fbuffer.c

帧缓冲#include <stdio.h> #include <stdlib.h> #include <string.h> #include <s

  #include <stdio.h>
       #include <stdlib.h>
       #include <string.h>
      #include <stdint.h>
      #include <unistd.h>
       #include <fcntl.h>
       #include <sys/ioctl.h>
       #include <sys/mman.h>
      #include <asm/page.h>
      #include <linux/fb.h>
    
      #define TRUE    1
      #define FALSE   2
    
      //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;
    
      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:%ld offset:%ld\n", pFbdev->fb_mem, 
                      pFbdev->fb_mem_offset);
              return FALSE;
          }
   
          return TRUE;
     }
   
      void fb_close(PFBDEV pFbdev)
      {
          close(pFbdev->fb);
        pFbdev->fb=-1;
     }
   
      void fb_memset (void *addr, int c, size_t len)
      {
          memset(addr, c, len);
      }
    
      void draw_dot (PFBDEV pFbdev, uint32_t x, uint32_t y, uint8_t r, uint8_t g, uint8_t b)
      {
         unsigned int offset;
         if (-1L == (long) pFbdev->fb_mem) 
        {
           printf("mmap error! mem:%ld offset:%ld\n", pFbdev->fb_mem, 
                      pFbdev->fb_mem_offset);
             return;
          }
          offset = y*pFbdev->fb_fix.line_length+4*x;
         fb_memset((void*)(pFbdev->fb_mem + pFbdev->fb_mem_offset + offset), b, 1);
        fb_memset((void*)(pFbdev->fb_mem + pFbdev->fb_mem_offset + offset + 1), g, 1);
          fb_memset((void*)(pFbdev->fb_mem + pFbdev->fb_mem_offset + offset + 2), r, 1);
          fb_memset((void*)(pFbdev->fb_mem + pFbdev->fb_mem_offset + offset + 3), 0x00, 1);
      }
    
      int main(void)
      {
          FBDEV fb;
          memset(&fb, 0, sizeof(FBDEV));
          strcpy(fb.dev, "/dev/fb0");
          if(fb_open(&fb)==FALSE)
         {
              printf("open frame buffer error\n");
            return 0;
         }
    
         printf("depth(bits per pixel) =  %d\n",fb.fb_var.bits_per_pixel);
          printf("smemlen = %d\n",fb.fb_fix.smem_len);
         printf("fix_line(in byte) = %d\n",fb.fb_fix.line_length);
  
         int i,j;
         for(i=100; i<300; ++i)
                 for(j = 80;j<100;++j)
                {
                         draw_dot(&fb,i,j,0xff,0x00,0x0);
                 }
  
         fb_close(&fb);
        return 0;
     }