| 1 | // -*- Mode: C -*- |
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| 2 | // |
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| 3 | // Cforall Version 1.0.0 Copyright (C) 2020 University of Waterloo |
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| 4 | // |
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| 5 | // The contents of this file are covered under the licence agreement in the |
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| 6 | // file "LICENCE" distributed with Cforall. |
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| 7 | // |
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| 8 | // bitmanip.hfa -- |
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| 9 | // |
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| 10 | // Author : Peter A. Buhr |
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| 11 | // Created On : Sat Mar 14 18:12:27 2020 |
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| 12 | // Last Modified By : Peter A. Buhr |
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| 13 | // Last Modified On : Sat Oct 8 08:28:15 2022 |
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| 14 | // Update Count : 142 |
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| 15 | // |
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| 16 | |
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| 17 | #pragma once |
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| 18 | |
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| 19 | // Reference: Bit Twiddling Hacks: http://graphics.stanford.edu/%7Eseander/bithacks.html#CountBitsSetNaive |
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| 20 | |
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| 21 | // Bits are numbered 1-N. |
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| 22 | |
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| 23 | #define __bitsizeof( n ) (sizeof(n) * __CHAR_BIT__) |
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| 24 | |
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| 25 | static inline __attribute__((always_inline)) { |
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| 26 | // Count leading 0 bits. |
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| 27 | unsigned int leading0s( unsigned char n ) { return n != 0 ? __builtin_clz( n ) - (__bitsizeof(unsigned int) - __bitsizeof(n)) : __bitsizeof(n); } |
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| 28 | unsigned int leading0s( unsigned short int n ) { return n != 0 ? __builtin_clz( n ) - (__bitsizeof(unsigned int) - __bitsizeof(n)) : __bitsizeof(n); } |
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| 29 | unsigned int leading0s( unsigned int n ) { return n != 0 ? __builtin_clz( n ) : __bitsizeof(n); } |
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| 30 | unsigned int leading0s( unsigned long int n ) { return n != 0 ? __builtin_clzl( n ) : __bitsizeof(n); } |
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| 31 | unsigned int leading0s( unsigned long long int n ) { return n != 0 ? __builtin_clzll( n ) : __bitsizeof(n); } |
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| 32 | |
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| 33 | // Count trailing 0 bits. |
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| 34 | unsigned int trailing0s( unsigned char n ) { return n != 0 ? __builtin_ctz( n ) : __bitsizeof(n); } |
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| 35 | unsigned int trailing0s( unsigned short int n ) { return n != 0 ? __builtin_ctz( n ) : __bitsizeof(n); } |
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| 36 | unsigned int trailing0s( unsigned int n ) { return n != 0 ? __builtin_ctz( n ) : __bitsizeof(n); } |
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| 37 | unsigned int trailing0s( unsigned long int n ) { return n != 0 ? __builtin_ctzl( n ) : __bitsizeof(n); } |
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| 38 | unsigned int trailing0s( unsigned long long int n ) { return n != 0 ? __builtin_ctzll( n ) : __bitsizeof(n); } |
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| 39 | |
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| 40 | // Count all 1 bits. |
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| 41 | unsigned int all1s( unsigned char n ) { return __builtin_popcount( n ); } |
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| 42 | unsigned int all1s( unsigned short int n ) { return __builtin_popcount( n ); } |
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| 43 | unsigned int all1s( unsigned int n ) { return __builtin_popcount( n ); } |
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| 44 | unsigned int all1s( unsigned long int n ) { return __builtin_popcountl( n ); } |
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| 45 | unsigned int all1s( unsigned long long int n ) { return __builtin_popcountll( n ); } |
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| 46 | |
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| 47 | // Count all 0 bits. |
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| 48 | unsigned int all0s( unsigned char n ) { return __builtin_popcount( (typeof(n))~n ); } |
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| 49 | unsigned int all0s( unsigned short int n ) { return __builtin_popcount( (typeof(n))~n ); } |
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| 50 | unsigned int all0s( unsigned int n ) { return __builtin_popcount( ~n ); } |
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| 51 | unsigned int all0s( unsigned long int n ) { return __builtin_popcountl( ~n ); } |
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| 52 | unsigned int all0s( unsigned long long int n ) { return __builtin_popcountll( ~n ); } |
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| 53 | |
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| 54 | // Find least significiant zero bit. (ffs) |
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| 55 | unsigned int low0( unsigned char n ) { return __builtin_ffs( (typeof(n))~n ); } |
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| 56 | unsigned int low0( unsigned short int n ) { return __builtin_ffs( (typeof(n))~n ); } |
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| 57 | unsigned int low0( unsigned int n ) { return __builtin_ffs( ~n ); } |
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| 58 | unsigned int low0( unsigned long int n ) { return __builtin_ffsl( ~n ); } |
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| 59 | unsigned int low0( unsigned long long int n ) { return __builtin_ffsll( ~n ); } |
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| 60 | |
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| 61 | // Find least significiant one bit. |
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| 62 | unsigned int low1( unsigned int n ) { return __builtin_ffs( n ); } |
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| 63 | unsigned int low1( unsigned long int n ) { return __builtin_ffsl( n ); } |
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| 64 | unsigned int low1( unsigned long long int n ) { return __builtin_ffsll( n ); } |
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| 65 | |
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| 66 | // Find most significiant zero bit. |
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| 67 | unsigned int high0( unsigned char n ) { return n == (typeof(n))-1 ? 0 : __bitsizeof(unsigned int) - __builtin_clz( (typeof(n))~n ); } |
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| 68 | unsigned int high0( unsigned short int n ) { return n == (typeof(n))-1 ? 0 : __bitsizeof(unsigned int) - __builtin_clz( (typeof(n))~n ); } |
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| 69 | unsigned int high0( unsigned int n ) { return n == -1 ? 0 : __bitsizeof(n) - __builtin_clz( ~n ); } |
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| 70 | unsigned int high0( unsigned long int n ) { return n == -1 ? 0 : __bitsizeof(n) - __builtin_clzl( ~n ); } |
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| 71 | unsigned int high0( unsigned long long int n ) { return n == -1 ? 0 : __bitsizeof(n) - __builtin_clzll( ~n ); } |
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| 72 | |
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| 73 | // Find most significiant one bit. |
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| 74 | unsigned int high1( unsigned char n ) { return n == 0 ? 0 : __bitsizeof(unsigned int) - __builtin_clz( n ); } |
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| 75 | unsigned int high1( unsigned short int n ) { return n == 0 ? 0 : __bitsizeof(unsigned int) - __builtin_clz( n ); } |
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| 76 | unsigned int high1( unsigned int n ) { return n == 0 ? 0 : __bitsizeof(n) - __builtin_clz( n ); } |
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| 77 | unsigned int high1( unsigned long int n ) { return n == 0 ? 0 : __bitsizeof(n) - __builtin_clzl( n ); } |
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| 78 | unsigned int high1( unsigned long long int n ) { return n == 0 ? 0 : __bitsizeof(n) - __builtin_clzll( n ); } |
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| 79 | |
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| 80 | // Check for power of 2, clears bits below n, rounding down to the next lower multiple of n. 0 is not a power of 2 |
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| 81 | // but this computation returns true because of the two's complement, so it is a special case. |
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| 82 | bool is_pow2( unsigned char n ) { return n == 0 ? false : (n & (n - 1)) == 0; } |
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| 83 | bool is_pow2( unsigned short int n ) { return n == 0 ? false : (n & (n - 1)) == 0; } |
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| 84 | bool is_pow2( unsigned int n ) { return n == 0 ? false : (n & (n - 1)) == 0; } |
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| 85 | bool is_pow2( unsigned long int n ) { return n == 0 ? false : (n & (n - 1)) == 0; } |
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| 86 | bool is_pow2( unsigned long long int n ) { return n == 0 ? false : (n & (n - 1)) == 0; } |
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| 87 | |
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| 88 | // Returns n aligned at the floor of align, clear bits above or equal to align, giving n % align. |
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| 89 | signed char floor2( signed char n, signed char align ) { verify( is_pow2( align ) ); return n & -align; } |
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| 90 | unsigned char floor2( unsigned char n, unsigned char align ) { verify( is_pow2( align ) ); return n & -align; } |
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| 91 | short int floor2( short int n, short int align ) { verify( is_pow2( align ) ); return n & -align; } |
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| 92 | unsigned short int floor2( unsigned short int n, unsigned short int align ) { verify( is_pow2( align ) ); return n & -align; } |
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| 93 | int floor2( int n, int align ) { verify( is_pow2( align ) ); return n & -align; } |
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| 94 | unsigned int floor2( unsigned int n, unsigned int align ) { verify( is_pow2( align ) ); return n & -align; } |
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| 95 | long int floor2( long int n, long int align ) { verify( is_pow2( align ) ); return n & -align; } |
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| 96 | unsigned long int floor2( unsigned long int n, unsigned long int align ) { verify( is_pow2( align ) ); return n & -align; } |
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| 97 | long long int floor2( long long int n, long long int align ) { verify( is_pow2( align ) ); return n & -align; } |
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| 98 | unsigned long long int floor2( unsigned long long int n, unsigned long long int align ) { verify( is_pow2( align ) ); return n & -align; } |
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| 99 | |
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| 100 | // forall( T | { T ?&?( T, T ); T -?( T ); } ) |
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| 101 | // T floor2( T n, T align ) { verify( is_pow2( align ) ); return n & -align; } |
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| 102 | |
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| 103 | // Returns n aligned at the ceiling of align, negate, round down, negate is the same as round up. |
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| 104 | signed char ceiling2( signed char n, signed char align ) { verify( is_pow2( align ) ); return -floor2( -n, align ); } |
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| 105 | unsigned char ceiling2( unsigned char n, unsigned char align ) { verify( is_pow2( align ) ); return -floor2( -n, align ); } |
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| 106 | short int ceiling2( short int n, short int align ) { verify( is_pow2( align ) ); return -floor2( -n, align ); } |
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| 107 | unsigned short int ceiling2( unsigned short int n, unsigned short int align ) { verify( is_pow2( align ) ); return -floor2( -n, align ); } |
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| 108 | int ceiling2( int n, int align ) { verify( is_pow2( align ) ); return -floor2( -n, align ); } |
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| 109 | unsigned int ceiling2( unsigned int n, unsigned int align ) { verify( is_pow2( align ) ); return -floor2( -n, align ); } |
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| 110 | long int ceiling2( long int n, long int align ) { verify( is_pow2( align ) ); return -floor2( -n, align ); } |
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| 111 | unsigned long int ceiling2( unsigned long int n, unsigned long int align ) { verify( is_pow2( align ) ); return -floor2( -n, align ); } |
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| 112 | long long int ceiling2( long long int n, long long int align ) { verify( is_pow2( align ) ); return -floor2( -n, align ); } |
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| 113 | unsigned long long int ceiling2( unsigned long long int n, unsigned long long int align ) { verify( is_pow2( align ) ); return -floor2( -n, align ); } |
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| 114 | |
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| 115 | // forall( T | { T floor2( T, T ); T -?( T ); } ) |
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| 116 | // T ceiling2( T n, T align ) { verify( is_pow2( align ) ); return -floor2( -n, align ); } |
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| 117 | } // distribution |
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| 118 | |
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| 119 | // Local Variables: // |
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| 120 | // tab-width: 4 // |
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| 121 | // End: // |
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