Bit (0) search from MSB side (search zero from left).
Searches the word data of the register specified by the first operand, from the left (MSB side), and stores the position of the first bit (0) found in the register specified by the second operand in hexadecimal. (For example, if bit 31 of the register specified by the first operand is 0, 01H is stored in the register specified by the second operand.)
If no bit (0) is found, 0 is written into the register specified by the second operand, and the Z flag is simultaneously set (1). If a bit (0) is found at the end, the CY flag is set (1).