customasm

This is an assembler that takes custom instruction set definitions and uses them to assemble source files.
This can be useful if you'd like to test out a new virtual machine's bytecode, or even if you're eager to write programs for that new processor architecture you just implemented in FPGA!

Try it right now on your browser!

Check out the Releases section for pre-built binaries.

Check out the documentation for user instructions.

Also, check out an example project which targets the NES!

You can compile from source by simply doing cargo build. There's also a battery of tests available at cargo test.

Command Line Usage

Usage: customasm [options] <asm-file-1> ... <asm-file-N>

Options:
    -f, --format FORMAT The format of the output file. Possible formats:
                        binary, binstr, hexstr, bindump, hexdump
    -i, --include FILE  Specifies an additional file for processing before the
                        given <asm-files>.
    -o, --output FILE   The name of the output file.
    -p, --print         Print output to stdout instead of writing to a file.
    -q, --quiet         Suppress progress reports.
    -v, --version       Display version information.
    -h, --help          Display this information.

Example

Given the following file:

#cpudef
{
    #bits 8
    
    load r1, {value} -> 0x11 @ value[7:0]
    load r2, {value} -> 0x12 @ value[7:0]
    load r3, {value} -> 0x13 @ value[7:0]
    add  r1, r2      -> 0x21
    sub  r3, {value} -> 0x33 @ value[7:0]
    jnz  {address}   -> 0x40 @ address[15:0]
    ret              -> 0x50
}

#addr 0x100

multiply3x4:
    load r1, 0
    load r2, 3
    load r3, 4
    
    .loop:
        add r1, r2
        sub r3, 1
        jnz .loop
    
    ret

...the assembler would use the #cpudef rules to convert the instructions into binary code:

0x0100: 11 00
0x0102: 12 03
0x0104: 13 04
0x0106: 21
0x0107: 33 01
0x0109: 40 01 06
0x010c: 50