1*d9a51c35Sjmc /* $OpenBSD: abuf.c,v 1.5 2022/12/26 19:16:03 jmc Exp $ */
287bc9f6aSratchov /*
387bc9f6aSratchov * Copyright (c) 2008-2012 Alexandre Ratchov <alex@caoua.org>
487bc9f6aSratchov *
587bc9f6aSratchov * Permission to use, copy, modify, and distribute this software for any
687bc9f6aSratchov * purpose with or without fee is hereby granted, provided that the above
787bc9f6aSratchov * copyright notice and this permission notice appear in all copies.
887bc9f6aSratchov *
987bc9f6aSratchov * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
1087bc9f6aSratchov * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
1187bc9f6aSratchov * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
1287bc9f6aSratchov * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
1387bc9f6aSratchov * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
1487bc9f6aSratchov * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
1587bc9f6aSratchov * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
1687bc9f6aSratchov */
1787bc9f6aSratchov /*
1887bc9f6aSratchov * Simple byte fifo.
1987bc9f6aSratchov *
2087bc9f6aSratchov * The abuf data is split in two parts: (1) valid data available to the reader
2187bc9f6aSratchov * (2) space available to the writer, which is not necessarily unused. It works
2287bc9f6aSratchov * as follows: the write starts filling at offset (start + used), once the data
2387bc9f6aSratchov * is ready, the writer adds to used the count of bytes available.
2487bc9f6aSratchov */
2587bc9f6aSratchov #include <stdio.h>
2687bc9f6aSratchov #include <stdlib.h>
2787bc9f6aSratchov #include <string.h>
2887bc9f6aSratchov
2987bc9f6aSratchov #include "abuf.h"
3087bc9f6aSratchov #include "utils.h"
3187bc9f6aSratchov
3287bc9f6aSratchov #ifdef DEBUG
3387bc9f6aSratchov void
abuf_log(struct abuf * buf)3487bc9f6aSratchov abuf_log(struct abuf *buf)
3587bc9f6aSratchov {
3687bc9f6aSratchov log_putu(buf->start);
3787bc9f6aSratchov log_puts("+");
3887bc9f6aSratchov log_putu(buf->used);
3987bc9f6aSratchov log_puts("/");
4087bc9f6aSratchov log_putu(buf->len);
4187bc9f6aSratchov }
4287bc9f6aSratchov #endif
4387bc9f6aSratchov
4487bc9f6aSratchov void
abuf_init(struct abuf * buf,unsigned int len)4587bc9f6aSratchov abuf_init(struct abuf *buf, unsigned int len)
4687bc9f6aSratchov {
4787bc9f6aSratchov buf->data = xmalloc(len);
4887bc9f6aSratchov buf->len = len;
4987bc9f6aSratchov buf->used = 0;
5087bc9f6aSratchov buf->start = 0;
5187bc9f6aSratchov }
5287bc9f6aSratchov
5387bc9f6aSratchov void
abuf_done(struct abuf * buf)5487bc9f6aSratchov abuf_done(struct abuf *buf)
5587bc9f6aSratchov {
5687bc9f6aSratchov #ifdef DEBUG
5787bc9f6aSratchov if (buf->used > 0) {
5887bc9f6aSratchov if (log_level >= 3) {
5987bc9f6aSratchov log_puts("deleting non-empty buffer, used = ");
6087bc9f6aSratchov log_putu(buf->used);
6187bc9f6aSratchov log_puts("\n");
6287bc9f6aSratchov }
6387bc9f6aSratchov }
6487bc9f6aSratchov #endif
6587bc9f6aSratchov xfree(buf->data);
6687bc9f6aSratchov buf->data = (void *)0xdeadbeef;
6787bc9f6aSratchov }
6887bc9f6aSratchov
6987bc9f6aSratchov /*
7087bc9f6aSratchov * return the reader pointer and the number of bytes available
7187bc9f6aSratchov */
7287bc9f6aSratchov unsigned char *
abuf_rgetblk(struct abuf * buf,int * rsize)7387bc9f6aSratchov abuf_rgetblk(struct abuf *buf, int *rsize)
7487bc9f6aSratchov {
7538b693edSratchov int count;
7687bc9f6aSratchov
7787bc9f6aSratchov count = buf->len - buf->start;
7887bc9f6aSratchov if (count > buf->used)
7987bc9f6aSratchov count = buf->used;
8087bc9f6aSratchov *rsize = count;
8187bc9f6aSratchov return buf->data + buf->start;
8287bc9f6aSratchov }
8387bc9f6aSratchov
8487bc9f6aSratchov /*
85*d9a51c35Sjmc * discard "count" bytes at the start position.
8687bc9f6aSratchov */
8787bc9f6aSratchov void
abuf_rdiscard(struct abuf * buf,int count)8887bc9f6aSratchov abuf_rdiscard(struct abuf *buf, int count)
8987bc9f6aSratchov {
9087bc9f6aSratchov #ifdef DEBUG
9187bc9f6aSratchov if (count < 0 || count > buf->used) {
9287bc9f6aSratchov log_puts("abuf_rdiscard: bad count = ");
9387bc9f6aSratchov log_putu(count);
9487bc9f6aSratchov log_puts("\n");
9587bc9f6aSratchov panic();
9687bc9f6aSratchov }
9787bc9f6aSratchov #endif
9887bc9f6aSratchov buf->used -= count;
9987bc9f6aSratchov buf->start += count;
10087bc9f6aSratchov if (buf->start >= buf->len)
10187bc9f6aSratchov buf->start -= buf->len;
10287bc9f6aSratchov }
10387bc9f6aSratchov
10487bc9f6aSratchov /*
10587bc9f6aSratchov * advance the writer pointer by "count" bytes
10687bc9f6aSratchov */
10787bc9f6aSratchov void
abuf_wcommit(struct abuf * buf,int count)10887bc9f6aSratchov abuf_wcommit(struct abuf *buf, int count)
10987bc9f6aSratchov {
11087bc9f6aSratchov #ifdef DEBUG
11187bc9f6aSratchov if (count < 0 || count > (buf->len - buf->used)) {
11287bc9f6aSratchov log_puts("abuf_wcommit: bad count = ");
11387bc9f6aSratchov log_putu(count);
11487bc9f6aSratchov log_puts("\n");
11587bc9f6aSratchov panic();
11687bc9f6aSratchov }
11787bc9f6aSratchov #endif
11887bc9f6aSratchov buf->used += count;
11987bc9f6aSratchov }
12087bc9f6aSratchov
12187bc9f6aSratchov /*
12287bc9f6aSratchov * get writer pointer and the number of bytes writable
12387bc9f6aSratchov */
12487bc9f6aSratchov unsigned char *
abuf_wgetblk(struct abuf * buf,int * rsize)12587bc9f6aSratchov abuf_wgetblk(struct abuf *buf, int *rsize)
12687bc9f6aSratchov {
12787bc9f6aSratchov int end, avail, count;
12887bc9f6aSratchov
12987bc9f6aSratchov end = buf->start + buf->used;
13087bc9f6aSratchov if (end >= buf->len)
13187bc9f6aSratchov end -= buf->len;
13287bc9f6aSratchov avail = buf->len - buf->used;
13387bc9f6aSratchov count = buf->len - end;
13487bc9f6aSratchov if (count > avail)
13587bc9f6aSratchov count = avail;
13687bc9f6aSratchov *rsize = count;
13787bc9f6aSratchov return buf->data + end;
13887bc9f6aSratchov }
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