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DAS (SPC700): Difference between revisions
From SnesLab
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|'''Speed''' | |'''Speed''' | ||
|+ | |+ | ||
| | |[[Accumulator Addressing | Accumulator]] | ||
|BE | |BE | ||
|1 byte | |1 byte | ||
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{| class="wikitable" style="float:right;clear:right;width:30%" | {| class="wikitable" style="float:right;clear:right;width:30%" | ||
!colspan="8"|Flags | !colspan="8"|Flags Affected | ||
|+ | |+ | ||
|N | |[[Negative Flag|N]] | ||
|V | |[[Overflow Flag|V]] | ||
|P | |[[Direct Page Flag|P]] | ||
|B | |[[Break Flag|B]] | ||
|H | |[[Half-Carry Flag|H]] | ||
|I | |[[Interrupt Enable Flag|I]] | ||
|Z | |[[Zero Flag|Z]] | ||
|C | |[[Carry Flag|C]] | ||
|+ | |+ | ||
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=== External Links === | === External Links === | ||
* Official Super Nintendo development manual on DAS: [https://archive.org/details/SNESDevManual/book1/page/n233 Appendix C-8 of Book I] | * Official Super Nintendo development manual on DAS: Table C-14 in [https://archive.org/details/SNESDevManual/book1/page/n233 Appendix C-8 of Book I] | ||
* [https://archive.org/details/SNESDevManual/book1/page/n180 page 3-8-2 of Book I], lbid | * [https://archive.org/details/SNESDevManual/book1/page/n180 page 3-8-2 of Book I], lbid | ||
* ares source code, SPC700::instructionDecimalAdjustSub | * ares source code, SPC700::instructionDecimalAdjustSub |
Latest revision as of 05:03, 27 November 2023
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, 0x60 is subtracted from the accumulator and the carry flag is cleared.
- Then, if either the half-carry flag is clear or the low nibble of the accumulator exceeds 0x09, 0x06 is subtracted from the accumulator
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