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back2root:ibm-pc-ms-dos:instr:mul

MUL

MUL - unsigned Multiply

Unsigned multiply of the accumulator by the source.

  • If “src” is a byte value, then AL is used as the other multiplicand and the result is placed in AX.
  • If “src” is a word value, then AX is multiplied by “src” and DX:AX receives the result.
  • If “src” is a double word value, then EAX is multiplied by “src” and EDX:EAX receives the result.

The 386+ uses an early out algorithm which makes multiplying any size value in EAX as fast as in the 8 or 16 bit registers.

Usage:

	MUL	src	

Modifies flags:

CF OF

Clocks Size
Operands 808x 286 386 486 Bytes
reg8 70-77 13 9-14 13-18 2
reg16 118-113 21 9-22 13-26 2
reg32 - - 9-38 13-41 2-4
mem8 (76-83)+EA 16 12-17 13-18 2-4
mem16 (124-139)+EA 24 12-25 13-26 2-4
mem32 - - 12-21 13-42 2-4
back2root/ibm-pc-ms-dos/instr/mul.txt · Dernière modification : 2023/02/24 14:16 de frater