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DAS (SPC700): Difference between revisions
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# If either the [[carry flag]] is clear or the accumulator exceeds 0x99, subtract 0x60 from the accumulator and clear the carry flag. | # 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. | # Then, if either the [[half-carry flag]] is clear or the low nibble of the accumulator exceeds 0x09, subtract 0x06 from the accumulator. | ||
==== Syntax ==== | |||
<pre> | |||
DAS | |||
</pre> | |||
=== See Also === | === See Also === | ||
Revision as of 17:33, 6 July 2024
| Basic Info | |||||||
|---|---|---|---|---|---|---|---|
| Addressing Mode | Opcode | Length | Speed | ||||
| Accumulator | BE | 1 byte | 3 cycles | ||||
| Flags Affected | |||||||
|---|---|---|---|---|---|---|---|
| N | V | P | B | H | I | Z | C |
| . | . | . | . | . | |||
DAS (Decimal Adjust for Subtraction) is an SPC700 instruction that performs the following:
- 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.
Syntax
DAS
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