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7-thaumaturgy-7964.md - tgtimes - The Gopher Times |
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git clone git://bitreich.org/tgtimes git://enlrupgkhuxnvlhsf6lc3fziv5h2hhfrinws65d7roiv6bfj7d652fid.onion/tgtimes (git://bitreich.org) |
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7-thaumaturgy-7964.md (585B) |
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1 # This's opus C Thaumaturgy |
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2 |
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3 // Returns the smaller integer of x and y but without a branch |
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4 // (if/else/ternary, goto etc..) |
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5 // Normally min is implemented something like this: |
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6 // return x < y ? x : y; |
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7 // But we have a branch there so let's do it witout. (The branch |
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8 // free min could be used to merge arrays for example.) |
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9 // If x < y, then -(x < y) => -1 => all 1's in two complement |
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10 // representation. |
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11 // So we have y ^ (x ^ y) => x |
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12 // If x >= y, then -(x < y) => 0 so y ^ 0 is y. |
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13 |
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14 static inline uint8_t min(const uint8_t x, const uint8_t y) { |
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15 return y ^ ((x ^ y) & -(x < y)); |
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16 } |
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