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151 lines
5 KiB
C
151 lines
5 KiB
C
/****************************************************************************
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* libs/libc/misc/lib_tempbuffer.c
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*
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* SPDX-License-Identifier: Apache-2.0
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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 <nuttx/config.h>
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#include <nuttx/atomic.h>
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#include <nuttx/lib/lib.h>
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#include <stdlib.h>
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#include <string.h>
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/****************************************************************************
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* Pre-processor definitions
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****************************************************************************/
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#if CONFIG_PATH_MAX > CONFIG_LINE_MAX
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# define TEMP_MAX_SIZE CONFIG_PATH_MAX
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#else
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# define TEMP_MAX_SIZE CONFIG_LINE_MAX
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#endif
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/****************************************************************************
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* Private Types
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****************************************************************************/
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struct tempbuffer_s
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{
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atomic_t free_bitmap; /* Bitmap of free buffer */
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char buffer[CONFIG_LIBC_MAX_TEMPBUFFER][TEMP_MAX_SIZE];
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};
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/****************************************************************************
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* Private Data
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****************************************************************************/
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static struct tempbuffer_s g_tempbuffer =
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{
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(1u << CONFIG_LIBC_MAX_TEMPBUFFER) - 1,
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};
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/****************************************************************************
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* Private Functions
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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_get_tempbuffer
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*
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* Description:
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* The lib_get_tempbuffer() function returns a pointer to a temporary
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* buffer. The buffer is allocated from a pool of pre-allocated buffers
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* and if the pool is exhausted, a new buffer is allocated through
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* kmm_malloc(). The size of the buffer is nbytes, and must freed by
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* calling lib_put_tempbuffer().
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*
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* Returned Value:
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* On success, lib_get_tempbuffer() returns a pointer to a temporary
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* buffer. On failure, NULL is returned.
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*
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****************************************************************************/
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FAR char *lib_get_tempbuffer(size_t nbytes)
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{
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if (nbytes <= TEMP_MAX_SIZE)
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{
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for (; ; )
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{
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int32_t update;
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int32_t free_bitmap = atomic_read(&g_tempbuffer.free_bitmap);
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int index = ffsl(free_bitmap) - 1;
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if (index < 0 || index >= CONFIG_LIBC_MAX_TEMPBUFFER)
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{
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break;
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}
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update = free_bitmap & ~(1u << index);
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if (atomic_cmpxchg(&g_tempbuffer.free_bitmap, &free_bitmap,
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update))
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{
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return g_tempbuffer.buffer[index];
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}
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}
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}
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/* If no free buffer is found, allocate a new one if
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* CONFIG_LIBC_TEMPBUFFER_MALLOC is enabled
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*/
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#ifdef CONFIG_LIBC_TEMPBUFFER_MALLOC
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return lib_malloc(nbytes);
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#else
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return NULL;
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#endif
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}
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/****************************************************************************
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* Name: lib_put_tempbuffer
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*
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* Description:
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* The lib_put_tempbuffer() function frees a temporary buffer that was
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* allocated by lib_get_tempbuffer(). If the buffer was allocated
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* dynamically, it is freed by calling kmm_free(). Otherwise, the buffer
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* is marked as free in the pool of pre-allocated buffers.
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*
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* Returned Value:
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* None
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*
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****************************************************************************/
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void lib_put_tempbuffer(FAR char *buffer)
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{
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int index = (buffer - &g_tempbuffer.buffer[0][0]) / TEMP_MAX_SIZE;
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if (index >= 0 && index < CONFIG_LIBC_MAX_TEMPBUFFER)
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{
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DEBUGASSERT((atomic_read(&g_tempbuffer.free_bitmap) &
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(1u << index)) == 0);
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atomic_fetch_or_acquire(&g_tempbuffer.free_bitmap, 1u << index);
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return;
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}
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/* Free the buffer if it was dynamically allocated */
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#ifdef CONFIG_LIBC_TEMPBUFFER_MALLOC
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lib_free(buffer);
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#endif
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}
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