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Diffstat (limited to 'contrib/awk/random.c')
| -rw-r--r-- | contrib/awk/random.c | 661 |
1 files changed, 403 insertions, 258 deletions
diff --git a/contrib/awk/random.c b/contrib/awk/random.c index 002b226..74ba7d4 100644 --- a/contrib/awk/random.c +++ b/contrib/awk/random.c @@ -1,66 +1,125 @@ /* - * Copyright (c) 1983 Regents of the University of California. - * All rights reserved. + * Copyright (c) 1983, 1993 + * The Regents of the University of California. 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. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by the University of + * California, Berkeley and its contributors. + * 4. Neither the name of the University nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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. + * + * $FreeBSD$ * - * Redistribution and use in source and binary forms are permitted - * provided that the above copyright notice and this paragraph are - * duplicated in all such forms and that any documentation, - * advertising materials, and other materials related to such - * distribution and use acknowledge that the software was developed - * by the University of California, Berkeley. The name of the - * University may not be used to endorse or promote products derived - * from this software without specific prior written permission. - * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR - * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED - * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. */ #if defined(LIBC_SCCS) && !defined(lint) -static char sccsid[] = "@(#)random.c 5.5 (Berkeley) 7/6/88"; +static char sccsid[] = "@(#)random.c 8.2 (Berkeley) 5/19/95"; #endif /* LIBC_SCCS and not lint */ +#include "random.h" /* gawk addition */ + +#if !defined (_MSC_VER) && !defined (__MINGW32__) && !defined (VMS) +#include <sys/time.h> /* for srandomdev() */ +#else +#include <time.h> /* for clock() */ +#define ssize_t size_t +#endif /* !defined (_MSC_VER) && !defined (__MINGW32__) && !defined (VMS) */ + #include <stdio.h> -#include "random.h" /* GAWK ADDITION */ + +/* For gawk, don't this, use the decl of random() in random.h */ +#if 0 +#include <stdlib.h> +#endif + +#ifdef HAVE_UNISTD_H +#include <unistd.h> /* for srandomdev() */ +#endif +#ifdef HAVE_FCNTL_H +#include <fcntl.h> /* for srandomdev() */ +#endif /* * random.c: + * * An improved random number generation package. In addition to the standard * rand()/srand() like interface, this package also has a special state info * interface. The initstate() routine is called with a seed, an array of - * bytes, and a count of how many bytes are being passed in; this array is then - * initialized to contain information for random number generation with that - * much state information. Good sizes for the amount of state information are - * 32, 64, 128, and 256 bytes. The state can be switched by calling the - * setstate() routine with the same array as was initiallized with initstate(). - * By default, the package runs with 128 bytes of state information and - * generates far better random numbers than a linear congruential generator. - * If the amount of state information is less than 32 bytes, a simple linear - * congruential R.N.G. is used. + * bytes, and a count of how many bytes are being passed in; this array is + * then initialized to contain information for random number generation with + * that much state information. Good sizes for the amount of state + * information are 32, 64, 128, and 256 bytes. The state can be switched by + * calling the setstate() routine with the same array as was initiallized + * with initstate(). By default, the package runs with 128 bytes of state + * information and generates far better random numbers than a linear + * congruential generator. If the amount of state information is less than + * 32 bytes, a simple linear congruential R.N.G. is used. + * * Internally, the state information is treated as an array of longs; the * zeroeth element of the array is the type of R.N.G. being used (small * integer); the remainder of the array is the state information for the * R.N.G. Thus, 32 bytes of state information will give 7 longs worth of - * state information, which will allow a degree seven polynomial. (Note: the - * zeroeth word of state information also has some other information stored - * in it -- see setstate() for details). + * state information, which will allow a degree seven polynomial. (Note: + * the zeroeth word of state information also has some other information + * stored in it -- see setstate() for details). + * * The random number generation technique is a linear feedback shift register * approach, employing trinomials (since there are fewer terms to sum up that * way). In this approach, the least significant bit of all the numbers in - * the state table will act as a linear feedback shift register, and will have - * period 2^deg - 1 (where deg is the degree of the polynomial being used, - * assuming that the polynomial is irreducible and primitive). The higher - * order bits will have longer periods, since their values are also influenced - * by pseudo-random carries out of the lower bits. The total period of the - * generator is approximately deg*(2**deg - 1); thus doubling the amount of - * state information has a vast influence on the period of the generator. - * Note: the deg*(2**deg - 1) is an approximation only good for large deg, - * when the period of the shift register is the dominant factor. With deg - * equal to seven, the period is actually much longer than the 7*(2**7 - 1) - * predicted by this formula. + * the state table will act as a linear feedback shift register, and will + * have period 2^deg - 1 (where deg is the degree of the polynomial being + * used, assuming that the polynomial is irreducible and primitive). The + * higher order bits will have longer periods, since their values are also + * influenced by pseudo-random carries out of the lower bits. The total + * period of the generator is approximately deg*(2**deg - 1); thus doubling + * the amount of state information has a vast influence on the period of the + * generator. Note: the deg*(2**deg - 1) is an approximation only good for + * large deg, when the period of the shift register is the dominant factor. + * With deg equal to seven, the period is actually much longer than the + * 7*(2**7 - 1) predicted by this formula. + * + * Modified 28 December 1994 by Jacob S. Rosenberg. + * The following changes have been made: + * All references to the type u_int have been changed to unsigned long. + * All references to type int have been changed to type long. Other + * cleanups have been made as well. A warning for both initstate and + * setstate has been inserted to the effect that on Sparc platforms + * the 'arg_state' variable must be forced to begin on word boundaries. + * This can be easily done by casting a long integer array to char *. + * The overall logic has been left STRICTLY alone. This software was + * tested on both a VAX and Sun SpacsStation with exactly the same + * results. The new version and the original give IDENTICAL results. + * The new version is somewhat faster than the original. As the + * documentation says: "By default, the package runs with 128 bytes of + * state information and generates far better random numbers than a linear + * congruential generator. If the amount of state information is less than + * 32 bytes, a simple linear congruential R.N.G. is used." For a buffer of + * 128 bytes, this new version runs about 19 percent faster and for a 16 + * byte buffer it is about 5 percent faster. */ - - /* * For each of the currently supported random number generators, we have a * break value on the amount of state information (you need at least this @@ -68,312 +127,398 @@ static char sccsid[] = "@(#)random.c 5.5 (Berkeley) 7/6/88"; * for the polynomial (actually a trinomial) that the R.N.G. is based on, and * the separation between the two lower order coefficients of the trinomial. */ - -#define TYPE_0 0 /* linear congruential */ -#define BREAK_0 8 -#define DEG_0 0 -#define SEP_0 0 - -#define TYPE_1 1 /* x**7 + x**3 + 1 */ -#define BREAK_1 32 -#define DEG_1 7 -#define SEP_1 3 - -#define TYPE_2 2 /* x**15 + x + 1 */ -#define BREAK_2 64 -#define DEG_2 15 -#define SEP_2 1 - -#define TYPE_3 3 /* x**31 + x**3 + 1 */ -#define BREAK_3 128 -#define DEG_3 31 -#define SEP_3 3 -#ifdef _CRAY -#define DEG_3_P1 32 /* bug - do addition here */ -#define SEP_3_P1 4 /* *_3 + 1 = _3_P1 */ -#endif - -#define TYPE_4 4 /* x**63 + x + 1 */ -#define BREAK_4 256 -#define DEG_4 63 -#define SEP_4 1 - +#define TYPE_0 0 /* linear congruential */ +#define BREAK_0 8 +#define DEG_0 0 +#define SEP_0 0 + +#define TYPE_1 1 /* x**7 + x**3 + 1 */ +#define BREAK_1 32 +#define DEG_1 7 +#define SEP_1 3 + +#define TYPE_2 2 /* x**15 + x + 1 */ +#define BREAK_2 64 +#define DEG_2 15 +#define SEP_2 1 + +#define TYPE_3 3 /* x**31 + x**3 + 1 */ +#define BREAK_3 128 +#define DEG_3 31 +#define SEP_3 3 + +#define TYPE_4 4 /* x**63 + x + 1 */ +#define BREAK_4 256 +#define DEG_4 63 +#define SEP_4 1 /* - * Array versions of the above information to make code run faster -- relies - * on fact that TYPE_i == i. + * Array versions of the above information to make code run faster -- + * relies on fact that TYPE_i == i. */ +#define MAX_TYPES 5 /* max number of types above */ -#define MAX_TYPES 5 /* max number of types above */ - -static int degrees[ MAX_TYPES ] = { DEG_0, DEG_1, DEG_2, - DEG_3, DEG_4 }; - -static int seps[ MAX_TYPES ] = { SEP_0, SEP_1, SEP_2, - SEP_3, SEP_4 }; - - +static long degrees[MAX_TYPES] = { DEG_0, DEG_1, DEG_2, DEG_3, DEG_4 }; +static long seps [MAX_TYPES] = { SEP_0, SEP_1, SEP_2, SEP_3, SEP_4 }; /* - * Initially, everything is set up as if from : - * initstate( 1, &randtbl, 128 ); + * Initially, everything is set up as if from: + * + * initstate(1, randtbl, 128); + * * Note that this initialization takes advantage of the fact that srandom() * advances the front and rear pointers 10*rand_deg times, and hence the * rear pointer which starts at 0 will also end up at zero; thus the zeroeth * element of the state information, which contains info about the current * position of the rear pointer is just - * MAX_TYPES*(rptr - state) + TYPE_3 == TYPE_3. + * + * MAX_TYPES * (rptr - state) + TYPE_3 == TYPE_3. */ -static long randtbl[ DEG_3 + 1 ] = { TYPE_3, - 0x9a319039, 0x32d9c024, 0x9b663182, 0x5da1f342, - 0xde3b81e0, 0xdf0a6fb5, 0xf103bc02, 0x48f340fb, - 0x7449e56b, 0xbeb1dbb0, 0xab5c5918, 0x946554fd, - 0x8c2e680f, 0xeb3d799f, 0xb11ee0b7, 0x2d436b86, - 0xda672e2a, 0x1588ca88, 0xe369735d, 0x904f35f7, - 0xd7158fd6, 0x6fa6f051, 0x616e6b96, 0xac94efdc, - 0x36413f93, 0xc622c298, 0xf5a42ab8, 0x8a88d77b, - 0xf5ad9d0e, 0x8999220b, 0x27fb47b9 }; +static long randtbl[DEG_3 + 1] = { + TYPE_3, +#ifdef USE_WEAK_SEEDING +/* Historic implementation compatibility */ +/* The random sequences do not vary much with the seed */ + 0x9a319039, 0x32d9c024, 0x9b663182, 0x5da1f342, 0xde3b81e0, 0xdf0a6fb5, + 0xf103bc02, 0x48f340fb, 0x7449e56b, 0xbeb1dbb0, 0xab5c5918, 0x946554fd, + 0x8c2e680f, 0xeb3d799f, 0xb11ee0b7, 0x2d436b86, 0xda672e2a, 0x1588ca88, + 0xe369735d, 0x904f35f7, 0xd7158fd6, 0x6fa6f051, 0x616e6b96, 0xac94efdc, + 0x36413f93, 0xc622c298, 0xf5a42ab8, 0x8a88d77b, 0xf5ad9d0e, 0x8999220b, + 0x27fb47b9, +#else /* !USE_WEAK_SEEDING */ + 0x991539b1, 0x16a5bce3, 0x6774a4cd, 0x3e01511e, 0x4e508aaa, 0x61048c05, + 0xf5500617, 0x846b7115, 0x6a19892c, 0x896a97af, 0xdb48f936, 0x14898454, + 0x37ffd106, 0xb58bff9c, 0x59e17104, 0xcf918a49, 0x09378c83, 0x52c7a471, + 0x8d293ea9, 0x1f4fc301, 0xc3db71be, 0x39b44e1c, 0xf8a44ef9, 0x4c8b80b1, + 0x19edc328, 0x87bf4bdd, 0xc9b240e5, 0xe9ee4b1b, 0x4382aee7, 0x535b6b41, + 0xf3bec5da +#endif /* !USE_WEAK_SEEDING */ +}; /* * fptr and rptr are two pointers into the state info, a front and a rear - * pointer. These two pointers are always rand_sep places aparts, as they cycle - * cyclically through the state information. (Yes, this does mean we could get - * away with just one pointer, but the code for random() is more efficient this - * way). The pointers are left positioned as they would be from the call - * initstate( 1, randtbl, 128 ) + * pointer. These two pointers are always rand_sep places aparts, as they + * cycle cyclically through the state information. (Yes, this does mean we + * could get away with just one pointer, but the code for random() is more + * efficient this way). The pointers are left positioned as they would be + * from the call + * + * initstate(1, randtbl, 128); + * * (The position of the rear pointer, rptr, is really 0 (as explained above * in the initialization of randtbl) because the state table pointer is set * to point to randtbl[1] (as explained below). */ - -#ifdef _CRAY -static long *fptr = &randtbl[ SEP_3_P1 ]; -#else -static long *fptr = &randtbl[ SEP_3 + 1 ]; -#endif -static long *rptr = &randtbl[ 1 ]; - - +static long *fptr = &randtbl[SEP_3 + 1]; +static long *rptr = &randtbl[1]; /* - * The following things are the pointer to the state information table, - * the type of the current generator, the degree of the current polynomial - * being used, and the separation between the two pointers. - * Note that for efficiency of random(), we remember the first location of - * the state information, not the zeroeth. Hence it is valid to access - * state[-1], which is used to store the type of the R.N.G. - * Also, we remember the last location, since this is more efficient than - * indexing every time to find the address of the last element to see if - * the front and rear pointers have wrapped. + * The following things are the pointer to the state information table, the + * type of the current generator, the degree of the current polynomial being + * used, and the separation between the two pointers. Note that for efficiency + * of random(), we remember the first location of the state information, not + * the zeroeth. Hence it is valid to access state[-1], which is used to + * store the type of the R.N.G. Also, we remember the last location, since + * this is more efficient than indexing every time to find the address of + * the last element to see if the front and rear pointers have wrapped. */ +static long *state = &randtbl[1]; +static long rand_type = TYPE_3; +static long rand_deg = DEG_3; +static long rand_sep = SEP_3; +static long *end_ptr = &randtbl[DEG_3 + 1]; -static long *state = &randtbl[ 1 ]; - -static int rand_type = TYPE_3; -static int rand_deg = DEG_3; -static int rand_sep = SEP_3; - -#ifdef _CRAY -static long *end_ptr = &randtbl[ DEG_3_P1 ]; -#else -static long *end_ptr = &randtbl[ DEG_3 + 1 ]; -#endif - +static long good_rand __P((long)); +static long good_rand (x) + register long x; +{ +#ifdef USE_WEAK_SEEDING +/* + * Historic implementation compatibility. + * The random sequences do not vary much with the seed, + * even with overflowing. + */ + return (1103515245 * x + 12345); +#else /* !USE_WEAK_SEEDING */ +/* + * Compute x = (7^5 * x) mod (2^31 - 1) + * wihout overflowing 31 bits: + * (2^31 - 1) = 127773 * (7^5) + 2836 + * From "Random number generators: good ones are hard to find", + * Park and Miller, Communications of the ACM, vol. 31, no. 10, + * October 1988, p. 1195. + */ + register long hi, lo; + + hi = x / 127773; + lo = x % 127773; + x = 16807 * lo - 2836 * hi; + if (x <= 0) + x += 0x7fffffff; + return (x); +#endif /* !USE_WEAK_SEEDING */ +} /* * srandom: + * * Initialize the random number generator based on the given seed. If the * type is the trivial no-state-information type, just remember the seed. * Otherwise, initializes state[] based on the given "seed" via a linear * congruential generator. Then, the pointers are set to known locations * that are exactly rand_sep places apart. Lastly, it cycles the state * information a given number of times to get rid of any initial dependencies - * introduced by the L.C.R.N.G. - * Note that the initialization of randtbl[] for default usage relies on - * values produced by this routine. + * introduced by the L.C.R.N.G. Note that the initialization of randtbl[] + * for default usage relies on values produced by this routine. */ - void -srandom( x ) +srandom(x) + unsigned long x; +{ + register long i; + + if (rand_type == TYPE_0) + state[0] = x; + else { + state[0] = x; + for (i = 1; i < rand_deg; i++) + state[i] = good_rand(state[i - 1]); + fptr = &state[rand_sep]; + rptr = &state[0]; + for (i = 0; i < 10 * rand_deg; i++) + (void)random(); + } +} - unsigned x; +/* + * srandomdev: + * + * Many programs choose the seed value in a totally predictable manner. + * This often causes problems. We seed the generator using the much more + * secure urandom(4) interface. Note that this particular seeding + * procedure can generate states which are impossible to reproduce by + * calling srandom() with any value, since the succeeding terms in the + * state buffer are no longer derived from the LC algorithm applied to + * a fixed seed. + */ +void +srandomdev() { - register int i, j; - long random(); + int fd, done; + size_t len; + + if (rand_type == TYPE_0) + len = sizeof state[0]; + else + len = rand_deg * sizeof state[0]; + + done = 0; +#ifdef O_RDONLY + fd = open("/dev/urandom", O_RDONLY, 0); + if (fd >= 0) { + if (read(fd, (void *) state, len) == (ssize_t) len) + done = 1; + close(fd); + } +#endif /*O_RDONLY*/ + + if (!done) { + unsigned long junk; +#if !defined (_MSC_VER) && !defined (__MINGW32__) + struct timeval tv; - if( rand_type == TYPE_0 ) { - state[ 0 ] = x; + gettimeofday(&tv, NULL); + srandom(getpid() ^ tv.tv_sec ^ tv.tv_usec ^ junk); +#else + clock_t ret_clock_t = clock(); + /* + * I don't like the idea of reading uninitialized memory + * even to generate a random number, but we do it anyway. + * SD. + */ + srandom(getpid() ^ ret_clock_t ^ junk); +#endif + + return; } - else { - j = 1; - state[ 0 ] = x; - for( i = 1; i < rand_deg; i++ ) { - state[i] = 1103515245*state[i - 1] + 12345; - } - fptr = &state[ rand_sep ]; - rptr = &state[ 0 ]; - for( i = 0; i < 10*rand_deg; i++ ) random(); + + if (rand_type != TYPE_0) { + fptr = &state[rand_sep]; + rptr = &state[0]; } } - - /* * initstate: - * Initialize the state information in the given array of n bytes for - * future random number generation. Based on the number of bytes we - * are given, and the break values for the different R.N.G.'s, we choose - * the best (largest) one we can and set things up for it. srandom() is - * then called to initialize the state information. + * + * Initialize the state information in the given array of n bytes for future + * random number generation. Based on the number of bytes we are given, and + * the break values for the different R.N.G.'s, we choose the best (largest) + * one we can and set things up for it. srandom() is then called to + * initialize the state information. + * * Note that on return from srandom(), we set state[-1] to be the type * multiplexed with the current value of the rear pointer; this is so - * successive calls to initstate() won't lose this information and will - * be able to restart with setstate(). + * successive calls to initstate() won't lose this information and will be + * able to restart with setstate(). + * * Note: the first thing we do is save the current state, if any, just like * setstate() so that it doesn't matter when initstate is called. + * * Returns a pointer to the old state. + * + * Note: The Sparc platform requires that arg_state begin on a long + * word boundary; otherwise a bus error will occur. Even so, lint will + * complain about mis-alignment, but you should disregard these messages. */ - -char * -initstate( seed, arg_state, n ) - - unsigned seed; /* seed for R. N. G. */ - char *arg_state; /* pointer to state array */ - int n; /* # bytes of state info */ +char * +initstate(seed, arg_state, n) + unsigned long seed; /* seed for R.N.G. */ + char *arg_state; /* pointer to state array */ + long n; /* # bytes of state info */ { - register char *ostate = (char *)( &state[ -1 ] ); - - if( rand_type == TYPE_0 ) state[ -1 ] = rand_type; - else state[ -1 ] = MAX_TYPES*(rptr - state) + rand_type; - if( n < BREAK_1 ) { - if( n < BREAK_0 ) { - fprintf( stderr, "initstate: not enough state (%d bytes) with which to do jack; ignored.\n", n ); - return 0; - } - rand_type = TYPE_0; - rand_deg = DEG_0; - rand_sep = SEP_0; + register char *ostate = (char *)(&state[-1]); + register long *long_arg_state = (long *) arg_state; + + if (rand_type == TYPE_0) + state[-1] = rand_type; + else + state[-1] = MAX_TYPES * (rptr - state) + rand_type; + if (n < BREAK_0) { + (void)fprintf(stderr, + "random: not enough state (%ld bytes); ignored.\n", n); + return(0); } - else { - if( n < BREAK_2 ) { + if (n < BREAK_1) { + rand_type = TYPE_0; + rand_deg = DEG_0; + rand_sep = SEP_0; + } else if (n < BREAK_2) { rand_type = TYPE_1; rand_deg = DEG_1; rand_sep = SEP_1; - } - else { - if( n < BREAK_3 ) { - rand_type = TYPE_2; - rand_deg = DEG_2; - rand_sep = SEP_2; - } - else { - if( n < BREAK_4 ) { - rand_type = TYPE_3; - rand_deg = DEG_3; - rand_sep = SEP_3; - } - else { - rand_type = TYPE_4; - rand_deg = DEG_4; - rand_sep = SEP_4; - } - } - } + } else if (n < BREAK_3) { + rand_type = TYPE_2; + rand_deg = DEG_2; + rand_sep = SEP_2; + } else if (n < BREAK_4) { + rand_type = TYPE_3; + rand_deg = DEG_3; + rand_sep = SEP_3; + } else { + rand_type = TYPE_4; + rand_deg = DEG_4; + rand_sep = SEP_4; } - state = &( ( (long *)arg_state )[1] ); /* first location */ - end_ptr = &state[ rand_deg ]; /* must set end_ptr before srandom */ - srandom( seed ); - if( rand_type == TYPE_0 ) state[ -1 ] = rand_type; - else state[ -1 ] = MAX_TYPES*(rptr - state) + rand_type; - return( ostate ); + state = (long *) (long_arg_state + 1); /* first location */ + end_ptr = &state[rand_deg]; /* must set end_ptr before srandom */ + srandom(seed); + if (rand_type == TYPE_0) + long_arg_state[0] = rand_type; + else + long_arg_state[0] = MAX_TYPES * (rptr - state) + rand_type; + return(ostate); } - - /* * setstate: + * * Restore the state from the given state array. + * * Note: it is important that we also remember the locations of the pointers * in the current state information, and restore the locations of the pointers * from the old state information. This is done by multiplexing the pointer * location into the zeroeth word of the state information. + * * Note that due to the order in which things are done, it is OK to call * setstate() with the same state as the current state. + * * Returns a pointer to the old state information. + * + * Note: The Sparc platform requires that arg_state begin on a long + * word boundary; otherwise a bus error will occur. Even so, lint will + * complain about mis-alignment, but you should disregard these messages. */ - -char * -setstate( arg_state ) - - char *arg_state; +char * +setstate(arg_state) + char *arg_state; /* pointer to state array */ { - register long *new_state = (long *)arg_state; - register int type = new_state[0]%MAX_TYPES; - register int rear = new_state[0]/MAX_TYPES; - char *ostate = (char *)( &state[ -1 ] ); - - if( rand_type == TYPE_0 ) state[ -1 ] = rand_type; - else state[ -1 ] = MAX_TYPES*(rptr - state) + rand_type; - switch( type ) { - case TYPE_0: - case TYPE_1: - case TYPE_2: - case TYPE_3: - case TYPE_4: + register long *new_state = (long *) arg_state; + register long type = new_state[0] % MAX_TYPES; + register long rear = new_state[0] / MAX_TYPES; + char *ostate = (char *)(&state[-1]); + + if (rand_type == TYPE_0) + state[-1] = rand_type; + else + state[-1] = MAX_TYPES * (rptr - state) + rand_type; + switch(type) { + case TYPE_0: + case TYPE_1: + case TYPE_2: + case TYPE_3: + case TYPE_4: rand_type = type; - rand_deg = degrees[ type ]; - rand_sep = seps[ type ]; + rand_deg = degrees[type]; + rand_sep = seps[type]; break; - - default: - fprintf( stderr, "setstate: state info has been munged; not changed.\n" ); + default: + (void)fprintf(stderr, + "random: state info corrupted; not changed.\n"); } - state = &new_state[ 1 ]; - if( rand_type != TYPE_0 ) { - rptr = &state[ rear ]; - fptr = &state[ (rear + rand_sep)%rand_deg ]; + state = (long *) (new_state + 1); + if (rand_type != TYPE_0) { + rptr = &state[rear]; + fptr = &state[(rear + rand_sep) % rand_deg]; } - end_ptr = &state[ rand_deg ]; /* set end_ptr too */ - return( ostate ); + end_ptr = &state[rand_deg]; /* set end_ptr too */ + return(ostate); } - - /* * random: + * * If we are using the trivial TYPE_0 R.N.G., just do the old linear - * congruential bit. Otherwise, we do our fancy trinomial stuff, which is the - * same in all ther other cases due to all the global variables that have been - * set up. The basic operation is to add the number at the rear pointer into - * the one at the front pointer. Then both pointers are advanced to the next - * location cyclically in the table. The value returned is the sum generated, - * reduced to 31 bits by throwing away the "least random" low bit. + * congruential bit. Otherwise, we do our fancy trinomial stuff, which is + * the same in all the other cases due to all the global variables that have + * been set up. The basic operation is to add the number at the rear pointer + * into the one at the front pointer. Then both pointers are advanced to + * the next location cyclically in the table. The value returned is the sum + * generated, reduced to 31 bits by throwing away the "least random" low bit. + * * Note: the code takes advantage of the fact that both the front and * rear pointers can't wrap on the same call by not testing the rear * pointer if the front one has wrapped. + * * Returns a 31-bit random number. */ - long random() { - long i; + register long i; + register long *f, *r; + + if (rand_type == TYPE_0) { + i = state[0]; + state[0] = i = (good_rand(i)) & 0x7fffffff; + } else { + /* + * Use local variables rather than static variables for speed. + */ + f = fptr; r = rptr; + *f += *r; + i = (*f >> 1) & 0x7fffffff; /* chucking least random bit */ + if (++f >= end_ptr) { + f = state; + ++r; + } + else if (++r >= end_ptr) { + r = state; + } - if( rand_type == TYPE_0 ) { - i = state[0] = ( state[0]*1103515245 + 12345 )&0x7fffffff; - } - else { - *fptr += *rptr; - i = (*fptr >> 1)&0x7fffffff; /* chucking least random bit */ - if( ++fptr >= end_ptr ) { - fptr = state; - ++rptr; - } - else { - if( ++rptr >= end_ptr ) rptr = state; - } + fptr = f; rptr = r; } - return( i ); + return(i); } |
