deemph.c revision 41050cdb033641ddf26831d9272c0930f7b40a2d 
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: deemph.c                                                 *
19*                                                                      *
20*	   Description:filtering through 1/(1-mu z^ -1)                    *
21*	               Deemph2 --> signal is divided by 2                  *
22*				   Deemph_32 --> for 32 bits signal.                   *
23*                                                                      *
24************************************************************************/
25
26#include "typedef.h"
27#include "basic_op.h"
28#include "math_op.h"
29
30void Deemph(
31		Word16 x[],                           /* (i/o)   : input signal overwritten by the output */
32		Word16 mu,                            /* (i) Q15 : deemphasis factor                      */
33		Word16 L,                             /* (i)     : vector size                            */
34		Word16 * mem                          /* (i/o)   : memory (y[-1])                         */
35	   )
36{
37	Word32 i;
38	Word32 L_tmp;
39
40	L_tmp = L_deposit_h(x[0]);
41	L_tmp = L_mac(L_tmp, *mem, mu);
42	x[0] = vo_round(L_tmp);
43
44	for (i = 1; i < L; i++)
45	{
46		L_tmp = L_deposit_h(x[i]);
47		L_tmp = L_mac(L_tmp, x[i - 1], mu);
48		x[i] = voround(L_tmp);
49	}
50
51	*mem = x[L - 1];
52
53	return;
54}
55
56
57void Deemph2(
58		Word16 x[],                           /* (i/o)   : input signal overwritten by the output */
59		Word16 mu,                            /* (i) Q15 : deemphasis factor                      */
60		Word16 L,                             /* (i)     : vector size                            */
61		Word16 * mem                          /* (i/o)   : memory (y[-1])                         */
62	    )
63{
64	Word32 i;
65	Word32 L_tmp;
66	L_tmp = x[0] << 15;
67	L_tmp += ((*mem) * mu)<<1;
68	x[0] = (L_tmp + 0x8000)>>16;
69	for (i = 1; i < L; i++)
70	{
71		L_tmp = x[i] << 15;
72		L_tmp += (x[i - 1] * mu)<<1;
73		x[i] = (L_tmp + 0x8000)>>16;
74	}
75	*mem = x[L - 1];
76	return;
77}
78
79
80void Deemph_32(
81		Word16 x_hi[],                        /* (i)     : input signal (bit31..16) */
82		Word16 x_lo[],                        /* (i)     : input signal (bit15..4)  */
83		Word16 y[],                           /* (o)     : output signal (x16)      */
84		Word16 mu,                            /* (i) Q15 : deemphasis factor        */
85		Word16 L,                             /* (i)     : vector size              */
86		Word16 * mem                          /* (i/o)   : memory (y[-1])           */
87	      )
88{
89	Word16 fac;
90	Word32 i, L_tmp;
91
92	fac = mu >> 1;                                /* Q15 --> Q14 */
93
94	L_tmp = L_deposit_h(x_hi[0]);
95	L_tmp += (x_lo[0] * 8)<<1;
96	L_tmp = (L_tmp << 3);
97	L_tmp += ((*mem) * fac)<<1;
98	L_tmp = (L_tmp << 1);
99	y[0] = (L_tmp + 0x8000)>>16;
100
101	for (i = 1; i < L; i++)
102	{
103		L_tmp = L_deposit_h(x_hi[i]);
104		L_tmp += (x_lo[i] * 8)<<1;
105		L_tmp = (L_tmp << 3);
106		L_tmp += (y[i - 1] * fac)<<1;
107		L_tmp = (L_tmp << 1);
108		y[i] = (L_tmp + 0x8000)>>16;
109	}
110
111	*mem = y[L - 1];
112
113	return;
114}
115
116
117
118