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Annotation of src/usr.bin/sndiod/abuf.c, Revision 1.3

1.3     ! ratchov     1: /*     $OpenBSD: abuf.c,v 1.2 2012/12/07 08:04:58 ratchov Exp $        */
1.1       ratchov     2: /*
                      3:  * Copyright (c) 2008-2012 Alexandre Ratchov <alex@caoua.org>
                      4:  *
                      5:  * Permission to use, copy, modify, and distribute this software for any
                      6:  * purpose with or without fee is hereby granted, provided that the above
                      7:  * copyright notice and this permission notice appear in all copies.
                      8:  *
                      9:  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
                     10:  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
                     11:  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
                     12:  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
                     13:  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
                     14:  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
                     15:  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
                     16:  */
                     17: /*
                     18:  * Simple byte fifo.
                     19:  *
                     20:  * The abuf data is split in two parts: (1) valid data available to the reader
                     21:  * (2) space available to the writer, which is not necessarily unused. It works
                     22:  * as follows: the write starts filling at offset (start + used), once the data
                     23:  * is ready, the writer adds to used the count of bytes available.
                     24:  */
                     25: #include <stdio.h>
                     26: #include <stdlib.h>
                     27: #include <string.h>
                     28:
                     29: #include "abuf.h"
                     30: #include "utils.h"
                     31:
                     32: #ifdef DEBUG
                     33: void
                     34: abuf_log(struct abuf *buf)
                     35: {
                     36:        log_putu(buf->start);
                     37:        log_puts("+");
                     38:        log_putu(buf->used);
                     39:        log_puts("/");
                     40:        log_putu(buf->len);
                     41: }
                     42: #endif
                     43:
                     44: void
                     45: abuf_init(struct abuf *buf, unsigned int len)
                     46: {
                     47:        buf->data = xmalloc(len);
                     48:        buf->len = len;
                     49:        buf->used = 0;
                     50:        buf->start = 0;
                     51: }
                     52:
                     53: void
                     54: abuf_done(struct abuf *buf)
                     55: {
                     56: #ifdef DEBUG
                     57:        if (buf->used > 0) {
                     58:                if (log_level >= 3) {
                     59:                        log_puts("deleting non-empty buffer, used = ");
                     60:                        log_putu(buf->used);
                     61:                        log_puts("\n");
                     62:                }
                     63:        }
                     64: #endif
                     65:        xfree(buf->data);
                     66:        buf->data = (void *)0xdeadbeef;
                     67: }
                     68:
                     69: /*
                     70:  * return the reader pointer and the number of bytes available
                     71:  */
                     72: unsigned char *
                     73: abuf_rgetblk(struct abuf *buf, int *rsize)
                     74: {
1.3     ! ratchov    75:        int count;
1.1       ratchov    76:
                     77:        count = buf->len - buf->start;
                     78:        if (count > buf->used)
                     79:                count = buf->used;
                     80:        *rsize = count;
                     81:        return buf->data + buf->start;
                     82: }
                     83:
                     84: /*
                     85:  * discard "count" bytes at the start postion.
                     86:  */
                     87: void
                     88: abuf_rdiscard(struct abuf *buf, int count)
                     89: {
                     90: #ifdef DEBUG
                     91:        if (count < 0 || count > buf->used) {
                     92:                log_puts("abuf_rdiscard: bad count = ");
                     93:                log_putu(count);
                     94:                log_puts("\n");
                     95:                panic();
                     96:        }
                     97: #endif
                     98:        buf->used -= count;
                     99:        buf->start += count;
                    100:        if (buf->start >= buf->len)
                    101:                buf->start -= buf->len;
                    102: }
                    103:
                    104: /*
                    105:  * advance the writer pointer by "count" bytes
                    106:  */
                    107: void
                    108: abuf_wcommit(struct abuf *buf, int count)
                    109: {
                    110: #ifdef DEBUG
                    111:        if (count < 0 || count > (buf->len - buf->used)) {
                    112:                log_puts("abuf_wcommit: bad count = ");
                    113:                log_putu(count);
                    114:                log_puts("\n");
                    115:                panic();
                    116:        }
                    117: #endif
                    118:        buf->used += count;
                    119: }
                    120:
                    121: /*
                    122:  * get writer pointer and the number of bytes writable
                    123:  */
                    124: unsigned char *
                    125: abuf_wgetblk(struct abuf *buf, int *rsize)
                    126: {
                    127:        int end, avail, count;
                    128:
                    129:        end = buf->start + buf->used;
                    130:        if (end >= buf->len)
                    131:                end -= buf->len;
                    132:        avail = buf->len - buf->used;
                    133:        count = buf->len - end;
                    134:        if (count > avail)
                    135:                count = avail;
                    136:        *rsize = count;
                    137:        return buf->data + end;
                    138: }