C Usage

Usage Instructions for C

See the release bundle for some examples of C programs which can be compiled and run on Valida. Here is an example C program from this repo, called cat.c:

#include <stdio.h>

const unsigned EOF_ = 0xFFFFFFFF;

int main() {
    unsigned c = 0;
    while (1) {
        c = getchar();
        if (c == EOF_) {
            break;
        } else {
            putchar(c);
        }
    }
}

To compile the cat.c example to Valida from within the Valida shell or the Valida Docker image shell:

clang -target valida /valida-toolchain/example/c/cat.c -o cat
valida run cat log

Once running, the cat example will wait for input. After you are done providing input, press ctrl+D. The program should echo back what you wrote, writing its output to log.

Compiling and running the other examples follows the same procedure, substituting $NAME for the name of the example:

clang -target valida /valida-toolchain/examples/c/${NAME}.c -o ${NAME}
valida run ${NAME} log

C standard libraries

See Using LLVM libc for instructions on how to use the libc support included with the Valida toolchain. This allows for the use of some libc header files and standard library functions and macros.

Floating point support

The LLVM Valida compiler toolchain supports floating point types via software emulation. All of the normal arithmetic operations on floating point are supported. fenv.h is not supported. It is recommended to avoid using floating point types in Valida, because it's not very efficient to do it using software emulation.