fb.c

在字符终端显示时钟 fb

#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>
#include <assert.h>
#include <linux/fb.h>
#include <sys/mman.h>

#include "fb.h"
#include "fbnum.h"


int fb_fd = 0;
int max_text_line, max_text_row;
struct fb_var_screeninfo fb_vsinfo;
struct fb_fix_screeninfo fb_fsinfo;
long int fb_scrsize = 0;
char *fb_mp = 0;
fb_color_t fb_text_color = {255, 255, 255, 0};
fb_color_t fb_back_color = {0, 0, 0, 0};


void
fb_open()
{
	/* Open the file for reading and writing */
	fb_fd = open ("/dev/fb0", O_RDWR);
	if (!fb_fd)
	{
		 printf ("Error: cannot open framebuffer device.\n");
		 exit (1);
	}
	printf ("The framebuffer device was opened successfully.\n");

	/* Get fixed screen information */
	if (ioctl (fb_fd, FBIOGET_FSCREENINFO, &fb_fsinfo))
	{
		 printf ("Error reading fixed information.\n");
		 exit (2);
	}

	/* Get variable screen information */
	if (ioctl (fb_fd, FBIOGET_VSCREENINFO, &fb_vsinfo))
	{
		 printf ("Error reading variable information.\n");
		 exit (3);
	}

	/* Figure out the size of the screen in bytes */
	fb_scrsize = fb_vsinfo.xres * fb_vsinfo.yres * fb_vsinfo.bits_per_pixel / 8;

	/* Map the device to memory */
	fb_mp = (char *) mmap (0, fb_scrsize, PROT_READ | PROT_WRITE, MAP_SHARED,
			    fb_fd, 0);
	if ((int) fb_mp == -1)
	{
		 printf ("Error: failed to map framebuffer device to memory.\n");
		 exit (4);
	}
	printf ("The framebuffer device was mapped to memory successfully.\n");

	/* Count the max line and row of texts */
	max_text_line = fb_vsinfo.yres / NUM_HEIGHT;
	max_text_row = fb_vsinfo.xres / NUM_WIDTH;

	return;
}


void
fb_close()
{
	munmap (fb_mp, fb_scrsize);
	close (fb_fd);

	return;
}


void
fb_pixel(int x, int y, fb_color_t *color)
{
	long location = 0;

	assert(color != NULL);

	/* Figure out where in memory to put the pixel */
	location = (x + fb_vsinfo.xoffset) * (fb_vsinfo.bits_per_pixel / 8) +
	  (y + fb_vsinfo.yoffset) * fb_fsinfo.line_length;

	*(fb_mp + location + 3) = color->t; /* If transparency */
	*(fb_mp + location + 2) = color->r; /* Red */
	*(fb_mp + location + 1) = color->g; /* Green */
	*(fb_mp + location) = color->b;     /* Blue */

	return;
}


void
fb_set_text_color(fb_color_t *color)
{
	memcpy(&fb_text_color, color, sizeof(fb_color_t));
	return;	
}


void
fb_set_back_color(fb_color_t *color)
{
	memcpy(&fb_back_color, color, sizeof(fb_color_t));
	return;	
}


static void
draw_char(int x, int y, const char *led_set)
{
	int i, j;

	for (i=0; i<NUM_WIDTH; i++)
	{
		for (j=0; j<NUM_HEIGHT; j++)
		{
			if (strchr(led_set, num_map[j][i]))
				fb_pixel(x+i, y+j, &fb_text_color);
			else
				fb_pixel(x+i, y+j, &fb_back_color);
		}
	}

	return;
}


int
fb_putc(int x, int y, char c)
{
	int i;
	int pixel_x = x * NUM_WIDTH;
	int pixel_y = y * NUM_HEIGHT;

	for (i=0; num_table[i]; i++)
	{
		if (*num_table[i] == c)
		{
			draw_char(pixel_x, pixel_y, num_table[i]+1);
			break;
		}
	}
	
	if (num_table[i])
		return (int)c;
	else
	{
		printf("fb_putc: no font infomation for '%c'.\n", c);
		return -1;
	}
}


int
fb_puts(int x, int y, const char *str)
{
	int i;
	int ret = 0;

	assert(str);
	for (i=0; str[i]; i++, x++)
		if (fb_putc(x, y, str[i]) == -1)
			ret = -1;

	if (ret = -1)
		return ret;
	else
		return i;
}