OSDev.org

BASICFreak wrote:C is not my native language, learning so much within 1500 lines. I'm starting to miss the OO languages though - or at the very least standard libraries.

BASICFreak wrote:And I'll continue to make my code C89 standard so I don't have to worry about anyone (mostly me) missing a -C99 gcc tag.

sortie wrote:

BASICFreak wrote:C is not my native language, learning so much within 1500 lines. I'm starting to miss the OO languages though - or at the very least standard libraries.

That's the best thing about osdev: You get to do everything from scratch. You'll end up deeply understanding a full complex system in full details.

sortie wrote:

BASICFreak wrote:And I'll continue to make my code C89 standard so I don't have to worry about anyone (mostly me) missing a -C99 gcc tag.

Just learn to use your compiler. Passing -std=c99 (or -std=gnu99 if you want extensions such as asm rather than __asm__) is easy and just takes a few moments to remember. Besides, you put that in build scripts anyways - other people building your code would be using these scripts too. I'd argue it is definitely worth the trade-off learning how to invoke your compiler compared with the advantages of not dealing with artificial ancient C restrictions. Note that it is called an option, not a tag.

if (streql(explode_cmd[0], "echo")) for (int i = 1; i <= args; i++) printf ("%s ", explode_cmd[i]);

CMD.c: In function 'doCommand':
CMD.c:50: warning: division by zero
CMD.c:50: warning: unused variable 'divz'

bwat wrote:

BASICFreak wrote:Tested and works fine, and returns -1 on error

I could not think of how to process in order thanks for that, makes more sense than what I was doing.

You've written a function with return type unsigned int that returns -1 on error. Interesting.......

int stringToInt(unsigned int *out, char* in) {
    unsigned int result = 0;

    while (*in != 0) {
        if ( (*in < '0') || (*in > '9') ) {
            return BAD_CHAR;
        }
        if(result > UINT_MAX/10 ) {
            return OVERFLOW;
        }
        result *= 10;
        if(result > UINT_MAX - (*in - '0') ) {
            return OVERFLOW;
        }
        ret += *in - '0';
        *in++;
    }
    *out = result;
    return OK;
}

sortie wrote:

BASICFreak wrote:And I'll continue to make my code C89 standard so I don't have to worry about anyone (mostly me) missing a -C99 gcc tag.

Just learn to use your compiler. Passing -std=c99 (or -std=gnu99 if you want extensions such as asm rather than __asm__) is easy and just takes a few moments to remember. Besides, you put that in build scripts anyways - other people building your code would be using these scripts too. I'd argue it is definitely worth the trade-off learning how to invoke your compiler compared with the advantages of not dealing with artificial ancient C restrictions. Note that it is called an option, not a tag.

BASICFreak wrote: And you know what sold me on C99, I had to get this all on one line to make it match everything else:

Code: Select all

if (streql(explode_cmd[0], "echo")) for (int i = 1; i <= args; i++) printf ("%s ", explode_cmd[i]);

if (streql(explode_cmd[0], "echo"))
    for (int i = 1; i <= args; i++)
        printf ("%s ", explode_cmd[i]);

BASICFreak wrote: I did have to go through my code and replace all (3) asm calls with __asm__ __volatile__

BASICFreak wrote: And still my favorite gcc warning:

Code: Select all

CMD.c: In function 'doCommand':
CMD.c:50: warning: division by zero
CMD.c:50: warning: unused variable 'divz'

type div0 at prompt and what do you know 1/0 does not compute, still useful for faulting the system and testing my error source