path: root/src/sa1.c

/*
 * Snes9x - Portable Super Nintendo Entertainment System (TM) emulator.
 *
 * (c) Copyright 1996 - 2001 Gary Henderson (gary.henderson@ntlworld.com) and
 *                           Jerremy Koot (jkoot@snes9x.com)
 *
 * Super FX C emulator code
 * (c) Copyright 1997 - 1999 Ivar (ivar@snes9x.com) and
 *                           Gary Henderson.
 * Super FX assembler emulator code (c) Copyright 1998 zsKnight and _Demo_.
 *
 * DSP1 emulator code (c) Copyright 1998 Ivar, _Demo_ and Gary Henderson.
 * C4 asm and some C emulation code (c) Copyright 2000 zsKnight and _Demo_.
 * C4 C code (c) Copyright 2001 Gary Henderson (gary.henderson@ntlworld.com).
 *
 * (c) Copyright 2014 - 2016 Daniel De Matteis. (UNDER NO CIRCUMSTANCE 
 * WILL COMMERCIAL RIGHTS EVER BE APPROPRIATED TO ANY PARTY)
 *
 * DOS port code contains the works of other authors. See headers in
 * individual files.
 *
 * Snes9x homepage: http://www.snes9x.com
 *
 * Permission to use, copy, modify and distribute Snes9x in both binary and
 * source form, for non-commercial purposes, is hereby granted without fee,
 * providing that this license information and copyright notice appear with
 * all copies and any derived work.
 *
 * This software is provided 'as-is', without any express or implied
 * warranty. In no event shall the authors be held liable for any damages
 * arising from the use of this software.
 *
 * Snes9x is freeware for PERSONAL USE only. Commercial users should
 * seek permission of the copyright holders first. Commercial use includes
 * charging money for Snes9x or software derived from Snes9x.
 *
 * The copyright holders request that bug fixes and improvements to the code
 * should be forwarded to them so everyone can benefit from the modifications
 * in future versions.
 *
 * Super NES and Super Nintendo Entertainment System are trademarks of
 * Nintendo Co., Limited and its subsidiary companies.
 */

#ifdef USE_SA1

#include "snes9x.h"
#include "ppu.h"
#include "cpuexec.h"

#include "sa1.h"

static void S9xSA1CharConv2();
static void S9xSA1DMA();
static void S9xSA1ReadVariableLengthData(bool8 inc, bool8 no_shift);

void S9xSA1Init()
{
   SA1.NMIActive = FALSE;
   SA1.IRQActive = FALSE;
   SA1.WaitingForInterrupt = FALSE;
   SA1.Waiting = FALSE;
   SA1.Flags = 0;
   SA1.Executing = FALSE;
   memset(&Memory.FillRAM [0x2200], 0, 0x200);
   Memory.FillRAM [0x2200] = 0x20;
   Memory.FillRAM [0x2220] = 0x00;
   Memory.FillRAM [0x2221] = 0x01;
   Memory.FillRAM [0x2222] = 0x02;
   Memory.FillRAM [0x2223] = 0x03;
   Memory.FillRAM [0x2228] = 0xff;
   SA1.op1 = 0;
   SA1.op2 = 0;
   SA1.arithmetic_op = 0;
   SA1.sum = 0;
   SA1.overflow = FALSE;
}

void S9xSA1Reset()
{
   SA1Registers.PB = 0;
   SA1Registers.PC = Memory.FillRAM [0x2203] |
                     (Memory.FillRAM [0x2204] << 8);
   SA1Registers.D.W = 0;
   SA1Registers.DB = 0;
   SA1Registers.SH = 1;
   SA1Registers.SL = 0xFF;
   SA1Registers.XH = 0;
   SA1Registers.YH = 0;
   SA1Registers.P.W = 0;

   SA1.ShiftedPB = 0;
   SA1.ShiftedDB = 0;
   SA1SetFlags(MemoryFlag | IndexFlag | IRQ | Emulation);
   SA1ClearFlags(Decimal);

   SA1.WaitingForInterrupt = FALSE;
   SA1.PC = NULL;
   SA1.PCBase = NULL;
   S9xSA1SetPCBase(SA1Registers.PC);
   SA1.S9xOpcodes = S9xSA1OpcodesM1X1;

   S9xSA1UnpackStatus();
   S9xSA1FixCycles();
   SA1.Executing = TRUE;
   SA1.BWRAM = Memory.SRAM;
   Memory.FillRAM [0x2225] = 0;
}

void S9xSA1SetBWRAMMemMap(uint8 val)
{
   int c;

   if (val & 0x80)
   {
      for (c = 0; c < 0x400; c += 16)
      {
         SA1_Map [c + 6] = SA1_Map [c + 0x806] = (uint8*) MAP_BWRAM_BITMAP2;
         SA1_Map [c + 7] = SA1_Map [c + 0x807] = (uint8*) MAP_BWRAM_BITMAP2;
         SA1_WriteMap [c + 6] = SA1_WriteMap [c + 0x806] = (uint8*) MAP_BWRAM_BITMAP2;
         SA1_WriteMap [c + 7] = SA1_WriteMap [c + 0x807] = (uint8*) MAP_BWRAM_BITMAP2;
      }
      SA1.BWRAM = Memory.SRAM + (val & 0x7f) * 0x2000 / 4;
   }
   else
   {
      for (c = 0; c < 0x400; c += 16)
      {
         SA1_Map [c + 6] = SA1_Map [c + 0x806] = (uint8*) MAP_BWRAM;
         SA1_Map [c + 7] = SA1_Map [c + 0x807] = (uint8*) MAP_BWRAM;
         SA1_WriteMap [c + 6] = SA1_WriteMap [c + 0x806] = (uint8*) MAP_BWRAM;
         SA1_WriteMap [c + 7] = SA1_WriteMap [c + 0x807] = (uint8*) MAP_BWRAM;
      }
      SA1.BWRAM = Memory.SRAM + (val & 7) * 0x2000;
   }
}

void S9xFixSA1AfterSnapshotLoad()
{
   SA1.ShiftedPB = (uint32) SA1Registers.PB << 16;
   SA1.ShiftedDB = (uint32) SA1Registers.DB << 16;

   S9xSA1SetPCBase(SA1.ShiftedPB + SA1Registers.PC);
   S9xSA1UnpackStatus();
   S9xSA1FixCycles();
   SA1.VirtualBitmapFormat = (Memory.FillRAM [0x223f] & 0x80) ? 2 : 4;
   Memory.BWRAM = Memory.SRAM + (Memory.FillRAM [0x2224] & 7) * 0x2000;
   S9xSA1SetBWRAMMemMap(Memory.FillRAM [0x2225]);

   SA1.Waiting = (Memory.FillRAM [0x2200] & 0x60) != 0;
   SA1.Executing = !SA1.Waiting;
}

// SA9xSA1GetByte --- begin
static uint8 S9xSA1GetByte_default(uint32 address)
{
#ifdef DEBUGGER
   // printf ("R(B) %06x\n", address);
#endif
   return (0);
}
static uint8 S9xSA1GetByte_PPU(uint32 address)
{
   return (S9xGetSA1(address & 0xffff));
}
static uint8 S9xSA1GetByte_SA1RAM(uint32 address)
{
   return (*(Memory.SRAM + (address & 0xffff)));
}
static uint8 S9xSA1GetByte_BWRAM(uint32 address)
{
   return (*(SA1.BWRAM + ((address & 0x7fff) - 0x6000)));
}
static uint8 S9xSA1GetByte_BWRAM_BITMAP(uint32 address)
{
   address -= 0x600000;
   if (SA1.VirtualBitmapFormat == 2)
      return ((Memory.SRAM [(address >> 2) & 0xffff] >> ((address & 3) << 1)) & 3);
   else
      return ((Memory.SRAM [(address >> 1) & 0xffff] >> ((address & 1) << 2)) & 15);
}
static uint8 S9xSA1GetByte_BWRAM_BITMAP2(uint32 address)
{
   address = (address & 0xffff) - 0x6000;
   if (SA1.VirtualBitmapFormat == 2)
      return ((SA1.BWRAM [(address >> 2) & 0xffff] >> ((address & 3) << 1)) & 3);
   else
      return ((SA1.BWRAM [(address >> 1) & 0xffff] >> ((address & 1) << 2)) & 15);
}

// GetByte JumpTable for Memmory map modes
uint8(*S9xSA1GetByte_JumpTable[(1 << (16 - 12))])(uint32 address) =
{
   S9xSA1GetByte_PPU, // MAP_PPU
   S9xSA1GetByte_default, // MAP_CPU
   S9xSA1GetByte_default, // MAP_DSP
   S9xSA1GetByte_SA1RAM, // MAP_LOROM_SRAM
   S9xSA1GetByte_default, // MAP_HIROM_SRAM
   S9xSA1GetByte_default, // MAP_NONE
   S9xSA1GetByte_default, // MAP_DEBUG
   S9xSA1GetByte_default, // MAP_C4
   S9xSA1GetByte_BWRAM, // MAP_BWRAM
   S9xSA1GetByte_BWRAM_BITMAP, // MAP_BWRAM_BITMAP
   S9xSA1GetByte_BWRAM_BITMAP2, // MAP_BWRAM_BITMAP2
   S9xSA1GetByte_SA1RAM, // MAP_SA1RAM
   S9xSA1GetByte_default, // MAP_LAST
   S9xSA1GetByte_default, // MAP_LAST+1
   S9xSA1GetByte_default, // MAP_LAST+2
   S9xSA1GetByte_default  // MAP_LAST+3
};

uint8 S9xSA1GetByte(uint32 address)
{
   uint8* GetAddress = SA1_Map [(address >> MEMMAP_SHIFT) & MEMMAP_MASK];
   if (GetAddress >= (uint8*) MAP_LAST) return (*(GetAddress + (address & 0xffff)));
   return S9xSA1GetByte_JumpTable[(intptr_t) GetAddress](address);
   // return (SA1_Map [(address >> MEMMAP_SHIFT) & MEMMAP_MASK] >= (uint8 *)MAP_LAST) ?
   //    (*((uint8 *)(SA1_Map [(address >> MEMMAP_SHIFT) & MEMMAP_MASK]) + (address & 0xffff))) :
   //    S9xSA1GetByte_JumpTable[(int) SA1_Map [(address >> MEMMAP_SHIFT) & MEMMAP_MASK]](address);
}

/*
uint16 S9xSA1GetWord (uint32 address)
{
    uint8 *GetAddress = SA1_Map [(address >> MEMMAP_SHIFT) & MEMMAP_MASK];
    if (GetAddress >= (uint8 *) MAP_LAST)
   return (*(GetAddress + (address & 0xffff))) | ((*(GetAddress + ((address+1) & 0xffff))) << 8);
    return (S9xSA1GetByte_JumpTable[(int) GetAddress](address)) | ((S9xSA1GetByte_JumpTable[(int) GetAddress](address+1)) << 8);
}
*/
// SA9xSA1SetByte --- begin
static void S9xSA1SetByte_default(uint8 byte, uint32 address)
{
}
static void S9xSA1SetByte_PPU(uint8 byte, uint32 address)
{
   S9xSetSA1(byte, address & 0xffff);
}
static void S9xSA1SetByte_SA1RAM(uint8 byte, uint32 address)
{
   *(Memory.SRAM + (address & 0xffff)) = byte;
}
static void S9xSA1SetByte_BWRAM(uint8 byte, uint32 address)
{
   *(SA1.BWRAM + ((address & 0x7fff) - 0x6000)) = byte;
}
static void S9xSA1SetByte_BWRAM_BITMAP(uint8 byte, uint32 address)
{
   uint8* ptr;
   address -= 0x600000;
   if (SA1.VirtualBitmapFormat == 2)
   {
      ptr = &Memory.SRAM [(address >> 2) & 0xffff];
      *ptr &= ~(3 << ((address & 3) << 1));
      *ptr |= (byte & 3) << ((address & 3) << 1);
   }
   else
   {
      ptr = &Memory.SRAM [(address >> 1) & 0xffff];
      *ptr &= ~(15 << ((address & 1) << 2));
      *ptr |= (byte & 15) << ((address & 1) << 2);
   }
   address -= 0x600000;
}
static void S9xSA1SetByte_BWRAM_BITMAP2(uint8 byte, uint32 address)
{
   uint8* ptr;
   address = (address & 0xffff) - 0x6000;
   if (SA1.VirtualBitmapFormat == 2)
   {
      ptr = &SA1.BWRAM [(address >> 2) & 0xffff];
      *ptr &= ~(3 << ((address & 3) << 1));
      *ptr |= (byte & 3) << ((address & 3) << 1);
   }
   else
   {
      ptr = &SA1.BWRAM [(address >> 1) & 0xffff];
      *ptr &= ~(15 << ((address & 1) << 2));
      *ptr |= (byte & 15) << ((address & 1) << 2);
   }
}

// SetByte JumpTable for Memmory map modes
void (*S9xSA1SetByte_JumpTable[(1 << (16 - 12))])(uint8 byte, uint32 address) =
{
   S9xSA1SetByte_PPU, // MAP_PPU
   S9xSA1SetByte_default, // MAP_CPU
   S9xSA1SetByte_default, // MAP_DSP
   S9xSA1SetByte_SA1RAM, // MAP_LOROM_SRAM
   S9xSA1SetByte_default, // MAP_HIROM_SRAM
   S9xSA1SetByte_default, // MAP_NONE
   S9xSA1SetByte_default, // MAP_DEBUG
   S9xSA1SetByte_default, // MAP_C4
   S9xSA1SetByte_BWRAM, // MAP_BWRAM
   S9xSA1SetByte_BWRAM_BITMAP, // MAP_BWRAM_BITMAP
   S9xSA1SetByte_BWRAM_BITMAP2, // MAP_BWRAM_BITMAP2
   S9xSA1SetByte_SA1RAM, // MAP_SA1RAM
   S9xSA1SetByte_default, // MAP_LAST
   S9xSA1SetByte_default, // MAP_LAST+1
   S9xSA1SetByte_default, // MAP_LAST+2
   S9xSA1SetByte_default  // MAP_LAST+3
};

void S9xSA1SetByte(uint8 byte, uint32 address)
{
   // MEMMAP_SHIFT 12
   // MEMMAP_MASK 0xFFF

   uint8* Setaddress = SA1_WriteMap [(address >> MEMMAP_SHIFT) & MEMMAP_MASK];
   if (Setaddress >= (uint8*) MAP_LAST)
   {
      *(Setaddress + (address & 0xffff)) = byte;
      return;
   }
   S9xSA1SetByte_JumpTable[(intptr_t)Setaddress](byte, address);
}

void S9xSA1SetPCBase(uint32 address)
{
   uint8* GetAddress = SA1_Map [(address >> MEMMAP_SHIFT) & MEMMAP_MASK];
   if (GetAddress >= (uint8*) MAP_LAST)
   {
      SA1.PCBase = GetAddress;
      SA1.PC = GetAddress + (address & 0xffff);
      return;
   }

   switch ((intptr_t) GetAddress)
   {
   case MAP_PPU:
      SA1.PCBase = Memory.FillRAM - 0x2000;
      SA1.PC = SA1.PCBase + (address & 0xffff);
      return;

   case MAP_CPU:
      SA1.PCBase = Memory.FillRAM - 0x4000;
      SA1.PC = SA1.PCBase + (address & 0xffff);
      return;

   case MAP_DSP:
      SA1.PCBase = Memory.FillRAM - 0x6000;
      SA1.PC = SA1.PCBase + (address & 0xffff);
      return;

   case MAP_SA1RAM:
   case MAP_LOROM_SRAM:
      SA1.PCBase = Memory.SRAM;
      SA1.PC = SA1.PCBase + (address & 0xffff);
      return;

   case MAP_BWRAM:
      SA1.PCBase = SA1.BWRAM - 0x6000;
      SA1.PC = SA1.PCBase + (address & 0xffff);
      return;
   case MAP_HIROM_SRAM:
      SA1.PCBase = Memory.SRAM - 0x6000;
      SA1.PC = SA1.PCBase + (address & 0xffff);
      return;

   case MAP_DEBUG:
#ifdef DEBUGGER
      printf("SBP %06x\n", address);
#endif

   default:
   case MAP_NONE:
      SA1.PCBase = Memory.RAM;
      SA1.PC = Memory.RAM + (address & 0xffff);
      return;
   }
}

void S9xSA1ExecuteDuringSleep()
{
}

void S9xSetSA1MemMap(uint32 which1, uint8 map)
{
   int c;
   int start = which1 * 0x100 + 0xc00;
   int start2 = which1 * 0x200;
   uint8* block;
   int i;

   if (which1 >= 2)
      start2 += 0x400;

   for (c = 0; c < 0x100; c += 16)
   {
      block = &Memory.ROM [(map & 7) * 0x100000 + (c << 12)];
      for (i = c; i < c + 16; i++)
         Memory.Map [start + i] = SA1_Map [start + i] = block;
   }

   for (c = 0; c < 0x200; c += 16)
   {
      block = &Memory.ROM [(map & 7) * 0x100000 + (c << 11) - 0x8000];
      for (i = c + 8; i < c + 16; i++)
         Memory.Map [start2 + i] = SA1_Map [start2 + i] = block;
   }
}

uint8 S9xGetSA1(uint32 address)
{
   if ((address < 0x2300) && (address > 0x230d))
      return (Memory.FillRAM [address]);

   switch (address)
   {
      case 0x2300:
         return ((uint8)((Memory.FillRAM [0x2209] & 0x5f) |
                  (CPU.IRQActive & (SA1_IRQ_SOURCE | SA1_DMA_IRQ_SOURCE))));
      case 0x2301:
         return ((Memory.FillRAM [0x2200] & 0xf) |
               (Memory.FillRAM [0x2301] & 0xf0));
      case 0x2306:
         return ((uint8)  SA1.sum);
      case 0x2307:
         return ((uint8)(SA1.sum >>  8));
      case 0x2308:
         return ((uint8)(SA1.sum >> 16));
      case 0x2309:
         return ((uint8)(SA1.sum >> 24));
      case 0x230a:
         return ((uint8)(SA1.sum >> 32));
      case 0x230b:
         return (Memory.FillRAM [address]);
      case 0x230c:
         return (Memory.FillRAM [0x230c]);
      case 0x230d:
         {
            uint8 byte = Memory.FillRAM [0x230d];

            if (Memory.FillRAM [0x2258] & 0x80)
               S9xSA1ReadVariableLengthData(TRUE, FALSE);
            return (byte);
         }
   }

   return (Memory.FillRAM [address]);
}

void S9xSetSA1(uint8 byte, uint32 address)
{

   if (address < 0x2200 || address > 0x22ff) return;

   switch (address)
   {
   case 0x2200:
      SA1.Waiting = (byte & 0x60) != 0;

      if (!(byte & 0x20) && (Memory.FillRAM [0x2200] & 0x20))
         S9xSA1Reset();
      if (byte & 0x80)
      {
         Memory.FillRAM [0x2301] |= 0x80;
         if (Memory.FillRAM [0x220a] & 0x80)
         {
            SA1.Flags |= IRQ_PENDING_FLAG;
            SA1.IRQActive |= SNES_IRQ_SOURCE;
            SA1.Executing = !SA1.Waiting && SA1.S9xOpcodes;
         }
      }
      if (byte & 0x10)
         Memory.FillRAM [0x2301] |= 0x10;
      break;

   case 0x2201:
      if (((byte ^ Memory.FillRAM [0x2201]) & 0x80) &&
            (Memory.FillRAM [0x2300] & byte & 0x80))
         S9xSetIRQ(SA1_IRQ_SOURCE);
      if (((byte ^ Memory.FillRAM [0x2201]) & 0x20) &&
            (Memory.FillRAM [0x2300] & byte & 0x20))
         S9xSetIRQ(SA1_DMA_IRQ_SOURCE);
      break;
   case 0x2202:
      if (byte & 0x80)
      {
         Memory.FillRAM [0x2300] &= ~0x80;
         S9xClearIRQ(SA1_IRQ_SOURCE);
      }
      if (byte & 0x20)
      {
         Memory.FillRAM [0x2300] &= ~0x20;
         S9xClearIRQ(SA1_DMA_IRQ_SOURCE);
      }
      break;

   case 0x2209:
      Memory.FillRAM [0x2209] = byte;
      if (byte & 0x80)
         Memory.FillRAM [0x2300] |= 0x80;

      if (byte & Memory.FillRAM [0x2201] & 0x80)
         S9xSetIRQ(SA1_IRQ_SOURCE);
      return;
   case 0x220a:
      if (((byte ^ Memory.FillRAM [0x220a]) & 0x80) &&
            (Memory.FillRAM [0x2301] & byte & 0x80))
      {
         SA1.Flags |= IRQ_PENDING_FLAG;
         SA1.IRQActive |= SNES_IRQ_SOURCE;
      }
      if (((byte ^ Memory.FillRAM [0x220a]) & 0x40) &&
            (Memory.FillRAM [0x2301] & byte & 0x40))
      {
         SA1.Flags |= IRQ_PENDING_FLAG;
         SA1.IRQActive |= TIMER_IRQ_SOURCE;
      }
      if (((byte ^ Memory.FillRAM [0x220a]) & 0x20) &&
            (Memory.FillRAM [0x2301] & byte & 0x20))
      {
         SA1.Flags |= IRQ_PENDING_FLAG;
         SA1.IRQActive |= DMA_IRQ_SOURCE;
      }
      if (((byte ^ Memory.FillRAM [0x220a]) & 0x10) &&
            (Memory.FillRAM [0x2301] & byte & 0x10))
      {
      }
      break;
   case 0x220b:
      if (byte & 0x80)
      {
         SA1.IRQActive &= ~SNES_IRQ_SOURCE;
         Memory.FillRAM [0x2301] &= ~0x80;
      }
      if (byte & 0x40)
      {
         SA1.IRQActive &= ~TIMER_IRQ_SOURCE;
         Memory.FillRAM [0x2301] &= ~0x40;
      }
      if (byte & 0x20)
      {
         SA1.IRQActive &= ~DMA_IRQ_SOURCE;
         Memory.FillRAM [0x2301] &= ~0x20;
      }
      if (byte & 0x10)
      {
         // Clear NMI
         Memory.FillRAM [0x2301] &= ~0x10;
      }
      if (!SA1.IRQActive)
         SA1.Flags &= ~IRQ_PENDING_FLAG;
      break;
   case 0x2220:
   case 0x2221:
   case 0x2222:
   case 0x2223:
      S9xSetSA1MemMap(address - 0x2220, byte);
      break;
   case 0x2224:
      Memory.BWRAM = Memory.SRAM + (byte & 7) * 0x2000;
      break;
   case 0x2225:
      if (byte != Memory.FillRAM [address])
         S9xSA1SetBWRAMMemMap(byte);
      break;
   case 0x2231:
      if (byte & 0x80)
         SA1.in_char_dma = FALSE;
      break;
   case 0x2236:
      Memory.FillRAM [address] = byte;
      if ((Memory.FillRAM [0x2230] & 0xa4) == 0x80)
      {
         // Normal DMA to I-RAM
         S9xSA1DMA();
      }
      else if ((Memory.FillRAM [0x2230] & 0xb0) == 0xb0)
      {
         Memory.FillRAM [0x2300] |= 0x20;
         if (Memory.FillRAM [0x2201] & 0x20)
            S9xSetIRQ(SA1_DMA_IRQ_SOURCE);
         SA1.in_char_dma = TRUE;
      }
      return;
   case 0x2237:
      Memory.FillRAM [address] = byte;
      if ((Memory.FillRAM [0x2230] & 0xa4) == 0x84)
      {
         // Normal DMA to BW-RAM
         S9xSA1DMA();
      }
      return;
   case 0x223f:
      SA1.VirtualBitmapFormat = (byte & 0x80) ? 2 : 4;
      break;

   case 0x224f:
      Memory.FillRAM [address] = byte;
      if ((Memory.FillRAM [0x2230] & 0xb0) == 0xa0)
      {
         // Char conversion 2 DMA enabled
         memmove(&Memory.ROM [MAX_ROM_SIZE - 0x10000] + (SA1.in_char_dma << 4),
                 &Memory.FillRAM [0x2240], 16);
         SA1.in_char_dma = (SA1.in_char_dma + 1) & 7;
         if ((SA1.in_char_dma & 3) == 0)
            S9xSA1CharConv2();
      }
      return;
   case 0x2250:
      if (byte & 2)
         SA1.sum = 0;
      SA1.arithmetic_op = byte & 3;
      break;

   case 0x2251:
      SA1.op1 = (SA1.op1 & 0xff00) | byte;
      break;
   case 0x2252:
      SA1.op1 = (SA1.op1 & 0xff) | (byte << 8);
      break;
   case 0x2253:
      SA1.op2 = (SA1.op2 & 0xff00) | byte;
      break;
   case 0x2254:
      SA1.op2 = (SA1.op2 & 0xff) | (byte << 8);
      switch (SA1.arithmetic_op)
      {
      case 0:  // multiply
         SA1.sum = SA1.op1 * SA1.op2;
         break;
      case 1: // divide
         if (SA1.op2 == 0)
            SA1.sum = SA1.op1 << 16;
         else
         {
            unsigned int x = (SA1.op1 / (int)((uint16) SA1.op2));
            SA1.sum = x | ((SA1.op1 - (x * (uint16) SA1.op2)) << 16);
            // SA1.sum = (SA1.op1 / (int) ((uint16) SA1.op2)) |
            //((SA1.op1 % (int) ((uint16) SA1.op2)) << 16);
         }
         break;
      default: // cumulative sum
         SA1.sum += SA1.op1 * SA1.op2;
         if (SA1.sum & ((int64) 0xffffff << 32))
            SA1.overflow = TRUE;
         break;
      }
      break;
   case 0x2258:    // Variable bit-field length/auto inc/start.
      Memory.FillRAM [0x2258] = byte;
      S9xSA1ReadVariableLengthData(TRUE, FALSE);
      return;
   case 0x2259:
   case 0x225a:
   case 0x225b:    // Variable bit-field start address
      Memory.FillRAM [address] = byte;
      // XXX: ???
      SA1.variable_bit_pos = 0;
      S9xSA1ReadVariableLengthData(FALSE, TRUE);
      return;
   }
   if (address >= 0x2200 && address <= 0x22ff)
      Memory.FillRAM [address] = byte;
}

static void S9xSA1CharConv2()
{
   uint32 dest = Memory.FillRAM [0x2235] | (Memory.FillRAM [0x2236] << 8);
   uint32 offset = (SA1.in_char_dma & 7) ? 0 : 1;
   int depth = (Memory.FillRAM [0x2231] & 3) == 0 ? 8 :
               (Memory.FillRAM [0x2231] & 3) == 1 ? 4 : 2;
   int bytes_per_char = 8 * depth;
   uint8* p = &Memory.FillRAM [0x3000] + dest + offset * bytes_per_char;
   uint8* q = &Memory.ROM [MAX_ROM_SIZE - 0x10000] + offset * 64;

   if (depth == 8)
   {
      int l;
      for (l = 0; l < 8; l++, q += 8)
      {
         int b;
         for (b = 0; b < 8; b++)
         {
            uint8 r = *(q + b);
            *(p +  0) = (*(p +  0) << 1) | ((r >> 0) & 1);
            *(p +  1) = (*(p +  1) << 1) | ((r >> 1) & 1);
            *(p + 16) = (*(p + 16) << 1) | ((r >> 2) & 1);
            *(p + 17) = (*(p + 17) << 1) | ((r >> 3) & 1);
            *(p + 32) = (*(p + 32) << 1) | ((r >> 4) & 1);
            *(p + 33) = (*(p + 33) << 1) | ((r >> 5) & 1);
            *(p + 48) = (*(p + 48) << 1) | ((r >> 6) & 1);
            *(p + 49) = (*(p + 49) << 1) | ((r >> 7) & 1);
         }
         p += 2;
      }
   }
}

static void S9xSA1DMA()
{
   uint32 src =  Memory.FillRAM [0x2232] |
                 (Memory.FillRAM [0x2233] << 8) |
                 (Memory.FillRAM [0x2234] << 16);
   uint32 dst =  Memory.FillRAM [0x2235] |
                 (Memory.FillRAM [0x2236] << 8) |
                 (Memory.FillRAM [0x2237] << 16);
   uint32 len =  Memory.FillRAM [0x2238] |
                 (Memory.FillRAM [0x2239] << 8);

   uint8* s;
   uint8* d;

   switch (Memory.FillRAM [0x2230] & 3)
   {
   case 0: // ROM
      s = SA1_Map [(src >> MEMMAP_SHIFT) & MEMMAP_MASK];
      if (s >= (uint8*) MAP_LAST)
         s += (src & 0xffff);
      else
         s = Memory.ROM + (src & 0xffff);
      break;
   case 1: // BW-RAM
      src &= CPU.Memory_SRAMMask;
      len &= CPU.Memory_SRAMMask;
      s = Memory.SRAM + src;
      break;
   default:
   case 2:
      src &= 0x3ff;
      len &= 0x3ff;
      s = &Memory.FillRAM [0x3000] + src;
      break;
   }

   if (Memory.FillRAM [0x2230] & 4)
   {
      dst &= CPU.Memory_SRAMMask;
      len &= CPU.Memory_SRAMMask;
      d = Memory.SRAM + dst;
   }
   else
   {
      dst &= 0x3ff;
      len &= 0x3ff;
      d = &Memory.FillRAM [0x3000] + dst;
   }
   memmove(d, s, len);
   Memory.FillRAM [0x2301] |= 0x20;

   if (Memory.FillRAM [0x220a] & 0x20)
   {
      SA1.Flags |= IRQ_PENDING_FLAG;
      SA1.IRQActive |= DMA_IRQ_SOURCE;
   }
}

void S9xSA1ReadVariableLengthData(bool8 inc, bool8 no_shift)
{
   uint32 data;
   uint8 s;
   uint32 addr =  Memory.FillRAM [0x2259] |
                  (Memory.FillRAM [0x225a] << 8) |
                  (Memory.FillRAM [0x225b] << 16);
   uint8 shift = Memory.FillRAM [0x2258] & 15;

   if (no_shift)
      shift = 0;
   else if (shift == 0)
      shift = 16;

   s = shift + SA1.variable_bit_pos;

   if (s >= 16)
   {
      addr += (s >> 4) << 1;
      s &= 15;
   }
   data   = S9xSA1GetWord(addr) |
                 (S9xSA1GetWord(addr + 2) << 16);

   data >>= s;
   Memory.FillRAM [0x230c] = (uint8) data;
   Memory.FillRAM [0x230d] = (uint8)(data >> 8);
   if (inc)
   {
      SA1.variable_bit_pos = (SA1.variable_bit_pos + shift) & 15;
      Memory.FillRAM [0x2259] = (uint8) addr;
      Memory.FillRAM [0x225a] = (uint8)(addr >> 8);
      Memory.FillRAM [0x225b] = (uint8)(addr >> 16);
   }
}

#endif // USE_SA1