IP

[fpgaboy.git] / daa.txt

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|           | C Flag | HEX value in | H Flag | HEX value in | Number  | C flag |
| Operation | Before | upper digit  | Before | lower digit  | added   | After  |
|           | DAA    | (bit 7-4)    | DAA    | (bit 3-0)    | to byte | DAA    |
|------------------------------------------------------------------------------|
|           |   0    |     0-9      |   0    |     0-9      |   00    |   0    |
|   ADD     |   0    |     0-8      |   0    |     A-F      |   06    |   0    |
|           |   0    |     0-9      |   1    |     0-3      |   06    |   0    |
|   ADC     |   0    |     A-F      |   0    |     0-9      |   60    |   1    |
|           |   0    |     9-F      |   0    |     A-F      |   66    |   1    |
|   INC     |   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    |
|------------------------------------------------------------------------------|
|       SUB |   0    |     0-9      |   0    |     0-9      |   00    |   0    |
|       SBC |   0    |     0-8      |   1    |     6-F      |   FA    |   0    |
|       DEC |   1    |     7-F      |   0    |     0-9      |   A0    |   1    |
|       NEG |   1    |     6-F      |   1    |     6-F      |   9A    |   1    |
|------------------------------------------------------------------------------|

Flags:
C: See instruction.
N: Unaffected.
P/V: Set if Acc. is even parity after operation, reset otherwise.
H: See instruction.
Z: Set if Acc. is Zero after operation, reset otherwise.
S: Set if most significant bit of Acc. is 1 after operation, reset otherwise.