mirror of https://github.com/ericonr/sndio.git
137 lines
3.0 KiB
C
137 lines
3.0 KiB
C
/* $OpenBSD$ */
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/*
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* Copyright (c) 2008-2012 Alexandre Ratchov <alex@caoua.org>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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/*
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* Simple byte fifo.
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*
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* The abuf data is split in two parts: (1) valid data available to the reader
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* (2) space available to the writer, which is not necessarily unused. It works
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* as follows: the write starts filling at offset (start + used), once the data
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* is ready, the writer adds to used the count of bytes available.
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*/
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#include <stdlib.h>
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#include "abuf.h"
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#include "utils.h"
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#ifdef DEBUG
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void
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abuf_log(struct abuf *buf)
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{
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log_putu(buf->start);
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log_puts("+");
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log_putu(buf->used);
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log_puts("/");
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log_putu(buf->len);
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}
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#endif
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void
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abuf_init(struct abuf *buf, unsigned int len)
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{
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buf->data = xmalloc(len);
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buf->len = len;
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buf->used = 0;
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buf->start = 0;
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}
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void
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abuf_done(struct abuf *buf)
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{
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#ifdef DEBUG
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if (buf->used > 0) {
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if (log_level >= 3) {
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log_puts("deleting non-empty buffer, used = ");
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log_putu(buf->used);
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log_puts("\n");
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}
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}
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#endif
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xfree(buf->data);
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buf->data = (void *)0xdeadbeef;
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}
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/*
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* return the reader pointer and the number of bytes available
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*/
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unsigned char *
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abuf_rgetblk(struct abuf *buf, int *rsize)
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{
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int count;
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count = buf->len - buf->start;
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if (count > buf->used)
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count = buf->used;
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*rsize = count;
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return buf->data + buf->start;
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}
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/*
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* discard "count" bytes at the start postion.
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*/
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void
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abuf_rdiscard(struct abuf *buf, int count)
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{
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#ifdef DEBUG
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if (count < 0 || count > buf->used) {
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log_puts("abuf_rdiscard: bad count = ");
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log_putu(count);
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log_puts("\n");
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panic();
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}
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#endif
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buf->used -= count;
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buf->start += count;
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if (buf->start >= buf->len)
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buf->start -= buf->len;
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}
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/*
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* advance the writer pointer by "count" bytes
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*/
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void
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abuf_wcommit(struct abuf *buf, int count)
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{
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#ifdef DEBUG
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if (count < 0 || count > (buf->len - buf->used)) {
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log_puts("abuf_wcommit: bad count = ");
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log_putu(count);
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log_puts("\n");
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panic();
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}
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#endif
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buf->used += count;
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}
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/*
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* get writer pointer and the number of bytes writable
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*/
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unsigned char *
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abuf_wgetblk(struct abuf *buf, int *rsize)
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{
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int end, avail, count;
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end = buf->start + buf->used;
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if (end >= buf->len)
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end -= buf->len;
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avail = buf->len - buf->used;
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count = buf->len - end;
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if (count > avail)
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count = avail;
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*rsize = count;
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return buf->data + end;
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}
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