00001 /* 00002 * AC-3 DSP utils 00003 * Copyright (c) 2011 Justin Ruggles 00004 * 00005 * This file is part of FFmpeg. 00006 * 00007 * FFmpeg is free software; you can redistribute it and/or 00008 * modify it under the terms of the GNU Lesser General Public 00009 * License as published by the Free Software Foundation; either 00010 * version 2.1 of the License, or (at your option) any later version. 00011 * 00012 * FFmpeg is distributed in the hope that it will be useful, 00013 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00014 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 00015 * Lesser General Public License for more details. 00016 * 00017 * You should have received a copy of the GNU Lesser General Public 00018 * License along with FFmpeg; if not, write to the Free Software 00019 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 00020 */ 00021 00022 #include "avcodec.h" 00023 #include "ac3dsp.h" 00024 00025 static void ac3_exponent_min_c(uint8_t *exp, int num_reuse_blocks, int nb_coefs) 00026 { 00027 int blk, i; 00028 00029 if (!num_reuse_blocks) 00030 return; 00031 00032 for (i = 0; i < nb_coefs; i++) { 00033 uint8_t min_exp = *exp; 00034 uint8_t *exp1 = exp + 256; 00035 for (blk = 0; blk < num_reuse_blocks; blk++) { 00036 uint8_t next_exp = *exp1; 00037 if (next_exp < min_exp) 00038 min_exp = next_exp; 00039 exp1 += 256; 00040 } 00041 *exp++ = min_exp; 00042 } 00043 } 00044 00045 static int ac3_max_msb_abs_int16_c(const int16_t *src, int len) 00046 { 00047 int i, v = 0; 00048 for (i = 0; i < len; i++) 00049 v |= abs(src[i]); 00050 return v; 00051 } 00052 00053 av_cold void ff_ac3dsp_init(AC3DSPContext *c) 00054 { 00055 c->ac3_exponent_min = ac3_exponent_min_c; 00056 c->ac3_max_msb_abs_int16 = ac3_max_msb_abs_int16_c; 00057 00058 if (HAVE_MMX) 00059 ff_ac3dsp_init_x86(c); 00060 }