Tiny assembler + cart builder for ECJR
To build the example program dvdlogo.asm into a cartridge, with dvdlogo.png as the video rom, run (if you are on Linux I assume you understand how to run a binary with ./):
asmjr.exe -i dvdlogo.png dvdlogo.asm dvdlogo.cart
Help:
asmjr 0.1.0
USAGE:
asmjr.exe [OPTIONS] <SOURCE> [OUTPUT]
ARGS:
<SOURCE> Assembly source file
<OUTPUT> Output ECJR cartridge file
OPTIONS:
--author <AUTHOR> Author to embed into metadata
--bare Export bare program without .cart container
-h, --help Print help information
-i, --imagerom <IMAGEROM> Load image (red channel only) into rom
-l, --listing Dump out ops to terminal
-m, --message <MESSAGE> Simple message to embed in metadata
-r, --rawrom <RAWROM> Load raw bytes into rom
--readme <README> Readme file to embed in metadata
-u, --uncompressed Leave cart body uncompressed
-V, --version Print version information
The included assembler is extremely minimal. This snippet covers basically all the syntax:
// This file merely demonstrates syntax, the program is nonsense
// and does nothing.
// Comments can be like this,
# or like this if you want.
; or like this
// Constants can be declared like this
const SPRITES = 0x200 // comments can be on the same line
const TAU = 6.28318
const can_be_lowercase_or_whatever = 0b1010101
const Ω = "hello!"
// the builtin register names are
// x0 x1 x2 x3 x4 ... x255
// zero (always immutably zero, x0)
// ra (return address, x1)
// sp (stack pointer, x2)
// gp (global pointer, x3)
// tp (thread pointer, x4)
addi sp, sp, 1
jal ra, anything-goes-with-labels-too
// you can create aliases to refer to registers
reg temp = x5
muli temp, temp, 2
// Opcodes look like this (can be uppercase or lowercase)
li x1, 12
LI x2, Ω
addi x3, zero, "a"
nop
add x1, x1, x2
jal zero, LABEL_DECLARED_LATER
// the memory operations (load/store) have an alternate syntax too
store x1, zero, SPRITES
store x1, zero[SPRITES]
load x2, gp[SPRITES]
// Known ECJR memory addresses are builtin constants prefixed with $
li x1, 64
store x1, zero[$VIDEO_SPRITE_COUNT]
// Jump/branch labels are declared like this
LABEL_DECLARED_LATER:
anything-goes-with-labels-too:
// Unlike constants, labels can be used before declaration
The Eclipse/Snakefield ISA is beyond the scope of this document, see the ECJR emulator documentation.
This builds in the normal way with cargo (e.g., cargo build --release) however you will need to have
the Google protocol buffer compiler (protoc) on your path because prost needs it (see: https://grpc.io/docs/protoc-installation/).