https://github.com/akabane-boy/bumriscvassembler
https://github.com/akabane-boy/bumriscvassembler
assembler assembly c risc-v
Last synced: 3 months ago
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- Host: GitHub
- URL: https://github.com/akabane-boy/bumriscvassembler
- Owner: akabane-boy
- Created: 2025-07-01T13:34:19.000Z (about 1 year ago)
- Default Branch: main
- Last Pushed: 2025-07-12T06:50:25.000Z (12 months ago)
- Last Synced: 2025-10-10T20:04:59.500Z (9 months ago)
- Topics: assembler, assembly, c, risc-v
- Language: C
- Homepage:
- Size: 243 KB
- Stars: 0
- Watchers: 0
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# bumriscvassembler
**bumriscvassembler** is a simple RISC-V assembler in C.
Aims to learn how assembler works and get C programming experience.
## Usage
```console
foo@bar:~$ make
foo@bar:~$ ./bumriscvassembler
```
## Result
- Example assembly file.
- Results of executing the program.
- Resulting .txt and .bin files.
## Instruction format
Logical (assembly) order
### R-type:
add, sub, and, or, sll, slt, sra, xor
| opcode | rd | funct3 | rs1 | rs2 | funct7 |
| --------- | --------- | --------- | --------- | --------- | --------- |
| 7 | 5 | 3 | 5 | 5 | 7 |
### I-type:
addi, andi, ori, lb, ln, lw, jalr
| opcode | rd | funct3 | rs1 | imm[11:0] |
| --------- | --------- | --------- | --------- | --------- |
| 7 | 5 | 3 | 5 | 12 |
### S-type:
sb, sh, sw
| opcode | imm[4:0] | funct3 | rs1 | rs2 | imm[11:5] |
| --------- | --------- | --------- | --------- | --------- | --------- |
| 7 | 5 | 3 | 5 | 5 | 7 |
### B-type:
beq, bne, blt, bge, bltu, bgeu
| opcode | imm | imm[4:1] | funct3 | rs1 | rs2 | imm[10:5] | imm |
| --------- | --------- | --------- | --------- | --------- | --------- | --------- | --------- |
| 7 | 1 | 4 | 3 | 5 | 5 | 6 | 1 |
### U-type:
lui, auipc
| opcode | rd | imm[31:12] |
| --------- | --------- | --------- |
| 7 | 5 | 20 |
### J-type:
jal
| opcode | rd | imm[19:12] | imm[11] | imm[10:1] | imm[20] |
| --------- | --------- | --------- | --------- | --------- | --------- |
| 7 | 5 | 8 | 1 | 10 | 1 |
## Process
This section illustrates how **bum_riscv_assembler works**.
1. Get a assembly file.
2. getline() and tokenize.
3. Identify instruction mnemonic.
4. Verify legal syntax.
5. Create array of Instruction consists of instruction fields.
6. Create hash table of all labels and their addresses.
7. Parse and Encode.
8. Write into .txt and .bin files.