mirror of
git://git.musl-libc.org/musl
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d960d4f2cb
this port assumes eabi calling conventions, eabi linux syscall convention, and presence of the kernel helpers at 0xffff0f?0 needed for threads support. otherwise it makes very few assumptions, and the code should work even on armv4 without thumb support, as well as on systems with thumb interworking. the bits headers declare this a little endian system, but as far as i can tell the code should work equally well on big endian. some small details are probably broken; so far, testing has been limited to qemu/aboriginal linux.
113 lines
1.8 KiB
C
113 lines
1.8 KiB
C
#ifndef _INTERNAL_ATOMIC_H
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#define _INTERNAL_ATOMIC_H
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#include <stdint.h>
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static inline int a_ctz_l(unsigned long x)
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{
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static const char debruijn32[32] = {
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0, 1, 23, 2, 29, 24, 19, 3, 30, 27, 25, 11, 20, 8, 4, 13,
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31, 22, 28, 18, 26, 10, 7, 12, 21, 17, 9, 6, 16, 5, 15, 14
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};
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return debruijn32[(x&-x)*0x076be629 >> 27];
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}
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static inline int a_ctz_64(uint64_t x)
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{
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uint32_t y = x;
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if (!y) {
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y = x>>32;
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return 32 + a_ctz_l(y);
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}
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return a_ctz_l(y);
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}
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static inline int a_cas(volatile int *p, int t, int s)
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{
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int old;
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for (;;) {
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if (!((int (*)(int, int, volatile int *))0xffff0fc0)(t, s, p))
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return t;
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if ((old=*p) != t)
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return old;
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}
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}
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static inline void *a_cas_p(volatile void *p, void *t, void *s)
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{
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return (void *)a_cas(p, (int)t, (int)s);
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}
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static inline long a_cas_l(volatile void *p, long t, long s)
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{
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return a_cas(p, t, s);
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}
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static inline int a_swap(volatile int *x, int v)
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{
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int old;
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do old = *x;
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while (a_cas(x, old, v) != old);
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return old;
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}
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static inline int a_fetch_add(volatile int *x, int v)
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{
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int old;
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do old = *x;
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while (a_cas(x, old, old+v) != old);
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return old;
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}
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static inline void a_inc(volatile int *x)
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{
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a_fetch_add(x, 1);
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}
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static inline void a_dec(volatile int *x)
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{
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a_fetch_add(x, -1);
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}
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static inline void a_store(volatile int *p, int x)
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{
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*p=x;
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}
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static inline void a_spin()
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{
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}
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static inline void a_crash()
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{
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*(volatile char *)0=0;
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}
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static inline void a_and(volatile int *p, int v)
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{
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int old;
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do old = *p;
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while (a_cas(p, old, old&v) != old);
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}
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static inline void a_or(volatile int *p, int v)
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{
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int old;
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do old = *p;
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while (a_cas(p, old, old|v) != old);
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}
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static inline void a_and_64(volatile uint64_t *p, uint64_t v)
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{
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a_and((int *)p, v);
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a_and((int *)p+1, v>>32);
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}
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static inline void a_or_64(volatile uint64_t *p, uint64_t v)
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{
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a_or((int *)p, v);
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a_or((int *)p+1, v>>32);
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}
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#endif
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