kernel.soso/spinlock.c


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#include "spinlock.h"

static inline int32 exchangeAtomic(volatile int32* oldValueAddress, int32 newValue) {
    //no need to use lock instruction on xchg

    asm volatile ("xchgl %0, %1"
                   : "=r"(newValue)
                   : "m"(*oldValueAddress), "0"(newValue)
                   : "memory");
    return newValue;
}

void Spinlock_Init(Spinlock* spinlock) {
    *spinlock = 0;
}

void Spinlock_Lock(Spinlock* spinlock) {
    while (exchangeAtomic((int32*)spinlock, 1)) {
        halt();
    }
}

void Spinlock_Unlock(Spinlock* spinlock) {
    *spinlock = 0;
}