cosmopolitan/libc/mem/shuffle.internal.h
Jōshin 89fc95fefd
Rerun clang-format on the repo (#1217)
🚨 clang-format changes output per version!

This is with version 19.0.0. The modifications seem to be fixing the old
version’s errors - mainly involving omitted whitespace around binary ops
and inserted whitespace between goto labels and colons (if followed by a
curly brace.)

Also fixes a few mistakes made by e.g. someone (ahem) forgetting to pass
his ctl/string.h modifications through it.

We should add this to .git-blame-ignore-revs once we have its final hash
on master.
2024-06-15 16:34:48 -04:00

21 lines
645 B
C

#ifndef COSMOPOLITAN_LIBC_RAND_SHUFFLE_H_
#define COSMOPOLITAN_LIBC_RAND_SHUFFLE_H_
#include "libc/intrin/xchg.internal.h"
/**
* Fisher-Yates shuffle.
*
* @param R is a function like rand() → ≥0
* @param A is a typed array
* @param n is the number of items in A
* @see ARRAYLEN()
*/
#define shuffle(R, A, n) \
do { \
autotype(A) Array = (A); \
for (size_t i = (n) - 1; i >= 1; --i) { \
xchg(&Array[i], &Array[R() % (i + 1)]); \
} \
} while (0)
#endif /* COSMOPOLITAN_LIBC_RAND_SHUFFLE_H_ */