/* | |
** 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: isp_isf.c * | |
* * | |
* Description: * | |
* Isp_isf Transformation isp to isf * | |
* Isf_isp Transformation isf to isp * | |
* * | |
* The transformation from isp[i] to isf[i] and isf[i] to isp[i] * | |
* are approximated by a look-up table and interpolation * | |
* * | |
************************************************************************/ | |
#include "typedef.h" | |
#include "basic_op.h" | |
#include "isp_isf.tab" /* Look-up table for transformations */ | |
void Isp_isf( | |
Word16 isp[], /* (i) Q15 : isp[m] (range: -1<=val<1) */ | |
Word16 isf[], /* (o) Q15 : isf[m] normalized (range: 0.0<=val<=0.5) */ | |
Word16 m /* (i) : LPC order */ | |
) | |
{ | |
Word32 i, ind; | |
Word32 L_tmp; | |
ind = 127; /* beging at end of table -1 */ | |
for (i = (m - 1); i >= 0; i--) | |
{ | |
if (i >= (m - 2)) | |
{ /* m-2 is a constant */ | |
ind = 127; /* beging at end of table -1 */ | |
} | |
/* find value in table that is just greater than isp[i] */ | |
while (table[ind] < isp[i]) | |
ind--; | |
/* acos(isp[i])= ind*128 + ( ( isp[i]-table[ind] ) * slope[ind] )/2048 */ | |
L_tmp = vo_L_mult(vo_sub(isp[i], table[ind]), slope[ind]); | |
isf[i] = vo_round((L_tmp << 4)); /* (isp[i]-table[ind])*slope[ind])>>11 */ | |
isf[i] = add1(isf[i], (ind << 7)); | |
} | |
isf[m - 1] = (isf[m - 1] >> 1); | |
return; | |
} | |
void Isf_isp( | |
Word16 isf[], /* (i) Q15 : isf[m] normalized (range: 0.0<=val<=0.5) */ | |
Word16 isp[], /* (o) Q15 : isp[m] (range: -1<=val<1) */ | |
Word16 m /* (i) : LPC order */ | |
) | |
{ | |
Word16 offset; | |
Word32 i, ind, L_tmp; | |
for (i = 0; i < m - 1; i++) | |
{ | |
isp[i] = isf[i]; | |
} | |
isp[m - 1] = (isf[m - 1] << 1); | |
for (i = 0; i < m; i++) | |
{ | |
ind = (isp[i] >> 7); /* ind = b7-b15 of isf[i] */ | |
offset = (Word16) (isp[i] & 0x007f); /* offset = b0-b6 of isf[i] */ | |
/* isp[i] = table[ind]+ ((table[ind+1]-table[ind])*offset) / 128 */ | |
L_tmp = vo_L_mult(vo_sub(table[ind + 1], table[ind]), offset); | |
isp[i] = add1(table[ind], (Word16)((L_tmp >> 8))); | |
} | |
return; | |
} | |