lc4go

LC4 ISA emulator, written in Go. A CLI app that acts like a GDB for LC4.

LC4 is an assembly language. For more information about the instruction set, see here.

This tool takes in .obj files, which are the bytecodes.

Usage

Launching the CLI

From the root directory of the project, the application can be launched with the following command:

go run main.go

CLI Commands

Loading an .obj File

To load an .obj file, you can use the load command:

lc4> load -b <path/to/obj/file>

Breakpoint

You can set breakpoints anywhere in memory with the breakpoint/b command:

lc4> breakpoint 0x1234

Printing

You can print the states and values stored in the machine at any point. This includes:

• p code: print code at the current program counter
• p mem <addr>: print the value stored in memory at the provided address
• p reg: print all register values
• p psr: print thet NZP bits and privilege bit
• p: print all of the above at once

Execution

Basic execution commands are provided, with convenient aliases:

• step/s: execute one instruction
• next/n: run until PC = current PC + 1
• continue/c: run from current PC to the end
• run/r: run from from the beginning to the end

Miscellaneous

Additionally, there are a couple of other helper commands:

• reset: reset only states, but keep memory and breakpoints
• clear: reset all states and values

Example

# go run main.go

lc4> load -b example/os.obj
lc4> load -b example/math.obj
lc4> b 4
lc4> r
lc4> p
lc4> clear

Note that the os.obj file should always be loaded in.