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cwfs: remove orphaned lrand.c

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This commit is contained in:
cinap_lenrek 2019-06-20 14:15:20 +02:00
parent d8a8ac237a
commit b767b2ce23
1 changed files with 0 additions and 83 deletions
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83
sys/src/cmd/cwfs/lrand.c
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@ -1,83 +0,0 @@
#include "all.h"
/*
* algorithm by
* D. P. Mitchell & J. A. Reeds
*/
enum {
LEN = 607,
TAP = 273,
MASK = 0x7fffffffL,
A = 48271,
M = 2147483647,
Q = 44488,
R = 3399,
};
#define NORM (1.0/(1.0+MASK))
static ulong rng_vec[LEN];
static ulong* rng_tap = rng_vec;
static ulong* rng_feed = 0;
static Lock lk;
static void
isrand(long seed)
{
long lo, hi, x;
int i;
rng_tap = rng_vec;
rng_feed = rng_vec+LEN-TAP;
seed %= M;
if(seed < 0)
seed += M;
if(seed == 0)
seed = 89482311;
x = seed;
/*
* Initialize by x[n+1] = 48271 * x[n] mod (2**31 - 1)
*/
for(i = -20; i < LEN; i++) {
hi = x / Q;
lo = x % Q;
x = A*lo - R*hi;
if(x < 0)
x += M;
if(i >= 0)
rng_vec[i] = x;
}
}
void
srand(long seed)
{
lock(&lk);
isrand(seed);
unlock(&lk);
}
long
lrand(void)
{
ulong x;
lock(&lk);
rng_tap--;
if(rng_tap < rng_vec) {
if(rng_feed == 0) {
isrand(1);
rng_tap--;
}
rng_tap += LEN;
}
rng_feed--;
if(rng_feed < rng_vec)
rng_feed += LEN;
x = (*rng_feed + *rng_tap) & MASK;
*rng_feed = x;
unlock(&lk);
return x;
}