xref: /frameworks/av/media/libstagefright/codecs/amrwbenc/src/deemph.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: deemph.c                                                 *
*                                                                      *
*      Description:filtering through 1/(1-mu z^ -1)                    *
*                  Deemph2 --> signal is divided by 2                  *
*                  Deemph_32 --> for 32 bits signal.                   *
*                                                                      *
************************************************************************/

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

void Deemph(
        Word16 x[],                           /* (i/o)   : input signal overwritten by the output */
        Word16 mu,                            /* (i) Q15 : deemphasis factor                      */
        Word16 L,                             /* (i)     : vector size                            */
        Word16 * mem                          /* (i/o)   : memory (y[-1])                         */
       )
{
    Word32 i;
    Word32 L_tmp;

    L_tmp = L_deposit_h(x[0]);
    L_tmp = L_mac(L_tmp, *mem, mu);
    x[0] = vo_round(L_tmp);

    for (i = 1; i < L; i++)
    {
        L_tmp = L_deposit_h(x[i]);
        L_tmp = L_mac(L_tmp, x[i - 1], mu);
        x[i] = voround(L_tmp);
    }

    *mem = x[L - 1];

    return;
}


void Deemph2(
        Word16 x[],                           /* (i/o)   : input signal overwritten by the output */
        Word16 mu,                            /* (i) Q15 : deemphasis factor                      */
        Word16 L,                             /* (i)     : vector size                            */
        Word16 * mem                          /* (i/o)   : memory (y[-1])                         */
        )
{
    Word32 i;
    Word32 L_tmp;
    L_tmp = x[0] << 15;
    i = L_mult(*mem, mu);
    L_tmp = L_add(L_tmp, i);
    x[0] = voround(L_tmp);
    for (i = 1; i < L; i++)
    {
        Word32 tmp;
        L_tmp = x[i] << 15;
        tmp = (x[i - 1] * mu)<<1;
        L_tmp = L_add(L_tmp, tmp);
        x[i] = voround(L_tmp);
    }
    *mem = x[L - 1];
    return;
}


void Deemph_32(
        Word16 x_hi[],                        /* (i)     : input signal (bit31..16) */
        Word16 x_lo[],                        /* (i)     : input signal (bit15..4)  */
        Word16 y[],                           /* (o)     : output signal (x16)      */
        Word16 mu,                            /* (i) Q15 : deemphasis factor        */
        Word16 L,                             /* (i)     : vector size              */
        Word16 * mem                          /* (i/o)   : memory (y[-1])           */
          )
{
    Word16 fac;
    Word32 i, L_tmp;

    fac = mu >> 1;                                /* Q15 --> Q14 */

    L_tmp = L_deposit_h(x_hi[0]);
    L_tmp += (x_lo[0] * 8)<<1;
    L_tmp = (L_tmp << 3);
    L_tmp += ((*mem) * fac)<<1;
    L_tmp = (L_tmp << 1);
    y[0] = (L_tmp + 0x8000)>>16;

    for (i = 1; i < L; i++)
    {
        L_tmp = L_deposit_h(x_hi[i]);
        L_tmp += (x_lo[i] * 8)<<1;
        L_tmp = (L_tmp << 3);
        L_tmp += (y[i - 1] * fac)<<1;
        L_tmp = (L_tmp << 1);
        y[i] = (L_tmp + 0x8000)>>16;
    }

    *mem = y[L - 1];

    return;
}