1ff36b5d4d
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com> Reviewed-by: Peter Lieven <pl@kamp.de> Reviewed-by: Daniel P. Berrange <berrange@redhat.com> Message-id: 1446203414-4013-6-git-send-email-kraxel@redhat.com
128 lines
3.1 KiB
C
128 lines
3.1 KiB
C
/*
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* QEMU generic buffers
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*
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* Copyright (c) 2015 Red Hat, Inc.
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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 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, see <http://www.gnu.org/licenses/>.
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*
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*/
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#include "qemu/buffer.h"
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#define BUFFER_MIN_INIT_SIZE 4096
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#define BUFFER_MIN_SHRINK_SIZE 65536
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void buffer_init(Buffer *buffer, const char *name, ...)
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{
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va_list ap;
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va_start(ap, name);
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buffer->name = g_strdup_vprintf(name, ap);
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va_end(ap);
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}
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void buffer_shrink(Buffer *buffer)
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{
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/*
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* Only shrink in case the used size is *much* smaller than the
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* capacity, to avoid bumping up & down the buffers all the time.
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* realloc() isn't exactly cheap ...
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*/
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if (buffer->offset < (buffer->capacity >> 3) &&
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buffer->capacity > BUFFER_MIN_SHRINK_SIZE) {
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return;
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}
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buffer->capacity = pow2ceil(buffer->offset);
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buffer->capacity = MAX(buffer->capacity, BUFFER_MIN_SHRINK_SIZE);
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buffer->buffer = g_realloc(buffer->buffer, buffer->capacity);
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}
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void buffer_reserve(Buffer *buffer, size_t len)
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{
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if ((buffer->capacity - buffer->offset) < len) {
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buffer->capacity = pow2ceil(buffer->offset + len);
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buffer->capacity = MAX(buffer->capacity, BUFFER_MIN_INIT_SIZE);
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buffer->buffer = g_realloc(buffer->buffer, buffer->capacity);
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}
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}
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gboolean buffer_empty(Buffer *buffer)
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{
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return buffer->offset == 0;
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}
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uint8_t *buffer_end(Buffer *buffer)
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{
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return buffer->buffer + buffer->offset;
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}
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void buffer_reset(Buffer *buffer)
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{
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buffer->offset = 0;
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}
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void buffer_free(Buffer *buffer)
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{
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g_free(buffer->buffer);
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g_free(buffer->name);
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buffer->offset = 0;
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buffer->capacity = 0;
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buffer->buffer = NULL;
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buffer->name = NULL;
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}
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void buffer_append(Buffer *buffer, const void *data, size_t len)
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{
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memcpy(buffer->buffer + buffer->offset, data, len);
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buffer->offset += len;
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}
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void buffer_advance(Buffer *buffer, size_t len)
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{
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memmove(buffer->buffer, buffer->buffer + len,
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(buffer->offset - len));
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buffer->offset -= len;
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}
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void buffer_move_empty(Buffer *to, Buffer *from)
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{
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assert(to->offset == 0);
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g_free(to->buffer);
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to->offset = from->offset;
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to->capacity = from->capacity;
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to->buffer = from->buffer;
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from->offset = 0;
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from->capacity = 0;
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from->buffer = NULL;
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}
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void buffer_move(Buffer *to, Buffer *from)
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{
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if (to->offset == 0) {
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buffer_move_empty(to, from);
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return;
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}
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buffer_reserve(to, from->offset);
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buffer_append(to, from->buffer, from->offset);
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g_free(from->buffer);
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from->offset = 0;
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from->capacity = 0;
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from->buffer = NULL;
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}
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