/*
|
/*
|
* Copyright (c) 1983 Regents of the University of California.
|
* Copyright (c) 1983 Regents of the University of California.
|
* All rights reserved.
|
* All rights reserved.
|
*
|
*
|
* Redistribution and use in source and binary forms, with or without
|
* Redistribution and use in source and binary forms, with or without
|
* modification, are permitted provided that the following conditions
|
* modification, are permitted provided that the following conditions
|
* are met:
|
* are met:
|
* 1. Redistributions of source code must retain the above copyright
|
* 1. Redistributions of source code must retain the above copyright
|
* notice, this list of conditions and the following disclaimer.
|
* notice, this list of conditions and the following disclaimer.
|
* 2. Redistributions in binary form must reproduce the above copyright
|
* 2. Redistributions in binary form must reproduce the above copyright
|
* notice, this list of conditions and the following disclaimer in the
|
* notice, this list of conditions and the following disclaimer in the
|
* documentation and/or other materials provided with the distribution.
|
* documentation and/or other materials provided with the distribution.
|
* 3. [rescinded 22 July 1999]
|
* 3. [rescinded 22 July 1999]
|
* 4. Neither the name of the University nor the names of 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
|
* may be used to endorse or promote products derived from this software
|
* without specific prior written permission.
|
* without specific prior written permission.
|
*
|
*
|
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
* 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
|
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
* SUCH DAMAGE.
|
* SUCH DAMAGE.
|
*/
|
*/
|
|
|
/*
|
/*
|
* This is derived from the Berkeley source:
|
* This is derived from the Berkeley source:
|
* @(#)random.c 5.5 (Berkeley) 7/6/88
|
* @(#)random.c 5.5 (Berkeley) 7/6/88
|
* It was reworked for the GNU C Library by Roland McGrath.
|
* It was reworked for the GNU C Library by Roland McGrath.
|
*/
|
*/
|
|
|
/*
|
/*
|
|
|
@deftypefn Supplement {long int} random (void)
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@deftypefn Supplement {long int} random (void)
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@deftypefnx Supplement void srandom (unsigned int @var{seed})
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@deftypefnx Supplement void srandom (unsigned int @var{seed})
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@deftypefnx Supplement void* initstate (unsigned int @var{seed}, void *@var{arg_state}, unsigned long @var{n})
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@deftypefnx Supplement void* initstate (unsigned int @var{seed}, void *@var{arg_state}, unsigned long @var{n})
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@deftypefnx Supplement void* setstate (void *@var{arg_state})
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@deftypefnx Supplement void* setstate (void *@var{arg_state})
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|
|
Random number functions. @code{random} returns a random number in the
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Random number functions. @code{random} returns a random number in the
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range 0 to @code{LONG_MAX}. @code{srandom} initializes the random
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range 0 to @code{LONG_MAX}. @code{srandom} initializes the random
|
number generator to some starting point determined by @var{seed}
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number generator to some starting point determined by @var{seed}
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(else, the values returned by @code{random} are always the same for each
|
(else, the values returned by @code{random} are always the same for each
|
run of the program). @code{initstate} and @code{setstate} allow fine-grained
|
run of the program). @code{initstate} and @code{setstate} allow fine-grained
|
control over the state of the random number generator.
|
control over the state of the random number generator.
|
|
|
@end deftypefn
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@end deftypefn
|
|
|
*/
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*/
|
|
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#include <errno.h>
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#include <errno.h>
|
|
|
#if 0
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#if 0
|
|
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#include <ansidecl.h>
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#include <ansidecl.h>
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#include <limits.h>
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#include <limits.h>
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#include <stddef.h>
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#include <stddef.h>
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#include <stdlib.h>
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#include <stdlib.h>
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|
|
#else
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#else
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|
|
#define ULONG_MAX ((unsigned long)(~0L)) /* 0xFFFFFFFF for 32-bits */
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#define ULONG_MAX ((unsigned long)(~0L)) /* 0xFFFFFFFF for 32-bits */
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#define LONG_MAX ((long)(ULONG_MAX >> 1)) /* 0x7FFFFFFF for 32-bits*/
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#define LONG_MAX ((long)(ULONG_MAX >> 1)) /* 0x7FFFFFFF for 32-bits*/
|
|
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#ifdef __STDC__
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#ifdef __STDC__
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# define PTR void *
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# define PTR void *
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# ifndef NULL
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# ifndef NULL
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# define NULL (void *) 0
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# define NULL (void *) 0
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# endif
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# endif
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#else
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#else
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# define PTR char *
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# define PTR char *
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# ifndef NULL
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# ifndef NULL
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# define NULL (void *) 0
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# define NULL (void *) 0
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# endif
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# endif
|
#endif
|
#endif
|
|
|
#endif
|
#endif
|
|
|
long int random (void);
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long int random (void);
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|
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/* An improved random number generation package. In addition to the standard
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/* An improved random number generation package. In addition to the standard
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rand()/srand() like interface, this package also has a special state info
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rand()/srand() like interface, this package also has a special state info
|
interface. The initstate() routine is called with a seed, an array of
|
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
|
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
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then initialized to contain information for random number generation with
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that much state information. Good sizes for the amount of state
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that much state information. Good sizes for the amount of state
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information are 32, 64, 128, and 256 bytes. The state can be switched by
|
information are 32, 64, 128, and 256 bytes. The state can be switched by
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calling the setstate() function with the same array as was initiallized
|
calling the setstate() function with the same array as was initiallized
|
with initstate(). By default, the package runs with 128 bytes of state
|
with initstate(). By default, the package runs with 128 bytes of state
|
information and generates far better random numbers than a linear
|
information and generates far better random numbers than a linear
|
congruential generator. If the amount of state information is less than
|
congruential generator. If the amount of state information is less than
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32 bytes, a simple linear congruential R.N.G. is used. Internally, the
|
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
|
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
|
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
|
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
|
state information will give 7 longs worth of state information, which will
|
allow a degree seven polynomial. (Note: The zeroeth word of state
|
allow a degree seven polynomial. (Note: The zeroeth word of state
|
information also has some other information stored in it; see setstate
|
information also has some other information stored in it; see setstate
|
for details). The random number generation technique is a linear feedback
|
for details). The random number generation technique is a linear feedback
|
shift register approach, employing trinomials (since there are fewer terms
|
shift register approach, employing trinomials (since there are fewer terms
|
to sum up that way). In this approach, the least significant bit of all
|
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,
|
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
|
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).
|
being used, assuming that the polynomial is irreducible and primitive).
|
The higher order bits will have longer periods, since their values are
|
The higher order bits will have longer periods, since their values are
|
also influenced by pseudo-random carries out of the lower bits. The
|
also influenced by pseudo-random carries out of the lower bits. The
|
total period of the generator is approximately deg*(2**deg - 1); thus
|
total period of the generator is approximately deg*(2**deg - 1); thus
|
doubling the amount of state information has a vast influence on the
|
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
|
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
|
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
|
dominant factor. With deg equal to seven, the period is actually much
|
longer than the 7*(2**7 - 1) predicted by this formula. */
|
longer than the 7*(2**7 - 1) predicted by this formula. */
|
|
|
|
|
|
|
/* For each of the currently supported random number generators, we have a
|
/* For each of the currently supported random number generators, we have a
|
break value on the amount of state information (you need at least thi
|
break value on the amount of state information (you need at least thi
|
bytes of state info to support this random number generator), a degree for
|
bytes of state info to support this random number generator), a degree for
|
the polynomial (actually a trinomial) that the R.N.G. is based on, and
|
the polynomial (actually a trinomial) that the R.N.G. is based on, and
|
separation between the two lower order coefficients of the trinomial. */
|
separation between the two lower order coefficients of the trinomial. */
|
|
|
/* Linear congruential. */
|
/* Linear congruential. */
|
#define TYPE_0 0
|
#define TYPE_0 0
|
#define BREAK_0 8
|
#define BREAK_0 8
|
#define DEG_0 0
|
#define DEG_0 0
|
#define SEP_0 0
|
#define SEP_0 0
|
|
|
/* x**7 + x**3 + 1. */
|
/* x**7 + x**3 + 1. */
|
#define TYPE_1 1
|
#define TYPE_1 1
|
#define BREAK_1 32
|
#define BREAK_1 32
|
#define DEG_1 7
|
#define DEG_1 7
|
#define SEP_1 3
|
#define SEP_1 3
|
|
|
/* x**15 + x + 1. */
|
/* x**15 + x + 1. */
|
#define TYPE_2 2
|
#define TYPE_2 2
|
#define BREAK_2 64
|
#define BREAK_2 64
|
#define DEG_2 15
|
#define DEG_2 15
|
#define SEP_2 1
|
#define SEP_2 1
|
|
|
/* x**31 + x**3 + 1. */
|
/* x**31 + x**3 + 1. */
|
#define TYPE_3 3
|
#define TYPE_3 3
|
#define BREAK_3 128
|
#define BREAK_3 128
|
#define DEG_3 31
|
#define DEG_3 31
|
#define SEP_3 3
|
#define SEP_3 3
|
|
|
/* x**63 + x + 1. */
|
/* x**63 + x + 1. */
|
#define TYPE_4 4
|
#define TYPE_4 4
|
#define BREAK_4 256
|
#define BREAK_4 256
|
#define DEG_4 63
|
#define DEG_4 63
|
#define SEP_4 1
|
#define SEP_4 1
|
|
|
|
|
/* Array versions of the above information to make code run faster.
|
/* Array versions of the above information to make code run faster.
|
Relies on fact that TYPE_i == i. */
|
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 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 int seps[MAX_TYPES] = { SEP_0, SEP_1, SEP_2, SEP_3, SEP_4 };
|
|
|
|
|
|
|
/* Initially, everything is set up as if from:
|
/* Initially, everything is set up as if from:
|
initstate(1, randtbl, 128);
|
initstate(1, randtbl, 128);
|
Note that this initialization takes advantage of the fact that srandom
|
Note that this initialization takes advantage of the fact that srandom
|
advances the front and rear pointers 10*rand_deg times, and hence the
|
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
|
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
|
element of the state information, which contains info about the current
|
position of the rear pointer is just
|
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 int randtbl[DEG_3 + 1] =
|
static long int randtbl[DEG_3 + 1] =
|
{ TYPE_3,
|
{ TYPE_3,
|
0x9a319039, 0x32d9c024, 0x9b663182, 0x5da1f342,
|
0x9a319039, 0x32d9c024, 0x9b663182, 0x5da1f342,
|
0xde3b81e0, 0xdf0a6fb5, 0xf103bc02, 0x48f340fb,
|
0xde3b81e0, 0xdf0a6fb5, 0xf103bc02, 0x48f340fb,
|
0x7449e56b, 0xbeb1dbb0, 0xab5c5918, 0x946554fd,
|
0x7449e56b, 0xbeb1dbb0, 0xab5c5918, 0x946554fd,
|
0x8c2e680f, 0xeb3d799f, 0xb11ee0b7, 0x2d436b86,
|
0x8c2e680f, 0xeb3d799f, 0xb11ee0b7, 0x2d436b86,
|
0xda672e2a, 0x1588ca88, 0xe369735d, 0x904f35f7,
|
0xda672e2a, 0x1588ca88, 0xe369735d, 0x904f35f7,
|
0xd7158fd6, 0x6fa6f051, 0x616e6b96, 0xac94efdc,
|
0xd7158fd6, 0x6fa6f051, 0x616e6b96, 0xac94efdc,
|
0x36413f93, 0xc622c298, 0xf5a42ab8, 0x8a88d77b,
|
0x36413f93, 0xc622c298, 0xf5a42ab8, 0x8a88d77b,
|
0xf5ad9d0e, 0x8999220b, 0x27fb47b9
|
0xf5ad9d0e, 0x8999220b, 0x27fb47b9
|
};
|
};
|
|
|
/* FPTR and RPTR are two pointers into the state info, a front and a rear
|
/* 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
|
pointer. These two pointers are always rand_sep places aparts, as they
|
cycle through the state information. (Yes, this does mean we could get
|
cycle through the state information. (Yes, this does mean we could get
|
away with just one pointer, but the code for random is more efficient
|
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:
|
this way). The pointers are left positioned as they would be from the call:
|
initstate(1, randtbl, 128);
|
initstate(1, randtbl, 128);
|
(The position of the rear pointer, rptr, is really 0 (as explained above
|
(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
|
in the initialization of randtbl) because the state table pointer is set
|
to point to randtbl[1] (as explained below).) */
|
to point to randtbl[1] (as explained below).) */
|
|
|
static long int *fptr = &randtbl[SEP_3 + 1];
|
static long int *fptr = &randtbl[SEP_3 + 1];
|
static long int *rptr = &randtbl[1];
|
static long int *rptr = &randtbl[1];
|
|
|
|
|
|
|
/* The following things are the pointer to the state information table,
|
/* The following things are the pointer to the state information table,
|
the type of the current generator, the degree of the current polynomial
|
the type of the current generator, the degree of the current polynomial
|
being used, and the separation between the two pointers.
|
being used, and the separation between the two pointers.
|
Note that for efficiency of random, we remember the first location of
|
Note that for efficiency of random, we remember the first location of
|
the state information, not the zeroeth. Hence it is valid to access
|
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.
|
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
|
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
|
indexing every time to find the address of the last element to see if
|
the front and rear pointers have wrapped. */
|
the front and rear pointers have wrapped. */
|
|
|
static long int *state = &randtbl[1];
|
static long int *state = &randtbl[1];
|
|
|
static int rand_type = TYPE_3;
|
static int rand_type = TYPE_3;
|
static int rand_deg = DEG_3;
|
static int rand_deg = DEG_3;
|
static int rand_sep = SEP_3;
|
static int rand_sep = SEP_3;
|
|
|
static long int *end_ptr = &randtbl[sizeof(randtbl) / sizeof(randtbl[0])];
|
static long int *end_ptr = &randtbl[sizeof(randtbl) / sizeof(randtbl[0])];
|
|
|
/* Initialize the random number generator based on the given seed. If the
|
/* Initialize the random number generator based on the given seed. If the
|
type is the trivial no-state-information type, just remember the seed.
|
type is the trivial no-state-information type, just remember the seed.
|
Otherwise, initializes state[] based on the given "seed" via a linear
|
Otherwise, initializes state[] based on the given "seed" via a linear
|
congruential generator. Then, the pointers are set to known locations
|
congruential generator. Then, the pointers are set to known locations
|
that are exactly rand_sep places apart. Lastly, it cycles the state
|
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
|
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[]
|
introduced by the L.C.R.N.G. Note that the initialization of randtbl[]
|
for default usage relies on values produced by this routine. */
|
for default usage relies on values produced by this routine. */
|
void
|
void
|
srandom (unsigned int x)
|
srandom (unsigned int x)
|
{
|
{
|
state[0] = x;
|
state[0] = x;
|
if (rand_type != TYPE_0)
|
if (rand_type != TYPE_0)
|
{
|
{
|
register long int i;
|
register long int i;
|
for (i = 1; i < rand_deg; ++i)
|
for (i = 1; i < rand_deg; ++i)
|
state[i] = (1103515145 * state[i - 1]) + 12345;
|
state[i] = (1103515145 * state[i - 1]) + 12345;
|
fptr = &state[rand_sep];
|
fptr = &state[rand_sep];
|
rptr = &state[0];
|
rptr = &state[0];
|
for (i = 0; i < 10 * rand_deg; ++i)
|
for (i = 0; i < 10 * rand_deg; ++i)
|
random();
|
random();
|
}
|
}
|
}
|
}
|
|
|
/* Initialize the state information in the given array of N bytes for
|
/* Initialize the state information in the given array of N bytes for
|
future random number generation. Based on the number of bytes we
|
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
|
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
|
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
|
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
|
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
|
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.
|
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
|
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.
|
setstate so that it doesn't matter when initstate is called.
|
Returns a pointer to the old state. */
|
Returns a pointer to the old state. */
|
PTR
|
PTR
|
initstate (unsigned int seed, PTR arg_state, unsigned long n)
|
initstate (unsigned int seed, PTR arg_state, unsigned long n)
|
{
|
{
|
PTR ostate = (PTR) &state[-1];
|
PTR ostate = (PTR) &state[-1];
|
|
|
if (rand_type == TYPE_0)
|
if (rand_type == TYPE_0)
|
state[-1] = rand_type;
|
state[-1] = rand_type;
|
else
|
else
|
state[-1] = (MAX_TYPES * (rptr - state)) + rand_type;
|
state[-1] = (MAX_TYPES * (rptr - state)) + rand_type;
|
if (n < BREAK_1)
|
if (n < BREAK_1)
|
{
|
{
|
if (n < BREAK_0)
|
if (n < BREAK_0)
|
{
|
{
|
errno = EINVAL;
|
errno = EINVAL;
|
return NULL;
|
return NULL;
|
}
|
}
|
rand_type = TYPE_0;
|
rand_type = TYPE_0;
|
rand_deg = DEG_0;
|
rand_deg = DEG_0;
|
rand_sep = SEP_0;
|
rand_sep = SEP_0;
|
}
|
}
|
else if (n < BREAK_2)
|
else if (n < BREAK_2)
|
{
|
{
|
rand_type = TYPE_1;
|
rand_type = TYPE_1;
|
rand_deg = DEG_1;
|
rand_deg = DEG_1;
|
rand_sep = SEP_1;
|
rand_sep = SEP_1;
|
}
|
}
|
else if (n < BREAK_3)
|
else if (n < BREAK_3)
|
{
|
{
|
rand_type = TYPE_2;
|
rand_type = TYPE_2;
|
rand_deg = DEG_2;
|
rand_deg = DEG_2;
|
rand_sep = SEP_2;
|
rand_sep = SEP_2;
|
}
|
}
|
else if (n < BREAK_4)
|
else if (n < BREAK_4)
|
{
|
{
|
rand_type = TYPE_3;
|
rand_type = TYPE_3;
|
rand_deg = DEG_3;
|
rand_deg = DEG_3;
|
rand_sep = SEP_3;
|
rand_sep = SEP_3;
|
}
|
}
|
else
|
else
|
{
|
{
|
rand_type = TYPE_4;
|
rand_type = TYPE_4;
|
rand_deg = DEG_4;
|
rand_deg = DEG_4;
|
rand_sep = SEP_4;
|
rand_sep = SEP_4;
|
}
|
}
|
|
|
state = &((long int *) arg_state)[1]; /* First location. */
|
state = &((long int *) arg_state)[1]; /* First location. */
|
/* Must set END_PTR before srandom. */
|
/* Must set END_PTR before srandom. */
|
end_ptr = &state[rand_deg];
|
end_ptr = &state[rand_deg];
|
srandom(seed);
|
srandom(seed);
|
if (rand_type == TYPE_0)
|
if (rand_type == TYPE_0)
|
state[-1] = rand_type;
|
state[-1] = rand_type;
|
else
|
else
|
state[-1] = (MAX_TYPES * (rptr - state)) + rand_type;
|
state[-1] = (MAX_TYPES * (rptr - state)) + rand_type;
|
|
|
return ostate;
|
return ostate;
|
}
|
}
|
|
|
/* Restore the state from the given state array.
|
/* Restore the state from the given state array.
|
Note: It is important that we also remember the locations of the pointers
|
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
|
in the current state information, and restore the locations of the pointers
|
from the old state information. This is done by multiplexing the pointer
|
from the old state information. This is done by multiplexing the pointer
|
location into the zeroeth word of the state information. Note that due
|
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
|
to the order in which things are done, it is OK to call setstate with the
|
same state as the current state
|
same state as the current state
|
Returns a pointer to the old state information. */
|
Returns a pointer to the old state information. */
|
|
|
PTR
|
PTR
|
setstate (PTR arg_state)
|
setstate (PTR arg_state)
|
{
|
{
|
register long int *new_state = (long int *) arg_state;
|
register long int *new_state = (long int *) arg_state;
|
register int type = new_state[0] % MAX_TYPES;
|
register int type = new_state[0] % MAX_TYPES;
|
register int rear = new_state[0] / MAX_TYPES;
|
register int rear = new_state[0] / MAX_TYPES;
|
PTR ostate = (PTR) &state[-1];
|
PTR ostate = (PTR) &state[-1];
|
|
|
if (rand_type == TYPE_0)
|
if (rand_type == TYPE_0)
|
state[-1] = rand_type;
|
state[-1] = rand_type;
|
else
|
else
|
state[-1] = (MAX_TYPES * (rptr - state)) + rand_type;
|
state[-1] = (MAX_TYPES * (rptr - state)) + rand_type;
|
|
|
switch (type)
|
switch (type)
|
{
|
{
|
case TYPE_0:
|
case TYPE_0:
|
case TYPE_1:
|
case TYPE_1:
|
case TYPE_2:
|
case TYPE_2:
|
case TYPE_3:
|
case TYPE_3:
|
case TYPE_4:
|
case TYPE_4:
|
rand_type = type;
|
rand_type = type;
|
rand_deg = degrees[type];
|
rand_deg = degrees[type];
|
rand_sep = seps[type];
|
rand_sep = seps[type];
|
break;
|
break;
|
default:
|
default:
|
/* State info munged. */
|
/* State info munged. */
|
errno = EINVAL;
|
errno = EINVAL;
|
return NULL;
|
return NULL;
|
}
|
}
|
|
|
state = &new_state[1];
|
state = &new_state[1];
|
if (rand_type != TYPE_0)
|
if (rand_type != TYPE_0)
|
{
|
{
|
rptr = &state[rear];
|
rptr = &state[rear];
|
fptr = &state[(rear + rand_sep) % rand_deg];
|
fptr = &state[(rear + rand_sep) % rand_deg];
|
}
|
}
|
/* Set end_ptr too. */
|
/* Set end_ptr too. */
|
end_ptr = &state[rand_deg];
|
end_ptr = &state[rand_deg];
|
|
|
return ostate;
|
return ostate;
|
}
|
}
|
|
|
/* If we are using the trivial TYPE_0 R.N.G., just do the old linear
|
/* 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
|
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
|
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
|
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
|
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,
|
location cyclically in the table. The value returned is the sum generated,
|
reduced to 31 bits by throwing away the "least random" low bit.
|
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
|
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
|
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. */
|
pointer if the front one has wrapped. Returns a 31-bit random number. */
|
|
|
long int
|
long int
|
random (void)
|
random (void)
|
{
|
{
|
if (rand_type == TYPE_0)
|
if (rand_type == TYPE_0)
|
{
|
{
|
state[0] = ((state[0] * 1103515245) + 12345) & LONG_MAX;
|
state[0] = ((state[0] * 1103515245) + 12345) & LONG_MAX;
|
return state[0];
|
return state[0];
|
}
|
}
|
else
|
else
|
{
|
{
|
long int i;
|
long int i;
|
*fptr += *rptr;
|
*fptr += *rptr;
|
/* Chucking least random bit. */
|
/* Chucking least random bit. */
|
i = (*fptr >> 1) & LONG_MAX;
|
i = (*fptr >> 1) & LONG_MAX;
|
++fptr;
|
++fptr;
|
if (fptr >= end_ptr)
|
if (fptr >= end_ptr)
|
{
|
{
|
fptr = state;
|
fptr = state;
|
++rptr;
|
++rptr;
|
}
|
}
|
else
|
else
|
{
|
{
|
++rptr;
|
++rptr;
|
if (rptr >= end_ptr)
|
if (rptr >= end_ptr)
|
rptr = state;
|
rptr = state;
|
}
|
}
|
return i;
|
return i;
|
}
|
}
|
}
|
}
|
|
|
