31 lines
389 B
NASM
31 lines
389 B
NASM
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popcnt:
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push bx
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push cx
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mov bx, ax
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and ax, 0x5555 ; 8x 01
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and bx, 0xaaaa ; 8x 10
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shr bx, 1
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add ax, bx
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mov bx, ax
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and ax, 0x3333 ; 4x 0011
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and bx, 0xcccc ; 4x 1100
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mov cl, 2
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shr bx, cl
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add ax, bx
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mov bx, ax
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and ax, 0x0f0f ; 2x 00001111
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and bx, 0xf0f0 ; 2x 11110000
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mov cl, 4
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shr bx, cl
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add ax, bx
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add al, ah
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xor ah, ah
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pop cx
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pop bx
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ret
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