printk.c

用于汇编领域的,运用于OS的MAIN函数.基于硬件基础的源代码

// printk.c
//
// Reference from geekOS

#include <stdarg.h>
#include "hos.h"

#define NUM_SCREEN_DWORDS	((NUMROWS * NUMCOLS * 2) / 4)
#define NUM_SCROLL_DWORDS	(((NUMROWS - 1) * NUMCOLS * 2) / 4)
#define NUM_DWORDS_PER_LINE	((NUMCOLS * 2) / 4)

static int s_row, s_col;
static unsigned char s_currentAttr;

#define FILL_DWORD  (0x00200020 | (s_currentAttr << 24) | (s_currentAttr << 8))

/* Scroll the display one line */
static void scroll(void)
{
	unsigned int *v;
	int i, n = NUM_SCROLL_DWORDS;
	unsigned int fill = FILL_DWORD;

	/* Move lines from 1 to NUMROW-1 up by one */
	for(v = (unsigned int *)VIDEO_MEM, i = 0; i < n; ++i) {
		*v = *(v + NUM_DWORDS_PER_LINE);
		++v;
	}
	
	/* clear out last line */
	for(v = (unsigned int *)VIDEO_MEM + n, i = 0; i < NUM_DWORDS_PER_LINE; ++i)
		*v++ = fill;
}

/* Clear current cusor position to end of line */
static void clear_to_eol(void)
{
	int n = (NUMCOLS - s_col);
	unsigned char *v = VIDEO_MEM + s_row * (NUMCOLS * 2) + s_col * 2;

	while(n-- > 0) {
		*v++ = ' ';
		*v++ = s_currentAttr;
	}
}

/* Move to the beginning of the next line */
static void newline(void)
{
	++s_row;
	s_col = 0;
	if(s_row == NUMROWS) {
		scroll();
		s_row = NUMROWS - 1;
	}
}

static put_graphic_char(int c)
{
	unsigned char *v = VIDEO_MEM + s_row * (NUMCOLS * 2) + s_col * 2;

	*v++ = (unsigned char) c;
	*v = s_currentAttr;

	if(s_col < NUMCOLS - 1)
		++s_col;
	else
		newline();
}

void put_char_imp(int c)
{
	int num_spaces;

	switch(c) {
	case '\n':
		clear_to_eol();
		newline();
		break;
	
	case '\t':
		num_spaces = TABWIDTH - (s_col % TABWIDTH);
		while(num_spaces-- > 0)
			put_graphic_char(' ');
		break;
	
	default:
		put_graphic_char(c);
		break;
	}
}

static void update_cursor(void)
{
	unsigned character_pos = (s_row * NUMCOLS) + s_col;
	unsigned char orig_addr;

	orig_addr = inbyte(CRT_ADDR_REG);
	iodelay();

	outbyte(CRT_ADDR_REG, CRT_CURSOR_LOC_HIGH_REG);
	iodelay();
	outbyte(CRT_DATA_REG, (character_pos >> 8) & 0xff);
	iodelay();

	outbyte(CRT_ADDR_REG, CRT_CURSOR_LOC_LOW_REG);
	iodelay();
	outbyte(CRT_DATA_REG, character_pos & 0xff);
	iodelay();

	outbyte(CRT_ADDR_REG, orig_addr);
}

static void format_d(char *buf, int val)
{
	char stack[16];
	int top = 0;
	int is_neg;
	unsigned uval;

	if(val < 0) {
		is_neg = 1;
		uval = -val;
	} else {
		is_neg = 0;
		uval = val;
	}

	do {
		int digit = uval % 10;
		stack[top++] = digit + '0';
		uval /= 10;
	} while (uval > 0);

	if(is_neg)
		*buf++ = '-';

	do {
		*buf++ = stack[--top];
	} while (top > 0);

	*buf = '\0';
}

static void format_x(char *buf, int val)
{
	int i;

	for(i = 28; i >= 0; i -= 4) {
		int x = (val >> i) & 0xf;
		*buf++ = "0123456789abcdef"[x];
	}
	
	*buf = '\0';
}

/*===============================================================*/
/*===============================================================*/

void init_screen(void)
{
	s_row = s_col = 0;
	s_currentAttr = ATTRIB(BLACK, GRAY);
	clear_screen();
}

void clear_screen(void)
{
	unsigned int *v = (unsigned int *)VIDEO_MEM;
	int i;
	unsigned int fill = FILL_DWORD;

	for(i = 0; i < NUM_SCREEN_DWORDS; ++i)
		*v++ = fill;
}

void get_cursor(int *row, int *col)
{
	*row = s_row;
	*col = s_col;
}

void put_cursor(int row, int col)
{
	s_row = row;
	s_col = col;

	update_cursor();
}

unsigned char get_current_attr(void)
{
	return s_currentAttr;
}

void set_current_attr(unsigned char attrib)
{
	s_currentAttr = attrib;
}

void put_char(int c)
{
	put_char_imp(c);
	update_cursor();
}

void put_string(const char *s)
{
	while(*s != '\0') {
		put_char_imp(*s++);
	}

	update_cursor();
}

void put_buf(const char *buf, unsigned long length)
{
	while(length > 0) {
		put_char_imp(*buf++);
		--length;
	}

	update_cursor();
}

void printk(const char * fmt, ...)
{
	char buf[64];
	va_list args;
	int ival;
	const char *sval;

	va_start(args, fmt);

	while(*fmt != '\0') {
		switch (*fmt) {
		case '%':
			++fmt;
			switch(*fmt) {
			case 'd':
				ival = va_arg(args, int);
				format_d(buf, ival);
				put_string(buf);
				break;
			case 'x':
				ival = va_arg(args, int);
				format_x(buf, ival);
				put_string(buf);
				break;
			case 's':
				sval = va_arg(args, const char *);
				put_string(sval);
				break;
			case 'c':
				ival = va_arg(args, int);
				put_char_imp(ival & 0xff);
				break;
			default:
				put_char_imp(*fmt);
				break;
			}
		default:
			put_char_imp(*fmt);
			break;
		}

		++fmt;
	}

	update_cursor();

	va_end(args);
}