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/*
* Copyright (c) 2015-2017 Richard Braun.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*
* Upstream site with license notes :
* http://git.sceen.net/rbraun/librbraun.git/
*/
#include <assert.h>
#include <stddef.h>
#include <stdint.h>
#include <string.h>
#include "cbuf.h"
#include "error.h"
#include "macros.h"
/* Negative close to 0 so that an overflow occurs early */
#define CBUF_INIT_INDEX ((size_t)-500)
void
cbuf_init(struct cbuf *cbuf, void *buf, size_t capacity)
{
assert(ISP2(capacity));
cbuf->buf = buf;
cbuf->capacity = capacity;
cbuf->start = CBUF_INIT_INDEX;
cbuf->end = cbuf->start;
}
static size_t
cbuf_index(const struct cbuf *cbuf, size_t abs_index)
{
return abs_index & (cbuf->capacity - 1);
}
static void
cbuf_update_start(struct cbuf *cbuf)
{
/* Mind integer overflows */
if (cbuf_size(cbuf) > cbuf->capacity) {
cbuf->start = cbuf->end - cbuf->capacity;
}
}
int
cbuf_push(struct cbuf *cbuf, const void *buf, size_t size, bool erase)
{
size_t free_size;
if (!erase) {
free_size = cbuf_capacity(cbuf) - cbuf_size(cbuf);
if (size > free_size) {
return ERROR_AGAIN;
}
}
return cbuf_write(cbuf, cbuf_end(cbuf), buf, size);
}
int
cbuf_pop(struct cbuf *cbuf, void *buf, size_t *sizep)
{
int error;
if (cbuf_size(cbuf) == 0) {
return ERROR_AGAIN;
}
error = cbuf_read(cbuf, cbuf_start(cbuf), buf, sizep);
assert(!error);
cbuf->start += *sizep;
return 0;
}
int
cbuf_pushb(struct cbuf *cbuf, uint8_t byte, bool erase)
{
size_t free_size;
if (!erase) {
free_size = cbuf_capacity(cbuf) - cbuf_size(cbuf);
if (free_size == 0) {
return ERROR_AGAIN;
}
}
cbuf->buf[cbuf_index(cbuf, cbuf->end)] = byte;
cbuf->end++;
cbuf_update_start(cbuf);
return 0;
}
int
cbuf_popb(struct cbuf *cbuf, void *bytep)
{
uint8_t *ptr;
if (cbuf_size(cbuf) == 0) {
return ERROR_AGAIN;
}
ptr = bytep;
*ptr = cbuf->buf[cbuf_index(cbuf, cbuf->start)];
cbuf->start++;
return 0;
}
int
cbuf_write(struct cbuf *cbuf, size_t index, const void *buf, size_t size)
{
uint8_t *start, *end, *buf_end;
size_t new_end, skip;
if (!cbuf_range_valid(cbuf, index, cbuf->end)) {
return ERROR_INVAL;
}
new_end = index + size;
if (!cbuf_range_valid(cbuf, cbuf->start, new_end)) {
cbuf->end = new_end;
if (size > cbuf_capacity(cbuf)) {
skip = size - cbuf_capacity(cbuf);
buf += skip;
index += skip;
size = cbuf_capacity(cbuf);
}
}
start = &cbuf->buf[cbuf_index(cbuf, index)];
end = start + size;
buf_end = cbuf->buf + cbuf->capacity;
if ((end <= cbuf->buf) || (end > buf_end)) {
skip = buf_end - start;
memcpy(start, buf, skip);
buf += skip;
start = cbuf->buf;
size -= skip;
}
memcpy(start, buf, size);
cbuf_update_start(cbuf);
return 0;
}
int
cbuf_read(const struct cbuf *cbuf, size_t index, void *buf, size_t *sizep)
{
const uint8_t *start, *end, *buf_end;
size_t size;
/* At least one byte must be available */
if (!cbuf_range_valid(cbuf, index, index + 1)) {
return ERROR_INVAL;
}
size = cbuf->end - index;
if (*sizep > size) {
*sizep = size;
}
start = &cbuf->buf[cbuf_index(cbuf, index)];
end = start + *sizep;
buf_end = cbuf->buf + cbuf->capacity;
if ((end > cbuf->buf) && (end <= buf_end)) {
size = *sizep;
} else {
size = buf_end - start;
memcpy(buf, start, size);
buf += size;
start = cbuf->buf;
size = *sizep - size;
}
memcpy(buf, start, size);
return 0;
}
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