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diff --git a/src/libspeex/lpc.c b/src/libspeex/lpc.c
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-/*
- Copyright 1992, 1993, 1994 by Jutta Degener and Carsten Bormann,
- Technische Universitaet Berlin
-
- Any use of this software is permitted provided that this notice is not
- removed and that neither the authors nor the Technische Universitaet Berlin
- are deemed to have made any representations as to the suitability of this
- software for any purpose nor are held responsible for any defects of
- this software. THERE IS ABSOLUTELY NO WARRANTY FOR THIS SOFTWARE.
-
- As a matter of courtesy, the authors request to be informed about uses
- this software has found, about bugs in this software, and about any
- improvements that may be of general interest.
-
- Berlin, 28.11.1994
- Jutta Degener
- Carsten Bormann
-
-
- Code modified by Jean-Marc Valin
-
- Speex License:
-
- Redistribution and use in source and binary forms, with or without
- modification, are permitted provided that the following conditions
- are met:
-
- - Redistributions of source code must retain the above copyright
- notice, this list of conditions and the following disclaimer.
-
- - Redistributions in binary form must reproduce the above copyright
- notice, this list of conditions and the following disclaimer in the
- documentation and/or other materials provided with the distribution.
-
- - Neither the name of the Xiph.org Foundation nor the names of its
- contributors may be used to endorse or promote products derived from
- this software without specific prior written permission.
-
- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR
- CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
- EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
- PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
- PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
- LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
- NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
- SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-*/
-
-#ifdef HAVE_CONFIG_H
-#include "config.h"
-#endif
-
-#include "lpc.h"
-
-#ifdef BFIN_ASM
-#include "lpc_bfin.h"
-#endif
-
-/* LPC analysis
- *
- * The next two functions calculate linear prediction coefficients
- * and/or the related reflection coefficients from the first P_MAX+1
- * values of the autocorrelation function.
- */
-
-/* Invented by N. Levinson in 1947, modified by J. Durbin in 1959.
- */
-
-/* returns minimum mean square error */
-spx_word32_t _spx_lpc(
-spx_coef_t *lpc, /* out: [0...p-1] LPC coefficients */
-const spx_word16_t *ac, /* in: [0...p] autocorrelation values */
-int p
-)
-{
- int i, j;
- spx_word16_t r;
- spx_word16_t error = ac[0];
-
- if (ac[0] == 0)
- {
- for (i = 0; i < p; i++)
- lpc[i] = 0;
- return 0;
- }
-
- for (i = 0; i < p; i++) {
-
- /* Sum up this iteration's reflection coefficient */
- spx_word32_t rr = NEG32(SHL32(EXTEND32(ac[i + 1]),13));
- for (j = 0; j < i; j++)
- rr = SUB32(rr,MULT16_16(lpc[j],ac[i - j]));
-#ifdef FIXED_POINT
- r = DIV32_16(rr+PSHR32(error,1),ADD16(error,8));
-#else
- r = rr/(error+.003*ac[0]);
-#endif
- /* Update LPC coefficients and total error */
- lpc[i] = r;
- for (j = 0; j < i>>1; j++)
- {
- spx_word16_t tmp = lpc[j];
- lpc[j] = MAC16_16_P13(lpc[j],r,lpc[i-1-j]);
- lpc[i-1-j] = MAC16_16_P13(lpc[i-1-j],r,tmp);
- }
- if (i & 1)
- lpc[j] = MAC16_16_P13(lpc[j],lpc[j],r);
-
- error = SUB16(error,MULT16_16_Q13(r,MULT16_16_Q13(error,r)));
- }
- return error;
-}
-
-
-#ifdef FIXED_POINT
-
-/* Compute the autocorrelation
- * ,--,
- * ac(i) = > x(n) * x(n-i) for all n
- * `--'
- * for lags between 0 and lag-1, and x == 0 outside 0...n-1
- */
-
-#ifndef OVERRIDE_SPEEX_AUTOCORR
-void _spx_autocorr(
-const spx_word16_t *x, /* in: [0...n-1] samples x */
-spx_word16_t *ac, /* out: [0...lag-1] ac values */
-int lag,
-int n
-)
-{
- spx_word32_t d;
- int i, j;
- spx_word32_t ac0=1;
- int shift, ac_shift;
-
- for (j=0;j<n;j++)
- ac0 = ADD32(ac0,SHR32(MULT16_16(x[j],x[j]),8));
- ac0 = ADD32(ac0,n);
- shift = 8;
- while (shift && ac0<0x40000000)
- {
- shift--;
- ac0 <<= 1;
- }
- ac_shift = 18;
- while (ac_shift && ac0<0x40000000)
- {
- ac_shift--;
- ac0 <<= 1;
- }
-
-
- for (i=0;i<lag;i++)
- {
- d=0;
- for (j=i;j<n;j++)
- {
- d = ADD32(d,SHR32(MULT16_16(x[j],x[j-i]), shift));
- }
-
- ac[i] = SHR32(d, ac_shift);
- }
-}
-#endif
-
-
-#else
-
-
-
-/* Compute the autocorrelation
- * ,--,
- * ac(i) = > x(n) * x(n-i) for all n
- * `--'
- * for lags between 0 and lag-1, and x == 0 outside 0...n-1
- */
-void _spx_autocorr(
-const spx_word16_t *x, /* in: [0...n-1] samples x */
-float *ac, /* out: [0...lag-1] ac values */
-int lag,
-int n
-)
-{
- float d;
- int i;
- while (lag--)
- {
- for (i = lag, d = 0; i < n; i++)
- d += x[i] * x[i-lag];
- ac[lag] = d;
- }
- ac[0] += 10;
-}
-
-#endif
-
-