/* * Copyright © 2019, VideoLAN and dav1d authors * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are met: * * 1. Redistributions of source code must retain the above copyright notice, this *    list of conditions and the following disclaimer. * * 2. Redistributions in binary form must reproduce the above copyright notice, *    this list of conditions and the following disclaimer in the documentation *    and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #include <SDL.h>#include <assert.h> #include "dp_fifo.h" // FIFO structurestruct dp_fifo{    SDL_mutex *lock;    SDL_cond *cond_change;    size_t capacity;    size_t count;    void **entries;};  Dav1dPlayPtrFifo *dp_fifo_create(size_t capacity){    Dav1dPlayPtrFifo *fifo;     assert(capacity > 0);    if (capacity <= 0)        return NULL;     fifo = malloc(sizeof(*fifo));    if (fifo == NULL)        return NULL;     fifo->capacity = capacity;    fifo->count = 0;     fifo->lock = SDL_CreateMutex();    if (fifo->lock == NULL) {        free(fifo);        return NULL;    }    fifo->cond_change = SDL_CreateCond();    if (fifo->cond_change == NULL) {        SDL_DestroyMutex(fifo->lock);        free(fifo);        return NULL;    }     fifo->entries = calloc(capacity, sizeof(void*));    if (fifo->entries == NULL) {        dp_fifo_destroy(fifo);        return NULL;    }     return fifo;} // Destroy FIFOvoid dp_fifo_destroy(Dav1dPlayPtrFifo *fifo){    assert(fifo->count == 0);    SDL_DestroyMutex(fifo->lock);    SDL_DestroyCond(fifo->cond_change);    free(fifo->entries);    free(fifo);} // Push to FIFOvoid dp_fifo_push(Dav1dPlayPtrFifo *fifo, void *element){    SDL_LockMutex(fifo->lock);    while (fifo->count == fifo->capacity)        SDL_CondWait(fifo->cond_change, fifo->lock);    fifo->entries[fifo->count++] = element;    if (fifo->count == 1)        SDL_CondSignal(fifo->cond_change);    SDL_UnlockMutex(fifo->lock);} // Helper that shifts the FIFO arraystatic void *dp_fifo_array_shift(void **arr, size_t len){    void *shifted_element = arr[0];    for (size_t i = 1; i < len; ++i)        arr[i-1] = arr[i];    return shifted_element;} // Get item from FIFOvoid *dp_fifo_shift(Dav1dPlayPtrFifo *fifo){    SDL_LockMutex(fifo->lock);    while (fifo->count == 0)        SDL_CondWait(fifo->cond_change, fifo->lock);    void *res = dp_fifo_array_shift(fifo->entries, fifo->count--);    if (fifo->count == fifo->capacity - 1)        SDL_CondSignal(fifo->cond_change);    SDL_UnlockMutex(fifo->lock);    return res;}