mirror of
https://github.com/jart/cosmopolitan.git
synced 2025-02-01 20:13:31 +00:00
046c7ebd4a
- Introduce fast spinlock API - Double rand64() perf w/ spinlock - Improve raise() on New Technology - Support gettid() across platforms - Implement SA_NODEFER on New Technology - Move the lock intrinsics into LIBC_INTRIN - Make SIGTRAP recoverable on New Technology - Block SIGCHLD in wait4() on New Technology - Add threading prototypes for XNU and FreeBSD - Rewrite abort() fixing its minor bugs on XNU/NT - Shave down a lot of the content in libc/bits/bits.h - Let signal handlers modify CPU registers on New Technology
46 lines
1.5 KiB
C
46 lines
1.5 KiB
C
#ifndef COSMOPOLITAN_LIBC_BITS_CMPXCHG16B_INTERNAL_H_
|
|
#define COSMOPOLITAN_LIBC_BITS_CMPXCHG16B_INTERNAL_H_
|
|
#include "libc/bits/asmflag.h"
|
|
#if !(__ASSEMBLER__ + __LINKER__ + 0)
|
|
COSMOPOLITAN_C_START_
|
|
|
|
/**
|
|
* Compares and exchanges 128-bit value, i.e.
|
|
*
|
|
* if (*IfThing == *IsEqualToMe) {
|
|
* *IfThing = ReplaceItWithMe;
|
|
* return true;
|
|
* } else {
|
|
* *IsEqualToMe = *IfThing;
|
|
* return false;
|
|
* }
|
|
*
|
|
* Please note that Intel Architecture doesn't guarantee 16-byte memory
|
|
* accesses to be atomic on their own. Therefore _lockcmpxchg16b should
|
|
* be considered instead for both thread and asynchronous signal safety
|
|
*
|
|
* @param IfThing should point to aligned memory
|
|
* @param IsEqualToMe should point to in/out local variable
|
|
* @param ReplaceItWithMe might become the new memory value
|
|
* @return true if *IfThing was changed
|
|
*/
|
|
static inline bool _cmpxchg16b(uint128_t *IfThing, uint128_t *IsEqualToMe,
|
|
uint128_t ReplaceItWithMe) {
|
|
bool DidIt;
|
|
uint64_t ax, bx, cx, dx;
|
|
ax = *IsEqualToMe;
|
|
dx = *IsEqualToMe >> 64;
|
|
bx = ReplaceItWithMe;
|
|
cx = ReplaceItWithMe >> 64;
|
|
asm volatile(ZFLAG_ASM("cmpxchg16b\t%1")
|
|
: ZFLAG_CONSTRAINT(DidIt), "+m"(*IfThing), "+a"(ax), "+d"(dx)
|
|
: "b"(bx), "c"(cx));
|
|
if (!DidIt) {
|
|
*IsEqualToMe = ax | (uint128_t)dx << 64;
|
|
}
|
|
return DidIt;
|
|
}
|
|
|
|
COSMOPOLITAN_C_END_
|
|
#endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
|
|
#endif /* COSMOPOLITAN_LIBC_BITS_CMPXCHG16B_INTERNAL_H_ */
|