147 lines
3.7 KiB
C
147 lines
3.7 KiB
C
/*
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* Copyright (c) 2008 Travis Geiselbrecht
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files
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* (the "Software"), to deal in the Software without restriction,
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* including without limitation the rights to use, copy, modify, merge,
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* publish, distribute, sublicense, and/or sell copies of the Software,
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* and to permit persons to whom the Software is furnished to do so,
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* subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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#include <stdlib.h>
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#include <debug.h>
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#include <pow2.h>
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#include <string.h>
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#include <lib/cbuf.h>
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#include <kernel/event.h>
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#define LOCAL_TRACE 0
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#define INC_POINTER(cbuf, ptr, inc) \
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modpow2(((ptr) + (inc)), (cbuf)->len_pow2)
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void cbuf_initialize(cbuf_t *cbuf, size_t len)
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{
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DEBUG_ASSERT(cbuf);
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DEBUG_ASSERT(len > 0);
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DEBUG_ASSERT(ispow2(len));
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cbuf->head = 0;
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cbuf->tail = 0;
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cbuf->len_pow2 = log2(len);
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cbuf->buf = malloc(len);
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event_init(&cbuf->event, false, 0);
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LTRACEF("len %zd, len_pow2 %u\n", len, cbuf->len_pow2);
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}
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static size_t cbuf_space_avail(cbuf_t *cbuf)
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{
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return (cbuf->head + valpow2(cbuf->len_pow2) - cbuf->tail - 1);
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}
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size_t cbuf_write(cbuf_t *cbuf, const void *_buf, size_t len, bool canreschedule)
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{
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const char *buf = (const char *)_buf;
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LTRACEF("len %zd\n", len);
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DEBUG_ASSERT(cbuf);
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DEBUG_ASSERT(_buf);
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DEBUG_ASSERT(len < valpow2(cbuf->len_pow2));
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enter_critical_section();
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size_t write_len;
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size_t pos = 0;
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while (pos < len && cbuf_space_avail(cbuf) > 0) {
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if (cbuf->head >= cbuf->tail) {
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write_len = MIN(valpow2(cbuf->len_pow2) - cbuf->head, len - pos);
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} else {
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write_len = MIN(cbuf->tail - cbuf->head - 1, len - pos);
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}
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// if it's full, abort and return how much we've written
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if (write_len == 0) {
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break;
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}
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memcpy(cbuf->buf + cbuf->head, buf + pos, write_len);
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cbuf->head = INC_POINTER(cbuf, cbuf->head, write_len);
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pos += write_len;
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}
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if (cbuf->head != cbuf->tail)
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event_signal(&cbuf->event, canreschedule);
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exit_critical_section();
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return pos;
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}
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size_t cbuf_read(cbuf_t *cbuf, void *_buf, size_t buflen, bool block)
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{
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size_t ret;
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char *buf = (char *)_buf;
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DEBUG_ASSERT(cbuf);
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DEBUG_ASSERT(_buf);
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enter_critical_section();
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if (block)
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event_wait(&cbuf->event);
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// see if there's data available
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if (cbuf->tail != cbuf->head) {
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size_t pos = 0;
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// loop until we've read everything we need
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// at most this will make two passes to deal with wraparound
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while (pos < buflen && cbuf->tail != cbuf->head) {
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size_t read_len;
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if (cbuf->head > cbuf->tail) {
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// simple case where there is no wraparound
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read_len = MIN(cbuf->head - cbuf->tail, buflen - pos);
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} else {
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// read to the end of buffer in this pass
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read_len = MIN(valpow2(cbuf->len_pow2) - cbuf->tail, buflen - pos);
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}
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memcpy(buf + pos, cbuf->buf + cbuf->tail, read_len);
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cbuf->tail = INC_POINTER(cbuf, cbuf->tail, read_len);
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pos += read_len;
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}
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if (cbuf->tail == cbuf->head) {
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// we've emptied the buffer, unsignal the event
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event_unsignal(&cbuf->event);
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}
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ret = pos;
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} else {
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DEBUG_ASSERT(!block);
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ret = 0;
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}
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exit_critical_section();
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return ret;
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}
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