Samsung S3C8275X User Manual
Page 167
S3C8275X/F8275X/C8278X/F8278X/C8274X/F8274X
INSTRUCTION SET
6-33
DA
—
Decimal Adjust
DA
dst
Operation: dst
← DA dst
The destination operand is adjusted to form two 4-bit BCD digits following an addition or
subtraction operation. For addition (ADD, ADC) or subtraction (SUB, SBC), the following table
indicates the operation performed. (The operation is undefined if the destination operand was not
the result of a valid addition or subtraction of BCD digits):
Instruction Carry
Before DA
Bits 4–7
Value (Hex)
H Flag
Before DA
Bits 0–3
Value (Hex)
Number Added
to Byte
Carry
After DA
0 0–9 0 0–9 00 0
0 0–8 0 A–F 06 0
0 0–9 1 0–3 06 0
ADD 0 A–F 0 0–9 60 1
ADC 0 9–F 0 A–F 66 1
0
A–F
1
0–3
66
1
1 0–2 0 0–9 60 1
1 0–2 0 A–F 66 1
1 0–3 1 0–3 66 1
0
0–9
0
0–9
00 = – 00
0
SUB
0
0–8
1
6–F
FA = – 06
0
SBC
1
7–F
0
0–9
A0 = – 60
1
1
6–F
1
6–F
9A = – 66
1
Flags: C:
Set if there was a carry from the most significant bit; cleared otherwise (see table).
Z: Set if result is "0"; cleared otherwise.
S: Set if result bit 7 is set; cleared otherwise.
V: Undefined.
D: Unaffected.
H: Unaffected.
Format:
Bytes
Cycles
Opcode
(Hex)
Addr Mode
dst
opc
dst
2
4
40 R
4 41 IR