g72x.c

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	    fmult(state_ptr->a[0] >> 2, state_ptr->sr[0]));
}
/*
 * step_size()
 *
 * computes the quantization step size of the adaptive quantizer.
 *
 */
int  step_size (G72x_STATE *state_ptr)
{
	int		y;
	int		dif;
	int		al;

	if (state_ptr->ap >= 256)
		return (state_ptr->yu);
	else {
		y = state_ptr->yl >> 6;
		dif = state_ptr->yu - y;
		al = state_ptr->ap >> 2;
		if (dif > 0)
			y += (dif * al) >> 6;
		else if (dif < 0)
			y += (dif * al + 0x3F) >> 6;
		return (y);
	}
}

/*
 * quantize()
 *
 * Given a raw sample, 'd', of the difference signal and a
 * quantization step size scale factor, 'y', this routine returns the
 * ADPCM codeword to which that sample gets quantized.  The step
 * size scale factor division operation is done in the log base 2 domain
 * as a subtraction.
 */
int quantize(
	int		d,	/* Raw difference signal sample */
	int		y,	/* Step size multiplier */
	short	*table,	/* quantization table */
	int		size)	/* table size of short integers */
{
	short		dqm;	/* Magnitude of 'd' */
	short		expon;	/* Integer part of base 2 log of 'd' */
	short		mant;	/* Fractional part of base 2 log */
	short		dl;	/* Log of magnitude of 'd' */
	short		dln;	/* Step size scale factor normalized log */
	int		i;

	/*
	 * LOG
	 *
	 * Compute base 2 log of 'd', and store in 'dl'.
	 */
	dqm = abs(d);
	expon = quan(dqm >> 1, power2, 15);
	mant = ((dqm << 7) >> expon) & 0x7F;	/* Fractional portion. */
	dl = (expon << 7) + mant;

	/*
	 * SUBTB
	 *
	 * "Divide" by step size multiplier.
	 */
	dln = dl - (y >> 2);

	/*
	 * QUAN
	 *
	 * Obtain codword i for 'd'.
	 */
	i = quan(dln, table, size);
	if (d < 0)			/* take 1's complement of i */
		return ((size << 1) + 1 - i);
	else if (i == 0)		/* take 1's complement of 0 */
		return ((size << 1) + 1); /* new in 1988 */
	else
		return (i);
}
/*
 * reconstruct()
 *
 * Returns reconstructed difference signal 'dq' obtained from
 * codeword 'i' and quantization step size scale factor 'y'.
 * Multiplication is performed in log base 2 domain as addition.
 */
int
reconstruct(
	int		sign,	/* 0 for non-negative value */
	int		dqln,	/* G.72x codeword */
	int		y)	/* Step size multiplier */
{
	short		dql;	/* Log of 'dq' magnitude */
	short		dex;	/* Integer part of log */
	short		dqt;
	short		dq;	/* Reconstructed difference signal sample */

	dql = dqln + (y >> 2);	/* ADDA */

	if (dql < 0) {
		return ((sign) ? -0x8000 : 0);
	} else {		/* ANTILOG */
		dex = (dql >> 7) & 15;
		dqt = 128 + (dql & 127);
		dq = (dqt << 7) >> (14 - dex);
		return ((sign) ? (dq - 0x8000) : dq);
	}
}


/*
 * update()
 *
 * updates the state variables for each output code
 */
void
update(
	int		code_size,	/* distinguish 723_40 with others */
	int		y,		/* quantizer step size */
	int		wi,		/* scale factor multiplier */
	int		fi,		/* for long/short term energies */
	int		dq,		/* quantized prediction difference */
	int		sr,		/* reconstructed signal */
	int		dqsez,		/* difference from 2-pole predictor */
	G72x_STATE *state_ptr)	/* coder state pointer */
{
	int		cnt;
	short		mag, expon;	/* Adaptive predictor, FLOAT A */
	short		a2p = 0;	/* LIMC */
	short		a1ul;		/* UPA1 */
	short		pks1;		/* UPA2 */
	short		fa1;
	char		tr;		/* tone/transition detector */
	short		ylint, thr2, dqthr;
	short  		ylfrac, thr1;
	short		pk0;

	pk0 = (dqsez < 0) ? 1 : 0;	/* needed in updating predictor poles */

	mag = dq & 0x7FFF;		/* prediction difference magnitude */
	/* TRANS */
	ylint = state_ptr->yl >> 15;	/* exponent part of yl */
	ylfrac = (state_ptr->yl >> 10) & 0x1F;	/* fractional part of yl */
	thr1 = (32 + ylfrac) << ylint;		/* threshold */
	thr2 = (ylint > 9) ? 31 << 10 : thr1;	/* limit thr2 to 31 << 10 */
	dqthr = (thr2 + (thr2 >> 1)) >> 1;	/* dqthr = 0.75 * thr2 */
	if (state_ptr->td == 0)		/* signal supposed voice */
		tr = 0;
	else if (mag <= dqthr)		/* supposed data, but small mag */
		tr = 0;			/* treated as voice */
	else				/* signal is data (modem) */
		tr = 1;

	/*
	 * Quantizer scale factor adaptation.
	 */

	/* FUNCTW & FILTD & DELAY */
	/* update non-steady state step size multiplier */
	state_ptr->yu = y + ((wi - y) >> 5);

	/* LIMB */
	if (state_ptr->yu < 544)	/* 544 <= yu <= 5120 */
		state_ptr->yu = 544;
	else if (state_ptr->yu > 5120)
		state_ptr->yu = 5120;

	/* FILTE & DELAY */
	/* update steady state step size multiplier */
	state_ptr->yl += state_ptr->yu + ((-state_ptr->yl) >> 6);

	/*
	 * Adaptive predictor coefficients.
	 */
	if (tr == 1) {			/* reset a's and b's for modem signal */
		state_ptr->a[0] = 0;
		state_ptr->a[1] = 0;
		state_ptr->b[0] = 0;
		state_ptr->b[1] = 0;
		state_ptr->b[2] = 0;
		state_ptr->b[3] = 0;
		state_ptr->b[4] = 0;
		state_ptr->b[5] = 0;
	} else {			/* update a's and b's */
		pks1 = pk0 ^ state_ptr->pk[0];		/* UPA2 */

		/* update predictor pole a[1] */
		a2p = state_ptr->a[1] - (state_ptr->a[1] >> 7);
		if (dqsez != 0) {
			fa1 = (pks1) ? state_ptr->a[0] : -state_ptr->a[0];
			if (fa1 < -8191)	/* a2p = function of fa1 */
				a2p -= 0x100;
			else if (fa1 > 8191)
				a2p += 0xFF;
			else
				a2p += fa1 >> 5;

			if (pk0 ^ state_ptr->pk[1])
			{	/* LIMC */
				if (a2p <= -12160)
					a2p = -12288;
				else if (a2p >= 12416)
					a2p = 12288;
				else
					a2p -= 0x80;
				}
			else if (a2p <= -12416)
				a2p = -12288;
			else if (a2p >= 12160)
				a2p = 12288;
			else
				a2p += 0x80;
		}

		/* TRIGB & DELAY */
		state_ptr->a[1] = a2p;

		/* UPA1 */
		/* update predictor pole a[0] */
		state_ptr->a[0] -= state_ptr->a[0] >> 8;
		if (dqsez != 0)
		{	if (pks1 == 0)
				state_ptr->a[0] += 192;
			else
				state_ptr->a[0] -= 192;
			} ;

		/* LIMD */
		a1ul = 15360 - a2p;
		if (state_ptr->a[0] < -a1ul)
			state_ptr->a[0] = -a1ul;
		else if (state_ptr->a[0] > a1ul)
			state_ptr->a[0] = a1ul;

		/* UPB : update predictor zeros b[6] */
		for (cnt = 0; cnt < 6; cnt++) {
			if (code_size == 5)		/* for 40Kbps G.723 */
				state_ptr->b[cnt] -= state_ptr->b[cnt] >> 9;
			else			/* for G.721 and 24Kbps G.723 */
				state_ptr->b[cnt] -= state_ptr->b[cnt] >> 8;
			if (dq & 0x7FFF) {			/* XOR */
				if ((dq ^ state_ptr->dq[cnt]) >= 0)
					state_ptr->b[cnt] += 128;
				else
					state_ptr->b[cnt] -= 128;
			}
		}
	}

	for (cnt = 5; cnt > 0; cnt--)
		state_ptr->dq[cnt] = state_ptr->dq[cnt-1];
	/* FLOAT A : convert dq[0] to 4-bit exp, 6-bit mantissa f.p. */
	if (mag == 0) {
		state_ptr->dq[0] = (dq >= 0) ? 0x20 : 0xFC20;
	} else {
		expon = quan(mag, power2, 15);
		state_ptr->dq[0] = (dq >= 0) ?
		    (expon << 6) + ((mag << 6) >> expon) :
		    (expon << 6) + ((mag << 6) >> expon) - 0x400;
	}

	state_ptr->sr[1] = state_ptr->sr[0];
	/* FLOAT B : convert sr to 4-bit exp., 6-bit mantissa f.p. */
	if (sr == 0) {
		state_ptr->sr[0] = 0x20;
	} else if (sr > 0) {
		expon = quan(sr, power2, 15);
		state_ptr->sr[0] = (expon << 6) + ((sr << 6) >> expon);
	} else if (sr > -32768) {
		mag = -sr;
		expon = quan(mag, power2, 15);
		state_ptr->sr[0] =  (expon << 6) + ((mag << 6) >> expon) - 0x400;
	} else
		state_ptr->sr[0] = (short) 0xFC20;

	/* DELAY A */
	state_ptr->pk[1] = state_ptr->pk[0];
	state_ptr->pk[0] = pk0;

	/* TONE */
	if (tr == 1)		/* this sample has been treated as data */
		state_ptr->td = 0;	/* next one will be treated as voice */
	else if (a2p < -11776)	/* small sample-to-sample correlation */
		state_ptr->td = 1;	/* signal may be data */
	else				/* signal is voice */
		state_ptr->td = 0;

	/*
	 * Adaptation speed control.
	 */
	state_ptr->dms += (fi - state_ptr->dms) >> 5;		/* FILTA */
	state_ptr->dml += (((fi << 2) - state_ptr->dml) >> 7);	/* FILTB */

	if (tr == 1)
		state_ptr->ap = 256;
	else if (y < 1536)					/* SUBTC */
		state_ptr->ap += (0x200 - state_ptr->ap) >> 4;
	else if (state_ptr->td == 1)
		state_ptr->ap += (0x200 - state_ptr->ap) >> 4;
	else if (abs((state_ptr->dms << 2) - state_ptr->dml) >=
	    (state_ptr->dml >> 3))
		state_ptr->ap += (0x200 - state_ptr->ap) >> 4;
	else
		state_ptr->ap += (-state_ptr->ap) >> 4;
		
	return ;
} /* update */

/*
** Do not edit or modify anything in this comment block.
** The arch-tag line is a file identity tag for the GNU Arch 
** revision control system.
**
** arch-tag: 6298dc75-fd0f-4062-9b90-f73ed69f22d4
*/