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EOR: Difference between revisions

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'''EOR''' is a 65x instruction that performs an [https://mathworld.wolfram.com/XOR.html exclusive or].
{| class="wikitable" style="float:right;clear:right;width:50%"
!colspan="8"|Basic Info
|+
|'''Addressing Mode'''
|'''Opcode'''
|'''Length'''
|'''Speed'''
|+
|[[Immediate]]
|49
|2 bytes
|2 cycles*
|+
|[[Absolute]]
|4D
|3 bytes
|4 cycles*
|+
|[[Absolute Long Addressing|Absolute Long]]
|4F
|4 bytes
|5 cycles*
|+
|[[Direct Page Addressing|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*
|}


{| class="wikitable" style="float:right;clear:right;width:30%"
{| class="wikitable" style="float:right;clear:right;width:30%"
!colspan="8"|Flags Clobbered
!colspan="8"|Flags Affected
|+
|+
|N
|[[Negative Flag|N]]
|V
|[[Overflow Flag|V]]
|M
|[[M Flag|M]]
|X
|[[X Flag|X]]
|D
|[[Decimal Flag|D]]
|I
|[[I Flag|I]]
|Z
|[[Zero Flag|Z]]
|C
|[[Carry Flag|C]]
|+
|+
|
|
|.
|.
|.
|.
|.
|
|
|
|.
|
|
|
|
|
|}
|}
'''EOR''' is a 65x instruction that performs an [https://mathworld.wolfram.com/XOR.html exclusive or].
===== 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 ===
=== See Also ===
* [[ORA]]
* [[ORA]]
* [[EOR (SPC700)]]
* [[XOR (Super FX)]]
=== External Links ===
* [[Eyes & Lichty]] page 454, on EOR: https://archive.org/details/0893037893ProgrammingThe65816/page/n480
* [[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


[[Category:ASM]]
[[Category:ASM]]
[[Category:Group One Instructions]]
[[Category:Inherited from 6502]]

Latest revision as of 04:18, 6 December 2023

Basic Info
Addressing Mode Opcode Length Speed
Immediate 49 2 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.

Cycle Penalties

See Also

External Links

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