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//#include "halfix/plugindev.h"

//Typedefs
typedef unsigned char byte;
typedef unsigned short word;
typedef unsigned int dword;

typedef signed char sbyte;
typedef signed short sword;
typedef signed int sdword;

//Defines
#define SUCCESS 1
#define FAILURE 0
#define NULL    (void*)0

//Utils
byte strncmp(byte *a_string1, byte *a_string2, dword a_len)
{
  dword _count=0;
  
  while(_count<a_len)
  {
    if(a_string1[_count] != a_string2[_count])
    {
      return FAILURE;
    }
    _count++;
  }
  
  return SUCCESS;
}

//DEBUG.inc variables
word *pdebug;
byte debug_x;
byte debug_y;
byte debug_color;

//DEBUG.inc functions
byte debug_init()
{
  debug_color=0x7;
  debug_x=0;
  debug_y=0;
  pdebug=(word*)0xB8000;
  
  return SUCCESS;
}

void debug_clear()
{
  dword _count=0;
  
  while(_count<(80*25))
  {
    pdebug[_count]=(byte)' ' | (debug_color<<8);
    
    _count++;
  }
  
  debug_x=0;
  debug_y=0;
}

void debug_next()
{
  if(debug_y>=25)
  {
    debug_clear();
  }
  else
  {
    debug_x=0;
    debug_y++;
  }
}

void debug_write(byte *a_string)
{
  dword _count=0;
  
  while(a_string[_count]!='\0')
  {
    if(debug_x >= 80)
    {
      debug_x=0;
      
      if(debug_y>=25)
      {
        debug_clear();
      }
      else
      {
        debug_y++;
      }
    }
    
    pdebug[debug_y*80+debug_x]=(byte)a_string[_count] | (debug_color<<8);
    
    debug_x++;
    _count++;
  }
}

//VESA.inc structures
//Note, gotten from VESA.org docs, not my structs
typedef struct VESA_PMID
{
  byte pmid[4];        //PM Info Block Signature
  dword entry;         //Offset of PM entry point within BIOS
  dword PMInitialize;  //Offset of PM initialization entry point
  dword BIOSDataSel;   //Selector to BIOS data area emulation block
  dword A0000Sel;      //Selector to access A0000h physical mem
  dword B0000Sel;      //Selector to access B0000h physical mem
  dword B8000Sel;      //Selector to access B8000h physical mem
  dword CodeSegSel;    //Selector to access code segment as data
  byte InProtectMode; //Set to 1 when in protected mode
  byte Checksum;       //Checksum byte for structure
} VESA_PMID;

//VESA.inc variables
VESA_PMID *pvesa_pmid=NULL;
//byte *pbiosdatasel=NULL;

//VESA.inc functions
byte vesa_crc(VESA_PMID *a_pmid)
{
  byte *_pvesacrc=(byte*)a_pmid;
  byte _CRC=0;
  word _total=sizeof(VESA_PMID);
  
  while(_total>0)
  {
    _CRC+=*_pvesacrc;
    _pvesacrc++;  //Prev9999: pointer bug fixed
    
    _total--;
  }
  
  if(_CRC != 0)
  {
    return FAILURE;
  }  
  else
  {
    return SUCCESS;
  }
}

byte vesa_init()
{
  byte *_pvideo=(byte*)0xC0000;
  dword _size=0;
  dword _count=0;
  
  if((_pvideo[0] != 0x55) || (_pvideo[1] != 0xAA))
  {
    debug_write("Failed to find VIDEO ID 1"); debug_next();
    
    return FAILURE;
  }
  
  debug_write("Found VIDEO ID 1"); debug_next();
  
  _size=_pvideo[2]*512;
  
  vesa_init_continue:
  while(_count<_size)
  {
    if(strncmp("PMID", _pvideo, 4) == SUCCESS)
    {
      debug_write("Found VIDEO ID 2"); debug_next();
      
      //Here it really begins
      pvesa_pmid=(VESA_PMID*)0xC0000+_count;
      
      //Attempt the VESA checksum
      if(vesa_crc((VESA_PMID*)pvesa_pmid) == FAILURE)
      {
        debug_write("VIDEO ID 2 was a false alarm"); debug_next();
        debug_write("Or, the programmer screwed up"); debug_next();
        debug_write("Continuing the search..."); debug_next();
        
        _count++; //Prevents the same PMID being found
        
        continue;
      }

      debug_write("VIDEO ID 2 was verified, and all systems GO"); debug_next();
      
      //vesa_setup((VESA_PMID*)pvesa_pmid);
      
      return SUCCESS;
    }
    
    *_pvideo++;
    _count++;
  }
  
  debug_write("Failed to find VIDEO ID 2"); debug_next();
  debug_write("Might you be on VMWare or Bochs?"); debug_next();
  debug_write("Also, this only works on newer vesa cards"); debug_next();
}

//MAIN.c functions
void main()
{
  debug_init();
  vesa_init();
  
  debug_write("Please turn off your PC now");
  debug_next();
}