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/*
** 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: preemph.c *
* *
* Description: Preemphasis: filtering through 1 - g z^-1 *
* Preemph2 --> signal is multiplied by 2 *
* *
************************************************************************/
#include "typedef.h"
#include "basic_op.h"
void Preemph(
Word16 x[], /* (i/o) : input signal overwritten by the output */
Word16 mu, /* (i) Q15 : preemphasis coefficient */
Word16 lg, /* (i) : lenght of filtering */
Word16 * mem /* (i/o) : memory (x[-1]) */
)
{
Word16 temp;
Word32 i, L_tmp;
temp = x[lg - 1];
for (i = lg - 1; i > 0; i--)
{
L_tmp = L_deposit_h(x[i]);
L_tmp -= (x[i - 1] * mu)<<1;
x[i] = (L_tmp + 0x8000)>>16;
}
L_tmp = L_deposit_h(x[0]);
L_tmp -= ((*mem) * mu)<<1;
x[0] = (L_tmp + 0x8000)>>16;
*mem = temp;
return;
}
void Preemph2(
Word16 x[], /* (i/o) : input signal overwritten by the output */
Word16 mu, /* (i) Q15 : preemphasis coefficient */
Word16 lg, /* (i) : lenght of filtering */
Word16 * mem /* (i/o) : memory (x[-1]) */
)
{
Word16 temp;
Word32 i, L_tmp;
temp = x[lg - 1];
for (i = (Word16) (lg - 1); i > 0; i--)
{
L_tmp = L_deposit_h(x[i]);
L_tmp -= (x[i - 1] * mu)<<1; // only called with mu == 22282, so this won't overflow
if (L_tmp > INT32_MAX / 2) {
L_tmp = INT32_MAX / 2;
}
L_tmp = (L_tmp << 1);
if (L_tmp > INT32_MAX - 0x8000) {
L_tmp = INT32_MAX - 0x8000;
}
x[i] = (L_tmp + 0x8000)>>16;
}
L_tmp = L_deposit_h(x[0]);
L_tmp -= ((*mem) * mu)<<1;
if (L_tmp > INT32_MAX / 2) {
L_tmp = INT32_MAX / 2;
}
L_tmp = (L_tmp << 1);
if (L_tmp > INT32_MAX - 0x8000) {
L_tmp = INT32_MAX - 0x8000;
}
x[0] = (L_tmp + 0x8000)>>16;
*mem = temp;
return;
}
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