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# puce6502 # puce6502
This is a simple and readable emulation of the MOS 6502 CPU\ This is a simple and readable emulation of the MOS 6502 CPU\
It passes the [Klaus Test Suite](https://github.com/Klaus2m5/6502_65C02_functional_tests)\ It passes the [Klaus Test Suite](https://github.com/Klaus2m5/6502_65C02_functional_tests), implements all original instructions and is cycle accurate excepted for :
It implements all original instruction and is cycle accurate excepted for :
*Absolute-X, absolute-Y, and Zero page-Y addressing modes which need an extra cycle if indexing crosses a page boundary, or if the instruction writes to memory.* *Absolute-X, absolute-Y, and Zero page-Y addressing modes which need an extra cycle if indexing crosses a page boundary, or if the instruction writes to memory.*
You can easely interface it with your code using the two provided functions :
You can easely interface it with your code using :
``` ```
void puce6502Reset(); void puce6502Reset();
void puce6502Exec(long long int cycleCount); void puce6502Exec(long long int cycleCount);
``` ```
The first emulates a reset signal, the second will execute as many instruction as needed to reach cycleCount
RAM and ROM are implemented using 8 bits integer arrays. And are directly accessible to your code to load ROM binary images and, for example, generate video output\ RAM and ROM are implemented using 8 bits integer arrays. And are directly accessible to your code to load ROM binary images and, for example, generate video output\
RAM starts at adress 0x000\ RAM starts at adress 0x000\
Update the three #define to adapt it to your needs : Update the three #define to adapt the ranges to your needs :
``` ```
#define ROMSTART 0xD000 #define ROMSTART 0xD000
#define ROMSIZE 0x3000 #define ROMSIZE 0x3000
#define RAMSIZE 0xC000 #define RAMSIZE 0xC000
``` ```
you are expected to provide a function to handle read and writes to locations not You are expected to provide a function to handle read and writes to locations not in ROM or in RAM (for Soft Switches, extension cards ROMs, PIA, VIA, ACIA etc...)
in ROM or in RAM (for Soft Switches, extension cards ROMs, PIA, VIA, ACIA etc...)
``` ```
extern uint8_t softSwitches(uint16_t address, uint8_t value); extern uint8_t softSwitches(uint16_t address, uint8_t value);
``` ```
Finally, the variable `ticks` is a long long int holding the number of cycles since last reset.
For an example of use, you can refer to [reinette II plus](https://github.com/ArthurFerreira2/reinette-II-plus) a french Apple II plus emulator. For an example of use, you can refer to [reinette II plus](https://github.com/ArthurFerreira2/reinette-II-plus) a french Apple II plus emulator.
Have fun ! Have fun !