134 lines
4.1 KiB
C
134 lines
4.1 KiB
C
/****************************************************************************
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* libs/libc/stream/lib_memsistream.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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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, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <assert.h>
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#include "libc.h"
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: memsistream_getc
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****************************************************************************/
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static int memsistream_getc(FAR struct lib_sistream_s *this)
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{
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FAR struct lib_memsistream_s *mthis = (FAR struct lib_memsistream_s *)this;
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int ret;
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DEBUGASSERT(this);
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/* Get the next character (if any) from the buffer */
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if (mthis->offset < mthis->buflen)
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{
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ret = mthis->buffer[mthis->offset];
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mthis->offset++;
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this->nget++;
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}
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else
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{
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ret = EOF;
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}
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return ret;
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}
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/****************************************************************************
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* Name: memsistream_seek
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****************************************************************************/
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static off_t memsistream_seek(FAR struct lib_sistream_s *this, off_t offset,
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int whence)
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{
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FAR struct lib_memsistream_s *mthis = (FAR struct lib_memsistream_s *)this;
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off_t newpos;
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DEBUGASSERT(this);
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switch (whence)
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{
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case SEEK_CUR:
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newpos = (off_t)mthis->offset + offset;
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break;
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case SEEK_SET:
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newpos = offset;
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break;
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case SEEK_END:
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newpos = (off_t)mthis->buflen + offset;
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break;
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default:
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return (off_t)ERROR;
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}
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/* Make sure that the new position is within range */
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if (newpos < 0 || newpos >= (off_t)mthis->buflen)
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{
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return (off_t)ERROR;
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}
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/* Return the new position */
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mthis->offset = (size_t)newpos;
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return newpos;
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}
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: lib_memsistream
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*
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* Description:
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* Initializes a stream for use with a fixed-size memory buffer.
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*
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* Input Parameters:
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* instream - User allocated, uninitialized instance of struct
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* lib_memsistream_s to be initialized.
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* bufstart - Address of the beginning of the fixed-size memory buffer
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* buflen - Size of the fixed-sized memory buffer in bytes
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*
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* Returned Value:
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* None (instream initialized).
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*
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****************************************************************************/
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void lib_memsistream(FAR struct lib_memsistream_s *instream,
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FAR const char *bufstart, int buflen)
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{
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instream->public.get = memsistream_getc;
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instream->public.seek = memsistream_seek;
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instream->public.nget = 0; /* Total number of characters read */
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instream->buffer = bufstart; /* Start of buffer */
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instream->offset = 0; /* Will be the buffer index */
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instream->buflen = buflen; /* Length of the buffer */
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}
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