https://github.com/visrealm/vremu6502

6502/65C02 emulator library (C99)
https://github.com/visrealm/vremu6502

6502 6502-emulation 6510 65c02 65c02-emulation c c99 emulator r65c02 wdc65c02

Last synced: about 1 month ago
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6502/65C02 emulator library (C99)

• Host: GitHub
• URL: https://github.com/visrealm/vremu6502
• Owner: visrealm
• License: mit
• Created: 2022-01-22T07:01:35.000Z (almost 3 years ago)
• Default Branch: main
• Last Pushed: 2024-11-03T05:21:10.000Z (3 months ago)
• Last Synced: 2024-12-19T08:09:06.714Z (about 1 month ago)
• Topics: 6502, 6502-emulation, 6510, 65c02, 65c02-emulation, c, c99, emulator, r65c02, wdc65c02
• Language: C
• Homepage:
• Size: 490 KB
• Stars: 45
• Watchers: 3
• Forks: 16
• Open Issues: 1
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# vrEmu6502



6502/65C02 emulator written in standard C99 with no external dependencies.

Initially created for my [HBC-56 (6502 on a backplane) Emulator](https://github.com/visrealm/hbc-56)

Includes:

* Support for standard 6502/6510, 65C02, WDC65C02 and R65C02.

* Supports all unofficial ("illegal") 6502/6510 opcodes (Use model value `CPU_6502U`).

* Correct handling of Decimal mode.

* Accurate instruction timing.

* All WDC and Rockwell-specific 65C02 instructions.

* User-supplied I/O callbacks.

* IRQ and NMI signals.

* Multiple CPU instances.

* Instruction disassembler.

* Test runner.

## Test suite

Includes a test program which was designed to run [Klaus Dormann's 6502 tests](https://github.com/Klaus2m5/6502_65C02_functional_tests).

Passes all tests:

* 6502_functional_test (all models)

* 6502_decimal_test (with valid and invalid bcd) (6502)

* 65C02_decimal_test (with valid and invalid bcd) (all 65C02 models)

* 65C02_extended_opcodes_test (Standard 65C02)

* W65C02_extended_opcodes_test (WDC65C02)

* R65C02_extended_opcodes_test (R65C02)

See the [test](test) directory or more details.

## Building

vrEmu6502 uses the CMake build system

#### Checkout repository:

```

git clone https://github.com/visrealm/vrEmu6502.git

cd vrEmu6502

```

#### Setup build:

```

mkdir build

cd build

cmake ..

```

#### Build

```

cmake --build .

```

Windows: Optionally, open the generated solution file

#### Run tests

```

ctest

```

Windows: Optionally, build the ALL_TESTS project in the generated solution file

## Quick start

```C

#include "vrEmu6502.h"

uint8_t ram[0x8000];

uint8_t rom[0x8000];

uint8_t My6502MemoryReadFunction(uint16_t addr, bool isDbg)

{

  if (addr < 0x8000)

  {

    return ram[addr];

  }

  return rom[addr & 0x7fff];

}

void My6502MemoryWriteFunction(uint16_t addr, uint8_t val)

{

  if (addr < 0x8000)

  {

    ram[addr] = val;

  }

}

/* fill rom with something that makes sense here */

/* create a new WDC 65C02. */  

VrEmu6502 *my6502 = vrEmu6502New(CPU_W65C02, My6502MemoryReadFunction, My6502MemoryWriteFunction);

if (my6502)

{

  /* if you want to interrupt the CPU, get a handle to its IRQ "pin" */

  vrEmu6502Interrupt *irq = vrEmu6502Int(my6502);

  /* reset the cpu (technically don't need to do this as vrEmu6502New does reset it) */

  vrEmu6502Reset(my6502);

  while (1)

  {

    /* call me once for each clock cycle (eg. 1,000,000 times per second for a 1MHz clock) */

    vrEmu6502Tick(my6502);

        

    /* interrupt it? */

    if (myHardwareWantsAttention)

    {

      *irq = IntRequested;

      

      /* at some point, the hardware will be happy and it will need to release the interrupt */

    }

  }

  vrEmu6502Destroy(my6502);

  my6502 = NULL;

}

```

See  [HBC-56](https://github.com/visrealm/hbc-56) for real-life example usage.

## License

This code is licensed under the [MIT](https://opensource.org/licenses/MIT "MIT") license