incubator-nuttx/libs/libc/stream/lib_meminstream.c

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/****************************************************************************
* libs/libc/stream/lib_meminstream.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <assert.h>
#include <string.h>
#include "libc.h"
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: meminstream_getc
****************************************************************************/
static int meminstream_getc(FAR struct lib_instream_s *self)
{
FAR struct lib_meminstream_s *stream =
(FAR struct lib_meminstream_s *)self;
int ret;
DEBUGASSERT(self);
/* Get the next character (if any) from the buffer */
if (self->nget < stream->buflen)
{
ret = stream->buffer[self->nget];
self->nget++;
}
else
{
ret = EOF;
}
return ret;
}
/****************************************************************************
* Name: meminstream_gets
****************************************************************************/
static int meminstream_gets(FAR struct lib_instream_s *self,
FAR void *buffer, int len)
{
FAR struct lib_meminstream_s *stream =
(FAR struct lib_meminstream_s *)self;
int ret;
DEBUGASSERT(self);
/* Get the buffer (if any) from the stream */
if (self->nget < stream->buflen)
{
ret = stream->buflen - self->nget < len ?
stream->buflen - self->nget : len;
self->nget += ret;
memcpy(buffer, stream->buffer, ret);
}
else
{
ret = EOF;
}
return ret;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: lib_meminstream
*
* Description:
* Initializes a stream for use with a fixed-size memory buffer.
*
* Input Parameters:
* stream - User allocated, uninitialized instance of struct
* lib_meminstream_s to be initialized.
* bufstart - Address of the beginning of the fixed-size memory buffer
* buflen - Size of the fixed-sized memory buffer in bytes
*
* Returned Value:
* None (stream initialized).
*
****************************************************************************/
void lib_meminstream(FAR struct lib_meminstream_s *stream,
FAR const char *bufstart, int buflen)
{
stream->common.getc = meminstream_getc;
stream->common.gets = meminstream_gets;
stream->common.nget = 0; /* Will be buffer index */
stream->buffer = bufstart; /* Start of buffer */
stream->buflen = buflen; /* Length of the buffer */
}