X-Git-Url: https://scm.cri.ensmp.fr/git/Faustine.git/blobdiff_plain/1059e1cc0c2ecfa237406949aa26155b6a5b9154..66f23d4fabf89ad09adbd4dfc15ac6b5b2b7da83:/interpreter/lib/src/libsndfile-1.0.25/src/G72x/g721.c

diff --git a/interpreter/lib/src/libsndfile-1.0.25/src/G72x/g721.c b/interpreter/lib/src/libsndfile-1.0.25/src/G72x/g721.c
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+/*
+ * This source code is a product of Sun Microsystems, Inc. and is provided
+ * for unrestricted use.  Users may copy or modify this source code without
+ * charge.
+ *
+ * SUN SOURCE CODE IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING
+ * THE WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE.
+ *
+ * Sun source code is provided with no support and without any obligation on
+ * the part of Sun Microsystems, Inc. to assist in its use, correction,
+ * modification or enhancement.
+ *
+ * SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE
+ * INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY THIS SOFTWARE
+ * OR ANY PART THEREOF.
+ *
+ * In no event will Sun Microsystems, Inc. be liable for any lost revenue
+ * or profits or other special, indirect and consequential damages, even if
+ * Sun has been advised of the possibility of such damages.
+ *
+ * Sun Microsystems, Inc.
+ * 2550 Garcia Avenue
+ * Mountain View, California  94043
+ */
+
+/*
+ * g721.c
+ *
+ * Description:
+ *
+ * g721_encoder(), g721_decoder()
+ *
+ * These routines comprise an implementation of the CCITT G.721 ADPCM
+ * coding algorithm.  Essentially, this implementation is identical to
+ * the bit level description except for a few deviations which
+ * take advantage of work station attributes, such as hardware 2's
+ * complement arithmetic and large memory.  Specifically, certain time
+ * consuming operations such as multiplications are replaced
+ * with lookup tables and software 2's complement operations are
+ * replaced with hardware 2's complement.
+ *
+ * The deviation from the bit level specification (lookup tables)
+ * preserves the bit level performance specifications.
+ *
+ * As outlined in the G.721 Recommendation, the algorithm is broken
+ * down into modules.  Each section of code below is preceded by
+ * the name of the module which it is implementing.
+ *
+ */
+
+#include "g72x.h"
+#include "g72x_priv.h"
+
+static short qtab_721[7] = {-124, 80, 178, 246, 300, 349, 400};
+/*
+ * Maps G.721 code word to reconstructed scale factor normalized log
+ * magnitude values.
+ */
+static short	_dqlntab[16] = {-2048, 4, 135, 213, 273, 323, 373, 425,
+				425, 373, 323, 273, 213, 135, 4, -2048};
+
+/* Maps G.721 code word to log of scale factor multiplier. */
+static short	_witab[16] = {-12, 18, 41, 64, 112, 198, 355, 1122,
+				1122, 355, 198, 112, 64, 41, 18, -12};
+/*
+ * Maps G.721 code words to a set of values whose long and short
+ * term averages are computed and then compared to give an indication
+ * how stationary (steady state) the signal is.
+ */
+static short	_fitab[16] = {0, 0, 0, 0x200, 0x200, 0x200, 0x600, 0xE00,
+				0xE00, 0x600, 0x200, 0x200, 0x200, 0, 0, 0};
+
+/*
+ * g721_encoder()
+ *
+ * Encodes the input vale of linear PCM, A-law or u-law data sl and returns
+ * the resulting code. -1 is returned for unknown input coding value.
+ */
+int
+g721_encoder(
+	int		sl,
+	G72x_STATE *state_ptr)
+{
+	short		sezi, se, sez;		/* ACCUM */
+	short		d;			/* SUBTA */
+	short		sr;			/* ADDB */
+	short		y;			/* MIX */
+	short		dqsez;			/* ADDC */
+	short		dq, i;
+
+	/* linearize input sample to 14-bit PCM */
+	sl >>= 2;			/* 14-bit dynamic range */
+
+	sezi = predictor_zero(state_ptr);
+	sez = sezi >> 1;
+	se = (sezi + predictor_pole(state_ptr)) >> 1;	/* estimated signal */
+
+	d = sl - se;				/* estimation difference */
+
+	/* quantize the prediction difference */
+	y = step_size(state_ptr);		/* quantizer step size */
+	i = quantize(d, y, qtab_721, 7);	/* i = ADPCM code */
+
+	dq = reconstruct(i & 8, _dqlntab[i], y);	/* quantized est diff */
+
+	sr = (dq < 0) ? se - (dq & 0x3FFF) : se + dq;	/* reconst. signal */
+
+	dqsez = sr + sez - se;			/* pole prediction diff. */
+
+	update(4, y, _witab[i] << 5, _fitab[i], dq, sr, dqsez, state_ptr);
+
+	return (i);
+}
+
+/*
+ * g721_decoder()
+ *
+ * Description:
+ *
+ * Decodes a 4-bit code of G.721 encoded data of i and
+ * returns the resulting linear PCM, A-law or u-law value.
+ * return -1 for unknown out_coding value.
+ */
+int
+g721_decoder(
+	int		i,
+	G72x_STATE *state_ptr)
+{
+	short		sezi, sei, sez, se;	/* ACCUM */
+	short		y;			/* MIX */
+	short		sr;			/* ADDB */
+	short		dq;
+	short		dqsez;
+
+	i &= 0x0f;			/* mask to get proper bits */
+	sezi = predictor_zero(state_ptr);
+	sez = sezi >> 1;
+	sei = sezi + predictor_pole(state_ptr);
+	se = sei >> 1;			/* se = estimated signal */
+
+	y = step_size(state_ptr);	/* dynamic quantizer step size */
+
+	dq = reconstruct(i & 0x08, _dqlntab[i], y); /* quantized diff. */
+
+	sr = (dq < 0) ? (se - (dq & 0x3FFF)) : se + dq;	/* reconst. signal */
+
+	dqsez = sr - se + sez;			/* pole prediction diff. */
+
+	update(4, y, _witab[i] << 5, _fitab[i], dq, sr, dqsez, state_ptr);
+
+	/* sr was 14-bit dynamic range */
+	return (sr << 2);	
+}
+