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MOVW (SPC700): Difference between revisions
From SnesLab
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|+ | |+ | ||
|to YA | |to YA | ||
| | |[[Direct Page Addressing | Direct Page]] | ||
|BA | |BA | ||
|2 bytes | |2 bytes | ||
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|+ | |+ | ||
|from YA | |from YA | ||
| | |[[Direct Page Addressing | Direct Page]] | ||
|DA | |DA | ||
|2 bytes | |2 bytes | ||
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{| class="wikitable" style="float:right;clear:right;width:30%" | {| class="wikitable" style="float:right;clear:right;width:30%" | ||
!colspan="9"|Flags | !colspan="9"|Flags Affected | ||
|+ | |+ | ||
|Direction | |Direction | ||
|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]] | ||
|+ | |+ | ||
|to YA | |to YA | ||
| | |N | ||
|. | |. | ||
|. | |. | ||
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|. | |. | ||
|. | |. | ||
| | |Z | ||
| | |. | ||
|+ | |+ | ||
|from YA | |from YA | ||
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|} | |} | ||
'''MOVW''' (Move Word) is an [[SPC700]] instruction that moves a 16-bit [[direct page]] value to or from the [[YA]] register. There are no variations of MOVW that do not operate on YA. MOVW performs a read cycle on the low byte of the destination, but not the source.<sup>[2]</sup> | |||
The operands are stored in the instruction stream in the opposite order they appear in the assembler source. In the assembler source, the operand on the right is the source and the operand on the left is the destination. | |||
=== Example === | === Example === | ||
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<pre> | <pre> | ||
MOVW YA, $F6 ; load the byte at | MOVW YA, $F6 ; load the byte at direct page location $F6 into A and the byte at direct page location $F7 into Y | ||
MOVW $00, YA ; store the value in Y to | MOVW $00, YA ; store the value in Y to direct page location $01 and the value in A to direct page location $00 | ||
</pre> | </pre> | ||
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* [[MOV]] | * [[MOV]] | ||
* [[MOV1]] | * [[MOV1]] | ||
* [[ADDW]] | |||
* [[SUBW]] | |||
* [[CMPW]] | |||
=== | === References === | ||
# Official Super Nintendo development manual on MOVW: Table C-11 in [https://archive.org/details/SNESDevManual/book1/page/n233 Appendix C-8 of Book I] | |||
# [https://www.romhacking.net/documents/197 anomie's SPC700 doc] | |||
[[Category:ASM]] | [[Category:ASM]] | ||
[[Category:SPC700]] | [[Category:SPC700]] | ||
[[Category:16-bit Data Transmission Commands]] | [[Category:16-bit Data Transmission Commands]] | ||
[[Category:Two-byte Instructions]] | |||
Latest revision as of 14:05, 30 July 2024
| Basic Info | ||||
|---|---|---|---|---|
| Direction | Addressing Mode | Opcode | Length | Speed |
| to YA | Direct Page | BA | 2 bytes | 5 cycles |
| from YA | Direct Page | DA | 2 bytes | 4 cycles |
| Flags Affected | ||||||||
|---|---|---|---|---|---|---|---|---|
| Direction | N | V | P | B | H | I | Z | C |
| to YA | N | . | . | . | . | . | Z | . |
| from YA | . | . | . | . | . | . | . | . |
MOVW (Move Word) is an SPC700 instruction that moves a 16-bit direct page value to or from the YA register. There are no variations of MOVW that do not operate on YA. MOVW performs a read cycle on the low byte of the destination, but not the source.[2]
The operands are stored in the instruction stream in the opposite order they appear in the assembler source. In the assembler source, the operand on the right is the source and the operand on the left is the destination.
Example
From the IPL ROM,
MOVW YA, $F6 ; load the byte at direct page location $F6 into A and the byte at direct page location $F7 into Y MOVW $00, YA ; store the value in Y to direct page location $01 and the value in A to direct page location $00
See Also
References
- Official Super Nintendo development manual on MOVW: Table C-11 in Appendix C-8 of Book I
- anomie's SPC700 doc