fe9a3d9a10
The memory buffer already supported appending and prepending data, but not inserting data anywhere in the buffer. That's exactly what the new function does. The free space is still maintained at either the start or the end of the buffer.
334 lines
6.5 KiB
C
334 lines
6.5 KiB
C
/*
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* libdivecomputer
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*
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* Copyright (C) 2009 Jef Driesen
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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* MA 02110-1301 USA
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*/
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#include <stdlib.h> // malloc, realloc, free
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#include <string.h> // memcpy, memmove
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#include <libdivecomputer/buffer.h>
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struct dc_buffer_t {
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unsigned char *data;
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size_t capacity, offset, size;
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};
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dc_buffer_t *
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dc_buffer_new (size_t capacity)
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{
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dc_buffer_t *buffer = (dc_buffer_t *) malloc (sizeof (dc_buffer_t));
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if (buffer == NULL)
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return NULL;
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if (capacity) {
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buffer->data = (unsigned char *) malloc (capacity);
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if (buffer->data == NULL) {
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free (buffer);
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return NULL;
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}
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} else {
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buffer->data = NULL;
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}
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buffer->capacity = capacity;
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buffer->offset = 0;
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buffer->size = 0;
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return buffer;
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}
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void
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dc_buffer_free (dc_buffer_t *buffer)
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{
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if (buffer == NULL)
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return;
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if (buffer->data)
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free (buffer->data);
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free (buffer);
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}
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int
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dc_buffer_clear (dc_buffer_t *buffer)
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{
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if (buffer == NULL)
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return 0;
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buffer->offset = 0;
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buffer->size = 0;
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return 1;
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}
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static size_t
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dc_buffer_expand_calc (dc_buffer_t *buffer, size_t n)
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{
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size_t oldsize = buffer->capacity;
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size_t newsize = (oldsize ? oldsize : n);
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while (newsize < n)
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newsize *= 2;
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return newsize;
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}
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static int
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dc_buffer_expand_append (dc_buffer_t *buffer, size_t n)
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{
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if (n > buffer->capacity - buffer->offset) {
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if (n > buffer->capacity) {
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size_t capacity = dc_buffer_expand_calc (buffer, n);
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unsigned char *data = (unsigned char *) malloc (capacity);
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if (data == NULL)
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return 0;
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if (buffer->size)
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memcpy (data, buffer->data + buffer->offset, buffer->size);
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free (buffer->data);
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buffer->data = data;
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buffer->capacity = capacity;
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buffer->offset = 0;
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} else {
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if (buffer->size)
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memmove (buffer->data, buffer->data + buffer->offset, buffer->size);
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buffer->offset = 0;
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}
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}
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return 1;
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}
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static int
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dc_buffer_expand_prepend (dc_buffer_t *buffer, size_t n)
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{
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size_t available = buffer->capacity - buffer->size;
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if (n > buffer->offset + buffer->size) {
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if (n > buffer->capacity) {
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size_t capacity = dc_buffer_expand_calc (buffer, n);
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unsigned char *data = (unsigned char *) malloc (capacity);
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if (data == NULL)
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return 0;
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if (buffer->size)
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memcpy (data + capacity - buffer->size, buffer->data + buffer->offset, buffer->size);
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free (buffer->data);
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buffer->data = data;
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buffer->capacity = capacity;
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buffer->offset = capacity - buffer->size;
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} else {
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if (buffer->size)
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memmove (buffer->data + available, buffer->data + buffer->offset, buffer->size);
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buffer->offset = available;
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}
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}
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return 1;
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}
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int
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dc_buffer_reserve (dc_buffer_t *buffer, size_t capacity)
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{
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if (buffer == NULL)
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return 0;
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if (capacity <= buffer->capacity)
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return 1;
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unsigned char *data = (unsigned char *) realloc (buffer->data, capacity);
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if (data == NULL)
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return 0;
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buffer->data = data;
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buffer->capacity = capacity;
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return 1;
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}
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int
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dc_buffer_resize (dc_buffer_t *buffer, size_t size)
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{
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if (buffer == NULL)
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return 0;
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if (!dc_buffer_expand_append (buffer, size))
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return 0;
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if (size > buffer->size)
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memset (buffer->data + buffer->offset + buffer->size, 0, size - buffer->size);
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buffer->size = size;
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return 1;
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}
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int
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dc_buffer_append (dc_buffer_t *buffer, const unsigned char data[], size_t size)
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{
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if (buffer == NULL)
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return 0;
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if (!dc_buffer_expand_append (buffer, buffer->size + size))
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return 0;
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if (size)
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memcpy (buffer->data + buffer->offset + buffer->size, data, size);
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buffer->size += size;
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return 1;
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}
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int
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dc_buffer_prepend (dc_buffer_t *buffer, const unsigned char data[], size_t size)
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{
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if (buffer == NULL)
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return 0;
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if (!dc_buffer_expand_prepend (buffer, buffer->size + size))
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return 0;
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if (size)
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memcpy (buffer->data + buffer->offset - size, data, size);
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buffer->size += size;
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buffer->offset -= size;
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return 1;
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}
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int
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dc_buffer_insert (dc_buffer_t *buffer, size_t offset, const unsigned char data[], size_t size)
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{
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if (buffer == NULL)
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return 0;
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if (offset > buffer->size)
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return 0;
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size_t head = buffer->offset;
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size_t tail = buffer->capacity - (buffer->offset + buffer->size);
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unsigned char *ptr = buffer->data + buffer->offset;
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if (size <= head) {
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if (buffer->size)
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memmove (ptr - size, ptr, offset);
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buffer->offset -= size;
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} else if (size <= tail) {
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if (buffer->size)
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memmove (ptr + offset + size, ptr + offset, buffer->size - offset);
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} else if (size <= tail + head) {
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size_t n = buffer->size + size;
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size_t available = buffer->capacity - n;
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size_t tmp_offset = head > tail ? available : 0;
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unsigned char *tmp = buffer->data;
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if (buffer->size) {
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memmove (tmp + tmp_offset, ptr, offset);
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memmove (tmp + tmp_offset + offset + size, ptr + offset, buffer->size - offset);
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}
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buffer->offset = tmp_offset;
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} else {
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size_t n = buffer->size + size;
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size_t capacity = dc_buffer_expand_calc (buffer, n);
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size_t available = capacity - n;
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size_t tmp_offset = head > tail ? available : 0;
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unsigned char *tmp = (unsigned char *) malloc (capacity);
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if (tmp == NULL)
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return 0;
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if (buffer->size) {
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memcpy (tmp + tmp_offset, ptr, offset);
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memcpy (tmp + tmp_offset + offset + size, ptr + offset, buffer->size - offset);
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}
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free (buffer->data);
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buffer->data = tmp;
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buffer->capacity = capacity;
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buffer->offset = tmp_offset;
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}
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if (size)
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memcpy (buffer->data + buffer->offset + offset, data, size);
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buffer->size += size;
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return 1;
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}
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int
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dc_buffer_slice (dc_buffer_t *buffer, size_t offset, size_t size)
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{
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if (buffer == NULL)
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return 0;
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if (offset + size > buffer->size)
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return 0;
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buffer->offset += offset;
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buffer->size = size;
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return 1;
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}
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size_t
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dc_buffer_get_size (dc_buffer_t *buffer)
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{
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if (buffer == NULL)
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return 0;
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return buffer->size;
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}
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unsigned char *
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dc_buffer_get_data (dc_buffer_t *buffer)
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{
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if (buffer == NULL)
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return NULL;
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return buffer->size ? buffer->data + buffer->offset : NULL;
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}
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