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248 lines
7.9 KiB
C
248 lines
7.9 KiB
C
/* $Id: serial.c,v 1.4 2003/05/05 23:14:34 fredette Exp $ */
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/* generic/serial.c - generic serial implementation support: */
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/*
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* Copyright (c) 2003 Matt Fredette
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by Matt Fredette.
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* 4. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
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* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <tme/common.h>
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_TME_RCSID("$Id: serial.c,v 1.4 2003/05/05 23:14:34 fredette Exp $");
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/* includes: */
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#include <tme/generic/serial.h>
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/* this initializes a serial buffer: */
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int
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tme_serial_buffer_init(struct tme_serial_buffer *buffer, unsigned int size)
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{
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/* round the buffer size up to a power of two: */
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if (size & (size - 1)) {
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do {
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size &= (size - 1);
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} while (size & (size - 1));
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size <<= 1;
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}
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/* set the buffer size: */
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buffer->tme_serial_buffer_size = size;
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/* set the head and tail pointers: */
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buffer->tme_serial_buffer_head = 0;
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buffer->tme_serial_buffer_tail = 0;
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/* allocate the buffer data and flags: */
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buffer->tme_serial_buffer_data =
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tme_new(tme_uint8_t, size);
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buffer->tme_serial_buffer_data_flags =
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tme_new(tme_serial_data_flags_t, size);
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/* done: */
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return (TME_OK);
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}
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/* this copies data into a serial buffer: */
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unsigned int
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tme_serial_buffer_copyin(struct tme_serial_buffer *buffer,
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const tme_uint8_t *data,
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unsigned int count,
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tme_serial_data_flags_t data_flags,
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int copy_flags)
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{
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unsigned int resid;
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unsigned int buffer_head, buffer_tail, buffer_size_mask;
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unsigned int buffer_size;
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/* get the head, tail, and size mask: */
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buffer_head = buffer->tme_serial_buffer_head;
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buffer_tail = buffer->tme_serial_buffer_tail;
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buffer_size_mask = buffer->tme_serial_buffer_size - 1;
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/* while we have more data to copy in: */
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for (resid = count; resid > 0; ) {
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/* if the buffer is full: */
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if (((buffer_head + 1) & buffer_size_mask)
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== buffer_tail) {
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/* if a full buffer means an overrun, mark it: */
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if (copy_flags & TME_SERIAL_COPY_FULL_IS_OVERRUN) {
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buffer->tme_serial_buffer_data_flags[buffer_head] |= TME_SERIAL_DATA_OVERRUN;
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}
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/* we're done copying in: */
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break;
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}
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/* otherwise, the buffer is not full, meaning there is always some
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space starting at the buffer head. if the buffer head >= the
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buffer tail, there is space from the buffer head up to the end
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of the buffer, otherwise there is space from the buffer head up
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to one before the buffer tail: */
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buffer_size = ((buffer_head >= buffer_tail)
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? (buffer_size_mask - buffer_head) + 1
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: (buffer_tail - buffer_head) - 1);
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/* don't copy in more data than is available: */
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buffer_size = TME_MIN(buffer_size, resid);
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assert(buffer_size > 0);
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/* copy in this data: */
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memcpy(buffer->tme_serial_buffer_data + buffer_head,
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data,
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buffer_size);
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memset(buffer->tme_serial_buffer_data_flags + buffer_head,
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data_flags,
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buffer_size);
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/* update and loop: */
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buffer_head = (buffer_head + buffer_size) & buffer_size_mask;
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data += buffer_size;
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resid -= buffer_size;
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}
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/* store our new head pointer: */
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buffer->tme_serial_buffer_head = buffer_head;
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/* done: */
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return (count - resid);
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}
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/* this copies data out of a buffer: */
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unsigned int
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tme_serial_buffer_copyout(struct tme_serial_buffer *buffer,
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tme_uint8_t *data,
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unsigned int count,
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tme_serial_data_flags_t *_data_flags,
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int copy_flags)
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{
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unsigned int resid;
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unsigned int buffer_head, buffer_tail, buffer_size_mask;
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unsigned int buffer_size;
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tme_serial_data_flags_t data_flags, *scan_flags;
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unsigned int scan_resid;
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/* get the head, tail, and size mask: */
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buffer_head = buffer->tme_serial_buffer_head;
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buffer_tail = buffer->tme_serial_buffer_tail;
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buffer_size_mask = buffer->tme_serial_buffer_size - 1;
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/* we can only return data with the same data flags: */
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data_flags = buffer->tme_serial_buffer_data_flags[buffer_tail];
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/* while we have more data to copy out: */
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for (resid = count; resid > 0; ) {
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/* if the buffer is empty: */
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if (buffer_tail == buffer_head) {
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/* we're done copying out: */
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break;
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}
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/* otherwise, the buffer is not empty, meaning there is always some
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data starting at the buffer tail. if the buffer tail > the
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buffer head, there is space from the buffer tail up to the end
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of the buffer, otherwise there is space from the buffer tail up
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to the buffer head: */
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buffer_size = ((buffer_tail > buffer_head)
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? (buffer_size_mask - buffer_tail) + 1
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: (buffer_head - buffer_tail));
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/* don't copy out more data than there is space available: */
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buffer_size = TME_MIN(buffer_size, resid);
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assert(buffer_size > 0);
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/* only copy out data with the same buffer flags. if we just
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wrapped in the buffer, we may find that no new data has the
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same buffer flags as data we already copied out: */
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scan_flags = buffer->tme_serial_buffer_data_flags + buffer_tail;
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scan_resid = buffer_size;
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for (; (*(scan_flags++) == data_flags
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&& --scan_resid > 0); );
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buffer_size -= scan_resid;
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if (buffer_size == 0) {
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break;
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}
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/* copy out this data: */
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if (data != NULL) {
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memcpy(data,
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buffer->tme_serial_buffer_data + buffer_tail,
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buffer_size);
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data += buffer_size;
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}
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/* update and loop: */
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buffer_tail = (buffer_tail + buffer_size) & buffer_size_mask;
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resid -= buffer_size;
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}
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/* store our new tail pointer: */
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if (!(copy_flags & TME_SERIAL_COPY_PEEK)) {
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buffer->tme_serial_buffer_tail = buffer_tail;
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}
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/* done: */
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if (_data_flags != NULL) {
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*_data_flags = data_flags;
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}
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return (count - resid);
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}
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/* this returns the amount of busy space in the buffer: */
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unsigned int
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tme_serial_buffer_space_busy(const struct tme_serial_buffer *buffer)
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{
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unsigned int buffer_head, buffer_tail, buffer_size;
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/* get the head, tail, and size: */
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buffer_head = buffer->tme_serial_buffer_head;
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buffer_tail = buffer->tme_serial_buffer_tail;
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buffer_size = buffer->tme_serial_buffer_size;
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if (buffer_head >= buffer_tail) {
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return (buffer_head - buffer_tail);
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}
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else {
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return (buffer_size - (buffer_tail - buffer_head));
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}
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}
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/* this returns the amount of free space in the buffer: */
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unsigned int
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tme_serial_buffer_space_free(const struct tme_serial_buffer *buffer)
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{
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/* you can't completely fill the buffer: */
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return ((buffer->tme_serial_buffer_size - 1)
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- tme_serial_buffer_space_busy(buffer));
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}
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