add more OKed parts of the E-AC-3 decoder

Originally committed as revision 14912 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/eac3dec.c

+/*
+ * E-AC-3 decoder
+ * Copyright (c) 2007 Bartlomiej Wolowiec <bartek.wolowiec@gmail.com>
+ * Copyright (c) 2008 Justin Ruggles
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 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
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU 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
+ */
+
+#include "avcodec.h"
+#include "ac3.h"
+#include "ac3_parser.h"
+#include "ac3dec.h"
+#include "ac3dec_data.h"
+
+/** gain adaptive quantization mode */
+typedef enum {
+    EAC3_GAQ_NO =0,
+    EAC3_GAQ_12,
+    EAC3_GAQ_14,
+    EAC3_GAQ_124
+} EAC3GaqMode;
+
+#define EAC3_SR_CODE_REDUCED  3
+
+/** lrint(M_SQRT2*cos(2*M_PI/12)*(1<<23)) */
+#define COEFF_0 10273905LL
+
+/** lrint(M_SQRT2*cos(0*M_PI/12)*(1<<23)) = lrint(M_SQRT2*(1<<23)) */
+#define COEFF_1 11863283LL
+
+/** lrint(M_SQRT2*cos(5*M_PI/12)*(1<<23)) */
+#define COEFF_2  3070444LL
+
+/**
+ * Calculate 6-point IDCT of the pre-mantissas.
+ * All calculations are 24-bit fixed-point.
+ */
+static void idct6(int pre_mant[6])
+{
+    int tmp;
+    int even0, even1, even2, odd0, odd1, odd2;
+
+    odd1 = pre_mant[1] - pre_mant[3] - pre_mant[5];
+
+    even2 = ( pre_mant[2]                * COEFF_0) >> 23;
+    tmp   = ( pre_mant[4]                * COEFF_1) >> 23;
+    odd0  = ((pre_mant[1] + pre_mant[5]) * COEFF_2) >> 23;
+
+    even0 = pre_mant[0] + (tmp >> 1);
+    even1 = pre_mant[0] - tmp;
+
+    tmp = even0;
+    even0 = tmp + even2;
+    even2 = tmp - even2;
+
+    tmp = odd0;
+    odd0 = tmp + pre_mant[1] + pre_mant[3];
+    odd2 = tmp + pre_mant[5] - pre_mant[3];
+
+    pre_mant[0] = even0 + odd0;
+    pre_mant[1] = even1 + odd1;
+    pre_mant[2] = even2 + odd2;
+    pre_mant[3] = even2 - odd2;
+    pre_mant[4] = even1 - odd1;
+    pre_mant[5] = even0 - odd0;
+}