63 lines
1.2 KiB
C
63 lines
1.2 KiB
C
#pragma omp
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#define LRWL_WRITE_ACTIVE (1UL<<31)
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#define LRWL_MASK (LRWL_WRITE_ACTIVE - 1)
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#define LRWL_MAX_READERS 1024
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typedef struct LRWL {
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_Atomic uint32_t data;
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} LRWL;
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static inline void lrwl_read_lock(LRWL *self) {
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while(1) {
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uint32_t data = atomic_load(&self->data);
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if((data & LRWL_WRITE_ACTIVE) || (data & LRWL_MASK) >= LRWL_MAX_READERS) {
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continue;
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}
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if(atomic_compare_exchange_weak(&self->data, &data, data + 1)) {
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return;
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}
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}
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}
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static inline void lrwl_read_unlock(LRWL *self) {
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while(1) {
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uint32_t data = atomic_load(&self->data);
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assert((data & LRWL_MASK) > 0);
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if(atomic_compare_exchange_weak(&self->data, &data, data - 1)) {
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return;
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}
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}
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}
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static inline void lrwl_write_lock(LRWL *self) {
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while(1) {
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uint32_t data = atomic_load(&self->data);
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if(data & LRWL_WRITE_ACTIVE) {
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continue;
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}
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if(atomic_compare_exchange_weak(&self->data, &data, data | LRWL_WRITE_ACTIVE)) {
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while((atomic_load(&self->data) & LRWL_MASK) > 0);
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return;
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}
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}
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}
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static inline void lrwl_write_unlock(LRWL *self) {
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while(1) {
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uint32_t data = atomic_load(&self->data);
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assert(data & LRWL_WRITE_ACTIVE);
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if(atomic_compare_exchange_weak(&self->data, &data, data & ~LRWL_WRITE_ACTIVE)) {
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return;
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}
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}
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} |