2 #include "os/os_thread.h"
3 #include "pipe/p_defines.h"
4 #include "util/u_ringbuffer.h"
5 #include "util/u_math.h"
6 #include "util/u_memory.h"
10 struct util_ringbuffer
12 struct util_packet *buf;
15 /* Can this be done with atomic variables??
24 struct util_ringbuffer *util_ringbuffer_create( unsigned dwords )
26 struct util_ringbuffer *ring = CALLOC_STRUCT(util_ringbuffer);
30 assert(util_is_power_of_two(dwords));
32 ring->buf = MALLOC( dwords * sizeof(unsigned) );
33 if (ring->buf == NULL)
36 ring->mask = dwords - 1;
38 pipe_condvar_init(ring->change);
39 pipe_mutex_init(ring->mutex);
48 void util_ringbuffer_destroy( struct util_ringbuffer *ring )
50 pipe_condvar_destroy(ring->change);
51 pipe_mutex_destroy(ring->mutex);
57 * Return number of free entries in the ring
59 static INLINE unsigned util_ringbuffer_space( const struct util_ringbuffer *ring )
61 return (ring->tail - (ring->head + 1)) & ring->mask;
65 * Is the ring buffer empty?
67 static INLINE boolean util_ringbuffer_empty( const struct util_ringbuffer *ring )
69 return util_ringbuffer_space(ring) == ring->mask;
72 void util_ringbuffer_enqueue( struct util_ringbuffer *ring,
73 const struct util_packet *packet )
77 /* XXX: over-reliance on mutexes, etc:
79 pipe_mutex_lock(ring->mutex);
81 /* make sure we don't request an impossible amount of space
83 assert(packet->dwords <= ring->mask);
85 /* Wait for free space:
87 while (util_ringbuffer_space(ring) < packet->dwords)
88 pipe_condvar_wait(ring->change, ring->mutex);
92 for (i = 0; i < packet->dwords; i++) {
94 /* Copy all dwords of the packet. Note we're abusing the
95 * typesystem a little - we're being passed a pointer to
96 * something, but probably not an array of packet structs:
98 ring->buf[ring->head] = packet[i];
100 ring->head &= ring->mask;
105 pipe_condvar_signal(ring->change);
106 pipe_mutex_unlock(ring->mutex);
109 enum pipe_error util_ringbuffer_dequeue( struct util_ringbuffer *ring,
110 struct util_packet *packet,
114 const struct util_packet *ring_packet;
118 /* XXX: over-reliance on mutexes, etc:
120 pipe_mutex_lock(ring->mutex);
122 /* Get next ring entry:
125 while (util_ringbuffer_empty(ring))
126 pipe_condvar_wait(ring->change, ring->mutex);
129 if (util_ringbuffer_empty(ring)) {
130 ret = PIPE_ERROR_OUT_OF_MEMORY;
135 ring_packet = &ring->buf[ring->tail];
137 /* Both of these are considered bugs. Raise an assert on debug builds.
139 if (ring_packet->dwords > ring->mask + 1 - util_ringbuffer_space(ring) ||
140 ring_packet->dwords > max_dwords) {
142 ret = PIPE_ERROR_BAD_INPUT;
146 /* Copy data from ring:
148 for (i = 0; i < ring_packet->dwords; i++) {
149 packet[i] = ring->buf[ring->tail];
151 ring->tail &= ring->mask;
157 pipe_condvar_signal(ring->change);
158 pipe_mutex_unlock(ring->mutex);