Function:

Swaps all bytes in 32 bit registers, changing the sequence from ABCD to
DCBA, handy for converting numbers to a CPU format where the byte order
is reversed. Bug appears when BSWAP is not preceded by prefix 66h to
indicate 32 bit registers in 16 bit mode or when it IS preceded by 66h
in 32 bit mode.
Do not use this instruction with 16 bit registers as operand.
Results are undefined in that case. Use XCHG reg8,reg8 instead if you need
to swap 2 bytes in a 16 bit register like AX.




BT op1,op2  Bit Test
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