From 7b9a310d0e27c1c67c62289b5578ad1518cd07ac Mon Sep 17 00:00:00 2001 From: Nicolas George Date: Sat, 8 Mar 2014 21:26:59 +0100 Subject: [PATCH] lavu: add AV_DYNARRAY_ADD() macro. Signed-off-by: Nicolas George Reviewed-by: Lukasz Marek Signed-off-by: Michael Niedermayer --- libavutil/dynarray.h | 72 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 72 insertions(+) create mode 100644 libavutil/dynarray.h diff --git a/libavutil/dynarray.h b/libavutil/dynarray.h new file mode 100644 index 0000000000..3a3d24c693 --- /dev/null +++ b/libavutil/dynarray.h @@ -0,0 +1,72 @@ +/* + * This file is part of FFmpeg. + * + * FFmpeg is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public License + * as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * FFmpeg is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public License + * along with FFmpeg; if not, write to the Free Software Foundation, Inc., + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#ifndef AVUTIL_DYNARRAY_H +#define AVUTIL_DYNARRAY_H + +#include "log.h" +#include "mem.h" + +/** + * Add an element of to a dynamic array. + * + * The array is reallocated when its number of elements reaches powers of 2. + * Therefore, the amortized cost of adding an element is constant. + * + * In case of success, the pointer to the array is updated in order to + * point to the new grown array, and the size is incremented. + * + * @param av_size_max maximum size of the array, usually the MAX macro of + * the type of the size + * @param av_elt_size size of the elements in the array, in bytes + * @param av_array pointer to the array, must be a lvalue + * @param av_size size of the array, must be an interger lvalue + * @param av_success statement to execute on success; at this point, the + * size variable is not yet incremented + * @param av_failure statement to execute on failure; if this happens, the + * array and size are not changed; the statement can end + * with a return or a goto + */ +#define AV_DYNARRAY_ADD(av_size_max, av_elt_size, av_array, av_size, \ + av_success, av_failure) \ + do { \ + size_t av_size_new = (av_size); \ + if (!((av_size) & ((av_size) - 1))) { \ + av_size_new = (av_size) ? (av_size) << 1 : 1; \ + if (av_size_new > (av_size_max) / (av_elt_size)) { \ + av_size_new = 0; \ + } else { \ + void *av_array_new = \ + av_realloc((av_array), av_size_new * (av_elt_size)); \ + av_log(NULL, AV_LOG_DEBUG, "Resizing array to %zd\n", \ + av_size_new); \ + if (!av_array_new) \ + av_size_new = 0; \ + else \ + (av_array) = av_array_new; \ + } \ + } \ + if (av_size_new) { \ + { av_success } \ + (av_size)++; \ + } else { \ + av_failure \ + } \ + } while (0) + +#endif /* AVUTIL_DYNARRAY_H */