0F BC         BSF r16,r/m16                 Bit scan forward on r/m16

0F BC         BSF r32,r/m32                 Bit scan forward on r/m32


Description

Searches the source operand (second operand) for the least significant set bit (1 bit). If a least significant 1 bit is found, its bit index is stored in the destination operand (first operand). The source operand can be a register or a memory location; the destination operand is a register. The bit index is an unsigned offset from bit 0 of the source operand. If the contents source operand are 0, the contents of the destination operand is undefined.


Operands        Bytes                Clocks

r16, r16             3                  6-34  NP

r32, r32             3                6-42  NP

r16, m16          3+d(0,1,2)        6-35  NP

r32, m32          3+d(0,1,2,4)        6-43  NP


Flags

The ZF flag is set to 1 if all the source operand is 0; otherwise, the ZF flag is cleared. The CF, OF, SF, AF, and PF, flags are undefined.

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