This is a customized version of David Welch's thumbulator, an emulator targetting the thumb subset of the ARM instruction set.
The thumbulator itself has been transpiled from C using emscripten, the glue code around it is written in Typescript. As such, the module can be directly used with TS, no external typings required (of course, it works in plain JS, too).
The package is available on NPM
$ npm install thumbulator.ts
The package has a single default export: the Thumbulator
class. In order to
instantiate, you need to pass a bus
object that implements reading and writing
from the bus.
import Thumbulator from 'thumbulator.ts';
const thumbulator = new Thumbulator({
read16: (address: number): number => {
// read a 16 bit word at the given address
},
read32: (address: number): number => {
// optional; read a 32 bit word (will use read16 instead if not defined)
},
write16: (address: number, value: number) => {
// write a 16 bit word to the given address
},
write32: (address: number, value: number) => {
// optional; write a 32 bit word (will use write16 if not defined)
}
}, {
printer: (line: string): void => {
// optional; override logging (uses console.log and console.error by default)
},
stopAddress: number, // optional; the emulation stops with TrapReason.stop when
// execution reaches this address
trapOnInstructionFetch: (address: number): number => {
// optional; return a nonzero trap code to trap and stop the emulation on
// instruction fetch. This is evaluated only if stopAddress is not set.
},
trapOnBx32: (instructionAddress: number, targetAddress: number): number => {
// optional; handle BX out of thumb mode.
}
});
The second options object is optional
After instantiation, call init and wait for the promise to resolve in order to make sure that the emscripten runtime has initialized.
await thumbulator.init();
const trapReason: Thumbulator.TrapReason = thumbulator.run(cycles);
Run the emulation for cycles
instructions or until a trap occurs. See the
source
for trap codes.
thumbulator.abort();
This will cause run
to return immediatelly with TrapReason.abort
(10).
thumbulator.reset();
const value = thumbulator.readRegister(r);
thumbulator.writeRegister(r, value);
These will read and write registers.
thumbulator.enableDebug(true);
This will cause the emulator to enter verbose mode and dump disassembly
This module is used in the 6502.ts VCS emulator for emulating the ARM SOC in the Harmony cartridge.
Both David Welch's original code and the glue around it are licensed under the MIT license.