src/libc/stdio.c


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#include <u.h>
#include <libc.h>

int
printf(byte* fmt, ...)
{
    va_list args;
    va_start(args, fmt);

    int nw, rem, peek, len;
    byte *str, c;

    while (*fmt) {
        rem = INT_MAX - nw;

        if (fmt[0] != '%' || fmt[1] == '%') {
            if (fmt[0] == '%') fmt++;

            for (peek = 1; fmt[peek] && fmt[peek] != '%'; peek++) {
                ;
            }
            if (rem < peek) return -1;
            // TODO: Print here.
            fmt += peek;
            nw  += peek;
            continue;
        }

        str = fmt++;

        switch (*fmt++) {
        case 'c':
            c = va_arg(args, int);
            if (rem < 0) return -1;
            // TODO: Print here
            nw++;
            break;

        case 's':
            str = va_arg(args, byte*);
            len = strlen(str);
            if (rem < len) return -1;
            // TODO: Print here
            nw += len;
            break;
        default:
            fmt = str;
            len = strlen(fmt);
            if (rem < len) return -1;
            // TODO: Print here
            nw += len;
            fmt += len;
            break;
        }
    }

    va_end(args);
    return nw;
}