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CMPW (SPC700): Difference between revisions
From SnesLab
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'''CMPW''' (Compare Word) is an [[SPC700]] command that performs a comparsion between [[YA]] and a 16-bit word in the [[direct page]]. Internally, this is done by the [[ALU]] subtracting the direct page word from YA, but the difference is not stored anywhere. | '''CMPW''' (Compare Word) is an [[SPC700]] command that performs a comparsion between [[YA]] and a 16-bit word in the [[direct page]]. Internally, this is done by the [[ALU]] subtracting the direct page word from YA, but the difference is not stored anywhere - the side effect is the N, Z, and C flags being modified. | ||
==== Syntax ==== | ==== Syntax ==== | ||
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=== External Links === | === External Links === | ||
* Official Nintendo documentation on CMPW: Table C-12 in [https://archive.org/details/SNESDevManual/book1/page/n233 Appendix C-8 of Book I] | * Official Nintendo documentation on CMPW: Table C-12 in [https://archive.org/details/SNESDevManual/book1/page/n233 Appendix C-8 of Book I] | ||
* anomie: https://github.com/yupferris/TasmShiz/blob/8fabc9764c33a7ae2520a76d80ed7220bb939f12/spc700.txt#L407 | |||
[[Category:ASM]] | [[Category:ASM]] | ||
Latest revision as of 13:55, 30 July 2024
| Basic Info | |||||||
|---|---|---|---|---|---|---|---|
| Addressing Mode | Opcode | Length | Speed | ||||
| Direct Page | 5A | 2 bytes | 4 cycles | ||||
| Flags Affected | |||||||
|---|---|---|---|---|---|---|---|
| N | V | P | B | H | I | Z | C |
| N | . | . | . | . | . | Z | C |
CMPW (Compare Word) is an SPC700 command that performs a comparsion between YA and a 16-bit word in the direct page. Internally, this is done by the ALU subtracting the direct page word from YA, but the difference is not stored anywhere - the side effect is the N, Z, and C flags being modified.
Syntax
CMPW YA, dp
See Also
External Links
- Official Nintendo documentation on CMPW: Table C-12 in Appendix C-8 of Book I
- anomie: https://github.com/yupferris/TasmShiz/blob/8fabc9764c33a7ae2520a76d80ed7220bb939f12/spc700.txt#L407