aedrix-kernel/kernel/print.c

#include <print.h>
#include <vargs.h>

/* This function exists solely so crashes don't happen if putc() gets
 * called before it is initialized. */
void putc_initial(char c) {
	(void)c;
}
void (*putc)(char) = &putc_initial;

void print_init(void (*putcfn)(char)) {
	if (putcfn)
		putc = putcfn;
}
 
void puts(const char *s)
{
    while (*s) putc (*s++);
}

void puti(int i)
{
	unsigned int left;
	char buf[1 << (sizeof(int)*8) / 10];
	char *p = buf;
	unsigned char negative = i < 0;

	if (!i)
		putc('0');

	left = negative ? -1*i : i;

	while (left) {
		unsigned int remainder = left % 10;
		left /= 10;
		*p = ('0'-0) + remainder;
		p++;
	}

	if (negative)
		putc('-');

	while (p-- != buf)
		putc(*p);
}

void putx(unsigned int i) {
	unsigned int left = i;
	char buf[1 << (sizeof(int)*8) / 16];
	char *p = buf;

	puts("0x");
	if (!i)
		putc('0');

	while (left) {
		unsigned int remainder = left % 16;
		left /= 16;
		if (remainder < 10)
			*p = ('0'-0) + remainder;
		else
			*p = ('a'-10) + remainder;
		p++;
	}

	while (p-- != buf)
		putc(*p);
}

int print(char *fmt, ...) {
	char *c;
	va_list arg;

	va_start(arg, fmt);
	for (c = fmt; *c; c++) {
		if (*c == '%') {
			switch (*++c) {
			case '%':
				putc('%');
				break;
			case 's':
				puts(va_arg(arg, char *));
				break;
			case 'c':
				putc(va_arg(arg, unsigned int));
				break;
			case 'd':
				puti(va_arg(arg, int));
				break;
			case 'x':
				putx(va_arg(arg, unsigned int));
				break;
			default:
				puts("\nError: print(): Invalid formatting character: '");
				putc(*c);
				puts("'\n");
				return -1;
			}
		} else {
			putc(*c);
		}
	}
	va_end(arg);

	return 0;
}