Siemens C16 Series Instruction Set Manual page 57

CMPD2
Syntax
Operation
Data Types
Description
Condition Flags
Addressing Modes
Semiconductor Group
30Mar98@15:00h
Integer Compare and Decrement by 2
CMPD2 op1, op2
(op1) ⇔ (op2)
(op1) ← (op1) - 2
WORD
This instruction is used to enhance the performance and flexibility of
loops. The source operand specified by op1 is compared to the source
operand specified by op2 by performing a 2's complement binary subtrac-
tion of op2 from op1. Operand op1 may specify ONLY GPR registers.
Once the subtraction has completed, the operand op1 is decremented by
two. Using the set flags, a branch instruction can then be used in conjunc-
tion with this instruction to form common high level language FOR loops of
any range.
E Z
* *
E Set if the value of op2 represents the lowest possible negative number.
Cleared otherwise. Used to signal the end of a table.
Z Set if result equals zero. Cleared otherwise.
V Set if an arithmetic underflow occurred, ie. the result cannot be repre-
sented in the specified data type. Cleared otherwise.
C Set if a borrow is generated. Cleared otherwise.
N Set if the most significant bit of the result is set. Cleared otherwise.
Mnemonic
CMPD2 Rw , #data4
n
CMPD2 Rw , #data16
n
CMPD2 Rw , mem
n
C166 Family Instruction Set
V C N
* S *
Format
B0 #n
B6 Fn ## ##
B2 Fn MM MM
57
Instruction Description
CMPD2
Version 1.2, 12.97
Bytes
2
4
4