Enclosed in this repository is a disassembler (binary to assembly) for 32-bit LEGv8 (a subset of ARM first described by David A. Patterson and John L. Hennessy) instructions written in C++.
This project was developed as part of COM S 321 (Computer Architecture) at Iowa State University, instructed by Dr. Jeremy Sheaffer.
The disassembler can handle the following instruction types:
- B
- CB
- D
- I
- IW
- R
Specifically, supporting the following instructions:
- ADD
- ADDI
- AND
- ANDI
- B
- B.cond (EQ, NE, HS, LO, MI, PL, VS, VC, HI, LS, GE, LT, GT, LE)
- BL
- BR
- CBNZ
- CBZ
- EOR
- EORI
- LDUR
- LSL
- LSR
- ORR
- ORRI
- STUR
- SUB
- SUBI
- SUBIS
- SUBS
- MUL
Along with these special instructions, implemented by some emulators:
- PRNT
- PRNL
- DUMP
- HALT
As most modern systems are little-endian, we assume that the input binary is little-endian.
Per course guidelines, the project ships with a build.sh and run.sh - these do what you expect.
To build the project, simply run ./build.sh. You must have make and g++ installed ahead of time. You will see the executable disasm generated. You may execute this binary directly, or use the provided run.sh script.
Next, to disassemble a binary, run ./run.sh <path-to-binary>. The disassembled output will be written to <path-to-binary>.legv8asm. For example, if you run ./run.sh test.bin, the output will be written to test.bin.legv8asm.
When originally approaching this project, I had wanted to use a more object-oriented approach. However, I quickly realized it'd be rather burdensome to ensure I was shifting out values and storing them in class members correctly.
Instead, I opted to create classic C structs to represent the various instruction types. Once I dynamically identify an instruction's opcode, I can then cast the uint32_t bitfield to the appropriate struct and access the fields directly without headache. For those interested in creating a disassembler, I highly recommend this approach.