ref: dfd6e714f97712bbfdf82fd78ff8bcf44ef08dfe
dir: /libcelt/plc.c/
/* Copyright (c) 2009-2010 Xiph.Org Foundation
Written by Jean-Marc Valin */
/*
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 "plc.h"
#include "stack_alloc.h"
#include "mathops.h"
void _celt_lpc(
celt_word16 *_lpc, /* out: [0...p-1] LPC coefficients */
const celt_word32 *ac, /* in: [0...p] autocorrelation values */
int p
)
{
int i, j;
celt_word32 r;
celt_word32 error = ac[0];
#ifdef FIXED_POINT
celt_word32 lpc[LPC_ORDER];
#else
float *lpc = _lpc;
#endif
for (i = 0; i < p; i++)
lpc[i] = 0;
if (ac[0] != 0)
{
for (i = 0; i < p; i++) {
/* Sum up this iteration's reflection coefficient */
celt_word32 rr = 0;
for (j = 0; j < i; j++)
rr += MULT32_32_Q31(lpc[j],ac[i - j]);
rr += SHR32(ac[i + 1],3);
r = -frac_div32(SHL32(rr,3), error);
/* Update LPC coefficients and total error */
lpc[i] = SHR32(r,3);
for (j = 0; j < (i+1)>>1; j++)
{
celt_word32 tmp1, tmp2;
tmp1 = lpc[j];
tmp2 = lpc[i-1-j];
lpc[j] = tmp1 + MULT32_32_Q31(r,tmp2);
lpc[i-1-j] = tmp2 + MULT32_32_Q31(r,tmp1);
}
error = error - MULT32_32_Q31(MULT32_32_Q31(r,r),error);
/* Bail out once we get 30 dB gain */
#ifdef FIXED_POINT
if (error<SHR32(ac[0],10))
break;
#else
if (error<.001f*ac[0])
break;
#endif
}
}
#ifdef FIXED_POINT
for (i=0;i<p;i++)
_lpc[i] = ROUND16(lpc[i],16);
#endif
}
void fir(const celt_word16 *x,
const celt_word16 *num,
celt_word16 *y,
int N,
int ord,
celt_word16 *mem)
{
int i,j;
for (i=0;i<N;i++)
{
celt_word32 sum = SHL32(EXTEND32(x[i]), SIG_SHIFT);
for (j=0;j<ord;j++)
{
sum += MULT16_16(num[j],mem[j]);
}
for (j=ord-1;j>=1;j--)
{
mem[j]=mem[j-1];
}
mem[0] = x[i];
y[i] = ROUND16(sum, SIG_SHIFT);
}
}
void iir(const celt_word32 *x,
const celt_word16 *den,
celt_word32 *y,
int N,
int ord,
celt_word16 *mem)
{
int i,j;
for (i=0;i<N;i++)
{
celt_word32 sum = x[i];
for (j=0;j<ord;j++)
{
sum -= MULT16_16(den[j],mem[j]);
}
for (j=ord-1;j>=1;j--)
{
mem[j]=mem[j-1];
}
mem[0] = ROUND16(sum,SIG_SHIFT);
y[i] = sum;
}
}
void _celt_autocorr(
const celt_word16 *x, /* in: [0...n-1] samples x */
celt_word32 *ac, /* out: [0...lag-1] ac values */
const celt_word16 *window,
int overlap,
int lag,
int n
)
{
celt_word32 d;
int i;
VARDECL(celt_word16, xx);
SAVE_STACK;
ALLOC(xx, n, celt_word16);
for (i=0;i<n;i++)
xx[i] = x[i];
for (i=0;i<overlap;i++)
{
xx[i] = MULT16_16_Q15(x[i],window[i]);
xx[n-i-1] = MULT16_16_Q15(x[n-i-1],window[i]);
}
#ifdef FIXED_POINT
{
celt_word32 ac0=0;
int shift;
for(i=0;i<n;i++)
ac0 += SHR32(MULT16_16(xx[i],xx[i]),8);
ac0 += 1+n;
shift = celt_ilog2(ac0)-30+9;
shift = (shift+1)/2;
for(i=0;i<n;i++)
xx[i] = VSHR32(xx[i], shift);
}
#endif
while (lag>=0)
{
for (i = lag, d = 0; i < n; i++)
d += xx[i] * xx[i-lag];
ac[lag] = d;
/*printf ("%f ", ac[lag]);*/
lag--;
}
/*printf ("\n");*/
ac[0] += 10;
RESTORE_STACK;
}