xref: /frameworks/av/media/libstagefright/codecs/amrwbenc/src/syn_filt.c

/*
 ** Copyright 2003-2010, VisualOn, Inc.
 **
 ** Licensed under the Apache License, Version 2.0 (the "License");
 ** you may not use this file except in compliance with the License.
 ** You may obtain a copy of the License at
 **
 **     http://www.apache.org/licenses/LICENSE-2.0
 **
 ** Unless required by applicable law or agreed to in writing, software
 ** distributed under the License is distributed on an "AS IS" BASIS,
 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 ** See the License for the specific language governing permissions and
 ** limitations under the License.
 */

/***********************************************************************
*       File: syn_filt.c                                               *
*                                                                      *
*       Description: Do the synthesis filtering 1/A(z)                 *
*                                                                      *
************************************************************************/

#include "typedef.h"
#include "basic_op.h"
#include "math_op.h"
#include "cnst.h"

#define UNUSED(x) (void)(x)

void Syn_filt(
        Word16 a[],                           /* (i) Q12 : a[m+1] prediction coefficients           */
        Word16 x[],                           /* (i)     : input signal                             */
        Word16 y[],                           /* (o)     : output signal                            */
        Word16 lg,                            /* (i)     : size of filtering                        */
        Word16 mem[],                         /* (i/o)   : memory associated with this filtering.   */
        Word16 update                         /* (i)     : 0=no update, 1=update of memory.         */
         )
{
    Word32 i, a0;
    Word16 y_buf[L_SUBFR16k + M16k];
    Word32 L_tmp;
    Word16 *yy, *p1, *p2;
    yy = &y_buf[0];
    /* copy initial filter states into synthesis buffer */
    for (i = 0; i < 16; i++)
    {
        *yy++ = mem[i];
    }
    a0 = (a[0] >> 1);                     /* input / 2 */
    /* Do the filtering. */
    for (i = 0; i < lg; i++)
    {
        p1 = &a[1];
        p2 = &yy[i-1];
        L_tmp  = vo_mult32(a0, x[i]);
        L_tmp -= vo_mult32((*p1++), (*p2--));
        L_tmp -= vo_mult32((*p1++), (*p2--));
        L_tmp -= vo_mult32((*p1++), (*p2--));
        L_tmp -= vo_mult32((*p1++), (*p2--));
        L_tmp -= vo_mult32((*p1++), (*p2--));
        L_tmp -= vo_mult32((*p1++), (*p2--));
        L_tmp -= vo_mult32((*p1++), (*p2--));
        L_tmp -= vo_mult32((*p1++), (*p2--));
        L_tmp -= vo_mult32((*p1++), (*p2--));
        L_tmp -= vo_mult32((*p1++), (*p2--));
        L_tmp -= vo_mult32((*p1++), (*p2--));
        L_tmp -= vo_mult32((*p1++), (*p2--));
        L_tmp -= vo_mult32((*p1++), (*p2--));
        L_tmp -= vo_mult32((*p1++), (*p2--));
        L_tmp -= vo_mult32((*p1++), (*p2--));
        L_tmp -= vo_mult32((*p1), (*p2));

        L_tmp = L_shl2(L_tmp, 4);
        y[i] = yy[i] = extract_h(L_add(L_tmp, 0x8000));
    }
    /* Update memory if required */
    if (update)
        for (i = 0; i < 16; i++)
        {
            mem[i] = yy[lg - 16 + i];
        }
    return;
}


void Syn_filt_32(
        Word16 a[],                           /* (i) Q12 : a[m+1] prediction coefficients */
        Word16 m,                             /* (i)     : order of LP filter             */
        Word16 exc[],                         /* (i) Qnew: excitation (exc[i] >> Qnew)    */
        Word16 Qnew,                          /* (i)     : exc scaling = 0(min) to 8(max) */
        Word16 sig_hi[],                      /* (o) /16 : synthesis high                 */
        Word16 sig_lo[],                      /* (o) /16 : synthesis low                  */
        Word16 lg                             /* (i)     : size of filtering              */
        )
{
    Word32 i,a0;
    Word32 L_tmp, L_tmp1;
    Word16 *p1, *p2, *p3;
        UNUSED(m);

    a0 = a[0] >> (4 + Qnew);          /* input / 16 and >>Qnew */
    /* Do the filtering. */
    for (i = 0; i < lg; i++)
    {
        L_tmp  = 0;
        L_tmp1 = 0;
        p1 = a;
        p2 = &sig_lo[i - 1];
        p3 = &sig_hi[i - 1];

        L_tmp  -= vo_mult32((*p2--), (*p1));
        L_tmp1 -= vo_mult32((*p3--), (*p1++));
        L_tmp  -= vo_mult32((*p2--), (*p1));
        L_tmp1 -= vo_mult32((*p3--), (*p1++));
        L_tmp  -= vo_mult32((*p2--), (*p1));
        L_tmp1 -= vo_mult32((*p3--), (*p1++));
        L_tmp  -= vo_mult32((*p2--), (*p1));
        L_tmp1 -= vo_mult32((*p3--), (*p1++));
        L_tmp  -= vo_mult32((*p2--), (*p1));
        L_tmp1 -= vo_mult32((*p3--), (*p1++));
        L_tmp  -= vo_mult32((*p2--), (*p1));
        L_tmp1 -= vo_mult32((*p3--), (*p1++));
        L_tmp  -= vo_mult32((*p2--), (*p1));
        L_tmp1 -= vo_mult32((*p3--), (*p1++));
        L_tmp  -= vo_mult32((*p2--), (*p1));
        L_tmp1 -= vo_mult32((*p3--), (*p1++));
        L_tmp  -= vo_mult32((*p2--), (*p1));
        L_tmp1 -= vo_mult32((*p3--), (*p1++));
        L_tmp  -= vo_mult32((*p2--), (*p1));
        L_tmp1 -= vo_mult32((*p3--), (*p1++));
        L_tmp  -= vo_mult32((*p2--), (*p1));
        L_tmp1 -= vo_mult32((*p3--), (*p1++));
        L_tmp  -= vo_mult32((*p2--), (*p1));
        L_tmp1 -= vo_mult32((*p3--), (*p1++));
        L_tmp  -= vo_mult32((*p2--), (*p1));
        L_tmp1 -= vo_mult32((*p3--), (*p1++));
        L_tmp  -= vo_mult32((*p2--), (*p1));
        L_tmp1 -= vo_mult32((*p3--), (*p1++));
        L_tmp  -= vo_mult32((*p2--), (*p1));
        L_tmp1 -= vo_mult32((*p3--), (*p1++));
        L_tmp  -= vo_mult32((*p2--), (*p1));
        L_tmp1 -= vo_mult32((*p3--), (*p1++));

        L_tmp = L_tmp >> 11;
        L_tmp += vo_L_mult(exc[i], a0);

        /* sig_hi = bit16 to bit31 of synthesis */
        L_tmp = L_tmp - (L_tmp1<<1);

        L_tmp = L_tmp >> 3;           /* ai in Q12 */
        sig_hi[i] = extract_h(L_tmp);

        /* sig_lo = bit4 to bit15 of synthesis */
        L_tmp >>= 4;           /* 4 : sig_lo[i] >> 4 */
        sig_lo[i] = (Word16)((L_tmp - (sig_hi[i] << 13)));
    }

    return;
}