/******************************************************************************/
/* Mednafen Sega Saturn Emulation Module                                      */
/******************************************************************************/
/* keyboard.cpp:
**  Copyright (C) 2017 Mednafen Team
**
** This program is free software; you can redistribute it and/or
** modify it under the terms of the GNU General Public License
** as published by the Free Software Foundation; either version 2
** of the License, or (at your option) any later version.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
** GNU General Public License for more details.
**
** You should have received a copy of the GNU General Public License
** along with this program; if not, write to the Free Software Foundation, Inc.,
** 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
*/

// TODO: Debouncing?

//
// PS/2 keyboard adapter seems to do PS/2 processing near/at the end of a Saturn-side read sequence, which creates about 1 frame of extra latency
// in practice.  We handle things a bit differently here, to avoid the latency.
//
// Also, the PS/2 adapter seems to set the typematic delay to around 250ms, but we emulate it here as 400ms, as 250ms is
// a tad bit too short.  It can be changed to 250ms by adjusting a single #if statement, though.
//
// During testing, a couple of early-1990s PS/2 keyboards malfunctioned and failed to work with the PS/2 adapter.
// Not sure why, maybe a power draw issue?
//
// The keyboard emulated doesn't have special Windows-keyboard keys, as they don't appear to work correctly with the PS/2 adapter
// (scancode field is updated, but no make nor break bits are set to 1), and it's good to have some non-shared keys for input grabbing toggling purposes...
//
//

// make and break bits should not both be set to 1 at the same time.
// pause is special
// new key press halts repeat of held key, and it doesn't restart even if new key is released.
//

#include "common.h"
#include "keyboard.h"

namespace MDFN_IEN_SS
{

IODevice_Keyboard::IODevice_Keyboard() : phys{0,0,0,0}
{

}

IODevice_Keyboard::~IODevice_Keyboard()
{

}

void IODevice_Keyboard::Power(void)
{
 phase = -1;
 tl = true;
 data_out = 0x01;

 simbutt = simbutt_pend = 0;
 lock = lock_pend = 0;

 mkbrk_pend = 0;
 memset(buffer, 0, sizeof(buffer));

 //memcpy(processed, phys, sizeof(processed));
 memset(processed, 0, sizeof(processed));
 memset(fifo, 0, sizeof(fifo));
 fifo_rdp = 0;
 fifo_wrp = 0;
 fifo_cnt = 0;

 rep_sc = -1;
 rep_dcnt = 0;
}

void IODevice_Keyboard::UpdateInput(const uint8* data, const int32 time_elapsed)
{
 phys[0] = MDFN_de64lsb(&data[0x00]);
 phys[1] = MDFN_de64lsb(&data[0x08]);
 phys[2] = MDFN_de16lsb(&data[0x10]);
 phys[3] = 0;
 //
 if(rep_dcnt > 0)
  rep_dcnt -= time_elapsed;

 for(unsigned i = 0; i < 4; i++)
 {
  uint64 tmp = phys[i] ^ processed[i];
  unsigned bp;

  while((bp = (63 ^ MDFN_lzcount64(tmp))) < 64)
  {
   const uint64 mask = ((uint64)1 << bp);
   const int sc = ((i << 6) + bp);

   if(fifo_cnt >= (fifo_size - (sc == 0x82)))
    goto fifo_oflow_abort;

   if(phys[i] & mask)
   {
    rep_sc = sc;
#if 1
    rep_dcnt = 400000;
#else
    rep_dcnt = 250000;
#endif
    fifo[fifo_wrp] = 0x800 | sc;
    fifo_wrp = (fifo_wrp + 1) % fifo_size;
    fifo_cnt++;
   }

   if(!(phys[i] & mask) == (sc != 0x82))
   {
    if(rep_sc == sc)
     rep_sc = -1;

    fifo[fifo_wrp] = 0x100 | sc;
    fifo_wrp = (fifo_wrp + 1) % fifo_size;
    fifo_cnt++;
   }

   processed[i] = (processed[i] & ~mask) | (phys[i] & mask);
   tmp &= ~mask;
  }
 }

 if(rep_sc >= 0)
 {
  while(rep_dcnt <= 0)
  {
   if(fifo_cnt >= fifo_size)
    goto fifo_oflow_abort;

   fifo[fifo_wrp] = 0x800 | rep_sc;
   fifo_wrp = (fifo_wrp + 1) % fifo_size;
   fifo_cnt++;

   rep_dcnt += 33333;
  }
 }

 fifo_oflow_abort:;
}

void IODevice_Keyboard::UpdateOutput(uint8* data)
{
 data[0x12] = lock;
}

uint8 IODevice_Keyboard::UpdateBus(const uint8 smpc_out, const uint8 smpc_out_asserted)
{
 if(smpc_out & 0x40)
 {
  phase = -1;
  tl = true;
  data_out = 0x01;
 }
 else
 {
  if((bool)(smpc_out & 0x20) != tl)
  {
   tl = !tl;
   phase += (phase < 11);

   if(!phase)
   {
    if(mkbrk_pend == (uint8)mkbrk_pend && fifo_cnt)
    {
     mkbrk_pend = fifo[fifo_rdp];
     fifo_rdp = (fifo_rdp + 1) % fifo_size;
     fifo_cnt--;

     bool p = mkbrk_pend & 0x800;

     switch(mkbrk_pend & 0xFF)
     {
      case 0x89: /*  Up */ simbutt_pend = simbutt & ~(1 <<  0); simbutt_pend &= ~(p <<  1); simbutt_pend |= (p <<  0); break;
      case 0x8A: /*Down */ simbutt_pend = simbutt & ~(1 <<  1); simbutt_pend &= ~(p <<  0); simbutt_pend |= (p <<  1); break;
      case 0x86: /*Left */ simbutt_pend = simbutt & ~(1 <<  2); simbutt_pend &= ~(p <<  3); simbutt_pend |= (p <<  2); break;
      case 0x8D: /*Right*/ simbutt_pend = simbutt & ~(1 <<  3); simbutt_pend &= ~(p <<  2); simbutt_pend |= (p <<  3); break;
      case 0x22: /*   X */ simbutt_pend = simbutt & ~(1 <<  4); simbutt_pend |= (p <<  4); break;
      case 0x21: /*   C */ simbutt_pend = simbutt & ~(1 <<  5); simbutt_pend |= (p <<  5); break;
      case 0x1A: /*   Z */ simbutt_pend = simbutt & ~(1 <<  6); simbutt_pend |= (p <<  6); break;
      case 0x76: /* Esc */ simbutt_pend = simbutt & ~(1 <<  7); simbutt_pend |= (p <<  7); break;
      case 0x23: /*   D */ simbutt_pend = simbutt & ~(1 <<  8); simbutt_pend |= (p <<  8); break;
      case 0x1B: /*   S */ simbutt_pend = simbutt & ~(1 <<  9); simbutt_pend |= (p <<  9); break;
      case 0x1C: /*   A */ simbutt_pend = simbutt & ~(1 << 10); simbutt_pend |= (p << 10); break;
      case 0x24: /*   E */ simbutt_pend = simbutt & ~(1 << 11); simbutt_pend |= (p << 11); break;
      case 0x15: /*   Q */ simbutt_pend = simbutt & ~(1 << 15); simbutt_pend |= (p << 15); break;

      case 0x7E: /* Scrl */ lock_pend = lock ^ (p ? LOCK_SCROLL : 0); break;
      case 0x77: /* Num  */ lock_pend = lock ^ (p ? LOCK_NUM : 0);    break;
      case 0x58: /* Caps */ lock_pend = lock ^ (p ? LOCK_CAPS : 0);   break;
     }
    }
    buffer[ 0] = 0x3;
    buffer[ 1] = 0x4;
    buffer[ 2] = (((simbutt_pend >>  0) ^ 0xF) & 0xF);
    buffer[ 3] = (((simbutt_pend >>  4) ^ 0xF) & 0xF);
    buffer[ 4] = (((simbutt_pend >>  8) ^ 0xF) & 0xF);
    buffer[ 5] = (((simbutt_pend >> 12) ^ 0xF) & 0x8) | 0x0;
    buffer[ 6] = lock_pend;
    buffer[ 7] = ((mkbrk_pend >> 8) & 0xF) | 0x6;
    buffer[ 8] =  (mkbrk_pend >> 4) & 0xF;
    buffer[ 9] =  (mkbrk_pend >> 0) & 0xF;
    buffer[10] = 0x0;
    buffer[11] = 0x1;
   }

   if(phase == 9)
   {
    mkbrk_pend = (uint8)mkbrk_pend;
    lock = lock_pend;
    simbutt = simbutt_pend;
   }

   data_out = buffer[phase];
  }
 }

 return (smpc_out & (smpc_out_asserted | 0xE0)) | (((tl << 4) | data_out) &~ smpc_out_asserted);
}

}