ref: 205443a1cccac1dcd3e9648ef53b7b7eba4e1fb8
dir: /amr-wb/isp_isf.c/
/*-------------------------------------------------------------------*
* ISP_ISF.C *
*-------------------------------------------------------------------*
* 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 "count.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 */
)
{
Word16 i, ind;
Word32 L_tmp;
ind = 127; move16(); /* beging at end of table -1 */
for (i = (Word16) (m - 1); i >= 0; i--)
{
test();
if (sub(i, sub(m, 2)) >= 0)
{ /* m-2 is a constant */
ind = 127; move16(); /* beging at end of table -1 */
}
/* find value in table that is just greater than isp[i] */
test();
while (sub(table[ind], isp[i]) < 0)
ind--;
/* acos(isp[i])= ind*128 + ( ( isp[i]-table[ind] ) * slope[ind] )/2048 */
L_tmp = L_mult(sub(isp[i], table[ind]), slope[ind]);
isf[i] = round(L_shl(L_tmp, 4)); /* (isp[i]-table[ind])*slope[ind])>>11 */
move16();
isf[i] = add(isf[i], shl(ind, 7)); move16();
}
isf[m - 1] = shr(isf[m - 1], 1); move16();
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 i, ind, offset;
Word32 L_tmp;
for (i = 0; i < m - 1; i++)
{
isp[i] = isf[i]; move16();
}
isp[m - 1] = shl(isf[m - 1], 1);
for (i = 0; i < m; i++)
{
ind = shr(isp[i], 7); /* ind = b7-b15 of isf[i] */
offset = (Word16) (isp[i] & 0x007f); logic16(); /* offset = b0-b6 of isf[i] */
/* isp[i] = table[ind]+ ((table[ind+1]-table[ind])*offset) / 128 */
L_tmp = L_mult(sub(table[ind + 1], table[ind]), offset);
isp[i] = add(table[ind], extract_l(L_shr(L_tmp, 8))); move16();
}
return;
}