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RTI: Difference between revisions
From SnesLab
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===== Cycle Skipped ===== | ===== Cycle Skipped ===== | ||
RTI takes one fewer cycle in [[emulation mode]] as the [[program bank register]] | RTI takes one fewer cycle in [[emulation mode]] as the [[program bank register]] doesn't need to be pulled from the [[stack]]. | ||
=== See Also === | === See Also === | ||
Revision as of 07:41, 26 November 2023
| Basic Info | |||||||
|---|---|---|---|---|---|---|---|
| Addressing Mode | Opcode | Length | Speed | ||||
| Stack (RTI) | 40 | 1 byte | 7 cycles* | ||||
| Flags Affected | ||||||||
|---|---|---|---|---|---|---|---|---|
| N | V | M | X | D | I | Z | C | |
| 65c816 native mode | ||||||||
| 6502 emulation mode | . | . | ||||||
RTI (Return from INterrupt) is a 65x instruction used to return control from an interrupt handler.
Pitfalls
- RTI should only be run when the e flag is in the same state as when the interrupt fired
Cycle Skipped
RTI takes one fewer cycle in emulation mode as the program bank register doesn't need to be pulled from the stack.
See Also
External Links
- Eyes & Lichty page 492, on RTI: https://archive.org/details/0893037893ProgrammingThe65816/page/n518
- Labiak page on RTI: https://archive.org/details/Programming_the_65816/page/n186
- MCS6500 Manual page on RTI: https://archive.org/details/mos_microcomputers_programming_manual/page/n152
- Carr page on RTI: https://archive.org/details/6502UsersManual/page/n283
- Leventhal page on RTI: https://archive.org/details/6502-assembly-language-programming/page/n138
- snes9x implementation of RTI: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L3272
- undisbeliever on RTI: https://undisbeliever.net/snesdev/65816-opcodes.html#rti-return-from-interrupt