Linux操作系统下使用FrameBuffer直接写屏

#ifndef _FBTOOLS_H_
#define _FBTOOLS_H_

#include <linux/fb.h>

/* a framebuffer device structure */
typedef struct fbdev{
int fb;
unsigned long fb_mem_offset;
unsigned long fb_mem;
struct fb_fix_screeninfo fb_fix;
struct fb_var_screeninfo fb_var;
char dev[20];
} FBDEV, *PFBDEV;

/* open & init a frame buffer */
/* to use this function,
you must set FBDEV.dev="/dev/fb0"
or "/dev/fbX" */
/* it's your frame buffer. */
int fb_open(PFBDEV pFbdev);

/*close a frame buffer*/
int fb_close(PFBDEV pFbdev);

/*get display depth*/
int get_display_depth(PFBDEV pFbdev);


/*full screen clear */
void fb_memset(void *addr, int c, size_t len);

#endif


#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <asm/page.h>

#include "fbtools.h"

#define TRUE 1
#define FALSE 0
#define MAX(x,y) ((x)>(y)?(x):(y))
#define MIN(x,y) ((x)<(y)?(x):(y))

/* open & init a frame buffer */
int fb_open(PFBDEV pFbdev)
{
pFbdev->fb = open(pFbdev->dev, O_RDWR);
if(pFbdev->fb < 0)
{
printf("Error opening %s: %m. Check kernel config\n", pFbdev->dev);
return FALSE;
}
if (-1 == ioctl(pFbdev->fb,FBIOGET_VSCREENINFO,&(pFbdev->fb_var)))
{
printf("ioctl FBIOGET_VSCREENINFO\n");
return FALSE;
}
if (-1 == ioctl(pFbdev->fb,FBIOGET_FSCREENINFO,&(pFbdev->fb_fix)))
{
printf("ioctl FBIOGET_FSCREENINFO\n");
return FALSE;
}

/*map physics address to virtual address */
pFbdev->fb_mem_offset = (unsigned long)(pFbdev->fb_fix.smem_start) & (~PAGE_MASK);
pFbdev->fb_mem = (unsigned long int)mmap(NULL, pFbdev->fb_fix.smem_len +
pFbdev->fb_mem_offset,
PROT_READ | PROT_WRITE, MAP_SHARED, pFbdev->fb, 0);
if (-1L == (long) pFbdev->fb_mem)
{
printf("mmap error! mem:%d offset:%d\n", pFbdev->fb_mem,
pFbdev->fb_mem_offset);
return FALSE;
}

return TRUE;
}

/* close frame buffer */
int fb_close(PFBDEV pFbdev)
{
close(pFbdev->fb);
pFbdev->fb=-1;
}

/* get display depth */
int get_display_depth(PFBDEV pFbdev);
{
if(pFbdev->fb<=0)
{
printf("fb device not open, open it first\n");
return FALSE;
}
return pFbdev->fb_var.bits_per_pixel;
}

/* full screen clear */
void fb_memset (void *addr, int c, size_t len)
{
memset(addr, c, len);
}

/* use by test */
#define DEBUG
#ifdef DEBUG
main()
{
FBDEV fbdev;
memset(&fbdev, 0, sizeof(FBDEV));
strcpy(fbdev.dev, "/dev/fb0");
if(fb_open(&fbdev)==FALSE)
{
printf("open frame buffer error\n");
return;
}

fb_memset(fbdev.fb_mem + fbdev.fb_mem_offset, 0, fbdev.fb_fix.smem_len);

fb_close(&fbdev);
}