# Another RISC-V ISA simulator.

**This code is suitable to hard refactor at any time**


This is another RISC-V ISA simulator, this is coded in SystemC + TLM-2.
It partially supports RV32I Instruction set by now.

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Brief description of the modules:
* CPU: Top entity that includes all other modules.
* Memory: Memory highly based on TLM-2 example with read file capability
* Registers: Implements the register file, PC register & CSR registers
* Execute: Executes ISA instructions
  * Executes C instruction extensions
  * Executes M instruction extensions
* Instruction: Decodes instruction and acces to any instruction field
  * C_Instruction: Decodes Compressed instructions (C extension)
  * M_INstruction: Decodes Multiplication and Division instructions (M extension)
* Simulator: Top-level entity that builds & starts the simulation
* BusCtrl: Simple bus manager
* Trace: Simple trace peripheral

Helper classes:
* Performance: Performance indicators stores here (singleton class)
* Log: Log class to log them all (singleton class)

Current performance is about 284500 instructions / sec in a Core-i5@2.2Ghz


### Structure
![Modules' hierarchy](https://github.com/mariusmm/RISC-V-TLM/blob/master/doc/Hierarchy.png)



## TODO
This is a preliminar and incomplete version.

Task to do:
* Implement all missing instructions (Execute)
* Implement CSRs (where?)
* Add full support to .elf ~~and .hex~~ filetypes to memory.h
(only partial .hex support)
* Connect some TLM peripherals
     * ~~Debug module similiar to ARM's ITM~~
     * Some standard UART model
     * ...
* Test, test, test & test. I'm sure there are a lot of bugs in the code
* Improve structure and modules hierarchy
* Add 64 & 128 bits architecture (RV64I, RV128I)

## Compile
In order to compile the project you need SystemC-2.3.2 installed in your system.
Just change SYSTEMC path in Makefile.

```
$ make
```

Then, you need to modifiy your LD_LIBRARY_PATH environtment variable to add
path systemc library. In my case:
```
$ export LD_LIBRARY_PATH=/home/marius/Work/RiscV/code/systemc-2.3.2/lib-linux64
```

And then you can execute the simulator:
```
$ ./RISCV_TLM asm/BasicLoop.hex
```

## Test
See [Test page](Test) for more information.

In the asm directory there are some basic assembly examples.

I "compile" one file with the follwing command:
```
$ cd asm
$ riscv32-unknown-linux-gnu-as  EternalLoop.asm -o EternalLoop.o
$ riscv32-unknown-linux-gnu-ld -T ../my_linker_script.ld EternalLoop.o -o EternalLoop.elf
$ objcopy -O ihex EternalLoop.elf EternalLoop.hex
$ cd ..
$ ./RISCV_SCTLM asm/EternalLoop.hex
```
This example needs that you hit Ctr+C to stop execution.

### C code
The C directory contains simple examples in C. Each directory contains
an example, to compile it just:
```
$ make
```
and then execute the .hex file like the example before.

## Documentation
The code is documented using doxygen. In the doc folder there is a Doxygen.cfg
file ready to be used.

## Contribute
There are several ways to contribute to this project:
* Test
* Pull request are welcome (see TODO list)
* Good documentation

##  License

Copyright (C) 2018 Màrius Montón ([\@mariusmonton](https://twitter.com/mariusmonton/))

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.