/src/opus/silk/sum_sqr_shift.c
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1 | | /*********************************************************************** |
2 | | Copyright (c) 2006-2011, Skype Limited. All rights reserved. |
3 | | Redistribution and use in source and binary forms, with or without |
4 | | modification, are permitted provided that the following conditions |
5 | | are met: |
6 | | - Redistributions of source code must retain the above copyright notice, |
7 | | this list of conditions and the following disclaimer. |
8 | | - Redistributions in binary form must reproduce the above copyright |
9 | | notice, this list of conditions and the following disclaimer in the |
10 | | documentation and/or other materials provided with the distribution. |
11 | | - Neither the name of Internet Society, IETF or IETF Trust, nor the |
12 | | names of specific contributors, may be used to endorse or promote |
13 | | products derived from this software without specific prior written |
14 | | permission. |
15 | | THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
16 | | AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
17 | | IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
18 | | ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE |
19 | | LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
20 | | CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
21 | | SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
22 | | INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
23 | | CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
24 | | ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
25 | | POSSIBILITY OF SUCH DAMAGE. |
26 | | ***********************************************************************/ |
27 | | |
28 | | #ifdef HAVE_CONFIG_H |
29 | | #include "config.h" |
30 | | #endif |
31 | | |
32 | | #include "SigProc_FIX.h" |
33 | | |
34 | | /* Compute number of bits to right shift the sum of squares of a vector */ |
35 | | /* of int16s to make it fit in an int32 */ |
36 | | void silk_sum_sqr_shift( |
37 | | opus_int32 *energy, /* O Energy of x, after shifting to the right */ |
38 | | opus_int *shift, /* O Number of bits right shift applied to energy */ |
39 | | const opus_int16 *x, /* I Input vector */ |
40 | | opus_int len /* I Length of input vector */ |
41 | | ) |
42 | 0 | { |
43 | 0 | opus_int i, shft; |
44 | 0 | opus_uint32 nrg_tmp; |
45 | 0 | opus_int32 nrg; |
46 | | |
47 | | /* Do a first run with the maximum shift we could have. */ |
48 | 0 | shft = 31-silk_CLZ32(len); |
49 | | /* Let's be conservative with rounding and start with nrg=len. */ |
50 | 0 | nrg = len; |
51 | 0 | for( i = 0; i < len - 1; i += 2 ) { |
52 | 0 | nrg_tmp = silk_SMULBB( x[ i ], x[ i ] ); |
53 | 0 | nrg_tmp = silk_SMLABB_ovflw( nrg_tmp, x[ i + 1 ], x[ i + 1 ] ); |
54 | 0 | nrg = (opus_int32)silk_ADD_RSHIFT_uint( nrg, nrg_tmp, shft ); |
55 | 0 | } |
56 | 0 | if( i < len ) { |
57 | | /* One sample left to process */ |
58 | 0 | nrg_tmp = silk_SMULBB( x[ i ], x[ i ] ); |
59 | 0 | nrg = (opus_int32)silk_ADD_RSHIFT_uint( nrg, nrg_tmp, shft ); |
60 | 0 | } |
61 | 0 | silk_assert( nrg >= 0 ); |
62 | | /* Make sure the result will fit in a 32-bit signed integer with two bits |
63 | | of headroom. */ |
64 | 0 | shft = silk_max_32(0, shft+3 - silk_CLZ32(nrg)); |
65 | 0 | nrg = 0; |
66 | 0 | for( i = 0 ; i < len - 1; i += 2 ) { |
67 | 0 | nrg_tmp = silk_SMULBB( x[ i ], x[ i ] ); |
68 | 0 | nrg_tmp = silk_SMLABB_ovflw( nrg_tmp, x[ i + 1 ], x[ i + 1 ] ); |
69 | 0 | nrg = (opus_int32)silk_ADD_RSHIFT_uint( nrg, nrg_tmp, shft ); |
70 | 0 | } |
71 | 0 | if( i < len ) { |
72 | | /* One sample left to process */ |
73 | 0 | nrg_tmp = silk_SMULBB( x[ i ], x[ i ] ); |
74 | 0 | nrg = (opus_int32)silk_ADD_RSHIFT_uint( nrg, nrg_tmp, shft ); |
75 | 0 | } |
76 | |
|
77 | 0 | silk_assert( nrg >= 0 ); |
78 | | |
79 | | /* Output arguments */ |
80 | 0 | *shift = shft; |
81 | 0 | *energy = nrg; |
82 | 0 | } |
83 | | |