#include "../copyright"

#include "seta.h"
#include "memmap.h"

ST018_Regs ST018;

static int line;  // line counter

uint8_t S9xGetST018(uint32_t Address)
{
   uint8_t t = 0; // Initialise to some value for the compiler
   uint16_t address = (uint16_t) Address & 0xFFFF;

   line++;

   // these roles may be flipped
   // op output
   if (address == 0x3804)
   {
      if (ST018.out_count)
      {
         t = (uint8_t) ST018.output [ST018.out_index];
         ST018.out_index++;
         if (ST018.out_count == ST018.out_index)
            ST018.out_count = 0;
      }
      else
         t = 0x81;
   }
   // status register
   else if (address == 0x3800)
      t = ST018.status;

   printf("ST018 R: %06X %02X\n", Address, t);

   return t;
}

void S9xSetST018(uint8_t Byte, uint32_t Address)
{
   uint16_t address = (uint16_t) Address & 0xFFFF;
   static bool reset = false;

   printf("ST018 W: %06X %02X\n", Address, Byte);

   line++;

   if (!reset)
   {
      // bootup values
      ST018.waiting4command = true;
      ST018.part_command = 0;
      reset = true;
   }

   Memory.SRAM[address] = Byte;

   // default status for now
   ST018.status = 0x00;

   // op data goes through this address
   if (address == 0x3804)
   {
      // check for new commands: 3 bytes length
      if (ST018.waiting4command && ST018.part_command == 2)
      {
         ST018.waiting4command = false;
         ST018.command <<= 8;
         ST018.command |= Byte;
         ST018.in_index = 0;
         ST018.out_index = 0;
         ST018.part_command = 0; // 3-byte commands
         ST018.pass = 0;   // data streams into the chip
         switch (ST018.command & 0xFFFFFF)
         {
         case 0x0100:
            ST018.in_count = 0;
            break;
         case 0xFF00:
            ST018.in_count = 0;
            break;
         default:
            ST018.waiting4command = true;
            break;
         }
      }
      else if (ST018.waiting4command)
      {
         // 3-byte commands
         ST018.part_command++;
         ST018.command <<= 8;
         ST018.command |= Byte;
      }
   }
   // extra parameters
   else if (address == 0x3802)
   {
      ST018.parameters[ST018.in_index] = Byte;
      ST018.in_index++;
   }

   if (ST018.in_count == ST018.in_index)
   {
      // Actually execute the command
      ST018.waiting4command = true;
      ST018.in_index = 0;
      ST018.out_index = 0;
      switch (ST018.command)
      {
      // hardware check?
      case 0x0100:
      case 0xFF00:
         ST018.waiting4command = false;
         ST018.pass++;
         if (ST018.pass == 1)
         {
            ST018.in_count = 1;
            ST018.out_count = 2;

            // Overload's research
            ST018.output[0x00] = 0x81;
            ST018.output[0x01] = 0x81;
         }
         else
         {
            ST018.out_count = 3;
            ST018.output[0x02] = 0x81;

            // done processing requests
            if (ST018.pass == 3)
               ST018.waiting4command = true;
         }
         break;
      }
   }
}