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ROL: Difference between revisions
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''' | {| class="wikitable" style="float:right;clear:right;width:40%" | ||
!colspan="8"|Basic Info | |||
|+ | |||
|'''Addressing Mode''' | |||
|'''Opcode''' | |||
|'''Length''' | |||
|'''Speed''' | |||
|+ | |||
|[[Accumulator Addressing|Accumulator]] | |||
|2A | |||
|1 byte | |||
|2 cycles | |||
|+ | |||
|[[Absolute]] | |||
|2E | |||
|3 bytes | |||
|6 cycles* | |||
|+ | |||
|[[Direct Page Addressing|Direct Page]] | |||
|26 | |||
|2 bytes | |||
|5 cycles* | |||
|+ | |||
|absolute indexed by X | |||
|3E | |||
|3 bytes | |||
|7 cycles* | |||
|+ | |||
|direct page indexed by X | |||
|36 | |||
|2 bytes | |||
|6 cycles* | |||
|} | |||
{| class="wikitable" style="float:right;clear:right;width:30%" | {| class="wikitable" style="float:right;clear:right;width:30%" | ||
!colspan="9"|Flags | !colspan="9"|Flags Affected | ||
|+ | |+ | ||
|N | |[[N Flag|N]] | ||
|V | |[[V Flag|V]] | ||
|M | |[[M Flag|M]] | ||
|X | |[[X Flag|X]] | ||
|D | |[[D Flag|D]] | ||
|I | |[[I Flag|I]] | ||
|Z | |[[Z Flag|Z]] | ||
|C | |[[C Flag|C]] | ||
|+ | |+ | ||
| | | | ||
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| | | | ||
|} | |} | ||
'''ROL''' (Rotate Left) is a 65x instruction that rotates a value and the [[carry flag]] left one bit. The most significant bit is shifted into the carry flag. The carry flag is shifted into the least significant bit. | |||
===== Cycle Penalties ===== | |||
* Except in [[accumulator addressing]], ROL takes two extra cycles when the accumulator is 16 bits wide. | |||
* In [[direct page addressing]] modes, ROL takes another extra cycle if the low byte of the [[direct page register]] is nonzero. | |||
[[File:rol.png]] | |||
=== See Also === | === See Also === | ||
* [[ROR]] | * [[ROR]] | ||
* [[ROL (SPC700)]] | |||
* [[ROL (Super FX)]] | |||
=== External Links === | |||
* [[Eyes & Lichty]] page 490, on ROL: https://archive.org/details/0893037893ProgrammingThe65816/page/n516 | |||
* lbid page 190 before & after diagram of ROL: https://archive.org/details/0893037893ProgrammingThe65816/page/n216 | |||
* [[Labiak]] page 174 on ROL: https://archive.org/details/Programming_the_65816/page/n184 | |||
* [[MCS6500 Manual]] page 149 on ROL: https://archive.org/details/mos_microcomputers_programming_manual/page/n170 | |||
* [[Carr]] page 269 on ROL: https://archive.org/details/6502UsersManual/page/n282 | |||
* [[Leventhal]] page 3-85 on ROL: https://archive.org/details/6502-assembly-language-programming/page/n134 | |||
* snes9x implementation of ROL: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L1011 | |||
* undisbeliever on ROL: https://undisbeliever.net/snesdev/65816-opcodes.html#rol-rotate-left | |||
[[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 | 2A | 1 byte | 2 cycles | ||||
Absolute | 2E | 3 bytes | 6 cycles* | ||||
Direct Page | 26 | 2 bytes | 5 cycles* | ||||
absolute indexed by X | 3E | 3 bytes | 7 cycles* | ||||
direct page indexed by X | 36 | 2 bytes | 6 cycles* |
Flags Affected | ||||||||
---|---|---|---|---|---|---|---|---|
N | V | M | X | D | I | Z | C | |
. | . | . | . | . |
ROL (Rotate Left) is a 65x instruction that rotates a value and the carry flag left one bit. The most significant bit is shifted into the carry flag. The carry flag is shifted into the least significant bit.
Cycle Penalties
- Except in accumulator addressing, ROL takes two extra cycles when the accumulator is 16 bits wide.
- In direct page addressing modes, ROL takes another extra cycle if the low byte of the direct page register is nonzero.
See Also
External Links
- Eyes & Lichty page 490, on ROL: https://archive.org/details/0893037893ProgrammingThe65816/page/n516
- lbid page 190 before & after diagram of ROL: https://archive.org/details/0893037893ProgrammingThe65816/page/n216
- Labiak page 174 on ROL: https://archive.org/details/Programming_the_65816/page/n184
- MCS6500 Manual page 149 on ROL: https://archive.org/details/mos_microcomputers_programming_manual/page/n170
- Carr page 269 on ROL: https://archive.org/details/6502UsersManual/page/n282
- Leventhal page 3-85 on ROL: https://archive.org/details/6502-assembly-language-programming/page/n134
- snes9x implementation of ROL: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L1011
- undisbeliever on ROL: https://undisbeliever.net/snesdev/65816-opcodes.html#rol-rotate-left