161 lines
3.6 KiB
C
161 lines
3.6 KiB
C
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#include "os/os_thread.h"
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#include "pipe/p_defines.h"
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#include "util/u_ringbuffer.h"
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#include "util/u_math.h"
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#include "util/u_memory.h"
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/* Generic ringbuffer:
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*/
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struct util_ringbuffer
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{
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struct util_packet *buf;
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unsigned mask;
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/* Can this be done with atomic variables??
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*/
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unsigned head;
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unsigned tail;
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pipe_condvar change;
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pipe_mutex mutex;
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};
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struct util_ringbuffer *util_ringbuffer_create( unsigned dwords )
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{
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struct util_ringbuffer *ring = CALLOC_STRUCT(util_ringbuffer);
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if (ring == NULL)
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return NULL;
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assert(util_is_power_of_two(dwords));
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ring->buf = MALLOC( dwords * sizeof(unsigned) );
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if (ring->buf == NULL)
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goto fail;
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ring->mask = dwords - 1;
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pipe_condvar_init(ring->change);
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pipe_mutex_init(ring->mutex);
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return ring;
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fail:
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FREE(ring->buf);
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FREE(ring);
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return NULL;
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}
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void util_ringbuffer_destroy( struct util_ringbuffer *ring )
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{
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pipe_condvar_destroy(ring->change);
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pipe_mutex_destroy(ring->mutex);
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FREE(ring->buf);
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FREE(ring);
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}
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/**
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* Return number of free entries in the ring
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*/
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static INLINE unsigned util_ringbuffer_space( const struct util_ringbuffer *ring )
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{
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return (ring->tail - (ring->head + 1)) & ring->mask;
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}
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/**
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* Is the ring buffer empty?
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*/
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static INLINE boolean util_ringbuffer_empty( const struct util_ringbuffer *ring )
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{
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return util_ringbuffer_space(ring) == ring->mask;
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}
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void util_ringbuffer_enqueue( struct util_ringbuffer *ring,
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const struct util_packet *packet )
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{
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unsigned i;
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/* XXX: over-reliance on mutexes, etc:
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*/
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pipe_mutex_lock(ring->mutex);
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/* make sure we don't request an impossible amount of space
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*/
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assert(packet->dwords <= ring->mask);
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/* Wait for free space:
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*/
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while (util_ringbuffer_space(ring) < packet->dwords)
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pipe_condvar_wait(ring->change, ring->mutex);
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/* Copy data to ring:
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*/
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for (i = 0; i < packet->dwords; i++) {
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/* Copy all dwords of the packet. Note we're abusing the
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* typesystem a little - we're being passed a pointer to
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* something, but probably not an array of packet structs:
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*/
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ring->buf[ring->head] = packet[i];
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ring->head++;
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ring->head &= ring->mask;
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}
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/* Signal change:
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*/
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pipe_condvar_signal(ring->change);
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pipe_mutex_unlock(ring->mutex);
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}
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enum pipe_error util_ringbuffer_dequeue( struct util_ringbuffer *ring,
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struct util_packet *packet,
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unsigned max_dwords,
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boolean wait )
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{
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const struct util_packet *ring_packet;
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unsigned i;
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int ret = PIPE_OK;
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/* XXX: over-reliance on mutexes, etc:
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*/
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pipe_mutex_lock(ring->mutex);
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/* Get next ring entry:
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*/
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if (wait) {
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while (util_ringbuffer_empty(ring))
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pipe_condvar_wait(ring->change, ring->mutex);
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}
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else {
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if (util_ringbuffer_empty(ring)) {
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ret = PIPE_ERROR_OUT_OF_MEMORY;
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goto out;
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}
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}
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ring_packet = &ring->buf[ring->tail];
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/* Both of these are considered bugs. Raise an assert on debug builds.
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*/
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if (ring_packet->dwords > ring->mask + 1 - util_ringbuffer_space(ring) ||
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ring_packet->dwords > max_dwords) {
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assert(0);
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ret = PIPE_ERROR_BAD_INPUT;
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goto out;
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}
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/* Copy data from ring:
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*/
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for (i = 0; i < ring_packet->dwords; i++) {
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packet[i] = ring->buf[ring->tail];
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ring->tail++;
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ring->tail &= ring->mask;
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}
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out:
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/* Signal change:
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*/
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pipe_condvar_signal(ring->change);
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pipe_mutex_unlock(ring->mutex);
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return ret;
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}
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