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INC: Difference between revisions
From SnesLab
(→See Also: INX, INY) |
(size of operation) |
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|'''Speed''' | |'''Speed''' | ||
|+ | |+ | ||
| | |[[Accumulator Addressing | Accumulator]] | ||
|1A | |1A | ||
|1 byte | |1 byte | ||
|2 cycles | |2 cycles | ||
|+ | |+ | ||
| | |[[Absolute Addressing | Absolute]] | ||
|EE | |EE | ||
|3 bytes | |3 bytes | ||
|6 cycles | |6 cycles* | ||
|+ | |+ | ||
| | |[[Direct Page Addressing | Direct Page]] | ||
|E6 | |E6 | ||
|2 bytes | |2 bytes | ||
|5 cycles | |5 cycles* | ||
|+ | |+ | ||
|absolute indexed X | |absolute indexed X | ||
|FE | |FE | ||
|3 bytes | |3 bytes | ||
|7 cycles | |7 cycles* | ||
|+ | |+ | ||
|direct page indexed X | |direct page indexed X | ||
|F6 | |F6 | ||
|2 bytes | |2 bytes | ||
|6 cycles | |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]] | ||
|+ | |+ | ||
| | | | ||
Line 55: | Line 55: | ||
|} | |} | ||
'''INC''' (Increment) is a 65x instruction that increments the value in the location specified by the operand. | '''INC''' (Increment) is a 65x instruction that increments the value in the location specified by the operand. The size of the [[accumulator]] determines whether this is an 8 or 16 bit operation. | ||
INC ignores the [[decimal mode flag]]. | |||
===== Cycle Penalties ===== | |||
* Except in [[accumulator addressing]], INC takes two extra cycles when the accumulator is 16 bits wide. | |||
* In [[direct page addressing]] modes, INC takes an extra cycle if the low byte of the [[direct page register]] is nonzero. | |||
=== See Also === | === See Also === | ||
Line 63: | Line 69: | ||
=== External Links === | === External Links === | ||
* [[Eyes & Lichty]] page on INC: https://archive.org/details/0893037893ProgrammingThe65816/page/n482 | * [[Eyes & Lichty]] page 456, on INC: https://archive.org/details/0893037893ProgrammingThe65816/page/n482 | ||
* [[Labiak]] page on INC: https://archive.org/details/Programming_the_65816/page/n152 | * [[Labiak]] page 142 on INC: https://archive.org/details/Programming_the_65816/page/n152 | ||
* [[MCS6500 Manual]] page on INC: https://archive.org/details/mos_microcomputers_programming_manual/page/n176 | * [[MCS6500 Manual]] page 155 on INC: https://archive.org/details/mos_microcomputers_programming_manual/page/n176 | ||
* [[Carr]] page on INC: https://archive.org/details/6502UsersManual/page/n273 | * [[Carr]] page 260 on INC: https://archive.org/details/6502UsersManual/page/n273 | ||
* [[Leventhal]] page on INC: https://archive.org/details/6502-assembly-language-programming/page/n114 | * [[Leventhal]] page 3-65 on INC: https://archive.org/details/6502-assembly-language-programming/page/n114 | ||
* snes9x implementation of INC: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L627 | * snes9x implementation of INC: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L627 | ||
* undisbeliever on INC: https://undisbeliever.net/snesdev/65816-opcodes.html#inc-increment | * undisbeliever on INC: https://undisbeliever.net/snesdev/65816-opcodes.html#inc-increment |
Latest revision as of 02:07, 10 December 2023
Basic Info | |||||||
---|---|---|---|---|---|---|---|
Addressing Mode | Opcode | Length | Speed | ||||
Accumulator | 1A | 1 byte | 2 cycles | ||||
Absolute | EE | 3 bytes | 6 cycles* | ||||
Direct Page | E6 | 2 bytes | 5 cycles* | ||||
absolute indexed X | FE | 3 bytes | 7 cycles* | ||||
direct page indexed X | F6 | 2 bytes | 6 cycles* |
Flags Affected | ||||||||
---|---|---|---|---|---|---|---|---|
N | V | M | X | D | I | Z | C | |
. | . | . | . | . | . |
INC (Increment) is a 65x instruction that increments the value in the location specified by the operand. The size of the accumulator determines whether this is an 8 or 16 bit operation.
INC ignores the decimal mode flag.
Cycle Penalties
- Except in accumulator addressing, INC takes two extra cycles when the accumulator is 16 bits wide.
- In direct page addressing modes, INC takes an extra cycle if the low byte of the direct page register is nonzero.
See Also
External Links
- Eyes & Lichty page 456, on INC: https://archive.org/details/0893037893ProgrammingThe65816/page/n482
- Labiak page 142 on INC: https://archive.org/details/Programming_the_65816/page/n152
- MCS6500 Manual page 155 on INC: https://archive.org/details/mos_microcomputers_programming_manual/page/n176
- Carr page 260 on INC: https://archive.org/details/6502UsersManual/page/n273
- Leventhal page 3-65 on INC: https://archive.org/details/6502-assembly-language-programming/page/n114
- snes9x implementation of INC: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L627
- undisbeliever on INC: https://undisbeliever.net/snesdev/65816-opcodes.html#inc-increment