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# QDMA - Quick and Dirty MIPS Assembler
## Intro
QDMA is a simple MIPS assembler written in Go for
[QDME](https://github.com/JacobMcDonnell/QDME), which is my simple MIPS
emulator. QDMA implements a partial version of the Executable and Linkable
Format (ELF), [See Partial ELF for more information](#Partial-ELF).
## Options
- `-o output` set an output file name
- `-b` Set byte order to big endian (default is native)
- `-l` Set byte order to little endian (default is native)
## TODO
- ~Assemble Instructions into Binary~
- ~Handle Labels and Jumps~
- ~Encode Data Section into Binary~
- ~Ignore Comments~
## Instructions
Here is a list of supported instructions.
|Instruction|Type|Action|
|-----------|----|------|
|add |R |rd = rs + rt|
|addu |R |rd = rs + rt|
|and |R |rd = rs & rt|
|or |R |rd = rs \| rt|
|slt |R |rd = rs < rt|
|sltu |R |rd = rs < rt|
|sub |R |rd = rs - rt|
|subu |R |rd = rs - rt|
|xor |R |rd = rs ^ rt|
|sll |R |rd = rt << shamt|
|sra |R |rd = rt >> shamt|
|srl |R |rd = rt >> shamt|
|div |R |hi = rs % rt lo = rs / rt|
|divu |R |hi = rs % rt lo = rs / rt|
|mult |R |hi, lo = rs * rt|
|multu |R |hi, lo = rs * rt|
|MFHI |R |rd = hi|
|MFLO |R |rd = lo|
|MTHI |R |rs = hi|
|MTLO |R |rs = lo|
|jr |R |pc = addr, pc = $ra|
|jalr |R |rd = pc, pc = addr|
|syscall |R |System Call|
|jal |J |$ra = pc, pc = addr|
|j |J |pc = addr|
|beq |I | pc = (rs == rt) ? imm + pc + 4 : pc|
|bne |I | pc = (rs != rt) ? imm + pc + 4 : pc|
|addi |I |rt = rs + imm|
|addiu |I |rt = rs + imm|
|andi |I |rt = rs & imm|
|ori |I |rt = rs \| imm|
|xori |I |rt = rs ^ imm|
|slti |R |rt = rs < imm|
|sltiu |R |rt = rs < imm|
|lui |I |rt = rs << 16|
|lw |I |rs = imm(rt)|
|sw |I |imm(rt) = rs|
## Partial ELF
QDMA is partiallialy complient with ELF, meaning that it supports segments but
not sections. The supported segments are `.text`, `.data`, `.rodata`, and
`.bss`. `.text` is for the instructions. `.data` and `.rodata` are for defined
data types with initial values, `.rodata` being read only. Supported data types
are `.word` for a 4 byte value, `.half` for a 2 byte value, `.byte` for a byte,
`.asciiz` for a null terminated string, and `.ascii` for a non null terminated
string. `.bss` is for variables where there is no initial value. In this
section you define the space that a variable will take up in bytes using
`.space`.
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