60 lines
1.3 KiB
C
60 lines
1.3 KiB
C
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#ifndef UTIL_FIFO_C
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#define UTIL_FIFO_C
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#define FIFO_INITIAL_SIZE 128
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#define FIFO_QUEUE_EMPTY -1
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#include <stddef.h>
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#include <stdbool.h>
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#include <stdint.h>
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#include "../memory.c"
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typedef struct fifo_struct {
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int num_elems;
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int max_elems;
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uint8_t* head;
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uint8_t* curr_elem;
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} fifo;
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fifo* fifo_new() {
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fifo* ret = alloc(sizeof(fifo));
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void* head = alloc(sizeof(uint8_t) * FIFO_INITIAL_SIZE);
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ret->num_elems = 0;
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ret->max_elems = FIFO_INITIAL_SIZE;
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ret->head = head;
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ret->curr_elem = head;
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return ret;
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}
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void fifo_optimize(fifo* queue) {
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if (queue->head == queue->curr_elem) {
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// resize, not implemented yet (blocked by reallocarray)
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} else {
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// move all items to the beginning of the list
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for(int i = 0; i < queue->num_elems; i++) {
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queue->head[i] = queue->curr_elem[i];
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}
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queue->curr_elem = queue->head;
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}
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}
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void fifo_enqueue(fifo* queue, uint8_t value) {
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if (queue->num_elems == queue->max_elems) {
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fifo_optimize(queue);
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}
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queue->curr_elem[queue->num_elems] = value;
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queue->num_elems++;
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}
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int16_t fifo_dequeue(fifo* queue) {
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if (queue->num_elems <= 0) {
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return FIFO_QUEUE_EMPTY;
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}
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uint8_t ret = queue->curr_elem[0];
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queue->curr_elem++;
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queue->num_elems--;
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return ret;
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}
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#endif //UTIL_FIFO_C
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