pitsyn.c

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		*ipito = *pitch;
		if (*ratio > 8.f) {
		    *rmso = *rms;
		}
	    }
/* SSVC - -   1  ,  1  ,  1 */
	    slope = (*pitch - *ipito) / (real) lsamp;
	    ivoice = voice[2];
	} else {
	    if (*ivoico != 1) {
		if (*ivoico == voice[1]) {
/* UV2VC2 - -  0  ,  0  ,  1 */
		    nl = lsamp - *lframe / 4;
		} else {
/* UV2VC1 - -  0  ,  1  ,  1 */
		    nl = lsamp - *lframe * 3 / 4;
		}
		ipiti[1] = nl / 2;
		ipiti[2] = nl - ipiti[1];
		ivuv[1] = 0;
		ivuv[2] = 0;
		rmsi[1] = *rmso;
		rmsi[2] = *rmso;
		i__1 = *order;
		for (i__ = 1; i__ <= i__1; ++i__) {
		    rci[i__ + rci_dim1] = rco[i__ - 1];
		    rci[i__ + (rci_dim1 << 1)] = rco[i__ - 1];
		    rco[i__ - 1] = rc[i__];
		}
		slope = 0.f;
		*nout = 2;
		*ipito = *pitch;
		jused = nl;
		istart = nl + 1;
		ivoice = 1;
	    } else {
		if (*ivoico != voice[1]) {
/* VC2UV1 - -   1  ,  0  ,  0 */
		    lsamp = *lframe / 4 + *jsamp;
		} else {
/* VC2UV2 - -   1  ,  1  ,  0 */
		    lsamp = *lframe * 3 / 4 + *jsamp;
		}
		i__1 = *order;
		for (i__ = 1; i__ <= i__1; ++i__) {
		    yarc[i__ - 1] = rc[i__];
		    rc[i__] = rco[i__ - 1];
		}
		ivoice = 1;
		slope = 0.f;
		vflag = 1;
	    }
	}
/* Here is the value of most variables that are used below, depending 
on */
/* the values of IVOICO, VOICE(1), and VOICE(2).  VOICE(1) and VOICE(2
) */
/* are input arguments, and IVOICO is the value of VOICE(2) on the */
/* previous call (see notes for the IF (NOUT .NE. 0) statement near th
e */
/* end).  Each of these three values is either 0 or 1.  These three */
/* values below are given as 3-bit long strings, in the order IVOICO, 
*/
/* VOICE(1), and VOICE(2).  It appears that the code above assumes tha
t */
/* the bit sequences 010 and 101 never occur, but I wonder whether a 
*/
/* large enough number of bit errors in the channel could cause such a
 */
/* thing to happen, and if so, could that cause NOUT to ever go over 1
1? */

/* Note that all of the 180 values in the table are really LFRAME, but
 */
/* 180 has fewer characters, and it makes the table a little more */
/* concrete.  If LFRAME is ever changed, keep this in mind.  Similarly
, */
/* 135's are 3*LFRAME/4, and 45's are LFRAME/4.  If LFRAME is not a */
/* multiple of 4, then the 135 for NL-JSAMP is actually LFRAME-LFRAME/
4, */
/* and the 45 for NL-JSAMP is actually LFRAME-3*LFRAME/4. */

/* Note that LSAMP-JSAMP is given as the variable.  This was just for 
*/
/* brevity, to avoid adding "+JSAMP" to all of the column entries. */
/* Similarly for NL-JSAMP. */

/* Variable    | 000  001    011,010  111       110       100,101 */
/* ------------+-------------------------------------------------- */
/* ISTART      | 1    NL+1   NL+1     1         1         1 */
/* LSAMP-JSAMP | 180  180    180      180       135       45 */
/* IPITO       | 45   PITCH  PITCH    oldPITCH  oldPITCH  oldPITCH */
/* SLOPE       | 0    0      0        seebelow  0         0 */
/* JUSED       | 0    NL     NL       0         0         0 */
/* PITCH       | 45   PITCH  PITCH    PITCH     PITCH     PITCH */
/* NL-JSAMP    | --   135    45       --        --        -- */
/* VFLAG       | 0    0      0        0         1         1 */
/* NOUT        | 0    2      2        0         0         0 */
/* IVOICE      | 0    1      1        1         1         1 */

/* while_loop  | once once   once     once      twice     twice */

/* ISTART      | --   --     --       --        JUSED+1   JUSED+1 */
/* LSAMP-JSAMP | --   --     --       --        180       180 */
/* IPITO       | --   --     --       --        oldPITCH  oldPITCH */
/* SLOPE       | --   --     --       --        0         0 */
/* JUSED       | --   --     --       --        ??        ?? */
/* PITCH       | --   --     --       --        PITCH     PITCH */
/* NL-JSAMP    | --   --     --       --        --        -- */
/* VFLAG       | --   --     --       --        0         0 */
/* NOUT        | --   --     --       --        ??        ?? */
/* IVOICE      | --   --     --       --        0         0 */


/* UVPIT is always 0.0 on the first pass through the DO WHILE (.TRUE.)
 */
/* loop below. */

/* The only possible non-0 value of SLOPE (in column 111) is */
/* (PITCH-IPITO)/FLOAT(LSAMP) */

/* Column 101 is identical to 100.  Any good properties we can prove 
*/
/* for 100 will also hold for 101.  Similarly for 010 and 011. */

/* SYNTHS calls this subroutine with PITCH restricted to the range 20 
to */
/* 156.  IPITO is similarly restricted to this range, after the first 
*/
/* call.  IP below is also restricted to this range, given the */
/* definitions of IPITO, SLOPE, UVPIT, and that I is in the range ISTA
RT */
/* to LSAMP. */

	while(TRUE_) {

/*             JUSED is the total length of all pitch periods curr
ently */
/*             in the output arrays, in samples. */

/*             An invariant of the DO I = ISTART,LSAMP loop below,
 under */
/*             the condition that IP is always in the range 1 thro
ugh */
/*             MAXPIT, is: */

/*             (I - MAXPIT) .LE. JUSED .LE. (I-1) */

/*             Note that the final value of I is LSAMP+1, so that 
after */
/*             the DO loop is complete, we know: */

/*             (LSAMP - MAXPIT + 1) .LE. JUSED .LE. LSAMP */

	    i__1 = lsamp;
	    for (i__ = istart; i__ <= i__1; ++i__) {
		r__1 = *ipito + slope * i__;
		ip = r__1 + .5f;
		if (uvpit != 0.f) {
		    ip = uvpit;
		}
		if (ip <= i__ - jused) {
		    ++(*nout);

/*                   The following check is no longer nece
ssary, now that */
/*                   we can prove that NOUT will never go 
over 16. */

/* 		    IF (NOUT .GT. 16) STOP 'PITSYN: too many epochs' 
*/

		    ipiti[*nout] = ip;
		    *pitch = ip;
		    ivuv[*nout] = ivoice;
		    jused += ip;
		    prop = (jused - ip / 2) / (real) lsamp;
		    i__2 = *order;
		    for (j = 1; j <= i__2; ++j) {
			alro = log((rco[j - 1] + 1) / (1 - rco[j - 1]));
			alrn = log((rc[j] + 1) / (1 - rc[j]));
			xxy = alro + prop * (alrn - alro);
			xxy = exp(xxy);
			rci[j + *nout * rci_dim1] = (xxy - 1) / (xxy + 1);
		    }
		    rmsi[*nout] = log(*rmso) + prop * (log(*rms) - log(*rmso));
		    rmsi[*nout] = exp(rmsi[*nout]);
		}
	    }
	    if (vflag != 1) {
		goto L100;
	    }

/*             I want to prove what range UVPIT must lie in after 
the */
/*             assignments to it below.  To do this, I must determ
ine */
/*             what range (LSAMP-ISTART) must lie in, after the */
/*             assignments to ISTART and LSAMP below. */

/*             Let oldLSAMP be the value of LSAMP at this point in
 the */
/*             execution.  This is 135+JSAMP in state 110, or 45+J
SAMP in */
/*             states 100 or 101. */

/*             Given the loop invariant on JUSED above, we know th
at: */

/*             (oldLSAMP - MAXPIT + 1) .LE. JUSED .LE. oldLSAMP */

/*             ISTART is one more than this. */

/*             Let newLSAMP be the value assigned to LSAMP below. 
 This */
/*             is 180+JSAMP.  Thus (newLSAMP-oldLSAMP) is either 4
5 or */
/*             135, depending on the state. */

/*             Thus, the range of newLSAMP-ISTART is: */

/*             (newLSAMP-(oldLSAMP+1)) .LE. newLSAMP-ISTART */
/*             .LE. (newLSAMP-(oldLSAMP - MAXPIT + 2)) */

/*             or: */

/*             46 .LE. newLSAMP-ISTART .LE. 133+MAXPIT .EQ. 289 */

/*             Therefore, UVPIT is in the range 23 to 144 after th
e first */
/*             assignment to UVPIT below, and after the conditiona
l */
/*             assignment, it is in the range 23 to 90. */

/*             The important thing is that it is in the range 20 t
o 156, */
/*             so that in the loop above, IP is always in this ran
ge. */

	    vflag = 0;
	    istart = jused + 1;
	    lsamp = *lframe + *jsamp;
	    slope = 0.f;
	    ivoice = 0;
	    uvpit = (real) ((lsamp - istart) / 2);
	    if (uvpit > 90.f) {
		uvpit /= 2;
	    }
	    *rmso = *rms;
	    i__1 = *order;
	    for (i__ = 1; i__ <= i__1; ++i__) {
		rc[i__] = yarc[i__ - 1];
		rco[i__ - 1] = yarc[i__ - 1];
	    }
	}
L100:
	*jsamp = lsamp - jused;
    }
/*       Given that the maximum pitch period MAXPIT .LT. LFRAME (this is 
*/
/*       currently true on every call, since SYNTHS always sets */
/*       LFRAME=180), NOUT will always be .GE. 1 at this point. */
    if (*nout != 0) {
	*ivoico = voice[2];
	*ipito = *pitch;
	*rmso = *rms;
	i__1 = *order;
	for (i__ = 1; i__ <= i__1; ++i__) {
	    rco[i__ - 1] = rc[i__];
	}
    }
    return 0;
} /* pitsyn_ */