SUB Instruction

The subtracts a source operand from a destination operand.

SUB — Arithmetic Subtraction
Usage: SUB dest, src

Flag O D I S Z A P C
Result *     * * * * *

The source is subtracted from the destination and the result is stored in the destination.
Clocks
Operands 286 386 486 Size Bytes
reg, reg 2 2 1 2
mem, reg 7 6 3 2-4
reg, mem 7 7 2 2-4
reg, immed 3 2 1 3-4
mem, immed 7 7 3 3-6
accum, immed 3 2 1 2-3

†Source is unchanged by the operation, and the difference is stored in the destination operand. The set of possible operands is the same as for the and instructions.

 Register & Immediate   Memory & Register   Clear  


  .data


  X   SDWORD  20h


  .code


  mov   eax, X


  sub   eax, 20


  call  WriteInt
 


  .data


  X   SDWORD  20h


  Y   SDWORD  20


  .code


  mov   eax, Y


  sub   X, eax


  call  WriteInt
 


  .data


  X   SDWORD  20h


  Y   SDWORD  20


  .code


  sub   eax, eax


  sub   eax, Y


  add   eax, X


  call  WriteInt
 Output   Output   Output