+++ /dev/null
-/*
- * 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);
-}
-
projects / Faustine.git / blobdiff
