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101 lines
1.5 KiB
101 lines
1.5 KiB
#include <stdint.h>
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#include <stdbool.h>
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#include <string.h>
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#include <malloc.h>
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#include "circbuf.h"
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void cbuf_init(circbuf_t *inst, size_t capacity)
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{
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inst->buf = malloc(capacity);
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inst->cap = capacity;
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cbuf_clear(inst);
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}
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void cbuf_deinit(circbuf_t *inst)
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{
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if (inst->buf != NULL) {
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free(inst->buf);
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}
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}
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bool cbuf_full(circbuf_t *inst)
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{
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return (inst->lr == inst->nw);
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}
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static bool can_read_at(circbuf_t *inst, size_t i)
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{
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if (inst->lr < inst->nw) {
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return i > inst->lr && i < inst->nw;
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} else {
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// NW < LR
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return (i < inst->cap && i > inst->lr) || i < inst->nw;
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}
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}
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bool cbuf_empty(circbuf_t *inst)
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{
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return ((inst->lr + 1) % inst->cap) == inst->nw;
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}
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bool cbuf_write(circbuf_t *inst, uint8_t b)
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{
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if (cbuf_full(inst)) return false;
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inst->buf[inst->nw] = b;
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// increment
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inst->nw++;
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if (inst->nw == inst->cap) inst->nw = 0;
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return true;
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}
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bool cbuf_read(circbuf_t *inst, uint8_t *b)
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{
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if (cbuf_empty(inst)) return false;
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// increment
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inst->lr++;
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if (inst->lr == inst->cap) inst->lr = 0;
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*b = inst->buf[inst->lr];
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//zero out the read byte (for debug)
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inst->buf[inst->lr] = 0;
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return true;
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}
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bool cbuf_peek(circbuf_t *inst, size_t nth, uint8_t *b)
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{
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// check if can read there (can't use modulo, could "wrap")
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size_t n = inst->lr;
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for (size_t i = 0; i <= nth; i++) {
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// increment N
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n++;
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if (n == inst->cap) n = 0;
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if (!can_read_at(inst, n)) return false;
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}
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*b = inst->buf[n];
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return true;
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}
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void cbuf_clear(circbuf_t *inst)
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{
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inst->lr = inst->cap - 1;
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inst->nw = 0;
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}
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