Samsung 8-Bit CMOS Microcontroller, S3C9228/P9228 user manual ADC Add With Carry, Flags

S3C9228/P9228 SAM88RCRI INSTRUCTION SET

ADC — Add With Carry

ADCdst,src

Operation: dst ¨ dst + src + c

The source operand, along with the setting of the carry flag, is added to the destination operand and the sum is stored in the destination. The contents of the source are unaffected. Two's- complement addition is performed. In multiple precision arithmetic, this instruction permits the carry from the addition of low-order operands to be carried into the addition of high-order operands.

Flags:	C: Set if there is a carry from the most significant bit of the result; 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 occurs, that is, if both operands are of the same sign and the
	result is of the opposite sign; cleared otherwise.
	D: Always cleared to "0".
	H: Set if there is a carry from the most significant bit of the low-order four bits of the result;

cleared otherwise.

Format:
Bytes Cycles	Opcode	Addr Mode
	(Hex)	dst	src

opc dst src

opc src dst

2	4	12	r	r
	6	13	r	lr
3	6	14	R	R
	6	15	R	IR

opc

dst

src

3 6 16 R IM

Examples: Given: R1 = 10H, R2 = 03H, C flag = "1", register 01H = 20H, register 02H = 03H, and register

03H = 0AH:

ADC	R1,R2	→	R1	= 14H, R2 = 03H
ADC	R1,@R2	→	R1	= 1BH, R2 = 03H
ADC	01H,02H	→	Register 01H		= 24H, register 02H = 03H
ADC	01H,@02H	→	Register 01H		= 2BH, register 02H = 03H
ADC	01H,#11H	→	Register 01H		= 32H

In the first example, destination register R1 contains the value 10H, the carry flag is set to "1", and the source working register R2 contains the value 03H. The statement "ADC R1,R2" adds 03H and the carry flag value ("1") to the destination value 10H, leaving 14H in register R1.

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