linux下直接寫framebuffer（轉）

 #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 <unistd.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
int main()
{
 int i =0;
 FBDEV fbdev;
 printf("hello my framebuffer world/n");
        memset(&fbdev, 0, sizeof(FBDEV));
 strcpy(fbdev.dev,  "/dev/fb0");
 if (fb_open(&fbdev) == FALSE)
 {
      printf(  "open frame buffer error/n");
             return 0;
 }

 //fb_memset(fbdev.fb_mem + fbdev.fb_mem_offset, 0, fbdev.fb_fix.smem_len);
       fb_memset((void *)(fbdev.fb_mem+fbdev.fb_mem_offset), 100, fbdev.fb_fix.smem_len);
       sleep(10);
        for(i=0;i<  fbdev.fb_fix.smem_len;i++)
        {
            //printf("fill buffer i =%d/n",i);
            *(unsigned char *)(fbdev.fb_mem + fbdev.fb_mem_offset + i)= i%255;
        }

 fb_close(&fbdev);
        printf("goodbye  my framebuffer world/n");
       return 0;
}
#endif