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EOR
From SnesLab
Basic Info | |||||||
---|---|---|---|---|---|---|---|
Addressing Mode | Opcode | Length | Speed | ||||
Immediate | 49 | 2/3 bytes | 2 cycles* | ||||
Absolute | 4D | 3 bytes | 4 cycles* | ||||
Absolute Long | 4F | 4 bytes | 5 cycles* | ||||
Direct Page | 45 | 2 bytes | 3 cycles* | ||||
Direct Page Indirect | 52 | 2 bytes | 5 cycles* | ||||
Direct Page Indirect Long | 47 | 2 bytes | 6 cycles* | ||||
Absolute Indexed by X | 5D | 3 bytes | 4 cycles* | ||||
Absolute Long Indexed by X | 5F | 4 bytes | 5 cycles* | ||||
Absolute Indexed by Y | 59 | 3 bytes | 4 cycles* | ||||
Direct Page Indexed by X | 55 | 2 bytes | 4 cycles* | ||||
Direct Page Indexed Indirect by X | 41 | 2 bytes | 6 cycles* | ||||
Direct Page Indirect Indexed by Y | 51 | 2 bytes | 5 cycles* | ||||
Direct Page Indirect Long Indexed by Y | 57 | 2 bytes | 6 cycles* | ||||
Stack Relative | 43 | 2 bytes | 4 cycles* | ||||
Stack Relative Indirect Indexed by Y | 53 | 2 bytes | 7 cycles* |
Flags Affected | |||||||
---|---|---|---|---|---|---|---|
N | V | M | X | D | I | Z | C |
. | . | . | . | . | . |
EOR is a 65x instruction that performs an exclusive or. The result is stored in the accumulator.
Syntax
EOR #const EOR addr EOR long EOR dp EOR (dp) EOR [dp] EOR addr, X EOR long, X EOR addr, Y EOR dp, X EOR (dp, X) EOR (dp), Y EOR [dp], Y EOR sr, S EOR (sr, S), Y
Cycle Penalties
- In all addressing modes, EOR takes one extra cycle when the accumulator is 16 bits wide.
- In direct page addressing modes, EOR takes one additional cycle if the low byte of the direct page register is nonzero.
- In both Absolute Indexed and DP Indirect Indexed, Y admodes, EOR takes an extra cycle if adding the index crosses a page boundary.
See Also
External Links
- Eyes & Lichty page 454, on EOR: https://archive.org/details/0893037893ProgrammingThe65816/page/454
- Labiak page 141 on EOR: https://archive.org/details/Programming_the_65816/page/n151
- MCS6500 Manual page 21 on EOR: https://archive.org/details/mos_microcomputers_programming_manual/page/n36
- Carr page 259 on EOR: https://archive.org/details/6502UsersManual/page/n272
- Leventhal page 3-63 on EOR: https://archive.org/details/6502-assembly-language-programming/page/n112
- snes9x implementation of EOR: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L533
- undisbeliever on EOR: https://undisbeliever.net/snesdev/65816-opcodes.html#eor-exclusive-or-accumulator-with-memory