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