76 lines
1.7 KiB
C
76 lines
1.7 KiB
C
#include <malloc.h>
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#include <errno.h>
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#include "circular_buffer.h"
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#define INC(v, size) {if (++v==size) v=0;}
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circular_buffer_t *new_circular_buffer(size_t size)
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{
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circular_buffer_t *head = NULL;
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if (size > 0) {
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if ((head=malloc(sizeof(*head)))) {
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clear_buffer(head);
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head->size = size;
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/* we could have only 1 alloc, I just prefer this double alloc
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*/
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if (!(head->buf = calloc(size, sizeof(buffer_value_t)))) {
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free(head);
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head = NULL;
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}
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}
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}
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return head;
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}
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int do_write(circular_buffer_t *b, buffer_value_t v, int f)
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{
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if (!f && b->used == b->size) {
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errno = ENOBUFS;
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return EXIT_FAILURE;
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}
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b->buf[b->head] = v;
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INC(b->head, b->size);
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if (f && b->used == b->size) /* overwrite and full */
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INC(b->tail, b->size);
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if (b->used < b->size) /* normal write */
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b->used++;
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return EXIT_SUCCESS;
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}
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int read(circular_buffer_t *b, buffer_value_t *p)
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{
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if (!b->used) {
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errno = ENODATA;
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return EXIT_FAILURE;
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}
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b->used--;
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*p = b->buf[b->tail];
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INC(b->tail, b->size);
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return EXIT_SUCCESS;
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}
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int clear_buffer(circular_buffer_t *b)
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{
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b->head = 0;
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b->tail = 0;
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b->used = 0;
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return EXIT_SUCCESS;
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}
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void delete_buffer(circular_buffer_t *b) {
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free(b->buf);
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free(b);
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}
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/* See GNUmakefile below for explanation
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* https://github.com/braoult/exercism/blob/master/c/templates/GNUmakefile
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*/
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#ifdef UNIT_TEST
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int main(int ac, char **av)
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{
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/* not done for circular buffer : simple exercise, with difficult testing */
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}
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#endif
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