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-rw-r--r--ac3dec/coeff.c353
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diff --git a/ac3dec/coeff.c b/ac3dec/coeff.c
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+/*
+ * coeff.c
+ *
+ * Copyright (C) Aaron Holtzman - May 1999
+ *
+ * This file is part of ac3dec, a free Dolby AC-3 stream decoder.
+ *
+ * ac3dec 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, or (at your option)
+ * any later version.
+ *
+ * ac3dec 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 GNU Make; see the file COPYING. If not, write to
+ * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ */
+
+
+#include <stdlib.h>
+#include <stdio.h>
+#include "ac3.h"
+#include "ac3_internal.h"
+
+
+#include "decode.h"
+#include "bitstream.h"
+#include "dither.h"
+#include "coeff.h"
+
+//
+//Lookup tables of 0.15 two's complement quantization values
+//
+static const uint_16 q_1[3] =
+{
+ ( -2 << 15)/3, 0,( 2 << 15)/3
+};
+
+static const uint_16 q_2[5] =
+{
+ ( -4 << 15)/5,( -2 << 15)/5, 0,
+ ( 2 << 15)/5,( 4 << 15)/5
+};
+
+static const uint_16 q_3[7] =
+{
+ ( -6 << 15)/7,( -4 << 15)/7,( -2 << 15)/7, 0,
+ ( 2 << 15)/7,( 4 << 15)/7,( 6 << 15)/7
+};
+
+static const uint_16 q_4[11] =
+{
+ (-10 << 15)/11,(-8 << 15)/11,(-6 << 15)/11, ( -4 << 15)/11,(-2 << 15)/11, 0,
+ ( 2 << 15)/11,( 4 << 15)/11,( 6 << 15)/11, ( 8 << 15)/11,(10 << 15)/11
+};
+
+static const uint_16 q_5[15] =
+{
+ (-14 << 15)/15,(-12 << 15)/15,(-10 << 15)/15,
+ ( -8 << 15)/15,( -6 << 15)/15,( -4 << 15)/15,
+ ( -2 << 15)/15, 0 ,( 2 << 15)/15,
+ ( 4 << 15)/15,( 6 << 15)/15,( 8 << 15)/15,
+ ( 10 << 15)/15,( 12 << 15)/15,( 14 << 15)/15
+};
+
+//
+// Scale factors for convert_to_float
+//
+
+static const uint_32 u32_scale_factors[25] =
+{
+ 0x38000000, //2 ^ -(0 + 15)
+ 0x37800000, //2 ^ -(1 + 15)
+ 0x37000000, //2 ^ -(2 + 15)
+ 0x36800000, //2 ^ -(3 + 15)
+ 0x36000000, //2 ^ -(4 + 15)
+ 0x35800000, //2 ^ -(5 + 15)
+ 0x35000000, //2 ^ -(6 + 15)
+ 0x34800000, //2 ^ -(7 + 15)
+ 0x34000000, //2 ^ -(8 + 15)
+ 0x33800000, //2 ^ -(9 + 15)
+ 0x33000000, //2 ^ -(10 + 15)
+ 0x32800000, //2 ^ -(11 + 15)
+ 0x32000000, //2 ^ -(12 + 15)
+ 0x31800000, //2 ^ -(13 + 15)
+ 0x31000000, //2 ^ -(14 + 15)
+ 0x30800000, //2 ^ -(15 + 15)
+ 0x30000000, //2 ^ -(16 + 15)
+ 0x2f800000, //2 ^ -(17 + 15)
+ 0x2f000000, //2 ^ -(18 + 15)
+ 0x2e800000, //2 ^ -(19 + 15)
+ 0x2e000000, //2 ^ -(20 + 15)
+ 0x2d800000, //2 ^ -(21 + 15)
+ 0x2d000000, //2 ^ -(22 + 15)
+ 0x2c800000, //2 ^ -(23 + 15)
+ 0x2c000000 //2 ^ -(24 + 15)
+};
+
+static float *scale_factor = (float*)u32_scale_factors;
+
+//These store the persistent state of the packed mantissas
+static uint_16 m_1[3];
+static uint_16 m_2[3];
+static uint_16 m_4[2];
+static uint_16 m_1_pointer;
+static uint_16 m_2_pointer;
+static uint_16 m_4_pointer;
+
+//Conversion from bap to number of bits in the mantissas
+//zeros account for cases 0,1,2,4 which are special cased
+static uint_16 qnttztab[16] = { 0, 0, 0, 3, 0 , 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 16};
+
+static void coeff_reset(void);
+static sint_16 coeff_get_mantissa(uint_16 bap, uint_16 dithflag);
+static void coeff_uncouple_ch(float samples[],bsi_t *bsi,audblk_t *audblk,uint_32 ch);
+
+//
+// Convert a 0.15 fixed point number into IEEE single
+// precision floating point and scale by 2^-exp
+//
+static inline float
+convert_to_float(uint_16 exp, sint_16 mantissa)
+{
+ float x;
+
+ //the scale by 2^-15 is built into the scale factor table
+ x = mantissa * scale_factor[exp];
+
+ return x;
+}
+
+void
+coeff_unpack(bsi_t *bsi, audblk_t *audblk, stream_samples_t samples)
+{
+ uint_16 i,j;
+ uint_32 done_cpl = 0;
+ sint_16 mantissa;
+
+ coeff_reset();
+
+ for(i=0; i< bsi->nfchans; i++)
+ {
+ for(j=0; j < audblk->endmant[i]; j++)
+ {
+ mantissa = coeff_get_mantissa(audblk->fbw_bap[i][j],audblk->dithflag[i]);
+ samples[i][j] = convert_to_float(audblk->fbw_exp[i][j],mantissa);
+ }
+
+ if(audblk->cplinu && audblk->chincpl[i] && !(done_cpl))
+ {
+ // ncplmant is equal to 12 * ncplsubnd
+ // Don't dither coupling channel until channel separation so that
+ // interchannel noise is uncorrelated
+ for(j=audblk->cplstrtmant; j < audblk->cplendmant; j++)
+ audblk->cplmant[j] = coeff_get_mantissa(audblk->cpl_bap[j],0);
+ done_cpl = 1;
+ }
+ }
+
+ //uncouple the channel if necessary
+ if(audblk->cplinu)
+ {
+ for(i=0; i< bsi->nfchans; i++)
+ {
+ if(audblk->chincpl[i])
+ coeff_uncouple_ch(samples[i],bsi,audblk,i);
+ }
+
+ }
+
+ if(bsi->lfeon)
+ {
+ // There are always 7 mantissas for lfe, no dither for lfe
+ for(j=0; j < 7 ; j++)
+ {
+ mantissa = coeff_get_mantissa(audblk->lfe_bap[j],0);
+ samples[5][j] = convert_to_float(audblk->lfe_exp[j],mantissa);
+ }
+ }
+}
+
+//
+//Fetch a mantissa from the bitstream
+//
+//The mantissa returned is a signed 0.15 fixed point number
+//
+static sint_16
+coeff_get_mantissa(uint_16 bap, uint_16 dithflag)
+{
+ uint_16 mantissa;
+ uint_16 group_code;
+
+ //If the bap is 0-5 then we have special cases to take care of
+ switch(bap)
+ {
+ case 0:
+ if(dithflag)
+ mantissa = dither_gen();
+ else
+ mantissa = 0;
+ break;
+
+ case 1:
+ if(m_1_pointer > 2)
+ {
+ group_code = bitstream_get(5);
+
+ if(group_code > 26)
+ goto error;
+
+ m_1[0] = group_code / 9;
+ m_1[1] = (group_code % 9) / 3;
+ m_1[2] = (group_code % 9) % 3;
+ m_1_pointer = 0;
+ }
+ mantissa = m_1[m_1_pointer++];
+ mantissa = q_1[mantissa];
+ break;
+ case 2:
+
+ if(m_2_pointer > 2)
+ {
+ group_code = bitstream_get(7);
+
+ if(group_code > 124)
+ goto error;
+
+ m_2[0] = group_code / 25;
+ m_2[1] = (group_code % 25) / 5 ;
+ m_2[2] = (group_code % 25) % 5 ;
+ m_2_pointer = 0;
+ }
+ mantissa = m_2[m_2_pointer++];
+ mantissa = q_2[mantissa];
+ break;
+
+ case 3:
+ mantissa = bitstream_get(3);
+
+ if(mantissa > 6)
+ goto error;
+
+ mantissa = q_3[mantissa];
+ break;
+
+ case 4:
+ if(m_4_pointer > 1)
+ {
+ group_code = bitstream_get(7);
+
+ if(group_code > 120)
+ goto error;
+
+ m_4[0] = group_code / 11;
+ m_4[1] = group_code % 11;
+ m_4_pointer = 0;
+ }
+ mantissa = m_4[m_4_pointer++];
+ mantissa = q_4[mantissa];
+ break;
+
+ case 5:
+ mantissa = bitstream_get(4);
+
+ if(mantissa > 14)
+ goto error;
+
+ mantissa = q_5[mantissa];
+ break;
+
+ default:
+ mantissa = bitstream_get(qnttztab[bap]);
+ mantissa <<= 16 - qnttztab[bap];
+ }
+
+ return mantissa;
+
+
+
+error:
+ if(!error_flag)
+ fprintf(stderr,"** Invalid mantissa - skipping frame **\n");
+ error_flag = 1;
+
+ return 0;
+}
+
+//
+// Reset the mantissa state
+//
+static void
+coeff_reset(void)
+{
+ m_1[2] = m_1[1] = m_1[0] = 0;
+ m_2[2] = m_2[1] = m_2[0] = 0;
+ m_4[1] = m_4[0] = 0;
+ m_1_pointer = m_2_pointer = m_4_pointer = 3;
+}
+
+//
+// Uncouple the coupling channel into a fbw channel
+//
+static void
+coeff_uncouple_ch(float samples[],bsi_t *bsi,audblk_t *audblk,uint_32 ch)
+{
+ uint_32 bnd = 0;
+ uint_32 sub_bnd = 0;
+ uint_32 i,j;
+ float cpl_coord = 1.0;
+ uint_32 cpl_exp_tmp;
+ uint_32 cpl_mant_tmp;
+ sint_16 mantissa;
+
+
+ for(i=audblk->cplstrtmant;i<audblk->cplendmant;)
+ {
+ if(!audblk->cplbndstrc[sub_bnd++])
+ {
+ cpl_exp_tmp = audblk->cplcoexp[ch][bnd] + 3 * audblk->mstrcplco[ch];
+ if(audblk->cplcoexp[ch][bnd] == 15)
+ cpl_mant_tmp = (audblk->cplcomant[ch][bnd]) << 11;
+ else
+ cpl_mant_tmp = ((0x10) | audblk->cplcomant[ch][bnd]) << 10;
+
+ cpl_coord = convert_to_float(cpl_exp_tmp,cpl_mant_tmp) * 8.0f;
+
+ //Invert the phase for the right channel if necessary
+ if(bsi->acmod == 0x2 && audblk->phsflginu && ch == 1 && audblk->phsflg[bnd])
+ cpl_coord *= -1;
+
+ bnd++;
+ }
+
+ for(j=0;j < 12; j++)
+ {
+ //Get new dither values for each channel if necessary, so
+ //the channels are uncorrelated
+ if(audblk->dithflag[ch] && audblk->cpl_bap[i] == 0)
+ mantissa = dither_gen();
+ else
+ mantissa = audblk->cplmant[i];
+
+ samples[i] = cpl_coord * convert_to_float(audblk->cpl_exp[i],mantissa);
+
+ i++;
+ }
+ }
+}
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