c2fj

Compiling C --> RiscV --> Flipjump --> .fjm

An example program, primes/main.c:

int main() {
    printf("Calculate primes up to: ");
    int max_number;
    scanf("%d", &max_number);
    
    ...
    
    for (int p = 3; p <= max_number; p += 2) {
        if (non_prime[p] == false) {
            for (int i = p*p; i <= max_number; i += p) {
                non_prime[i] = true;
            }
            printf("%d\n", p);
        }
    }
    
    return 0;
}

Compiled into this:

Which was compiled into this:

Which in turn compiled into:

Now, run it (Remember, these are flipjump ops that are running):

Calculate primes up to: 20
2
3
5
7
11
13
17
19
Program exited with exit code 0x0.

How to use

Simply python3 c2fj.py file.c will compile your c file into an elf, into fj files, into fjm, then run it.

c2fj supports the next flags:

• --breakpoints Place a fj-breakpoint at the start of the specified riscv addresses
• --single-step Place fj-breakpoints at the start of all riscv opcodes
• --unify_fj Unify the generated fj files into a single file
• --finish-after Stop the compilation at any step (before running, before creating fjm, etc.)
• --build-dir Save the builds in this directory

What if my project is more then a single c?

We support specifying a Makefile path, instead of the c file!
Your Makefile will have to rely on some constants that c2fj will fill:

C2FJ_GCC_OPTIONS
C2FJ_LINKER_SCRIPT
C2FJ_SOURCES
C2FJ_INCLUDE_DIRS
ELF_OUT_PATH

An example Makefile:

GCC := riscv64-unknown-elf-gcc
GCC_FLAGS := -O3

SOURCES := $(C2FJ_SOURCES) main.c globals.c calculate_int.c
OBJECTS := $(SOURCES:.c=.o)

all: |
	$(GCC) $(C2FJ_GCC_OPTIONS) $(GCC_FLAGS) $(SOURCES) -I $(C2FJ_INCLUDE_DIRS) -T $(C2FJ_LINKER_SCRIPT) -o $(ELF_OUT_PATH)

clean:
	rm -r build 2>/dev/null || true

.PHONY: clean all

Tests

Simply run pytest to run the tests.