the above copyright notice and this and the * following conditions are retained. * * This software is provided ``as is'', and comes with no warranties * of any kind. I shall in no event be liable for anything that happens * to anyone/anything when using this software. */ -#include - #include "rand48.h" long jrand48(unsigned short xseed[3]) { + uint48 tmp; - _dorand48(xseed); - return ((int32_t)(((uint32_t)xseed[2] << 16) | (uint32_t)xseed[1])); + DORAND48(tmp, xseed); + return ((int)((tmp >> 16) & 0xffffffff)); } diff --git a/lib/libc/gen/lcong48.c b/lib/libc/gen/lcong48.c index f13826b3d3f3..871b2110ed94 100644 --- a/lib/libc/gen/lcong48.c +++ b/lib/libc/gen/lcong48.c @@ -1,30 +1,22 @@ /* * Copyright (c) 1993 Martin Birgmeier * All rights reserved. * * You may redistribute unmodified or modified versions of this source * code provided that the above copyright notice and this and the * following conditions are retained. * * This software is provided ``as is'', and comes with no warranties * of any kind. I shall in no event be liable for anything that happens * to anyone/anything when using this software. */ #include "rand48.h" -extern unsigned short _rand48_seed[3]; -extern unsigned short _rand48_mult[3]; -extern unsigned short _rand48_add; - void lcong48(unsigned short p[7]) { - _rand48_seed[0] = p[0]; - _rand48_seed[1] = p[1]; - _rand48_seed[2] = p[2]; - _rand48_mult[0] = p[3]; - _rand48_mult[1] = p[4]; - _rand48_mult[2] = p[5]; + LOADRAND48(_rand48_seed, &p[0]); + LOADRAND48(_rand48_mult, &p[3]); _rand48_add = p[6]; } diff --git a/lib/libc/gen/lrand48.c b/lib/libc/gen/lrand48.c index a3d0111cf4d5..cc07044b8af9 100644 --- a/lib/libc/gen/lrand48.c +++ b/lib/libc/gen/lrand48.c @@ -1,23 +1,21 @@ /* * Copyright (c) 1993 Martin Birgmeier * All rights reserved. * * You may redistribute unmodified or modified versions of this source * code provided that the above copyright notice and this and the * following conditions are retained. * * This software is provided ``as is'', and comes with no warranties * of any kind. I shall in no event be liable for anything that happens * to anyone/anything when using this software. */ #include "rand48.h" -extern unsigned short _rand48_seed[3]; - long lrand48(void) { - _dorand48(_rand48_seed); - return ((long) _rand48_seed[2] << 15) + ((long) _rand48_seed[1] >> 1); + _DORAND48(_rand48_seed); + return (_rand48_seed >> 17) & 0x7fffffff; } diff --git a/lib/libc/gen/mrand48.c b/lib/libc/gen/mrand48.c index 15b0bfb1bd6e..f9128a6d4188 100644 --- a/lib/libc/gen/mrand48.c +++ b/lib/libc/gen/mrand48.c @@ -1,27 +1,23 @@ /* * Copyright (c) 1993 Martin Birgmeier * All rights reserved. * * You may redistribute unmodified or modified versions of this source * code provided that the above copyright notice and this and the * following conditions are retained. * * This software is provided ``as is'', and comes with no warranties * of any kind. I shall in no event be liable for anything that happens * to anyone/anything when using this software. */ #include #include "rand48.h" -extern unsigned short _rand48_seed[3]; - long mrand48(void) { - - _dorand48(_rand48_seed); - return ((int32_t)(((uint32_t)_rand48_seed[2] << 16) | - (uint32_t)_rand48_seed[1])); + _DORAND48(_rand48_seed); + return ((int)((_rand48_seed >> 16) & 0xffffffff)); } diff --git a/lib/libc/gen/nrand48.c b/lib/libc/gen/nrand48.c index 6c54065e7e0f..f6f4e231105c 100644 --- a/lib/libc/gen/nrand48.c +++ b/lib/libc/gen/nrand48.c @@ -1,21 +1,23 @@ /* * Copyright (c) 1993 Martin Birgmeier * All rights reserved. * * You may redistribute unmodified or modified versions of this source * code provided that the above copyright notice and this and the * following conditions are retained. * * This software is provided ``as is'', and comes with no warranties * of any kind. I shall in no event be liable for anything that happens * to anyone/anything when using this software. */ #include "rand48.h" long nrand48(unsigned short xseed[3]) { - _dorand48(xseed); - return ((long) xseed[2] << 15) + ((long) xseed[1] >> 1); + uint48 tmp; + + DORAND48(tmp, xseed); + return ((tmp >> 17) & 0x7fffffff); } diff --git a/lib/libc/gen/rand48.3 b/lib/libc/gen/rand48.3 index 1e47c843058e..3ea649354270 100644 --- a/lib/libc/gen/rand48.3 +++ b/lib/libc/gen/rand48.3 @@ -1,187 +1,190 @@ .\" Copyright (c) 1993 Martin Birgmeier .\" All rights reserved. .\" .\" You may redistribute unmodified or modified versions of this source .\" code provided that the above copyright notice and this and the .\" following conditions are retained. .\" .\" This software is provided ``as is'', and comes with no warranties .\" of any kind. I shall in no event be liable for anything that happens .\" to anyone/anything when using this software. .\" -.Dd September 4, 2012 +.Dd September 11, 2025 .Dt RAND48 3 .Os .Sh NAME .Nm drand48 , .Nm erand48 , .Nm lrand48 , .Nm nrand48 , .Nm mrand48 , .Nm jrand48 , .Nm srand48 , .Nm seed48 , .Nm lcong48 .Nd pseudo random number generators and initialization routines .Sh LIBRARY .Lb libc .Sh SYNOPSIS .In stdlib.h .Ft double .Fn drand48 void .Ft double .Fn erand48 "unsigned short xseed[3]" .Ft long .Fn lrand48 void .Ft long .Fn nrand48 "unsigned short xseed[3]" .Ft long .Fn mrand48 void .Ft long .Fn jrand48 "unsigned short xseed[3]" .Ft void .Fn srand48 "long seed" .Ft "unsigned short *" .Fn seed48 "unsigned short xseed[3]" .Ft void .Fn lcong48 "unsigned short p[7]" .Sh DESCRIPTION .Bf -symbolic The functions described in this manual page are not cryptographically secure. Cryptographic applications should use .Xr arc4random 3 instead. .Ef .Pp The .Fn rand48 family of functions generates pseudo-random numbers using a linear congruential algorithm working on integers 48 bits in size. The particular formula employed is r(n+1) = (a * r(n) + c) mod m where the default values are for the multiplicand a = 0x5deece66d = 25214903917 and the addend c = 0xb = 11. The modulo is always fixed at m = 2 ** 48. r(n) is called the seed of the random number generator. .Pp For all the six generator routines described next, the first computational step is to perform a single iteration of the algorithm. .Pp The .Fn drand48 and .Fn erand48 functions return values of type double. The full 48 bits of r(n+1) are loaded into the mantissa of the returned value, with the exponent set such that the values produced lie in the interval [0.0, 1.0). .Pp The .Fn lrand48 and .Fn nrand48 functions return values of type long in the range [0, 2**31-1]. The high-order (31) bits of r(n+1) are loaded into the lower bits of the returned value, with the topmost (sign) bit set to zero. .Pp The .Fn mrand48 and .Fn jrand48 functions return values of type long in the range [-2**31, 2**31-1]. The high-order (32) bits of r(n+1) are loaded into the returned value. .Pp The .Fn drand48 , .Fn lrand48 , and .Fn mrand48 functions use an internal buffer to store r(n). For these functions the initial value of r(0) = 0x1234abcd330e = 20017429951246. .Pp On the other hand, .Fn erand48 , .Fn nrand48 , and .Fn jrand48 use a user-supplied buffer to store the seed r(n), which consists of an array of 3 shorts, where the zeroth member holds the least significant bits. .Pp All functions share the same multiplicand and addend. .Pp The .Fn srand48 function is used to initialize the internal buffer r(n) of .Fn drand48 , .Fn lrand48 , and .Fn mrand48 such that the 32 bits of the seed value are copied into the upper 32 bits of r(n), with the lower 16 bits of r(n) arbitrarily being set to 0x330e. Additionally, the constant multiplicand and addend of the algorithm are reset to the default values given above. .Pp The .Fn seed48 function also initializes the internal buffer r(n) of .Fn drand48 , .Fn lrand48 , and .Fn mrand48 , but here all 48 bits of the seed can be specified in an array of 3 shorts, where the zeroth member specifies the lowest bits. Again, the constant multiplicand and addend of the algorithm are reset to the default values given above. The .Fn seed48 function returns a pointer to an array of 3 shorts which contains the old seed. This array is statically allocated, thus its contents are lost after each new call to .Fn seed48 . .Pp Finally, .Fn lcong48 allows full control over the multiplicand and addend used in .Fn drand48 , .Fn erand48 , .Fn lrand48 , .Fn nrand48 , .Fn mrand48 , and .Fn jrand48 , and the seed used in .Fn drand48 , .Fn lrand48 , and .Fn mrand48 . An array of 7 shorts is passed as argument; the first three shorts are used to initialize the seed; the second three are used to initialize the multiplicand; and the last short is used to initialize the addend. It is thus not possible to use values greater than 0xffff as the addend. .Pp Note that all three methods of seeding the random number generator always also set the multiplicand and addend for any of the six generator calls. .Sh SEE ALSO .Xr arc4random 3 , .Xr rand 3 , .Xr random 3 +.Sh STANDARDS +The functions described in this page are expected to conform to +.St -p1003.1-2008 . .Sh AUTHORS .An Martin Birgmeier diff --git a/lib/libc/gen/rand48.h b/lib/libc/gen/rand48.h index 9861e99683cb..d3326e851491 100644 --- a/lib/libc/gen/rand48.h +++ b/lib/libc/gen/rand48.h @@ -1,30 +1,89 @@ /* * Copyright (c) 1993 Martin Birgmeier * All rights reserved. * * You may redistribute unmodified or modified versions of this source * code provided that the above copyright notice and this and the * following conditions are retained. * * This software is provided ``as is'', and comes with no warranties * of any kind. I shall in no event be liable for anything that happens * to anyone/anything when using this software. */ #ifndef _RAND48_H_ #define _RAND48_H_ +#include #include #include -void _dorand48(unsigned short[3]); +#include "fpmath.h" #define RAND48_SEED_0 (0x330e) #define RAND48_SEED_1 (0xabcd) #define RAND48_SEED_2 (0x1234) #define RAND48_MULT_0 (0xe66d) #define RAND48_MULT_1 (0xdeec) #define RAND48_MULT_2 (0x0005) #define RAND48_ADD (0x000b) +typedef uint64_t uint48; + +extern uint48 _rand48_seed; +extern uint48 _rand48_mult; +extern uint48 _rand48_add; + +#define TOUINT48(x, y, z) \ + ((uint48)(x) + (((uint48)(y)) << 16) + (((uint48)(z)) << 32)) + +#define RAND48_SEED TOUINT48(RAND48_SEED_0, RAND48_SEED_1, RAND48_SEED_2) +#define RAND48_MULT TOUINT48(RAND48_MULT_0, RAND48_MULT_1, RAND48_MULT_2) + +#define LOADRAND48(l, x) do { \ + (l) = TOUINT48((x)[0], (x)[1], (x)[2]); \ +} while (0) + +#define STORERAND48(l, x) do { \ + (x)[0] = (unsigned short)(l); \ + (x)[1] = (unsigned short)((l) >> 16); \ + (x)[2] = (unsigned short)((l) >> 32); \ +} while (0) + +#define _DORAND48(l) do { \ + (l) = (l) * _rand48_mult + _rand48_add; \ +} while (0) + +#define DORAND48(l, x) do { \ + LOADRAND48(l, x); \ + _DORAND48(l); \ + STORERAND48(l, x); \ +} while (0) + +#define ERAND48_BEGIN \ + union { \ + union IEEEd2bits ieee; \ + uint64_t u64; \ + } u; \ + int s + +/* + * Optimization for speed: assume doubles are IEEE 754 and use bit fiddling + * rather than converting to double. Specifically, clamp the result to 48 bits + * and convert to a double in [0.0, 1.0) via division by 2^48. Normalize by + * shifting the most significant bit into the implicit one position and + * adjusting the exponent accordingly. The store to the exponent field + * overwrites the implicit one. + */ +#define ERAND48_END(x) do { \ + u.u64 = ((x) & 0xffffffffffffULL); \ + if (u.u64 == 0) \ + return (0.0); \ + u.u64 <<= 5; \ + for (s = 0; !(u.u64 & (1LL << 52)); s++, u.u64 <<= 1) \ + ; \ + u.ieee.bits.exp = 1022 - s; \ + return (u.ieee.d); \ +} while (0) + #endif /* _RAND48_H_ */ diff --git a/lib/libc/gen/seed48.c b/lib/libc/gen/seed48.c index 258c4bac3c9f..f57656ce1121 100644 --- a/lib/libc/gen/seed48.c +++ b/lib/libc/gen/seed48.c @@ -1,36 +1,26 @@ /* * Copyright (c) 1993 Martin Birgmeier * All rights reserved. * * You may redistribute unmodified or modified versions of this source * code provided that the above copyright notice and this and the * following conditions are retained. * * This software is provided ``as is'', and comes with no warranties * of any kind. I shall in no event be liable for anything that happens * to anyone/anything when using this software. */ #include "rand48.h" -extern unsigned short _rand48_seed[3]; -extern unsigned short _rand48_mult[3]; -extern unsigned short _rand48_add; - unsigned short * seed48(unsigned short xseed[3]) { static unsigned short sseed[3]; - sseed[0] = _rand48_seed[0]; - sseed[1] = _rand48_seed[1]; - sseed[2] = _rand48_seed[2]; - _rand48_seed[0] = xseed[0]; - _rand48_seed[1] = xseed[1]; - _rand48_seed[2] = xseed[2]; - _rand48_mult[0] = RAND48_MULT_0; - _rand48_mult[1] = RAND48_MULT_1; - _rand48_mult[2] = RAND48_MULT_2; + STORERAND48(_rand48_seed, sseed); + LOADRAND48(_rand48_seed, xseed); + _rand48_mult = RAND48_MULT; _rand48_add = RAND48_ADD; - return sseed; + return (sseed); } diff --git a/lib/libc/gen/srand48.c b/lib/libc/gen/srand48.c index fd369a094c51..4b82ece72db8 100644 --- a/lib/libc/gen/srand48.c +++ b/lib/libc/gen/srand48.c @@ -1,30 +1,23 @@ /* * Copyright (c) 1993 Martin Birgmeier * All rights reserved. * * You may redistribute unmodified or modified versions of this source * code provided that the above copyright notice and this and the * following conditions are retained. * * This software is provided ``as is'', and comes with no warranties * of any kind. I shall in no event be liable for anything that happens * to anyone/anything when using this software. */ #include "rand48.h" -extern unsigned short _rand48_seed[3]; -extern unsigned short _rand48_mult[3]; -extern unsigned short _rand48_add; - void srand48(long seed) { - _rand48_seed[0] = RAND48_SEED_0; - _rand48_seed[1] = (unsigned short) seed; - _rand48_seed[2] = (unsigned short) (seed >> 16); - _rand48_mult[0] = RAND48_MULT_0; - _rand48_mult[1] = RAND48_MULT_1; - _rand48_mult[2] = RAND48_MULT_2; + _rand48_seed = TOUINT48(RAND48_SEED_0, (unsigned short)seed, + (unsigned short)(seed >> 16)); + _rand48_mult = RAND48_MULT; _rand48_add = RAND48_ADD; }