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ROR: Difference between revisions
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'''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. | {| class="wikitable" style="float:right;clear:right;width:40%" | ||
!colspan="8"|Basic Info | |||
|+ | |||
|'''Addressing Mode''' | |||
|'''Opcode''' | |||
|'''Length''' | |||
|'''Speed''' | |||
|+ | |||
|[[Accumulator Addressing|Accumulator]] | |||
|6A | |||
|1 byte | |||
|2 cycles | |||
|+ | |||
|[[Absolute]] | |||
|6E | |||
|3 bytes | |||
|6 cycles* | |||
|+ | |||
|[[Direct Page Addressing|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* | |||
|} | |||
{| class="wikitable" style="float:right;clear:right;width:30%" | |||
!colspan="9"|Flags Affected | |||
|+ | |||
|[[N Flag|N]] | |||
|[[V Flag|V]] | |||
|[[M Flag|M]] | |||
|[[X Flag|X]] | |||
|[[D Flag|D]] | |||
|[[I Flag|I]] | |||
|[[Z Flag|Z]] | |||
|[[C Flag|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. | |||
===== Cycle Penalties ===== | |||
* 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 === | === See Also === | ||
* [[ROL]] | * [[ROL]] | ||
* [[ROR (SPC700)]] | |||
* [[ROR (Super FX)]] | |||
=== External Links === | |||
* [[Eyes & Lichty]] page 491, on ROR: https://archive.org/details/0893037893ProgrammingThe65816/page/n517 | |||
* lbid, page 191, before & after diagram on ROR: https://archive.org/details/0893037893ProgrammingThe65816/page/n217 | |||
* [[Labiak]] page 175 on ROR: https://archive.org/details/Programming_the_65816/page/n185 | |||
* [[MCS6500 Manual]] page 150 on ROR: https://archive.org/details/mos_microcomputers_programming_manual/page/n171 | |||
* [[Carr]] page 269 on ROR: https://archive.org/details/6502UsersManual/page/n282 | |||
* [[Leventhal]] page 3-87 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 | |||
[[Category:ASM]] | [[Category:ASM]] | ||
[[Category:Group Two Instructions]] | |||
[[Category:Read-Modify-Write Instructions]] | |||
[[Category:Inherited from 6502]] |
Latest revision as of 19:24, 8 January 2024
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.
Cycle Penalties
- 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 491, on ROR: https://archive.org/details/0893037893ProgrammingThe65816/page/n517
- lbid, page 191, before & after diagram on ROR: https://archive.org/details/0893037893ProgrammingThe65816/page/n217
- Labiak page 175 on ROR: https://archive.org/details/Programming_the_65816/page/n185
- MCS6500 Manual page 150 on ROR: https://archive.org/details/mos_microcomputers_programming_manual/page/n171
- Carr page 269 on ROR: https://archive.org/details/6502UsersManual/page/n282
- Leventhal page 3-87 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