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/*
* shm_ringbuf.c
*
* Copyright (C) 2004-2011 Simon Wunderlich <sw@simonwunderlich.de>
*
* This file is part of the s3d API, the API of s3d (the 3d network display server).
* See http://s3d.berlios.de/ for more updates.
*
* The s3d API is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* The s3d API is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with the s3d API; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "s3d.h"
#include "s3dlib.h"
#include <stdint.h> /* uint32_t */
#include <string.h> /* memcpy() */
#ifdef SHM
unsigned int shm_write(struct buf_t *rb, char *buf, unsigned int n)
{
unsigned int wrap = 0;
int rs;
uint32_t e, s, size;
char *data;
e = rb->end;
s = rb->start;
size = rb->bufsize;
data = ((char *)rb) + sizeof(struct buf_t);
if (e < s) {
wrap = 1;
}
while ((((s + size*(1 - wrap)) - e) < (n + 1))) { /* checking free space */
if /*((size*2)>RB_MAX_SIZE)*/ (1) {
/* s3dprintf(MED,"buffer reached maxsize, no resizing possible");*/
return 0;
}
/* printf("buffer full!! resizing ... (to size %d)",(int)size*2);
if (NULL==(realloc(rb, size*2+RB_OVERHEAD)))
{
printf("realloc failed - fatal!!");
return -1;
}
if (wrap)
{
memcpy(data+size,data,e);
e+=size;
wrap=0;
}
size=rb->bufsize=size*2;
rb->end=e;*/
}
if ((e + n) > size) {
rs = size - e;
memcpy(data + e, buf, rs); /* copy the first part ... */
memcpy(data, buf + rs, n - rs); /* .. end the rest */
} else {
memcpy(data + e, buf, n); /* plain copy */
}
rb->end = e + n; /* update end of the buffer */
if (rb->end >= rb->bufsize) rb->end -= rb->bufsize;
return n;
}
unsigned int shm_read(struct buf_t *rb, char *buf, unsigned int n)
{
int wrap = 0;
unsigned int mn;
unsigned int rs;
uint32_t e, s, size;
char *data;
e = rb->end;
s = rb->start;
size = rb->bufsize;
data = ((char *)rb) + sizeof(struct buf_t);
if (e < s) wrap = 1;
rs = (e + wrap * size - s);
mn = (n > rs) ? rs : n;
if ((wrap) && (mn > (size - s))) {
rs = size - s; /* size of the first part */
memcpy(buf, data + s, rs);
memcpy(buf + rs, data, mn - rs);
} else { /* no wrap (needed)*/
memcpy(buf, data + s, mn);
}
rb->start = s + mn;
if (rb->start >= rb->bufsize) rb->start -= rb->bufsize;
return mn;
}
#endif
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