syn_filt.c revision b676a05348e4c516fa8b57e33b10548e6142c3f8 
1/*
2 ** Copyright 2003-2010, VisualOn, Inc.
3 **
4 ** Licensed under the Apache License, Version 2.0 (the "License");
5 ** you may not use this file except in compliance with the License.
6 ** You may obtain a copy of the License at
7 **
8 **     http://www.apache.org/licenses/LICENSE-2.0
9 **
10 ** Unless required by applicable law or agreed to in writing, software
11 ** distributed under the License is distributed on an "AS IS" BASIS,
12 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 ** See the License for the specific language governing permissions and
14 ** limitations under the License.
15 */
16
17/***********************************************************************
18*       File: syn_filt.c                                               *
19*                                                                      *
20*       Description: Do the synthesis filtering 1/A(z)                 *
21*                                                                      *
22************************************************************************/
23
24#include "typedef.h"
25#include "basic_op.h"
26#include "math_op.h"
27#include "cnst.h"
28
29void Syn_filt(
30		Word16 a[],                           /* (i) Q12 : a[m+1] prediction coefficients           */
31		Word16 x[],                           /* (i)     : input signal                             */
32		Word16 y[],                           /* (o)     : output signal                            */
33		Word16 lg,                            /* (i)     : size of filtering                        */
34		Word16 mem[],                         /* (i/o)   : memory associated with this filtering.   */
35		Word16 update                         /* (i)     : 0=no update, 1=update of memory.         */
36	     )
37{
38	Word32 i, a0;
39	Word16 y_buf[L_SUBFR16k + M16k];
40	Word32 L_tmp;
41	Word16 *yy, *p1, *p2;
42	yy = &y_buf[0];
43	/* copy initial filter states into synthesis buffer */
44	for (i = 0; i < 16; i++)
45	{
46		*yy++ = mem[i];
47	}
48	a0 = (a[0] >> 1);                     /* input / 2 */
49	/* Do the filtering. */
50	for (i = 0; i < lg; i++)
51	{
52		p1 = &a[1];
53		p2 = &yy[i-1];
54		L_tmp  = vo_mult32(a0, x[i]);
55		L_tmp -= vo_mult32((*p1++), (*p2--));
56		L_tmp -= vo_mult32((*p1++), (*p2--));
57		L_tmp -= vo_mult32((*p1++), (*p2--));
58		L_tmp -= vo_mult32((*p1++), (*p2--));
59		L_tmp -= vo_mult32((*p1++), (*p2--));
60		L_tmp -= vo_mult32((*p1++), (*p2--));
61		L_tmp -= vo_mult32((*p1++), (*p2--));
62		L_tmp -= vo_mult32((*p1++), (*p2--));
63		L_tmp -= vo_mult32((*p1++), (*p2--));
64		L_tmp -= vo_mult32((*p1++), (*p2--));
65		L_tmp -= vo_mult32((*p1++), (*p2--));
66		L_tmp -= vo_mult32((*p1++), (*p2--));
67		L_tmp -= vo_mult32((*p1++), (*p2--));
68		L_tmp -= vo_mult32((*p1++), (*p2--));
69		L_tmp -= vo_mult32((*p1++), (*p2--));
70		L_tmp -= vo_mult32((*p1), (*p2));
71
72		L_tmp = L_shl2(L_tmp, 4);
73		y[i] = yy[i] = extract_h(L_add(L_tmp, 0x8000));
74	}
75	/* Update memory if required */
76	if (update)
77		for (i = 0; i < 16; i++)
78		{
79			mem[i] = yy[lg - 16 + i];
80		}
81	return;
82}
83
84
85void Syn_filt_32(
86		Word16 a[],                           /* (i) Q12 : a[m+1] prediction coefficients */
87		Word16 m,                             /* (i)     : order of LP filter             */
88		Word16 exc[],                         /* (i) Qnew: excitation (exc[i] >> Qnew)    */
89		Word16 Qnew,                          /* (i)     : exc scaling = 0(min) to 8(max) */
90		Word16 sig_hi[],                      /* (o) /16 : synthesis high                 */
91		Word16 sig_lo[],                      /* (o) /16 : synthesis low                  */
92		Word16 lg                             /* (i)     : size of filtering              */
93		)
94{
95	Word32 i,a0;
96	Word32 L_tmp, L_tmp1;
97	Word16 *p1, *p2, *p3;
98	a0 = a[0] >> (4 + Qnew);          /* input / 16 and >>Qnew */
99	/* Do the filtering. */
100	for (i = 0; i < lg; i++)
101	{
102		L_tmp  = 0;
103		L_tmp1 = 0;
104		p1 = a;
105		p2 = &sig_lo[i - 1];
106		p3 = &sig_hi[i - 1];
107
108		L_tmp  -= vo_mult32((*p2--), (*p1));
109		L_tmp1 -= vo_mult32((*p3--), (*p1++));
110		L_tmp  -= vo_mult32((*p2--), (*p1));
111		L_tmp1 -= vo_mult32((*p3--), (*p1++));
112		L_tmp  -= vo_mult32((*p2--), (*p1));
113		L_tmp1 -= vo_mult32((*p3--), (*p1++));
114		L_tmp  -= vo_mult32((*p2--), (*p1));
115		L_tmp1 -= vo_mult32((*p3--), (*p1++));
116		L_tmp  -= vo_mult32((*p2--), (*p1));
117		L_tmp1 -= vo_mult32((*p3--), (*p1++));
118		L_tmp  -= vo_mult32((*p2--), (*p1));
119		L_tmp1 -= vo_mult32((*p3--), (*p1++));
120		L_tmp  -= vo_mult32((*p2--), (*p1));
121		L_tmp1 -= vo_mult32((*p3--), (*p1++));
122		L_tmp  -= vo_mult32((*p2--), (*p1));
123		L_tmp1 -= vo_mult32((*p3--), (*p1++));
124		L_tmp  -= vo_mult32((*p2--), (*p1));
125		L_tmp1 -= vo_mult32((*p3--), (*p1++));
126		L_tmp  -= vo_mult32((*p2--), (*p1));
127		L_tmp1 -= vo_mult32((*p3--), (*p1++));
128		L_tmp  -= vo_mult32((*p2--), (*p1));
129		L_tmp1 -= vo_mult32((*p3--), (*p1++));
130		L_tmp  -= vo_mult32((*p2--), (*p1));
131		L_tmp1 -= vo_mult32((*p3--), (*p1++));
132		L_tmp  -= vo_mult32((*p2--), (*p1));
133		L_tmp1 -= vo_mult32((*p3--), (*p1++));
134		L_tmp  -= vo_mult32((*p2--), (*p1));
135		L_tmp1 -= vo_mult32((*p3--), (*p1++));
136		L_tmp  -= vo_mult32((*p2--), (*p1));
137		L_tmp1 -= vo_mult32((*p3--), (*p1++));
138		L_tmp  -= vo_mult32((*p2--), (*p1));
139		L_tmp1 -= vo_mult32((*p3--), (*p1++));
140
141		L_tmp = L_tmp >> 11;
142		L_tmp += vo_L_mult(exc[i], a0);
143
144		/* sig_hi = bit16 to bit31 of synthesis */
145		L_tmp = L_tmp - (L_tmp1<<1);
146
147		L_tmp = L_tmp >> 3;           /* ai in Q12 */
148		sig_hi[i] = extract_h(L_tmp);
149
150		/* sig_lo = bit4 to bit15 of synthesis */
151		L_tmp >>= 4;           /* 4 : sig_lo[i] >> 4 */
152		sig_lo[i] = (Word16)((L_tmp - (sig_hi[i] << 13)));
153	}
154
155	return;
156}
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