S3C72G9 Samsung semiconductor, S3C72G9 Datasheet - Page 5

• Manufacturer Part Number: S3C72G9
• Description: The S3C72G9 single-chip CMOS microcontroller has been designed for high performance using Samsungs newest 4-bit CPU core/ SAM47 (Samsung Arrangeable M
• Manufacturer: Samsung semiconductor

 
INSTRUCTIONS WHICH AFFECT THE CARRY FLAG
The only instructions which do not generate a skip signal, but which do affect the carry flag are as follows:
ADC AND SBC INSTRUCTION SKIP CONDITIONS
The instructions 'ADC A,@HL' and 'SBC A,@HL' can generate a skip signal, and set or clear the carry flag, when
they are executed in combination with the instruction 'ADS A,#im'.
If an 'ADS A,#im' instruction immediately follows an 'ADC A,@HL' or 'SBC A,@HL' instruction in a program
sequence, the ADS instruction does not skip the instruction following ADS, even if it has a skip function. If,
however, an 'ADC A,@HL' or 'SBC A,@HL' instruction is immediately followed by an 'ADS A,#im' instruction, the
ADC (or SBC) skips on overflow (or if there is no borrow) to the instruction immediately following the ADS, and
program execution continues. Table 5-3 contains additional information and examples of the 'ADC A,@HL' and
'SBC A,@HL' skip feature.
ADC A,@HL
ADS A,#im
xxx
xxx
SBC A,@HL
ADS A,#im
xxx
xxx
ADC
SBC
SCF
RCF
CCF
RRC
Instruction Sequences
Sample
LDB
BAND
BOR
BXOR
IRET
1
2
3
4
1
2
3
4
Table 5-3. Skip Conditions for ADC and SBC Instructions
C,(operand)
C,(operand)
C,(operand)
C,(operand)
instruction 1 is:
If the result of
No overflow
No borrow
Overflow
Borrow
Then, the execution
sequence is:
1, 2, 3, 4
1, 2, 3, 4
1, 3, 4
1, 3, 4
ADS cannot skip
instruction 3, even if it
has a skip function.
ADS cannot skip
instruction 3, even if it
has a skip function.

 


Reason