criscv/README.md

RISC-V (rv32i) emulator in C
This is just for me to understand how all this works, and to learn something new.
So don't use it.

Example programs:

• return.bin returns -1094647826 (puts it to register 10)
• return2.elf returns a different value with more steps. if it returns DADD, something's wrong

Emulator exit codes:

• -1 - reached end of address space
• 0 - never happens
• 1 - invalid opcode
• 2 - illegal instruction argument (like funct3)

Compile: 0. Dependencies: libelf

1. make # should display no warnings
   

2. Executable is build/criscv

Note: Prebuilts for x86_64 & aarch64 Linux are available here, pick the latest one, unpack and run the one for your architecture.
Those are dynamic, meaning you still need the dependencies! See compile step 0 above.

Compile programs: 0. Get the toolchain obviously

1. riscv32-unknown-elf-gcc -ffreestanding -nostdlib -Ttext=0x0 -e main -O0 -o program.elf program.c
   

2. program.bin is the binary file with the program, pass it as an argument

rv32i, ilp32 compatible toolchain for 64bit Linux: download adaa74f263dcba430da588b1109bc3b90bd90a84c67b06213bd03a7bbacd1a2a
Or just the stuff necessary to make a binary file: download 55e79dff7ba4093dedb8151461508fc157525ad89615d49d737845af03d1643f
Those were compiled with ./configure --prefix=$(pwd)/../toolchain --with-arch=rv32i --with-abi=ilp32 and make