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Diffstat (limited to 'src/utils/bit_ops.h')
-rw-r--r-- | src/utils/bit_ops.h | 103 |
1 files changed, 0 insertions, 103 deletions
diff --git a/src/utils/bit_ops.h b/src/utils/bit_ops.h deleted file mode 100644 index 0072fde71..000000000 --- a/src/utils/bit_ops.h +++ /dev/null @@ -1,103 +0,0 @@ -/* -* Bit/Word Operations -* (C) 1999-2008 Jack Lloyd -* -* Distributed under the terms of the Botan license -*/ - -#ifndef BOTAN_BIT_OPS_H__ -#define BOTAN_BIT_OPS_H__ - -#include <botan/types.h> - -namespace Botan { - -/** -* Power of 2 test. T should be an unsigned integer type -* @param arg an integer value -* @return true iff arg is 2^n for some n > 0 -*/ -template<typename T> -inline bool is_power_of_2(T arg) - { - return ((arg != 0 && arg != 1) && ((arg & (arg-1)) == 0)); - } - -/** -* Return the index of the highest set bit -* T is an unsigned integer type -* @param n an integer value -* @return index of the highest set bit in n -*/ -template<typename T> -inline size_t high_bit(T n) - { - for(size_t i = 8*sizeof(T); i > 0; --i) - if((n >> (i - 1)) & 0x01) - return i; - return 0; - } - -/** -* Return the index of the lowest set bit -* T is an unsigned integer type -* @param n an integer value -* @return index of the lowest set bit in n -*/ -template<typename T> -inline size_t low_bit(T n) - { - for(size_t i = 0; i != 8*sizeof(T); ++i) - if((n >> i) & 0x01) - return (i + 1); - return 0; - } - -/** -* Return the number of significant bytes in n -* @param n an integer value -* @return number of significant bytes in n -*/ -template<typename T> -inline size_t significant_bytes(T n) - { - for(size_t i = 0; i != sizeof(T); ++i) - if(get_byte(i, n)) - return sizeof(T)-i; - return 0; - } - -/** -* Compute Hamming weights -* @param n an integer value -* @return number of bits in n set to 1 -*/ -template<typename T> -inline size_t hamming_weight(T n) - { - const byte NIBBLE_WEIGHTS[] = { - 0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4 }; - - size_t weight = 0; - for(size_t i = 0; i != 2*sizeof(T); ++i) - weight += NIBBLE_WEIGHTS[(n >> (4*i)) & 0x0F]; - return weight; - } - -/** -* Count the trailing zero bits in n -* @param n an integer value -* @return maximum x st 2^x divides n -*/ -template<typename T> -inline size_t ctz(T n) - { - for(size_t i = 0; i != 8*sizeof(T); ++i) - if((n >> i) & 0x01) - return i; - return 8*sizeof(T); - } - -} - -#endif |