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/*
ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010,
2011 Giovanni Di Sirio.
This file is part of ChibiOS/RT.
ChibiOS/RT is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
ChibiOS/RT is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* @file memstreams.c
* @brief Memory streams code.
*
* @addtogroup memory_streams
* @{
*/
#include <string.h>
#include "ch.h"
#include "memstreams.h"
/*
* @brief Write virtual method implementation.
*
* @param[in] ip pointer to a @p MemoryStream object
* @param[in] bp pointer to the data buffer
* @param[in] n the maximum amount of data to be transferred
* @return The number of bytes transferred. The return value can
* be less than the specified number of bytes if the
* stream reaches a physical end of file and cannot be
* extended.
*/
static size_t writes(void *ip, const uint8_t *bp, size_t n) {
MemoryStream *msp = ip;
if (msp->size - msp->eos < n)
n = msp->size - msp->eos;
memcpy(msp->buffer + msp->eos, bp, n);
msp->eos += n;
return n;
}
/*
* @brief Read virtual method implementation.
*
* @param[in] ip pointer to a @p MemoryStream object
* @param[out] bp pointer to the data buffer
* @param[in] n the maximum amount of data to be transferred
* @return The number of bytes transferred. The return value can
* be less than the specified number of bytes if the
* stream reaches the end of the available data.
*/
static size_t reads(void *ip, uint8_t *bp, size_t n) {
MemoryStream *msp = ip;
if (msp->eos - msp->offset < n)
n = msp->eos - msp->offset;
memcpy(bp, msp->buffer + msp->offset, n);
msp->offset += n;
return n;
}
static const struct MemStreamVMT vmt = {writes, reads};
/**
* @brief Memory stream object initialization.
*
* @param[out] msp pointer to the @p MemoryStream object to be initialized
* @param[in] buffer pointer to the memory buffer for the memory stream
* @param[in] size total size of the memory stream buffer
* @param[in] eos initial End Of Stream offset. Normally you need to
* put this to zero for RAM buffers or equal to @p size
* for ROM streams.
*/
void msObjectInit(MemoryStream *msp, uint8_t *buffer, size_t size, size_t eos) {
msp->vmt = &vmt;
msp->buffer = buffer;
msp->size = size;
msp->eos = eos;
msp->offset = 0;
}
/** @} */
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