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usb_queue: Use ldrex/strex to avoid disabling interrupts

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This commit is contained in:
Ben Gamari
2013-07-07 21:54:25 -04:00
parent e23cc9bd6c
commit f50253eaa3
1 changed files with 13 additions and 6 deletions
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19
firmware/hackrf_usb/usb_queue.c
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@ -26,6 +26,7 @@
#include <assert.h>
#include <libopencm3/cm3/cortex.h>
#include <libopencm3/cm3/sync.h>
#include "usb.h"
#include "usb_queue.h"
@ -61,19 +62,25 @@ void usb_queue_init() {
/* Allocate a transfer */
static usb_transfer_t* allocate_transfer()
{
bool aborted;
usb_transfer_t* transfer;
while (free_transfers == NULL);
cm_disable_interrupts();
usb_transfer_t* const transfer = free_transfers;
free_transfers = transfer->next;
cm_enable_interrupts();
do {
transfer = (void *) __ldrex((uint32_t *) &free_transfers);
aborted = __strex((uint32_t) transfer->next, (uint32_t *) &free_transfers);
} while (aborted);
transfer->next = NULL;
return transfer;
}
/* Place a transfer in the free list */
static void free_transfer(usb_transfer_t* const transfer)
{
transfer->next = free_transfers;
free_transfers = transfer;
bool aborted;
do {
transfer->next = (void *) __ldrex((uint32_t *) &free_transfers);
aborted = __strex((uint32_t) transfer, (uint32_t *) &free_transfers);
} while (aborted);
}
/* Add a transfer to the end of an endpoint's queue */