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Introduce a `shuffle' utility function.

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[originally from svn r6090]
This commit is contained in:
Simon Tatham
2005-07-14 17:37:05 +00:00
parent 3d2c442bc4
commit bb63d0d399
2 changed files with 19 additions and 0 deletions
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16
misc.c
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@ -196,4 +196,20 @@ void game_mkhighlight(frontend *fe, float *ret,
} }
} }
void shuffle(void *array, int nelts, int eltsize, random_state *rs)
{
char *tmp = smalloc(eltsize);
char *carray = (char *)array;
int i;
for (i = nelts; i-- > 1 ;) {
int j = random_upto(rs, i+1);
if (j != i) {
memcpy(tmp, carray + eltsize * i, eltsize);
memcpy(carray + eltsize * i, carray + eltsize * j, eltsize);
memcpy(carray + eltsize * j, tmp, eltsize);
}
}
}
/* vim: set shiftwidth=4 tabstop=8: */ /* vim: set shiftwidth=4 tabstop=8: */

3
puzzles.h
View File

@ -223,6 +223,9 @@ unsigned char *hex2bin(const char *in, int outlen);
void game_mkhighlight(frontend *fe, float *ret, void game_mkhighlight(frontend *fe, float *ret,
int background, int highlight, int lowlight); int background, int highlight, int lowlight);
/* Randomly shuffles an array of items. */
void shuffle(void *array, int nelts, int eltsize, random_state *rs);
/* /*
* version.c * version.c
*/ */