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circ_buf.c
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circ_buf.c
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/*
* Copyright (c) 2018, Linaro Ltd.
* All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include "circ_buf.h"
/**
* circ_fill() - read data into circular buffer
* @fd: non-blocking file descriptor to read
* @circ: circ_buf object to write to
*
* Return: 0 if fifo is full or fd depleted, negative errno on failure
*/
ssize_t circ_fill(int fd, struct circ_buf *circ)
{
ssize_t space;
ssize_t n = 0;
do {
space = CIRC_SPACE_TO_END(circ);
if (!space) {
errno = EAGAIN;
return -1;
}
n = read(fd, circ->buf + circ->head, space);
if (n == 0) {
errno = EPIPE;
return -1;
} else if (n < 0)
return -1;
circ->head = (circ->head + n) & (CIRC_BUF_SIZE - 1);
} while (n != space);
return 0;
}
size_t circ_peak(struct circ_buf *circ, void *buf, size_t len)
{
size_t tail = circ->tail;
char *p = buf;
while (len--) {
if (tail == circ->head)
return 0;
*p++ = circ->buf[tail];
tail = (tail + 1) & (CIRC_BUF_SIZE - 1);
}
return p - (char *)buf;
}
size_t circ_read(struct circ_buf *circ, void *buf, size_t len)
{
char *p = buf;
while (len--) {
if (circ->tail == circ->head)
return 0;
*p++ = circ->buf[circ->tail];
circ->tail = (circ->tail + 1) & (CIRC_BUF_SIZE - 1);
}
return p - (char *)buf;
}