/*****************************************************************************
* This example program opens the RS Media's LCD (/dev/fb0), by mmap it into 
* memory, and then basically cycles back and forth through the different 16bit 
* colours
*
* Written by Nocturnal (Nocturnal@verbicide.com)
* http://www.evosapien.com/robosapien-hack/nocturnal2/
*****************************************************************************/

#define SIZE 23232 // Framebuffer size
#define FBSIZE SIZE * 2 // Framebuffer size in bytes

#include <stdio.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <fcntl.h>
#include <unistd.h>

int main() {
   int i=0;
   int fb0; // file decscriptor for the /dev/fb0 file
   unsigned short *lcd; // pointer for the mmap'ed lcd
   unsigned short colour=0; // current colour
   unsigned short red=0, green=0, blue=0; // place to store the colours
   int pos=0; // current position;

   // Open the framebuffer file /dev/fb0
//   if (fb0 = open("/dev/fb0", O_RDWR) == -1) {
   fb0 = open("/dev/fb0", O_RDWR);
   if (fb0 == -1) {
      perror("Failed to open /dev/fb0");
      exit(1);
   }

   // mmap the framebuffer device file
   lcd = (unsigned short *)mmap((caddr_t)0, FBSIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fb0, 0);
   if (lcd == NULL) {
      perror("Failed to mmap() /dev/fb0");
      exit(1);
   }

   // Loop for a while, constantly changing the LCD colour
   while (i < 65535) {
      i++;
      if ((red == 0) && (green == 0) && (blue < 0x1f)) {
         blue++;
      } else if ((blue == 0x1f) && (green < 0x3f) && (red == 0)) {
         green++;
      } else if ((green == 0x3f) && (blue > 0) && (red == 0)) {
         blue--;
      } else if ((green == 0x3f) && (red < 0x1f) && (blue == 0)) {
         red++;
      } else if ((red == 0x1f) && (green > 0) && (blue == 0)) {
         green--;
      } else if ((red == 0x1f) && (blue < 0x1f) && (green == 0)) {
         blue++;
      } else if ((blue == 0x1f) && (red > 0) && (green == 0)) {
         red--;
      } 
      
      // add the red, green and blue components to get the current colour
      colour = (green & 0x3F) << 5;
      colour |= red << 11;
      colour |= blue & 0x1F;


      // Loop forward through the colours
      for (pos=0; pos < SIZE; pos++) { // loop all pixels
         lcd[pos] = colour; // set the pixel colour
      }
      fsync(fb0); // sync the lcd
      usleep(100); // sleep for a little while
   }
}