dma.cpp

著名SFC模拟器Snes9x的源代码。

/*
 * Snes9x - Portable Super Nintendo Entertainment System (TM) emulator.
 *
 * (c) Copyright 1996 - 2001 Gary Henderson ([e-mail]) and
 *                           Jerremy Koot ([e-mail])
 *
 * Super FX C emulator code 
 * (c) Copyright 1997 - 1999 Ivar ([e-mail]) 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 ([e-mail]).
 *
 * DOS port code contains the works of other authors. See headers in
 * individual files.
 *
 * Snes9x homepage: 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.
 */
#include "snes9x.h"

#include "memmap.h"
#include "ppu.h"
#include "cpuexec.h"
#include "missing.h"
#include "dma.h"
#include "apu.h"
#include "gfx.h"
#include "sa1.h"

extern int HDMA_ModeByteCounts [8];
extern uint8 *HDMAMemPointers [8];
extern uint8 *HDMABasePointers [8];

/**********************************************************************************************/
/* S9xDoDMA()                                                                                   */
/* This function preforms the general dma transfer                                            */
/**********************************************************************************************/
void S9xDoDMA (uint8 Channel)
{
    uint8 Work;

    if (Channel > 7 || CPU.InDMA)
	return;

    CPU.InDMA = TRUE;
    bool8 in_sa1_dma = FALSE;
    SDMA *d = &DMA[Channel];

    int count = d->TransferBytes;

    if (count == 0)
	count = 0x10000;

    int inc = d->AAddressFixed ? 0 : (!d->AAddressDecrement ? 1 : -1);

    switch (d->BAddress)
    {
    case 0x18:
    case 0x19:
	if (IPPU.RenderThisFrame)
	    FLUSH_REDRAW ();
    if (Settings.SDD1 && d->AAddressFixed && 
	Memory.BlockIsROM [((d->ABank << 16) + d->AAddress) >> 12])
    {
	inc = !d->AAddressDecrement ? 1 : -1;
//    if (d->BAddress == 0x18 && Settings.SDD1 && d->AAddressFixed)
//    {
//	printf ("%02x%04x, count: %d\n", d->ABank, d->AAddress, d->TransferBytes);
#if 0
	uint8 *base = GetBasePointer ((d->ABank << 16) + d->AAddress) + d->AAddress;
	for (int i = 0; i < 16; i++)
	    printf ("%02x ", *base++);
	printf ("\n");
#endif
    }
	break;
    }

    if (d->BAddress == 0x18 && SA1.in_char_dma && (d->ABank & 0xf0) == 0x40)
    {
	// Perform packed bitmap to PPU character format conversion on the
	// data before transmitting it to V-RAM via-DMA.
	int num_chars = 1 << ((Memory.FillRAM [0x2231] >> 2) & 7);
	int depth = (Memory.FillRAM [0x2231] & 3) == 0 ? 8 :
		    (Memory.FillRAM [0x2231] & 3) == 1 ? 4 : 2;

	int bytes_per_char = 8 * depth;
	int bytes_per_line = depth * num_chars;
	int char_line_bytes = bytes_per_char * num_chars;
	uint32 addr = (d->AAddress / char_line_bytes) * char_line_bytes;
	uint8 *base = GetBasePointer ((d->ABank << 16) + addr) + addr;
	uint8 *buffer = &Memory.ROM [CMemory::MAX_ROM_SIZE - 0x10000];
	uint8 *p = buffer;
	uint32 inc = char_line_bytes - (d->AAddress % char_line_bytes);
	uint32 char_count = inc / bytes_per_char;

	in_sa1_dma = TRUE;
	
//printf ("%08x,", base); fflush (stdout);
//printf ("depth = %d, count = %d, bytes_per_char = %d, bytes_per_line = %d, num_chars = %d, char_line_bytes = %d\n",
//depth, count, bytes_per_char, bytes_per_line, num_chars, char_line_bytes);
	int i;

	switch (depth)
	{
	case 2:
	    for (i = 0; i < count; i += inc, base += char_line_bytes, 
		 inc = char_line_bytes, char_count = num_chars)
	    {
		uint8 *line = base + (num_chars - char_count) * 2;
		for (uint32 j = 0; j < char_count && p - buffer < count; 
		     j++, line += 2)
		{
		    uint8 *q = line;
		    for (int l = 0; l < 8; l++, q += bytes_per_line)
		    {
			for (int b = 0; b < 2; b++)
			{
			    uint8 r = *(q + b);
			    *(p + 0) = (*(p + 0) << 1) | ((r >> 0) & 1);
			    *(p + 1) = (*(p + 1) << 1) | ((r >> 1) & 1);
			    *(p + 0) = (*(p + 0) << 1) | ((r >> 2) & 1);
			    *(p + 1) = (*(p + 1) << 1) | ((r >> 3) & 1);
			    *(p + 0) = (*(p + 0) << 1) | ((r >> 4) & 1);
			    *(p + 1) = (*(p + 1) << 1) | ((r >> 5) & 1);
			    *(p + 0) = (*(p + 0) << 1) | ((r >> 6) & 1);
			    *(p + 1) = (*(p + 1) << 1) | ((r >> 7) & 1);
			}
			p += 2;
		    }
		}
	    }
	    break;
	case 4:
	    for (i = 0; i < count; i += inc, base += char_line_bytes, 
		 inc = char_line_bytes, char_count = num_chars)
	    {
		uint8 *line = base + (num_chars - char_count) * 4;
		for (uint32 j = 0; j < char_count && p - buffer < count; 
		     j++, line += 4)
		{
		    uint8 *q = line;
		    for (int l = 0; l < 8; l++, q += bytes_per_line)
		    {
			for (int b = 0; b < 4; 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 +  0) = (*(p +  0) << 1) | ((r >> 4) & 1);
			    *(p +  1) = (*(p +  1) << 1) | ((r >> 5) & 1);
			    *(p + 16) = (*(p + 16) << 1) | ((r >> 6) & 1);
			    *(p + 17) = (*(p + 17) << 1) | ((r >> 7) & 1);
			}
			p += 2;
		    }
		    p += 32 - 16;
		}
	    }
	    break;
	case 8:
	    for (i = 0; i < count; i += inc, base += char_line_bytes, 
		 inc = char_line_bytes, char_count = num_chars)
	    {
		uint8 *line = base + (num_chars - char_count) * 8;
		for (uint32 j = 0; j < char_count && p - buffer < count; 
		     j++, line += 8)
		{
		    uint8 *q = line;
		    for (int l = 0; l < 8; l++, q += bytes_per_line)
		    {
			for (int 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;
		    }
		    p += 64 - 16;
		}
	    }
	    break;
	}
    }

#ifdef DEBUGGER
    if (Settings.TraceDMA)
    {
	sprintf (String, "DMA[%d]: %s Mode: %d 0x%02X%04X->0x21%02X Bytes: %d (%s) V-Line:%ld",
		Channel, d->TransferDirection ? "read" : "write",
		d->TransferMode, d->ABank, d->AAddress,
		d->BAddress, d->TransferBytes,
		d->AAddressFixed ? "fixed" :
		(d->AAddressDecrement ? "dec" : "inc"),
		CPU.V_Counter);
	if (d->BAddress == 0x18 || d->BAddress == 0x19)
	    sprintf (String, "%s VRAM: %04X (%d,%d) %s", String,
		     PPU.VMA.Address,
		     PPU.VMA.Increment, PPU.VMA.FullGraphicCount,
		     PPU.VMA.High ? "word" : "byte");
	else
	if (d->BAddress == 0x22)
	    sprintf (String, "%s CGRAM: %02X (%x)", String, PPU.CGADD,
		     PPU.CGFLIP);
	else
	if (d->BAddress == 0x04)
	    sprintf (String, "%s OBJADDR: %04X", String, PPU.OAMAddr);
	S9xMessage (S9X_TRACE, S9X_DMA_TRACE, String);
    }
#endif

    if (!d->TransferDirection)
    {
#ifdef VAR_CYCLES
	CPU.Cycles += 8 * count;
#else
	CPU.Cycles += count + (count >> 2);
#endif
	uint8 *base = GetBasePointer ((d->ABank << 16) + d->AAddress);
	uint16 p = d->AAddress;

	if (!base)
	    base = Memory.ROM;

	if (in_sa1_dma)
	{
	    base = &Memory.ROM [CMemory::MAX_ROM_SIZE - 0x10000];
	    p = 0;
	}

	if (inc > 0)
	    d->AAddress += count;
	else
	if (inc < 0)
	    d->AAddress -= count;

	if (d->TransferMode == 0 || d->TransferMode == 2)
	{
	    switch (d->BAddress)
	    {
	    case 0x04:
		do
		{
		    Work = *(base + p);
		    REGISTER_2104(Work);
		    p += inc;
		    CHECK_SOUND();
		} while (--count > 0);
		break;
	    case 0x18:
		IPPU.FirstVRAMRead = TRUE;
		if (!PPU.VMA.FullGraphicCount)
		{
		    do
		    {
			Work = *(base + p);
			REGISTER_2118_linear(Work);
			p += inc;
			CHECK_SOUND();
		    } while (--count > 0);
		}
		else
		{
		    do
		    {
			Work = *(base + p);
			REGISTER_2118_tile(Work);
			p += inc;
			CHECK_SOUND();
		    } while (--count > 0);
		}
		break;
	    case 0x19:
		IPPU.FirstVRAMRead = TRUE;
		if (!PPU.VMA.FullGraphicCount)
		{
		    do
		    {
			Work = *(base + p);
			REGISTER_2119_linear(Work);
			p += inc;
			CHECK_SOUND();
		    } while (--count > 0);
		}
		else
		{
		    do
		    {
			Work = *(base + p);
			REGISTER_2119_tile(Work);
			p += inc;
			CHECK_SOUND();
		    } while (--count > 0);
		}
		break;
	    case 0x22:
		do
		{
		    Work = *(base + p);
		    REGISTER_2122(Work);
		    p += inc;
		    CHECK_SOUND();
		} while (--count > 0);
		break;
	    case 0x80:
		do
		{
		    Work = *(base + p);
		    REGISTER_2180(Work);
		    p += inc;
		    CHECK_SOUND();
		} while (--count > 0);
		break;
	    default:
		do
		{
		    Work = *(base + p);
		    S9xSetPPU (Work, 0x2100 + d->BAddress);
		    p += inc;
		    CHECK_SOUND();
		} while (--count > 0);
		break;
	    }
	}
	else
	if (d->TransferMode == 1 || d->TransferMode == 5)
	{
	    if (d->BAddress == 0x18)
	    {
		// Write to V-RAM
		IPPU.FirstVRAMRead = TRUE;
		if (!PPU.VMA.FullGraphicCount)
		{
		    while (count > 1)
		    {
			Work = *(base + p);
			REGISTER_2118_linear(Work);
			p += inc;

			Work = *(base + p);
			REGISTER_2119_linear(Work);
			p += inc;
			CHECK_SOUND();
			count -= 2;
		    }
		    if (count == 1)
		    {
			Work = *(base + p);
			REGISTER_2118_linear(Work);
			p += inc;
		    }
		}
		else
		{
		    while (count > 1)
		    {
			Work = *(base + p);
			REGISTER_2118_tile(Work);
			p += inc;

			Work = *(base + p);
			REGISTER_2119_tile(Work);
			p += inc;
			CHECK_SOUND();
			count -= 2;
		    }
		    if (count == 1)
		    {
			Work = *(base + p);
			REGISTER_2118_tile(Work);
			p += inc;
		    }
		}
	    }
	    else
	    {
		// DMA mode 1 general case
		while (count > 1)
		{
		    Work = *(base + p);
		    S9xSetPPU (Work, 0x2100 + d->BAddress);
		    p += inc;