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BBS (SPC700): Difference between revisions
From SnesLab
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|'''Speed''' | |'''Speed''' | ||
|+ | |+ | ||
|[[Direct Page | |[[Direct Page Bit Relative]] | ||
|03 | |03 | ||
|3 bytes | |3 bytes | ||
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when condition true: 7 cycles | when condition true: 7 cycles | ||
|+ | |+ | ||
|[[Direct Page | |[[Direct Page Bit Relative]] | ||
|23 | |23 | ||
|3 bytes | |3 bytes | ||
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when condition true: 7 cycles | when condition true: 7 cycles | ||
|+ | |+ | ||
|[[Direct Page | |[[Direct Page Bit Relative]] | ||
|43 | |43 | ||
|3 bytes | |3 bytes | ||
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when condition true: 7 cycles | when condition true: 7 cycles | ||
|+ | |+ | ||
|[[Direct Page | |[[Direct Page Bit Relative]] | ||
|63 | |63 | ||
|3 bytes | |3 bytes | ||
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when condition true: 7 cycles | when condition true: 7 cycles | ||
|+ | |+ | ||
|[[Direct Page | |[[Direct Page Bit Relative]] | ||
|83 | |83 | ||
|3 bytes | |3 bytes | ||
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when condition true: 7 cycles | when condition true: 7 cycles | ||
|+ | |+ | ||
|[[Direct Page | |[[Direct Page Bit Relative]] | ||
|A3 | |A3 | ||
|3 bytes | |3 bytes | ||
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when condition true: 7 cycles | when condition true: 7 cycles | ||
|+ | |+ | ||
|[[Direct Page | |[[Direct Page Bit Relative]] | ||
|C3 | |C3 | ||
|3 bytes | |3 bytes | ||
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when condition true: 7 cycles | when condition true: 7 cycles | ||
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|[[Direct Page | |[[Direct Page Bit Relative]] | ||
|E3 | |E3 | ||
|3 bytes | |3 bytes | ||
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=== References === | === References === | ||
* [https://archive.org/details/SNESDevManual/book1/page/n233 Appendix C-8 of Book I] of the official Super Nintendo development manual | * Table C-15, [https://archive.org/details/SNESDevManual/book1/page/n233 Appendix C-8 of Book I] of the official Super Nintendo development manual | ||
[[Category:ASM]] | [[Category:ASM]] | ||
[[Category:SPC700]] | [[Category:SPC700]] | ||
[[Category:Branching Commands]] | [[Category:Branching Commands]] | ||
Latest revision as of 07:53, 18 December 2023
| Basic Info | |||||||
|---|---|---|---|---|---|---|---|
| Addressing Mode | Opcode | Length | Speed | ||||
| Direct Page Bit Relative | 03 | 3 bytes | when condition false: 5 cycles
when condition true: 7 cycles |
||||
| Direct Page Bit Relative | 23 | 3 bytes | when condition false: 5 cycles
when condition true: 7 cycles |
||||
| Direct Page Bit Relative | 43 | 3 bytes | when condition false: 5 cycles
when condition true: 7 cycles |
||||
| Direct Page Bit Relative | 63 | 3 bytes | when condition false: 5 cycles
when condition true: 7 cycles |
||||
| Direct Page Bit Relative | 83 | 3 bytes | when condition false: 5 cycles
when condition true: 7 cycles |
||||
| Direct Page Bit Relative | A3 | 3 bytes | when condition false: 5 cycles
when condition true: 7 cycles |
||||
| Direct Page Bit Relative | C3 | 3 bytes | when condition false: 5 cycles
when condition true: 7 cycles |
||||
| Direct Page Bit Relative | E3 | 3 bytes | when condition false: 5 cycles
when condition true: 7 cycles | ||||
| Flags Affected | |||||||
|---|---|---|---|---|---|---|---|
| N | V | P | B | H | I | Z | C |
| . | . | . | . | . | . | . | . |
BBS (Branch on Bit Set) is an SPC700 instruction that performs a branch when a bit in the direct page is set. The index to the direct page byte that bit lives in is the first operand byte. Which bit within that byte is a specified by the top 3 bits of the opcode. The target relative address to jump to is the second operand byte.
In assembly source, the two operands appear in the same order that they do in the instruction stream.
See Also
References
- Table C-15, Appendix C-8 of Book I of the official Super Nintendo development manual