DEC
By Vesper Vei
1 minute read
Table of Contents
DEC (dec)
Basic function
Performs -1 on the operand:
dest = dest - 1
Instruction execution process
- Subtract 1 from the destination operand
- Update all flags except CF (different from SUB x,1)
Instruction format
dec r/m8dec r/m16dec r/m32dec r/m64Behavioral characteristics
- Does not modify CF
- Modifies other common flags (ZF, SF, OF, PF, AF)
- Symmetrical with INC
- Used for loop decrements, countdown counters, etc.
Common uses
- Common reverse pattern in for-loops
- Move a pointer backward
- Countdown control in state machines
- Simple counter decrement