106 lines
3.5 KiB
C
106 lines
3.5 KiB
C
/****************************************************************************
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* libs/libc/obstack/lib_obstack_make_room.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 <obstack.h>
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#include <assert.h>
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#include <string.h>
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#include "lib_obstack_malloc.h"
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: obstack_make_room
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*
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* Description:
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* This is non-standard function that is probably available only on NuttX!
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* Make sure that there is room in the buffer to fit object with given
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* size. The allocation performed is in multiples of chunk_size specified
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* for the obstack.
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*
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* Input Parameters:
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* h: pointer to the handle where room should be made
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* size: number of bytes to be free for growth
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*
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* Assumptions/Limitations:
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* The obstack's chunk_size is expected to be power of two. This helps to
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* eliminate division that might not be implemented in the HW and thus
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* inefficient.
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*
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****************************************************************************/
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void obstack_make_room(FAR struct obstack *h, size_t size)
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{
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unsigned i;
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size_t mask;
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DEBUGASSERT(h);
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if (obstack_room(h) >= size)
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{
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return; /* No need to allocate anything */
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}
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size_t object_size = obstack_object_size(h);
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size += object_size + sizeof(struct _obstack_chunk);
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/* Note: this is rounding up to the multiple of chunk size that is power of
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* two. Thus this creates limitation that chunks can be only power of two.
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*/
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mask = h->chunk_size;
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for (i = 1; i < sizeof(size_t); i <<= 1)
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mask |= mask >> i;
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size = (size + mask) & ~mask;
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if (h->chunk == NULL ||
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h->object_base != (FAR char *)h->chunk + sizeof(struct _obstack_chunk))
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{
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/* Allocate new chunk if there is something in the chunk already or if
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* there is no chunk yet.
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*/
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FAR struct _obstack_chunk *prev = h->chunk;
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h->chunk = lib_obstack_malloc(size);
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h->chunk->prev = prev;
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/* Move growing object to the new chunk */
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memcpy((FAR char *)h->chunk + sizeof(struct _obstack_chunk),
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h->object_base, object_size);
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}
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else
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{
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h->chunk = lib_obstack_realloc(h->chunk, size);
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}
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h->chunk->limit =
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(FAR char *)h->chunk + sizeof(struct _obstack_chunk) + size;
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h->object_base = (FAR char *)h->chunk + sizeof(struct _obstack_chunk);
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h->next_free = h->object_base + object_size;
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}
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