BSF/BSR Instruction - Assembly Language Help

Assembly Language Help (alang.hlp) (Table of Contents; Topic list)

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◄Summary► ◄Key► ◄Up► ◄Contents► ◄Index► ◄Back► ──────────────────────────────────────────────────────────────────────────── 00001111 10111100 mod,reg,r/m disp (0, 1, 2, or 4) ───────────────────┬─────────────────────────┬────────────────────────────── BSF reg16,reg16 │ bsf cx,bx │ 88/86 ── BSF reg32,reg32 │ │ 286 ── │ │ 386 10+3n │ │ 486 6-42* ───────────────────┼─────────────────────────┼────────────────────────────── BSF reg16,mem16 │ bsf ecx,bitmask │ 88/86 ── BSF reg32,mem32 │ │ 286 ── │ │ 386 10+3n │ │ 486 7-43 ───────────────────┴─────────────────────────┴────────────────────────────── 00001111 10111101 mod,reg,r/m disp (0, 1, 2, or 4) ───────────────────┬─────────────────────────┬────────────────────────────── BSR reg16,reg16 │ bsr cx,dx │ 88/86 ── BSR reg32,reg32 │ │ 286 ── │ │ 386 10+3n │ │ 486 103-3n# ───────────────────┼─────────────────────────┼────────────────────────────── BSR reg16,mem16 │ bsr eax,bitmask │ 88/86 ── BSR reg32,mem32 │ │ 286 ── │ │ 386 10+3n │ │ 486 104-3n# ───────────────────┴─────────────────────────┴────────────────────────────── * Clocks = 8 + 4 for each byte scanned + 3 for each nibble scanned in last byte + 3 for each bit scanned in last nibble or 6 if second operand equals 0 Same as footnote above, but add 1 clock. n = Bit position from 0 to 31 Clocks = 6 if second operand equals 0 # n = Bit position from 0 to 31 Clocks = 7 if second operand equals 0 -♦-