124 lines
3.9 KiB
C
124 lines
3.9 KiB
C
/*
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ChibiOS - Copyright (C) 2006..2018 Giovanni Di Sirio
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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/*
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This file was contributed by Alex Lewontin.
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*/
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/**
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* @file bufstreams.c
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* @brief Buffered streams code.
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*
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* @addtogroup HAL_BUFFERED_STREAMS
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* @details Wrapper for BaseSequentialStreams that allows some ungetting.
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* @{
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*/
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#include <string.h>
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#include "hal.h"
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#include "bufstreams.h"
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/*===========================================================================*/
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/* Driver local definitions. */
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/*===========================================================================*/
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/*===========================================================================*/
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/* Driver exported variables. */
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/*===========================================================================*/
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/*===========================================================================*/
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/* Driver local variables. */
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/*===========================================================================*/
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/*===========================================================================*/
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/* Driver local functions. */
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/*===========================================================================*/
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static size_t _writes(void *ip, const uint8_t *bp, size_t n) {
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BufferedStreamAdapter *bsap = ip;
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return bsap->bssp->vmt->write(bsap->bssp, bp, n);
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}
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static size_t _reads(void *ip, uint8_t *bp, size_t n) {
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BufferedStreamAdapter* bsap = ip;
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size_t buffered;
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if (n < (BUFSTREAM_BUFFER_SIZE - bsap->ndx)) {
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buffered = n;
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} else {
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buffered = BUFSTREAM_BUFFER_SIZE - bsap->ndx;
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}
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memcpy(bp, bsap->buffer + (BUFSTREAM_BUFFER_SIZE - buffered), buffered);
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bsap->ndx += buffered;
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return buffered + bsap->bssp->vmt->read(bsap->bssp, bp + buffered, n - buffered);
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}
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static msg_t _put(void *ip, uint8_t b) {
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BufferedStreamAdapter* bsap = ip;
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return bsap->bssp->vmt->put(bsap->bssp, b);
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}
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static msg_t _get(void *ip) {
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BufferedStreamAdapter* bsap = ip;
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if (bsap->ndx == BUFSTREAM_BUFFER_SIZE) {
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return bsap->bssp->vmt->get(bsap->bssp);
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}
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return bsap->buffer[bsap->ndx++];
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}
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static msg_t _unget(void* ip, uint8_t b) {
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BufferedStreamAdapter* bsap = ip;
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if (((int8_t)b == STM_RESET) || (bsap->ndx == 0)) {
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return STM_RESET;
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}
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bsap->buffer[--(bsap->ndx)] = b;
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return b;
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}
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static const struct BufferedStreamAdapterVMT vmt = {
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(size_t)0, _writes, _reads, _put, _get, _unget
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};
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/*===========================================================================*/
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/* Driver exported functions. */
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/*===========================================================================*/
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/**
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* @brief Buffered stream adapter object initialization.
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*
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* @param[out] bsap pointer to the @p BufferedStream object to be
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* initialized
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* @param[in] bssp pointer to a @p BaseSequentialStream fulfilling
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* object to be wrapped
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*/
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void bsaObjectInit(BufferedStreamAdapter *bsap, BaseSequentialStream* bssp) {
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bsap->vmt = &vmt;
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bsap->bssp = bssp;
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memset(bsap->buffer, STM_RESET, BUFSTREAM_BUFFER_SIZE);
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bsap->ndx = BUFSTREAM_BUFFER_SIZE;
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}
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/** @} */
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