70 lines
2.3 KiB
C++
70 lines
2.3 KiB
C++
#ifndef NALL_BIT_HPP
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#define NALL_BIT_HPP
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namespace nall {
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template<unsigned bits>
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constexpr inline uintmax_t uclamp(const uintmax_t x) {
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enum : uintmax_t { b = 1ull << (bits - 1), y = b * 2 - 1 };
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return y + ((x - y) & -(x < y)); //min(x, y);
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}
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template<unsigned bits>
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constexpr inline uintmax_t uclip(const uintmax_t x) {
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//zero 17-jun-2015 - revised to use more standard constexpr behaviour
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//enum : uintmax_t { b = 1ull << (bits - 1), m = b * 2 - 1 };
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//return (x & m); //test
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return (x & ((uintmax_t)(((uintmax_t)(1ull << (bits - 1))) * 2 - 1)));
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}
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template<unsigned bits>
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constexpr inline intmax_t sclamp(const intmax_t x) {
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//zero 17-jun-2015 - revised to use more standard constexpr behaviour
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//enum : intmax_t { b = 1ull << (bits - 1), m = b - 1 };
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//(intmax_t)(1ull << (bits - 1)) //b
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//(((intmax_t)(1ull << (bits - 1))) - 1) //m
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//return (x > m) ? m : (x < -b) ? -b : x;
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return (x > (((intmax_t)(1ull << (bits - 1))) - 1)) ? (((intmax_t)(1ull << (bits - 1))) - 1) : (x < -((intmax_t)(1ull << (bits - 1)))) ? -((intmax_t)(1ull << (bits - 1))) : x; //test
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}
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template<unsigned bits>
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constexpr inline intmax_t sclip(const intmax_t x) {
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//zero 17-jun-2015 - revised to use more standard constexpr behaviour
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//enum : uintmax_t { b = 1ull << (bits - 1), m = b * 2 - 1 }; //test
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return ((x & ((uintmax_t)(((uintmax_t)(1ull << (bits - 1))) * 2 - 1))) ^ ((uintmax_t)(1ull << (bits - 1)))) - ((uintmax_t)(1ull << (bits - 1)));
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}
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namespace bit {
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//lowest(0b1110) == 0b0010
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constexpr inline uintmax_t lowest(const uintmax_t x) {
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return x & -x;
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}
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//clear_lowest(0b1110) == 0b1100
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constexpr inline uintmax_t clear_lowest(const uintmax_t x) {
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return x & (x - 1);
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}
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//set_lowest(0b0101) == 0b0111
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constexpr inline uintmax_t set_lowest(const uintmax_t x) {
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return x | (x + 1);
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}
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//count number of bits set in a byte
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inline unsigned count(uintmax_t x) {
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unsigned count = 0;
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do count += x & 1; while(x >>= 1);
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return count;
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}
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//round up to next highest single bit:
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//round(15) == 16, round(16) == 16, round(17) == 32
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inline uintmax_t round(uintmax_t x) {
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if((x & (x - 1)) == 0) return x;
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while(x & (x - 1)) x &= x - 1;
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return x << 1;
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}
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}
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}
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#endif
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