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DAS (SPC700): Difference between revisions
From SnesLab
(corrects BCD difference) |
(→See Also: already have BCD in body) |
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=== See Also === | === See Also === | ||
* [[DAA]] | * [[DAA]] | ||
=== External Links === | === External Links === | ||
Revision as of 22:24, 4 August 2024
| Basic Info | |||||||
|---|---|---|---|---|---|---|---|
| Addressing Mode | Opcode | Length | Speed | ||||
| Accumulator | BE | 1 byte | 3 cycles | ||||
| Flags Affected | |||||||
|---|---|---|---|---|---|---|---|
| N | V | P | B | H | I | Z | C |
| N | . | . | . | . | . | Z | C |
DAS (Decimal Adjust for Subtraction) is an SPC700 instruction that corrects a BCD difference:
- If either the carry flag is clear or the accumulator exceeds 0x99, subtract 0x60 from the accumulator and clear the carry flag.
- Then, if either the half-carry flag is clear or the low nibble of the accumulator exceeds 0x09, subtract 0x06 from the accumulator.
The SPC700 has no decimal mode.
Syntax
DAS DAS A
See Also
External Links
- Official Super Nintendo development manual on DAS: Table C-14 in Appendix C-8 of Book I
- page 3-8-2 of Book I, lbid
- ares source code, SPC700::instructionDecimalAdjustSub
- anomie: https://github.com/yupferris/TasmShiz/blob/8fabc9764c33a7ae2520a76d80ed7220bb939f12/spc700.txt#L410