using size_t, peek with offset, better field names

master
Ondřej Hruška 9 years ago
parent a3485b9ced
commit 2f352b653f
  1. 72
      circbuf.c
  2. 19
      circbuf.h

@ -6,10 +6,10 @@
#include "circbuf.h"
void cbuf_init(circbuf_t *inst, uint16_t length)
void cbuf_init(circbuf_t *inst, size_t capacity)
{
inst->buffer = malloc(length);
inst->capacity = length;
inst->buf = malloc(capacity);
inst->cap = capacity;
cbuf_clear(inst);
}
@ -17,29 +17,32 @@ void cbuf_init(circbuf_t *inst, uint16_t length)
void cbuf_deinit(circbuf_t *inst)
{
if (inst->buffer != NULL) {
free(inst->buffer);
if (inst->buf != NULL) {
free(inst->buf);
}
}
bool cbuf_full(circbuf_t *inst)
{
if (inst->read_pos == 0) {
return inst->write_pos == inst->capacity - 1;
return (inst->lr == inst->nw);
}
static bool can_read_at(circbuf_t *inst, size_t i)
{
if (inst->lr < inst->nw) {
return i > inst->lr && i < inst->nw;
} else {
return inst->write_pos == inst->read_pos;
// NW < LR
return (i < inst->cap && i > inst->lr) || i < inst->nw;
}
}
bool cbuf_empty(circbuf_t *inst)
{
if (inst->write_pos == 0) {
return inst->read_pos == inst->capacity - 1;
} else {
return inst->read_pos == inst->write_pos - 1;
}
return ((inst->lr + 1) % inst->cap) == inst->nw;
}
@ -47,13 +50,11 @@ bool cbuf_write(circbuf_t *inst, uint8_t b)
{
if (cbuf_full(inst)) return false;
inst->buffer[inst->write_pos] = b;
inst->write_pos++;
inst->buf[inst->nw] = b;
// wrap
if (inst->write_pos >= inst->capacity) {
inst->write_pos = 0;
}
// increment
inst->nw++;
if (inst->nw == inst->cap) inst->nw = 0;
return true;
}
@ -63,33 +64,38 @@ bool cbuf_read(circbuf_t *inst, uint8_t *b)
{
if (cbuf_empty(inst)) return false;
inst->read_pos++;
// wrap
if (inst->read_pos >= inst->capacity) {
inst->read_pos = 0;
}
// increment
inst->lr++;
if (inst->lr == inst->cap) inst->lr = 0;
*b = inst->buffer[inst->read_pos];
*b = inst->buf[inst->lr];
// zero out the read byte (for debug)
//inst->buffer[inst->read_pos] = 0;
//zero out the read byte (for debug)
inst->buf[inst->lr] = 0;
return true;
}
bool cbuf_peek(circbuf_t *inst, uint8_t *b)
bool cbuf_peek(circbuf_t *inst, size_t nth, uint8_t *b)
{
if (cbuf_empty(inst)) return false;
// check if can read there (can't use module, could "wrap")
size_t n = inst->lr;
for (size_t i = 0; i <= nth; i++) {
// increment N
n++;
if (n == inst->cap) n = 0;
if (!can_read_at(inst, n)) return false;
}
*b = inst->buffer[inst->read_pos];
*b = inst->buf[n];
return true;
}
void cbuf_clear(circbuf_t *inst)
{
inst->read_pos = inst->capacity - 1;
inst->write_pos = 0;
inst->lr = inst->cap - 1;
inst->nw = 0;
}

@ -1,19 +1,20 @@
#pragma once
#include <stdint.h>
#include <stdbool.h>
#include <stdlib.h>
// Circular Character Buffer implementation
typedef struct {
uint8_t *buffer;
uint16_t capacity;
uint16_t read_pos;
uint16_t write_pos;
typedef struct CircularBuffer_struct {
uint8_t *buf;
size_t cap;
size_t lr; // last read pos
size_t nw; // next write pos
} circbuf_t;
/** Init a buffer */
void cbuf_init(circbuf_t *inst, uint16_t length);
void cbuf_init(circbuf_t *inst, size_t capacity);
/** Deinit a buffer (free the memory) */
@ -40,10 +41,10 @@ bool cbuf_read(circbuf_t *inst, uint8_t *b);
/**
* Get byte at the read cursor, without incrementing it.
* False on empty.
* Get n-th byte from the buffer, without removing it.
* Returns false if offset is invalid (ie. empty buffer).
*/
bool cbuf_peek(circbuf_t *inst, uint8_t *b);
bool cbuf_peek(circbuf_t *inst, size_t nth, uint8_t *b);
/** Remove all data from buffer */

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