57 lines
1.5 KiB
C
57 lines
1.5 KiB
C
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/*
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------------------------------------------------------------------------------
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rand.h: definitions for a random number generator
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By Bob Jenkins, 1996, Public Domain
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MODIFIED:
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960327: Creation (addition of randinit, really)
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970719: use context, not global variables, for internal state
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980324: renamed seed to flag
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980605: recommend RANDSIZL=4 for noncryptography.
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010626: note this is public domain
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------------------------------------------------------------------------------
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*/
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#ifndef STANDARD
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#include "standard.h"
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#endif
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#ifndef RAND
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#define RAND
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#define RANDSIZL (8) /* I recommend 8 for crypto, 4 for simulations */
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#define RANDSIZ (1<<RANDSIZL)
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/* context of random number generator */
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struct randctx
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{
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ub4 randcnt;
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ub4 randrsl[RANDSIZ];
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ub4 randmem[RANDSIZ];
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ub4 randa;
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ub4 randb;
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ub4 randc;
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};
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typedef struct randctx randctx;
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/*
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------------------------------------------------------------------------------
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If (flag==TRUE), then use the contents of randrsl[0..RANDSIZ-1] as the seed.
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------------------------------------------------------------------------------
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*/
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void randinit(randctx *r, word flag);
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void isaac(randctx *r);
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/*
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------------------------------------------------------------------------------
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Call rand(/o_ randctx *r _o/) to retrieve a single 32-bit random value
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------------------------------------------------------------------------------
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*/
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#define rand(r) \
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(!(r)->randcnt-- ? \
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(isaac(r), (r)->randcnt=RANDSIZ-1, (r)->randrsl[(r)->randcnt]) : \
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(r)->randrsl[(r)->randcnt])
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#endif /* RAND */
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