Calculator

Aims to be a calculator implemented in 32-bit RISC-V assembly, initially targeting the inexpensive CH32V003 RV32EC microcontroller: 48Mhz 2KB SRAM, 16KB Flash.

Notes

Disassemble

riscv64-unknown-elf-objdump -D main.o

List Symbols

riscv64-unknown-elf-nm calc.o

List segment info

readelf -l calc.elf

Build with LLVM

make AS=clang ASFLAGS="-g -mabi=ilp32e --target=riscv32-unknown-elf -nostdlib -c"

Resources

• https://riscv-programming.org/book/riscv-book.html
• CH32V003 Datasheet
• QingKeV2 Processor Manual — core used in the CH32V003

Syscalls on RV32E

Syscalls supported by rv32emu.

Consensus seems to be pass the syscall number in t0:

• https://github.com/riscvarchive/riscv-qemu/pull/61
• 1286b3c41e/src/syscall.c (L484)