ainc, adec, cas32, cas, casp, casl, cas64, mfence – atomic operations

#include <u.h>
#include <libc.h>

int ainc(long *p)

int adec(long *p)

int cas(uint *p, int ov, int nv)

int casp(void **p, void *ov, void *nv)

int casl(ulong *p, ulong ov, ulong nv)

int cas32(u32int *p, u32int ov, u32int nv)

int cas64(u64int *p, u64int ov, u64int nv)

void mfence(void)

These functions provide access to atomic operations, useful for synchronization.

Ainc and adec atomically increment and decrement (respectively) the integer pointed to by p, and return the resulting value after the operation.

Cas performs a compare and swap on the word pointed to by p, provided that the value is still ov (the old value), so that the new value is nv. Functions cas32, cas64, casp, and casul do the same for 32–bit values, 64–bit values, pointers, and unsigned long integers.

Mfence sets a memory fence so that all outstanding memory operations are performed before returning from it.



Some of them may not be implemented for some architectures.
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