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INC: Difference between revisions
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* 10.7 on [[MCS6500 Manual]], [https://archive.org/details/mos_microcomputers_programming_manual/page/n176 page 155] on INC | * 10.7 on [[MCS6500 Manual]], [https://archive.org/details/mos_microcomputers_programming_manual/page/n176 page 155] on INC | ||
* [[Carr]], [https://archive.org/details/6502UsersManual/page/n273 page 260] on INC | * [[Carr]], [https://archive.org/details/6502UsersManual/page/n273 page 260] on INC | ||
* [[Leventhal]] | * [[Leventhal]], [https://archive.org/details/6502-assembly-language-programming/page/n114 page 3-65] on INC | ||
* 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 | ||
Revision as of 12:47, 8 August 2024
| 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 by X | FE | 3 bytes | 7 cycles* | ||||
| Direct Page Indexed by X | F6 | 2 bytes | 6 cycles* | ||||
| Flags Affected | ||||||||
|---|---|---|---|---|---|---|---|---|
| N | V | M | X | D | I | Z | C | |
| N | . | . | . | . | . | Z | . | |
INC (Increment) is a 65x instruction that increments the value in the location specified by one. The size of the accumulator determines whether this is an 8 or 16 bit operation. An alternate mnemonic when the operand is the accumulator is "INA."
INC ignores the decimal mode flag and the carry flag.
Syntax
INC INC A INA INC addr INC dp INC addr, X INC dp, X
To test for wraparound, examine the zero flag. If you need to add two or more to the accumulator, consider ADC instead of INC.
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
- Labiak, page 142 on INC
- 10.7 on MCS6500 Manual, page 155 on INC
- Carr, page 260 on INC
- Leventhal, page 3-65 on INC
- 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
- Pickens, John. http://www.6502.org/tutorials/6502opcodes.html#INC
- Clark, Bruce. http://www.6502.org/tutorials/65c816opcodes.html#6.1.1.3