s3c72m9 Samsung Semiconductor, Inc., s3c72m9 Datasheet - Page 154

• Manufacturer Part Number: s3c72m9
• Description: The S3c72m5/s3c72m7/s3c72m9 Single-chip Cmos Microcontroller Has Been Designed For High Performance Using Samsung S
• Manufacturer: Samsung Semiconductor, Inc.

SAM47 INSTRUCTION SET
DECS —
DECS
Operation:
Description:
Examples:
5-50
1. Register pair HL contains the value 7FH (01111111B). The following instruction leaves the
2. Register A contains the value 0H. The following instruction sequence leaves the value 0FFH
dst
The destination is decremented by one. An original value of 00H will underflow to 0FFH. If a borrow
occurs, a skip is executed. The carry flag value is unaffected.
Decrement and Skip on Borrow
value 7EH in register pair HL:
in register A. Since a "borrow" occurs, the 'CALL PLAY1' instruction is skipped and the 'CALL
PLAY2' instruction is executed:
Operand
Operand
DECS
DECS
CALL
CALL
RR
RR
R
R
Decrement register (R); skip on borrow
Decrement register pair (RR); skip on borrow
HL
A
PLAY1
PLAY2
0
1
1
1
1
1
0
0
0
Binary Code
Operation Summary
0
1
1
; "Borrow" occurs
; Skipped
; Executed
1
1
1
r2
r2
1
S3C72M5/C72M7/C72M9/P72M9 (Preliminary Spec)
r1
r1
0
r0
0
0
R
RR
R–1; skip on borrow
RR–1; skip on borrow
Operation Notation
Bytes
1
2
Cycles
1 + S
2 + S