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INSTRUCTION SET
CP
— Compare
CP
dst,src
Operation:
dst – src
The source operand is compared to (subtracted from) the destination operand, and the
appropriate flags are set accordingly. The contents of both operands are unaffected by the
comparison.
Flags:
C: Set if a "borrow" occurred (src > dst); cleared otherwise.
Z: Set if the result is "0"; cleared otherwise.
S: Set if the result is negative; cleared otherwise.
V: Set if arithmetic overflow occurred; cleared otherwise.
D: Unaffected.
H: Unaffected.
Format:
opc
opc
opc
Examples:
1. Given: R1 = 02H and R2 = 03H:
Destination working register R1 contains the value 02H and source register R2 contains the value
03H. The statement "CP R1,R2" subtracts the R2 value (source/subtrahend) from the R1 value
(destination/minuend). Because a "borrow" occurs and the difference is negative, C and S are
"1".
2. Given: R1 = 05H and R2 = 0AH:
SKIP
In this example, destination working register R1 contains the value 05H which is less than the
contents of the source working register R2 (0AH). The statement "CP R1,R2" generates C = "1"
and the JP instruction does not jump to the SKIP location. After the statement "LD R3,R1"
executes, the value 06H remains in working register R3.
6-30
dst | src
src
dst
dst
src
R1,R2 →
CP
CP
R1,R2
JP
UGE,SKIP
INC
R1
LD
R3,R1
S3C8275X/F8275X/C8278X/F8278X/C8274X/F8274X
Bytes
2
3
3
Set the C and S flags
Cycles
Opcode
(Hex)
4
A2
6
A3
6
A4
6
A5
6
A6
Addr Mode
dst
src
r
r
r
lr
R
R
R
IR
R
IM
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