We've just updated MediaWiki and its underlying software. If anything doesn't look or work quite right, please mention it to us. --RanAS
REP: Difference between revisions
From SnesLab
(why REP can't modify m/x in emulation mode) |
(→References: hid archive URL for Labiak) |
||
| Line 67: | Line 67: | ||
=== References === | === References === | ||
# [[Eyes & Lichty]] page 489, on REP: https://archive.org/details/0893037893ProgrammingThe65816/page/489 | # [[Eyes & Lichty]] page 489, on REP: https://archive.org/details/0893037893ProgrammingThe65816/page/489 | ||
# [[Labiak]] | # [[Labiak]], [https://archive.org/details/Programming_the_65816/page/n183 page 173] on REP | ||
# snes9x implementation of REP: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L3145 | # snes9x implementation of REP: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L3145 | ||
# undisbeliever on REP: https://undisbeliever.net/snesdev/65816-opcodes.html#rep-reset-status-bits | # undisbeliever on REP: https://undisbeliever.net/snesdev/65816-opcodes.html#rep-reset-status-bits | ||
Revision as of 12:51, 6 August 2024
| Basic Info | |||||||
|---|---|---|---|---|---|---|---|
| Addressing Mode | Opcode | Length | Speed | ||||
| Immediate | C2 | 2 bytes | 3 cycles | ||||
| Flags Affected | ||||||||
|---|---|---|---|---|---|---|---|---|
| N | V | M | X | D | I | Z | C | |
| emulation mode | N | V | . | . | D | I | Z | C |
| native mode | N | V | M | X | D | I | Z | C |
REP (Reset Status Bits) is a 65c816 instruction that clears bits in the status register that correspond to set bits in the operand.
REP is the only way to clear the m and x flags directly (but PLP and RTI may clear them too.)[1] But, REP can't modify those two flags in emulation mode because they are being forced to be set.
Syntax
REP #nvmxdizc
See Also
References
- Eyes & Lichty page 489, on REP: https://archive.org/details/0893037893ProgrammingThe65816/page/489
- Labiak, page 173 on REP
- snes9x implementation of REP: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L3145
- undisbeliever on REP: https://undisbeliever.net/snesdev/65816-opcodes.html#rep-reset-status-bits