INSTRUCTION SETS3F80JB

SUB — Subtract

SUB

dst,src

Operation:

dst

dst – src

 

The source operand is subtracted from the destination operand and the result is stored in the

 

destination. The contents of the source are unaffected. Subtraction is performed by adding the

 

two's complement of the source operand to the destination operand.

Flags:

C: Set if a "borrow" occurred; 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, that is, if the operands were of opposite signs and the

 

 

sign of the result is of the same as the sign of the source operand; cleared otherwise.

 

D: Always set to "1".

 

H: Cleared if there is a carry from the most significant bit of the low-order four bits of the result;

set otherwise indicating a "borrow".

 

 

 

Format:

 

 

 

Bytes Cycles

Opcode

Addr Mode

 

(Hex)

dst

src

opc

dst

src

2

4

22

r

r

opc

src

dst

 

6

23

r

lr

3

6

24

R

R

 

6

25

R

IR

opc

dst

src

3

6

26

R

IM

Examples: Given: R1 = 12H, R2 = 03H, register 01H = 21H, register 02H = 03H, register 03H = 0AH:

SUB

R1,R2

R1

= 0FH, R2 = 03H

SUB

R1,@R2

R1

= 08H, R2 = 03H

SUB

01H,02H

Register 01H

= 1EH, register 02H = 03H

SUB

01H,@02H

Register 01H

= 17H, register 02H = 03H

SUB

01H,#90H

Register 01H

= 91H; C, S, and V = "1"

SUB

01H,#65H

Register 01H

= 0BCH; C and S = "1", V = "0"

In the first example, if working register R1 contains the value 12H and if register R2 contains the value 03H, the statement "SUB R1,R2" subtracts the source value (03H) from the destination value (12H) and stores the result (0FH) in destination register R1.

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Samsung S3F80JB manual SUB Subtract, Set otherwise indicating a borrow Format Bytes Cycles