ringbuffer.h

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/* Simple Plugin API
 *
 * Copyright © 2018 Wim Taymans
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */
 
#ifndef SPA_RINGBUFFER_H
#define SPA_RINGBUFFER_H
 
#ifdef __cplusplus
extern "C" {
#endif
 
struct spa_ringbuffer;
 
#include <string.h>
 
#include <spa/utils/defs.h>
 
struct spa_ringbuffer {
        uint32_t readindex;     /*< the current read index */
        uint32_t writeindex;    /*< the current write index */
};
 
#define SPA_RINGBUFFER_INIT()   (struct spa_ringbuffer) { 0, 0 }
 
/* static */ inline void spa_ringbuffer_init(struct spa_ringbuffer *rbuf)
{
        *rbuf = SPA_RINGBUFFER_INIT();
}
 
/* static */ inline void spa_ringbuffer_set_avail(struct spa_ringbuffer *rbuf, uint32_t size)
{
        rbuf->readindex = 0;
        rbuf->writeindex = size;
}
 
/* static */ inline int32_t spa_ringbuffer_get_read_index(struct spa_ringbuffer *rbuf, uint32_t *index)
{
        *index = __atomic_load_n(&rbuf->readindex, __ATOMIC_RELAXED);
        return (int32_t) (__atomic_load_n(&rbuf->writeindex, __ATOMIC_ACQUIRE) - *index);
}
 
/* static */ inline void
spa_ringbuffer_read_data(struct spa_ringbuffer *rbuf,
                         const void *buffer, uint32_t size,
                         uint32_t offset, void *data, uint32_t len)
{
        uint32_t l0 = SPA_MIN(len, size - offset), l1 = len - l0;
        spa_memcpy(data, SPA_PTROFF(buffer, offset, void), l0);
        if (SPA_UNLIKELY(l1 > 0))
                spa_memcpy(SPA_PTROFF(data, l0, void), buffer, l1);
}
 
/* static */ inline void spa_ringbuffer_read_update(struct spa_ringbuffer *rbuf, int32_t index)
{
        __atomic_store_n(&rbuf->readindex, index, __ATOMIC_RELEASE);
}
 
/* static */ inline int32_t spa_ringbuffer_get_write_index(struct spa_ringbuffer *rbuf, uint32_t *index)
{
        *index = __atomic_load_n(&rbuf->writeindex, __ATOMIC_RELAXED);
        return (int32_t) (*index - __atomic_load_n(&rbuf->readindex, __ATOMIC_ACQUIRE));
}
 
/* static */ inline void
spa_ringbuffer_write_data(struct spa_ringbuffer *rbuf,
                          void *buffer, uint32_t size,
                          uint32_t offset, const void *data, uint32_t len)
{
        uint32_t l0 = SPA_MIN(len, size - offset), l1 = len - l0;
        spa_memcpy(SPA_PTROFF(buffer, offset, void), data, l0);
        if (SPA_UNLIKELY(l1 > 0))
                spa_memcpy(buffer, SPA_PTROFF(data, l0, void), l1);
}
 
/* static */ inline void spa_ringbuffer_write_update(struct spa_ringbuffer *rbuf, int32_t index)
{
        __atomic_store_n(&rbuf->writeindex, index, __ATOMIC_RELEASE);
}
 
#ifdef __cplusplus
}  /* extern "C" */
#endif
 
#endif /* SPA_RINGBUFFER_H */