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1 /*********************************************************************** | 1 /*********************************************************************** |
2 Copyright (c) 2006-2011, Skype Limited. All rights reserved. | 2 Copyright (c) 2006-2011, Skype Limited. All rights reserved. |
3 Redistribution and use in source and binary forms, with or without | 3 Redistribution and use in source and binary forms, with or without |
4 modification, are permitted provided that the following conditions | 4 modification, are permitted provided that the following conditions |
5 are met: | 5 are met: |
6 - Redistributions of source code must retain the above copyright notice, | 6 - Redistributions of source code must retain the above copyright notice, |
7 this list of conditions and the following disclaimer. | 7 this list of conditions and the following disclaimer. |
8 - Redistributions in binary form must reproduce the above copyright | 8 - Redistributions in binary form must reproduce the above copyright |
9 notice, this list of conditions and the following disclaimer in the | 9 notice, this list of conditions and the following disclaimer in the |
10 documentation and/or other materials provided with the distribution. | 10 documentation and/or other materials provided with the distribution. |
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34 /* Compute number of bits to right shift the sum of squares of a vector */ | 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 */ | 35 /* of int16s to make it fit in an int32 */ |
36 void silk_sum_sqr_shift( | 36 void silk_sum_sqr_shift( |
37 opus_int32 *energy, /* O Energy of x, after sh
ifting to the right */ | 37 opus_int32 *energy, /* O Energy of x, after sh
ifting to the right */ |
38 opus_int *shift, /* O Number of bits right
shift applied to energy */ | 38 opus_int *shift, /* O Number of bits right
shift applied to energy */ |
39 const opus_int16 *x, /* I Input vector
*/ | 39 const opus_int16 *x, /* I Input vector
*/ |
40 opus_int len /* I Length of input vecto
r */ | 40 opus_int len /* I Length of input vecto
r */ |
41 ) | 41 ) |
42 { | 42 { |
43 opus_int i, shft; | 43 opus_int i, shft; |
44 opus_int32 nrg_tmp, nrg; | 44 opus_uint32 nrg_tmp; |
| 45 opus_int32 nrg; |
45 | 46 |
46 nrg = 0; | 47 /* Do a first run with the maximum shift we could have. */ |
47 shft = 0; | 48 shft = 31-silk_CLZ32(len); |
48 len--; | 49 /* Let's be conservative with rounding and start with nrg=len. */ |
49 for( i = 0; i < len; i += 2 ) { | 50 nrg = len; |
50 nrg = silk_SMLABB_ovflw( nrg, x[ i ], x[ i ] ); | 51 for( i = 0; i < len - 1; i += 2 ) { |
51 nrg = silk_SMLABB_ovflw( nrg, x[ i + 1 ], x[ i + 1 ] ); | |
52 if( nrg < 0 ) { | |
53 /* Scale down */ | |
54 nrg = (opus_int32)silk_RSHIFT_uint( (opus_uint32)nrg, 2 ); | |
55 shft = 2; | |
56 i+=2; | |
57 break; | |
58 } | |
59 } | |
60 for( ; i < len; i += 2 ) { | |
61 nrg_tmp = silk_SMULBB( x[ i ], x[ i ] ); | 52 nrg_tmp = silk_SMULBB( x[ i ], x[ i ] ); |
62 nrg_tmp = silk_SMLABB_ovflw( nrg_tmp, x[ i + 1 ], x[ i + 1 ] ); | 53 nrg_tmp = silk_SMLABB_ovflw( nrg_tmp, x[ i + 1 ], x[ i + 1 ] ); |
63 nrg = (opus_int32)silk_ADD_RSHIFT_uint( nrg, (opus_uint32)nrg_tmp, shft
); | 54 nrg = (opus_int32)silk_ADD_RSHIFT_uint( nrg, nrg_tmp, shft ); |
64 if( nrg < 0 ) { | |
65 /* Scale down */ | |
66 nrg = (opus_int32)silk_RSHIFT_uint( (opus_uint32)nrg, 2 ); | |
67 shft += 2; | |
68 } | |
69 } | 55 } |
70 if( i == len ) { | 56 if( i < len ) { |
| 57 /* One sample left to process */ |
| 58 nrg_tmp = silk_SMULBB( x[ i ], x[ i ] ); |
| 59 nrg = (opus_int32)silk_ADD_RSHIFT_uint( nrg, nrg_tmp, shft ); |
| 60 } |
| 61 silk_assert( nrg >= 0 ); |
| 62 /* Make sure the result will fit in a 32-bit signed integer with two bits |
| 63 of headroom. */ |
| 64 shft = silk_max_32(0, shft+3 - silk_CLZ32(nrg)); |
| 65 nrg = 0; |
| 66 for( i = 0 ; i < len - 1; i += 2 ) { |
| 67 nrg_tmp = silk_SMULBB( x[ i ], x[ i ] ); |
| 68 nrg_tmp = silk_SMLABB_ovflw( nrg_tmp, x[ i + 1 ], x[ i + 1 ] ); |
| 69 nrg = (opus_int32)silk_ADD_RSHIFT_uint( nrg, nrg_tmp, shft ); |
| 70 } |
| 71 if( i < len ) { |
71 /* One sample left to process */ | 72 /* One sample left to process */ |
72 nrg_tmp = silk_SMULBB( x[ i ], x[ i ] ); | 73 nrg_tmp = silk_SMULBB( x[ i ], x[ i ] ); |
73 nrg = (opus_int32)silk_ADD_RSHIFT_uint( nrg, nrg_tmp, shft ); | 74 nrg = (opus_int32)silk_ADD_RSHIFT_uint( nrg, nrg_tmp, shft ); |
74 } | 75 } |
75 | 76 |
76 /* Make sure to have at least one extra leading zero (two leading zeros in t
otal) */ | 77 silk_assert( nrg >= 0 ); |
77 if( nrg & 0xC0000000 ) { | |
78 nrg = silk_RSHIFT_uint( (opus_uint32)nrg, 2 ); | |
79 shft += 2; | |
80 } | |
81 | 78 |
82 /* Output arguments */ | 79 /* Output arguments */ |
83 *shift = shft; | 80 *shift = shft; |
84 *energy = nrg; | 81 *energy = nrg; |
85 } | 82 } |
86 | 83 |
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