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CPX: Difference between revisions
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'''CPX''' (Compare X) is a 65x instruction that compares the value of the [[X index register]]. | '''CPX''' (Compare X) is a 65x instruction that compares the value of the [[X index register]]. Internally, this is done via a subtraction, but the difference is not stored anywhere. The contents at the effective address and the X index register both remain unchanged. | ||
CPX assumes its operands are unsigned. | |||
=== See Also === | === See Also === | ||
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* [[Eyes & Lichty]] page 449, on CPX: https://archive.org/details/0893037893ProgrammingThe65816/page/n475 | * [[Eyes & Lichty]] page 449, on CPX: https://archive.org/details/0893037893ProgrammingThe65816/page/n475 | ||
* [[Labiak]] page 136 on CPX: https://archive.org/details/Programming_the_65816/page/n146 | * [[Labiak]] page 136 on CPX: https://archive.org/details/Programming_the_65816/page/n146 | ||
* [[MCS6500 Manual]] page on CPX: https://archive.org/details/mos_microcomputers_programming_manual/page/n117 | * [[MCS6500 Manual]] page 99 on CPX: https://archive.org/details/mos_microcomputers_programming_manual/page/n117 | ||
* [[Carr]] page on CPX: https://archive.org/details/6502UsersManual/page/n269 | * [[Carr]] page 256 on CPX: https://archive.org/details/6502UsersManual/page/n269 | ||
* [[Leventhal]] page on CPX: https://archive.org/details/6502-assembly-language-programming/page/n107 | * [[Leventhal]] page 3-58 on CPX: https://archive.org/details/6502-assembly-language-programming/page/n107 | ||
* snes9x implementation of CPX: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L402 | * snes9x implementation of CPX: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L402 | ||
* undisbeliever on CPX: https://undisbeliever.net/snesdev/65816-opcodes.html#cpx-compare-index-register-x-with-memory | * undisbeliever on CPX: https://undisbeliever.net/snesdev/65816-opcodes.html#cpx-compare-index-register-x-with-memory |
Latest revision as of 07:51, 19 December 2023
Basic Info | |||||||
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Addressing Mode | Opcode | Length | Speed | ||||
Immediate | E0 | 2 bytes* | 2 cycles* | ||||
Absolute | EC | 3 bytes | 4 cycles* | ||||
Direct Page | E4 | 2 bytes | 3 cycles* |
Flags Affected | ||||||||
---|---|---|---|---|---|---|---|---|
N | V | M | X | D | I | Z | C | |
. | . | . | . | . |
CPX (Compare X) is a 65x instruction that compares the value of the X index register. Internally, this is done via a subtraction, but the difference is not stored anywhere. The contents at the effective address and the X index register both remain unchanged.
CPX assumes its operands are unsigned.
See Also
External Links
- Eyes & Lichty page 449, on CPX: https://archive.org/details/0893037893ProgrammingThe65816/page/n475
- Labiak page 136 on CPX: https://archive.org/details/Programming_the_65816/page/n146
- MCS6500 Manual page 99 on CPX: https://archive.org/details/mos_microcomputers_programming_manual/page/n117
- Carr page 256 on CPX: https://archive.org/details/6502UsersManual/page/n269
- Leventhal page 3-58 on CPX: https://archive.org/details/6502-assembly-language-programming/page/n107
- snes9x implementation of CPX: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L402
- undisbeliever on CPX: https://undisbeliever.net/snesdev/65816-opcodes.html#cpx-compare-index-register-x-with-memory