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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: 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;
}
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