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ringbuffer: improve ringbuffer
Simplify the ringbuffer code by using ideas from the portaudio ringbuffer implementation.
This commit is contained in:
Wim Taymans
parent
4148e0ff78
commit
984375c0b2
2 changed files with 102 additions and 78 deletions
51
spa/include/spa/barrier.h
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51
spa/include/spa/barrier.h
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@ -0,0 +1,51 @@
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/* Simple Plugin API
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* Copyright (C) 2016 Wim Taymans <wim.taymans@gmail.com>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
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* Boston, MA 02110-1301, USA.
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*/
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#ifndef __SPA_BARRIER_H__
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#define __SPA_BARRIER_H__
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include <spa/defs.h>
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#if defined(__GNUC__)
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# if defined( __i386__ ) || defined( __i486__ ) || defined( __i586__ ) || defined( __i686__ ) || defined( __x86_64__ )
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# define spa_barrier_full() asm volatile("mfence":::"memory")
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# define spa_barrier_read() asm volatile("lfence":::"memory")
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# define spa_barrier_write() asm volatile("sfence":::"memory")
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# elif (__GNUC__ > 4) || (__GNUC__ == 4 && __GNUC_MINOR__ >= 1)
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# define spa_barrier_full() __sync_synchronize()
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# define spa_barrier_read() __sync_synchronize()
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# define spa_barrier_write() __sync_synchronize()
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# endif
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#else
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# warning no memory barriers support found
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# define spa_barrier_full()
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# define spa_barrier_read()
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# define spa_barrier_write()
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#endif
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#ifdef __cplusplus
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} /* extern "C" */
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#endif
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#endif /* __SPA_BARRIER_H__ */
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@ -30,6 +30,7 @@ typedef struct _SpaRingbuffer SpaRingbuffer;
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#define SPA_RINGBUFFER_PREFIX SPA_RINGBUFFER_URI "#"
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#include <spa/defs.h>
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#include <spa/barrier.h>
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typedef struct {
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off_t offset;
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@ -47,7 +48,8 @@ struct _SpaRingbuffer {
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volatile size_t readindex;
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volatile size_t writeindex;
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size_t size;
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size_t size_mask;
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size_t mask;
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size_t mask2;
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};
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/**
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@ -57,20 +59,24 @@ struct _SpaRingbuffer {
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* @size: the number of elements in @data
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*
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* Initialize a #SpaRingbuffer with @data and @size.
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* When size is a power of 2, size_mask will be set with the mask to
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* efficiently wrap around the indexes.
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* Size must be a power of 2.
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*
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* Returns: %SPA_RESULT_OK, unless size is not a power of 2.
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*/
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static inline void
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static inline SpaResult
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spa_ringbuffer_init (SpaRingbuffer *rbuf,
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size_t size)
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{
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if ((size & (size - 1)) != 0)
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return SPA_RESULT_ERROR;
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rbuf->size = size;
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rbuf->mask = size - 1;
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rbuf->mask2 = (size << 1) - 1;
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rbuf->readindex = 0;
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rbuf->writeindex = 0;
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if ((size & (size - 1)) == 0)
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rbuf->size_mask = size - 1;
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else
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rbuf->size_mask = 0;
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return SPA_RESULT_OK;
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}
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/**
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@ -86,6 +92,21 @@ spa_ringbuffer_clear (SpaRingbuffer *rbuf)
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rbuf->writeindex = 0;
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}
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static inline size_t
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spa_ringbuffer_get_read_offset (SpaRingbuffer *rbuf,
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size_t *offset)
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{
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size_t avail, r;
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r = rbuf->readindex;
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*offset = r & rbuf->mask;
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avail = (rbuf->writeindex - r) & rbuf->mask2;
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spa_barrier_read();
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return avail;
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}
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/**
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* spa_ringbuffer_get_read_areas:
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* @rbuf: a #SpaRingbuffer
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@ -98,17 +119,9 @@ static inline void
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spa_ringbuffer_get_read_areas (SpaRingbuffer *rbuf,
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SpaRingbufferArea areas[2])
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{
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size_t avail, end, w, r;
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size_t avail, end, r;
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w = rbuf->writeindex;
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r = rbuf->readindex;
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if (w > r) {
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avail = w - r;
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} else {
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avail = (w - r + rbuf->size);
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avail = (rbuf->size_mask ? avail & rbuf->size_mask : avail % rbuf->size);
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}
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avail = spa_ringbuffer_get_read_offset (rbuf, &r);
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end = r + avail;
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areas[0].offset = r;
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@ -123,25 +136,6 @@ spa_ringbuffer_get_read_areas (SpaRingbuffer *rbuf,
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}
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}
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static inline size_t
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spa_ringbuffer_get_read_offset (SpaRingbuffer *rbuf,
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size_t *offset)
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{
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size_t avail, w, r;
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w = rbuf->writeindex;
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r = rbuf->readindex;
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if (w > r) {
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avail = w - r;
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} else {
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avail = (w - r + rbuf->size);
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avail = (rbuf->size_mask ? avail & rbuf->size_mask : avail % rbuf->size);
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}
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*offset = r;
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return avail;
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}
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/**
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* spa_ringbuffer_read_advance:
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* @rbuf: a #SpaRingbuffer
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@ -153,9 +147,22 @@ static inline void
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spa_ringbuffer_read_advance (SpaRingbuffer *rbuf,
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ssize_t len)
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{
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size_t tmp = rbuf->readindex + len;
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__sync_synchronize();
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rbuf->readindex = (rbuf->size_mask ? tmp & rbuf->size_mask : tmp % rbuf->size);
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spa_barrier_full();
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rbuf->readindex = (rbuf->readindex + len) & rbuf->mask2;
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}
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static inline size_t
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spa_ringbuffer_get_write_offset (SpaRingbuffer *rbuf,
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size_t *offset)
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{
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size_t avail, w;
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w = rbuf->writeindex;
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*offset = w & rbuf->mask;
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avail = rbuf->size - ((w - rbuf->readindex) & rbuf->mask2);
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spa_barrier_full();
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return avail;
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}
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/**
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@ -170,20 +177,9 @@ static inline void
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spa_ringbuffer_get_write_areas (SpaRingbuffer *rbuf,
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SpaRingbufferArea areas[2])
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{
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size_t avail, end, w, r;
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size_t avail, end, w;
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w = rbuf->writeindex;
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r = rbuf->readindex;
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if (w > r) {
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avail = (r - w + rbuf->size);
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avail = (rbuf->size_mask ? avail & rbuf->size_mask : avail % rbuf->size);
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} else if (w < r) {
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avail = r - w;
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} else {
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avail = rbuf->size;
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}
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avail -= 1;
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avail = spa_ringbuffer_get_write_offset (rbuf, &w);
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end = w + avail;
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areas[0].offset = w;
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@ -198,28 +194,6 @@ spa_ringbuffer_get_write_areas (SpaRingbuffer *rbuf,
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}
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}
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static inline size_t
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spa_ringbuffer_get_write_offset (SpaRingbuffer *rbuf,
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size_t *offset)
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{
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size_t avail, w, r;
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w = rbuf->writeindex;
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r = rbuf->readindex;
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if (w > r) {
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avail = (r - w + rbuf->size);
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avail = (rbuf->size_mask ? avail & rbuf->size_mask : avail % rbuf->size);
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} else if (w < r) {
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avail = r - w;
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} else {
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avail = rbuf->size;
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}
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avail -= 1;
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*offset = w;
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return avail;
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}
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/**
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* spa_ringbuffer_write_advance:
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* @rbuf: a #SpaRingbuffer
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@ -232,9 +206,8 @@ static inline void
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spa_ringbuffer_write_advance (SpaRingbuffer *rbuf,
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ssize_t len)
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{
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size_t tmp = rbuf->writeindex + len;
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__sync_synchronize();
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rbuf->writeindex = (rbuf->size_mask ? tmp & rbuf->size_mask : tmp % rbuf->size);
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spa_barrier_write();
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rbuf->writeindex = (rbuf->writeindex + len) & rbuf->mask2;
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}
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#ifdef __cplusplus
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