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#include "itc.h"
void itc_chan_create(itc_chan *chan)
{
memset(chan, 0, sizeof(itc_chan));
chan->mutex = SDL_CreateMutex();
assert(chan->mutex);
chan->sem = SDL_CreateSemaphore(0);
assert(chan->sem);
}
void itc_chan_destroy(itc_chan *chan)
{
// todo: free queue
SDL_DestroySemaphore(chan->sem);
SDL_DestroyMutex(chan->mutex);
}
void itc_chan_push(itc_chan *chan, int number, void *data)
{
itc_message *msg;
msg = calloc(1, sizeof(itc_message));
assert(msg);
msg->number = number;
msg->data = data;
SDL_LockMutex(chan->mutex);
if (!chan->oldest) {
chan->oldest = msg;
chan->newest = msg;
} else {
/*
* head <---> ... <---> tail
*
*/
chan->newest->newer = msg;
msg->older = chan->newest;
chan->newest = msg;
}
SDL_SemPost(chan->sem);
SDL_UnlockMutex(chan->mutex);
}
int itc_chan_pop(itc_chan *chan, int *number, void **data)
{
itc_message *msg;
SDL_LockMutex(chan->mutex);
if (!chan->oldest) {
SDL_UnlockMutex(chan->mutex);
return 1;
}
msg = chan->oldest;
if (msg->newer) {
msg->newer->older = NULL;
chan->oldest = msg->newer;
} else {
chan->newest = NULL;
chan->oldest = NULL;
}
SDL_SemWait(chan->sem); // should be instant
SDL_UnlockMutex(chan->mutex);
*number = msg->number;
*data = msg->data;
free(msg);
return 0;
}
int itc_chan_pop_block(itc_chan *chan, int *number, void **data)
{
itc_message *msg;
SDL_SemWait(chan->sem);
SDL_LockMutex(chan->mutex);
if (!chan->oldest) {
SDL_UnlockMutex(chan->mutex);
return 1;
}
msg = chan->oldest;
if (msg->newer) {
msg->newer->older = NULL;
chan->oldest = msg->newer;
} else {
chan->newest = NULL;
chan->oldest = NULL;
}
SDL_UnlockMutex(chan->mutex);
*number = msg->number;
*data = msg->data;
free(msg);
return 0;
}
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