tsrb.h

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/*
 * Copyright (C) 2015 Kaspar Schleiser <kaspar@schleiser.de>
 *
 * This file is subject to the terms and conditions of the GNU Lesser
 * General Public License v2.1. See the file LICENSE in the top level
 * directory for more details.
 */
 
#ifndef TSRB_H
#define TSRB_H
 
#include <assert.h>
#include <stddef.h>
#include <stdint.h>
 
#include "irq.h"
 
#ifdef __cplusplus
extern "C" {
#endif
 
typedef struct tsrb {
    uint8_t *buf;               
    unsigned int size;          
    unsigned reads;             
    unsigned writes;            
} tsrb_t;
 
#define TSRB_INIT(BUF) { (BUF), sizeof (BUF), 0, 0 }
 
static inline void tsrb_init(tsrb_t *rb, uint8_t *buffer, unsigned bufsize)
{
    /* make sure bufsize is a power of two.
     * http://www.exploringbinary.com/ten-ways-to-check-if-an-integer-is-a-power-of-two-in-c/
     */
    assert((bufsize != 0) && ((bufsize & (~bufsize + 1)) == bufsize));
 
    rb->buf = buffer;
    rb->size = bufsize;
    rb->reads = 0;
    rb->writes = 0;
}
 
static inline int tsrb_empty(const tsrb_t *rb)
{
    unsigned irq_state = irq_disable();
    int retval = (rb->reads == rb->writes);
    irq_restore(irq_state);
    return retval;
}
 
 
static inline unsigned int tsrb_avail(const tsrb_t *rb)
{
    unsigned irq_state = irq_disable();
    int retval = (rb->writes - rb->reads);
    irq_restore(irq_state);
    return retval;
}
 
static inline int tsrb_full(const tsrb_t *rb)
{
    unsigned irq_state = irq_disable();
    int retval = (rb->writes - rb->reads) == rb->size;
    irq_restore(irq_state);
    return retval;
}
 
static inline unsigned int tsrb_free(const tsrb_t *rb)
{
    unsigned irq_state = irq_disable();
    int retval = (rb->size - rb->writes + rb->reads);
    irq_restore(irq_state);
    return retval;
}
 
int tsrb_get_one(tsrb_t *rb);
 
int tsrb_get(tsrb_t *rb, uint8_t *dst, size_t n);
 
int tsrb_drop(tsrb_t *rb, size_t n);
 
int tsrb_add_one(tsrb_t *rb, uint8_t c);
 
int tsrb_add(tsrb_t *rb, const uint8_t *src, size_t n);
 
#ifdef __cplusplus
}
#endif
 
#endif /* TSRB_H */