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DBNZ (SPC700): Difference between revisions
From SnesLab
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No flags are affected. | No flags are affected. | ||
==== Syntax ==== | |||
<pre> | |||
DBNZ dp, rel | |||
DBNZ Y, rel | |||
</pre> | |||
=== See Also === | === See Also === | ||
Revision as of 20:43, 6 July 2024
| Basic Info | |||||||
|---|---|---|---|---|---|---|---|
| Addressing Mode | Opcode | Length | Speed | ||||
| Direct Page / Program Counter Relative | 6E | 3 bytes | when condition is false: 5 cycles
when condition is true: 7 cycles |
||||
| Implied (type 1) / Program Counter Relative | FE | 2 bytes | when condition is false: 4 cycles
when condition is true: 6 cycles | ||||
| Flags Affected | |||||||
|---|---|---|---|---|---|---|---|
| N | V | P | B | H | I | Z | C |
| . | . | . | . | . | . | . | . |
DBNZ is an SPC700 instruction that decrements a direct page location or the Y index register and then jumps if that value is nonzero. The direct page index is the first operand and also the first byte immediately following the opcode. The relative branch offset is the second operand, the second byte following the opcode.[2]
No flags are affected.
Syntax
DBNZ dp, rel DBNZ Y, rel
See Also
References
- Official Super Nintendo development manual on DBNZ: Table C-15, Appendix C-8 of Book I
- anomie's SPC700 doc