kernel/printf.c


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#include "printf.h"
#include "types.h"
#include "framebuffer.h"

int printf(const char* format, ...) {
	int32_t* argp = (int32_t*)&format;
	int num;
	
	while(*format) {
		if(*format != '%') {
			framebuffer_putchar(*format++);
			num++;
			continue;
		}
		format++;
		
		bool is_signed = false;
		bool zero_pad = false;
		int radix = 16;
		int min_len = 0;
		
		if(*format == '0') {
			zero_pad = true;
		}
		
		while(*format >= '0' && *format <= '9') {
			min_len = min_len * 10 + *format++ - '0';
		}
		
		switch(*format++) {
			case '%':
				framebuffer_putchar('%');
				num++;
				break;
			
			case 'c':
				framebuffer_putchar((char)*++argp);
				num++;
				break;
			
			case 's':
				;
				char* str = (char*)*++argp;
				while(*str) {
					framebuffer_putchar(*str++);
					num++;
				}
				break;
			
			case 'd':
				is_signed = true;
			case 'u':
				radix = 10;
			case 'x':
				;
				uint32_t x = (uint32_t)*(++argp);
				if(is_signed && (int32_t)x < 0) {
					x = -x;
					framebuffer_putchar('-');
					min_len--;
				}
				
				char buf[11];
				char* bufp = &buf[sizeof(buf)];
				*--bufp = 0;
				
				do {
					int d = x % radix;
					*--bufp = d < 10 ? '0' + d : 'a' - 10 + d;
					x /= radix;
					min_len--;
				} while(x);
				
				while(min_len > 0) {
					framebuffer_putchar(zero_pad ? '0' : ' ');
					num++;
					min_len--;
				}
				
				while(*bufp) {
					framebuffer_putchar(*bufp++);
					num++;
				}
				break;
		}
	}
	
	framebuffer_move_cursor();
	
	return num;
}