1 files changed, 135 insertions, 0 deletions
diff --git a/ac3dec/exponent.c b/ac3dec/exponent.c
new file mode 100644
index 00000000..98111a5b
--- /dev/null
+++ b/ac3dec/exponent.c
@@ -0,0 +1,135 @@
+/* 
+ *    exponent.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 "exponent.h"
+
+
+static void exp_unpack_ch(uint_16 type,uint_16 expstr,uint_16 ngrps,uint_16 initial_exp, 
+		uint_16 exps[], uint_16 *dest);
+
+void
+exponent_unpack( bsi_t *bsi, audblk_t *audblk)
+{
+	uint_16 i;
+
+	for(i=0; i< bsi->nfchans; i++)
+		exp_unpack_ch(UNPACK_FBW, audblk->chexpstr[i], audblk->nchgrps[i], audblk->exps[i][0], 
+				&audblk->exps[i][1], audblk->fbw_exp[i]);
+
+	if(audblk->cplinu)
+		exp_unpack_ch(UNPACK_CPL, audblk->cplexpstr, audblk->ncplgrps, audblk->cplabsexp << 1,	
+				audblk->cplexps, &audblk->cpl_exp[audblk->cplstrtmant]);
+
+	if(bsi->lfeon)
+		exp_unpack_ch(UNPACK_LFE, audblk->lfeexpstr, 2, audblk->lfeexps[0], 
+				&audblk->lfeexps[1], audblk->lfe_exp);
+}
+
+
+static void
+exp_unpack_ch(uint_16 type,uint_16 expstr,uint_16 ngrps,uint_16 initial_exp, 
+		uint_16 exps[], uint_16 *dest)
+{
+	uint_16 i,j;
+	sint_16 exp_acc;
+	sint_16 exp_1,exp_2,exp_3;
+
+	if(expstr == EXP_REUSE)
+		return;
+
+	/* Handle the initial absolute exponent */
+	exp_acc = initial_exp;
+	j = 0;
+
+	/* In the case of a fbw channel then the initial absolute values is 
+	 * also an exponent */
+	if(type != UNPACK_CPL)
+		dest[j++] = exp_acc;
+
+	/* Loop through the groups and fill the dest array appropriately */
+	for(i=0; i< ngrps; i++)
+	{
+		if(exps[i] > 124)
+			goto error;
+
+		exp_1 = exps[i] / 25;
+		exp_2 = (exps[i] - (exp_1 * 25)) / 5;
+		exp_3 = exps[i] - (exp_1 * 25) - (exp_2 * 5) ;
+
+		exp_acc += (exp_1 - 2);
+
+		switch(expstr)
+		{
+			case EXP_D45:
+				dest[j++] = exp_acc;
+				dest[j++] = exp_acc;
+			case EXP_D25:
+				dest[j++] = exp_acc;
+			case EXP_D15:
+				dest[j++] = exp_acc;
+		}
+
+		exp_acc += (exp_2 - 2);
+
+		switch(expstr)
+		{
+			case EXP_D45:
+				dest[j++] = exp_acc;
+				dest[j++] = exp_acc;
+			case EXP_D25:
+				dest[j++] = exp_acc;
+			case EXP_D15:
+				dest[j++] = exp_acc;
+		}
+
+		exp_acc += (exp_3 - 2);
+
+		switch(expstr)
+		{
+			case EXP_D45:
+				dest[j++] = exp_acc;
+				dest[j++] = exp_acc;
+			case EXP_D25:
+				dest[j++] = exp_acc;
+			case EXP_D15:
+				dest[j++] = exp_acc;
+		}
+	}	
+
+	return;
+
+			goto error;
+error:
+	if(!error_flag)
+		fprintf(stderr,"** Invalid exponent - skipping frame **\n");
+	error_flag = 1;
+}
+