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added atomic_dec32le0 for sem/mutex lock

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This commit is contained in:
Oleg Borodin
2022-08-31 10:10:35 +02:00
parent 5424edfe5e
commit d071c0957b
5 changed files with 22 additions and 7 deletions
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18
atomic.S
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@@ -20,10 +20,24 @@ atomic_inc32:
.type atomic_dec32, %function .type atomic_dec32, %function
atomic_dec32: atomic_dec32:
2: ldrex r2, [r0] 1: ldrex r2, [r0]
sub r2, r2, r1 sub r2, r2, r1
strex r3, r2, [r0] strex r3, r2, [r0]
teq r3, #0 teq r3, #0
bne 2b bne 1b
mov r0, r2
bx lr
.globl atomic_dec32le0
.type atomic_dec32le0, %function
atomic_dec32le0:
1: ldrex r2, [r0]
cmp r2, #0
ble 1b
sub r2, r2, r1
strex r3, r2, [r0]
teq r3, #0
bne 1b
mov r0, r2 mov r0, r2
bx lr bx lr

2
atomic.h
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@@ -10,4 +10,6 @@
int32_t atomic_inc32(volatile int32_t *addr, int32_t value); int32_t atomic_inc32(volatile int32_t *addr, int32_t value);
int32_t atomic_dec32(volatile int32_t *addr, int32_t value); int32_t atomic_dec32(volatile int32_t *addr, int32_t value);
int32_t atomic_dec32le0(volatile int32_t *addr, int32_t value);
#endif #endif

3
mutex.c
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@@ -13,8 +13,7 @@ int32_t mutex_lock(mutex_t* mutex) {
//while(mutex->value <= 0); //while(mutex->value <= 0);
//mutex->value--; //mutex->value--;
//return mutex->value; //return mutex->value;
while (atomic_dec32(&(mutex->value), (int32_t)0) <= 0); return atomic_dec32le0(&(mutex->value), (int32_t)1);
return atomic_dec32(&(mutex->value), (int32_t)1);
} }
int32_t mutex_unlock(mutex_t* mutex) { int32_t mutex_unlock(mutex_t* mutex) {

2
scheduler.c
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@@ -73,7 +73,7 @@ void scheduler_task(scheduler_t *scheduler, int task_no, void (*entry)(void)) {
static void scheduler_switch(scheduler_t *scheduler) { static void scheduler_switch(scheduler_t *scheduler) {
do { do {
scheduler->current_task = (scheduler->current_task + 1) % SCHEDULER_NUM_TASKS; scheduler->current_task = (scheduler->current_task) % SCHEDULER_NUM_TASKS;
} while (!scheduler->tasks[scheduler->current_task].runnable); } while (!scheduler->tasks[scheduler->current_task].runnable);
} }

4
semaphore.c
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@@ -13,8 +13,8 @@ int32_t sem_wait(sem_t* sem) {
//while(sem->value <= 0); //while(sem->value <= 0);
//sem->value--; //sem->value--;
//return sem->value; //return sem->value;
while (atomic_dec32(&(sem->value), (int32_t)0) <= 0); //while (atomic_dec32(&(sem->value), (int32_t)0) <= 0);
return atomic_dec32(&(sem->value), (int32_t)1); return atomic_dec32le0(&(sem->value), (int32_t)1);
} }
int32_t sem_post(sem_t* sem) { int32_t sem_post(sem_t* sem) {