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ROR: Difference between revisions
From SnesLab
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| | |[[Direct Page Addressing|Direct Page]] | ||
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|2 bytes | |2 bytes | ||
Revision as of 07:11, 20 November 2023
| Basic Info | |||||||
|---|---|---|---|---|---|---|---|
| Addressing Mode | Opcode | Length | Speed | ||||
| accumulator | 6A | 1 byte | 2 cycles | ||||
| Absolute | 6E | 3 bytes | 6 cycles* | ||||
| Direct Page | 66 | 2 bytes | 5 cycles* | ||||
| absolute indexed by X | 7E | 3 bytes | 7 cycles* | ||||
| direct page indexed by X | 76 | 2 bytes | 6 cycles* | ||||
| Flags Affected | ||||||||
|---|---|---|---|---|---|---|---|---|
| N | V | M | X | D | I | Z | C | |
| . | . | . | . | . | ||||
ROR (Rotate Right) is a 65x instruction that rotates a value and the carry flag right one bit. The least significant bit is shifted into the carry flag. The carry flag is shifted into the most significant bit. Except in accumulator addressing, ROR takes two extra cycles when the accumulator is 16 bits wide. In direct page addressing modes, ROR takes another extra cycle if the low byte of the direct page register is nonzero.
See Also
External Links
- Eyes & Lichty page on ROR: https://archive.org/details/0893037893ProgrammingThe65816/page/n517
- Labiak page on ROR: https://archive.org/details/Programming_the_65816/page/n185
- MCS6500 Manual page on ROR: https://archive.org/details/mos_microcomputers_programming_manual/page/n171
- Carr page on ROR: https://archive.org/details/6502UsersManual/page/n282
- Leventhal page on ROR: https://archive.org/details/6502-assembly-language-programming/page/n136
- snes9x implementation of ROR: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L1070
- undisbeliever on ROR: https://undisbeliever.net/snesdev/65816-opcodes.html#ror-rotate-right