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1 /* Copyright (c) 2003-2008 Timothy B. Terriberry | 1 /* Copyright (c) 2003-2008 Timothy B. Terriberry |
2 Copyright (c) 2008 Xiph.Org Foundation */ | 2 Copyright (c) 2008 Xiph.Org Foundation */ |
3 /* | 3 /* |
4 Redistribution and use in source and binary forms, with or without | 4 Redistribution and use in source and binary forms, with or without |
5 modification, are permitted provided that the following conditions | 5 modification, are permitted provided that the following conditions |
6 are met: | 6 are met: |
7 | 7 |
8 - Redistributions of source code must retain the above copyright | 8 - Redistributions of source code must retain the above copyright |
9 notice, this list of conditions and the following disclaimer. | 9 notice, this list of conditions and the following disclaimer. |
10 | 10 |
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41 /*Modern gcc (4.x) can compile the naive versions of min and max with cmov if | 41 /*Modern gcc (4.x) can compile the naive versions of min and max with cmov if |
42 given an appropriate architecture, but the branchless bit-twiddling versions | 42 given an appropriate architecture, but the branchless bit-twiddling versions |
43 are just as fast, and do not require any special target architecture. | 43 are just as fast, and do not require any special target architecture. |
44 Earlier gcc versions (3.x) compiled both code to the same assembly | 44 Earlier gcc versions (3.x) compiled both code to the same assembly |
45 instructions, because of the way they represented ((_b)>(_a)) internally.*/ | 45 instructions, because of the way they represented ((_b)>(_a)) internally.*/ |
46 # define EC_MINI(_a,_b) ((_a)+(((_b)-(_a))&-((_b)<(_a)))) | 46 # define EC_MINI(_a,_b) ((_a)+(((_b)-(_a))&-((_b)<(_a)))) |
47 | 47 |
48 /*Count leading zeros. | 48 /*Count leading zeros. |
49 This macro should only be used for implementing ec_ilog(), if it is defined. | 49 This macro should only be used for implementing ec_ilog(), if it is defined. |
50 All other code should use EC_ILOG() instead.*/ | 50 All other code should use EC_ILOG() instead.*/ |
51 #if defined(_MSC_VER) | 51 #if defined(_MSC_VER) && (_MSC_VER >= 1400) |
52 # include <intrin.h> | 52 # include <intrin.h> |
53 /*In _DEBUG mode this is not an intrinsic by default.*/ | 53 /*In _DEBUG mode this is not an intrinsic by default.*/ |
54 # pragma intrinsic(_BitScanReverse) | 54 # pragma intrinsic(_BitScanReverse) |
55 | 55 |
56 static __inline int ec_bsr(unsigned long _x){ | 56 static __inline int ec_bsr(unsigned long _x){ |
57 unsigned long ret; | 57 unsigned long ret; |
58 _BitScanReverse(&ret,_x); | 58 _BitScanReverse(&ret,_x); |
59 return (int)ret; | 59 return (int)ret; |
60 } | 60 } |
61 # define EC_CLZ0 (1) | 61 # define EC_CLZ0 (1) |
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78 /*Note that __builtin_clz is not defined when _x==0, according to the gcc | 78 /*Note that __builtin_clz is not defined when _x==0, according to the gcc |
79 documentation (and that of the BSR instruction that implements it on x86). | 79 documentation (and that of the BSR instruction that implements it on x86). |
80 The majority of the time we can never pass it zero. | 80 The majority of the time we can never pass it zero. |
81 When we need to, it can be special cased.*/ | 81 When we need to, it can be special cased.*/ |
82 # define EC_ILOG(_x) (EC_CLZ0-EC_CLZ(_x)) | 82 # define EC_ILOG(_x) (EC_CLZ0-EC_CLZ(_x)) |
83 #else | 83 #else |
84 int ec_ilog(opus_uint32 _v); | 84 int ec_ilog(opus_uint32 _v); |
85 # define EC_ILOG(_x) (ec_ilog(_x)) | 85 # define EC_ILOG(_x) (ec_ilog(_x)) |
86 #endif | 86 #endif |
87 #endif | 87 #endif |
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