| /* |
| ** 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; |
| } |
| |
| |
| |