/* | |
** 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; | |
L_tmp = (L_tmp << 1); | |
x[i] = (L_tmp + 0x8000)>>16; | |
} | |
L_tmp = L_deposit_h(x[0]); | |
L_tmp -= ((*mem) * mu)<<1; | |
L_tmp = (L_tmp << 1); | |
x[0] = (L_tmp + 0x8000)>>16; | |
*mem = temp; | |
return; | |
} | |