96 lines
3.1 KiB
C
96 lines
3.1 KiB
C
/*
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ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010 Giovanni Di Sirio.
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This file is part of ChibiOS/RT.
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ChibiOS/RT is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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ChibiOS/RT is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/**
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* @file memstreams.c
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* @brief Memory streams code.
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*
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* @addtogroup memory_streams
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* @{
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*/
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#include <string.h>
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#include "ch.h"
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#include "memstreams.h"
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/*
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* @brief Write virtual method implementation.
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*
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* @param[in] ip pointer to a @p MemoryStream object
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* @param[in] bp pointer to the data buffer
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* @param[in] n the maximum amount of data to be transferred
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* @return The number of bytes transferred. The return value can
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* be less than the specified number of bytes if the
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* stream reaches a physical end of file and cannot be
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* extended.
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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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MemoryStream *msp = ip;
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if (msp->size - msp->eos < n)
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n = msp->size - msp->eos;
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memcpy(msp->buffer + msp->eos, bp, n);
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msp->eos += n;
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return n;
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}
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/*
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* @brief Read virtual method implementation.
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*
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* @param[in] ip pointer to a @p MemoryStream object
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* @param[out] bp pointer to the data buffer
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* @param[in] n the maximum amount of data to be transferred
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* @return The number of bytes transferred. The return value can
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* be less than the specified number of bytes if the
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* stream reaches the end of the available data.
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*/
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static size_t reads(void *ip, uint8_t *bp, size_t n) {
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MemoryStream *msp = ip;
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if (msp->eos - msp->offset < n)
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n = msp->eos - msp->offset;
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memcpy(bp, msp->buffer + msp->offset, n);
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msp->offset += n;
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return n;
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}
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static const struct MemStreamVMT vmt = {writes, reads};
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/**
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* @brief Memory stream object initialization.
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*
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* @param[out] msp pointer to the @p MemoryStream object to be initialized
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* @param[in] buffer pointer to the memory buffer for the memory stream
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* @param[in] size total size of the memory stream buffer
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* @param[in] eos initial End Of Stream offset. Normally you need to
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* put this to zero for RAM buffers or equal to @p size
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* for ROM streams.
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*/
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void msObjectInit(MemoryStream *msp, uint8_t *buffer, size_t size, size_t eos) {
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msp->vmt = &vmt;
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msp->buffer = buffer;
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msp->size = size;
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msp->eos = eos;
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msp->offset = 0;
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}
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/** @} */
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