path: root/source/spec.c

/*

   dsspec - Nintendo DS Sinclair Spectrum 48K emulator.

   Copyright (C) 2006  Ian Cowburn
   
   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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  
   $Id$

*/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <nds.h>

#include "spec.h"
#include "snap.h"
#include "spec48_bin.h"

#ifndef TRUE
#define TRUE 1
#endif

#ifndef FALSE
#define FALSE 0
#endif

#define HIBYTE(w)	((w)>>8)
#define LOBYTE(w)	((w)&0xff)


/* ---------------------------------------- STATICS
*/
static uint16		*vram;

static const int	ROMLEN=0x4000;
static const int	ROM_SAVE=0x4c6;
static const int	ROM_LOAD=0x562;

#define LOAD_PATCH	0xf0
#define SAVE_PATCH	0xf1

/* The SPEC screen
*/
#define			SCR_W	256
#define			SCR_H	192
#define			TXT_W	32
#define			TXT_H	24
#define			SCRDATA	0x4000
#define			ATTR	0x5800

#define			ATTR_AT(x,y)	mem[ATTR+(x)+((y)/8)*32]

static Z80Byte		mem[0x10000];

/* Number of cycles per frame
*/
static Z80Val		FRAME_CYCLES=69888;


/* GFX vars
*/
#define			FLASH	16	/* Frames per flash */

static int		flash=0;
static int		flashctr=0;

#define 		NVAL	25	/* Normal RGB intensity */
#define 		BVAL	31	/* Bright RGB intensity */

static Z80Byte		*line[SCR_H];	/* Accelerators to screen data */

static struct
{
    uint16	col;
    int		r,g,b;
} coltable[16]=
{
    {0,     0x00,0x00,0x00},        /* BLACK */
    {0,     0x00,0x00,NVAL},        /* BLUE */
    {0,     NVAL,0x00,0x00},        /* RED */
    {0,     NVAL,0x00,NVAL},        /* MAGENTA */
    {0,     0x00,NVAL,0x00},        /* GREEN */
    {0,     0x00,NVAL,NVAL},        /* CYAN */
    {0,     NVAL,NVAL,0x00},        /* YELLOW */
    {0,     NVAL,NVAL,NVAL},        /* WHITE */

    {0,     0x00,0x00,0x00},        /* BLACK */
    {0,     0x00,0x00,BVAL},        /* BLUE */
    {0,     BVAL,0x00,0x00},        /* RED */
    {0,     BVAL,0x00,BVAL},        /* MAGENTA */
    {0,     0x00,BVAL,0x00},        /* GREEN */
    {0,     0x00,BVAL,BVAL},        /* CYAN */
    {0,     BVAL,BVAL,0x00},        /* YELLOW */
    {0,     BVAL,BVAL,BVAL},        /* WHITE */

};


/* The keyboard
*/
static Z80Byte		matrix[8];


/* ---------------------------------------- PRIVATE FUNCTIONS
*/
static void DrawScreen(void)
{
    int f,r;
    int ink,paper,t;
    int y;
    Z80Byte *scr;
    Z80Byte b;
    Z80Byte att;
    uint16 *vr;

    vr=vram;

    swiWaitForVBlank();

    for(y=0;y<SCR_H;y++)
    {
	scr=line[y];

	for(f=0;f<TXT_W;f++)
	{
	    att=ATTR_AT(f,y);

	    ink=(att&0x07);
	    paper=(att&0x38)>>3;

	    if (att&0x40)
	    {
		ink+=8;
		paper+=8;
	    }

	    if ((att&0x80)&&(flash))
	    {
		t=ink;
		ink=paper;
		paper=t;
	    }

	    b=*scr++;

	    for(r=0;r<8;r++)
	    {
		if (b&(1<<(7-r)))
		{
		    *vr++=coltable[ink].col;
		}
		else
		{
		    *vr++=coltable[paper].col;
		}
	    }
	}
    }
}

static void RomPatch(void)
{
    static const Z80Byte save[]=
    {
    	0xed, SAVE_PATCH,	/* ED illegal op	*/
	0xc9,			/* RET 			*/
	0xff			/* End of patch		*/
    };

    static const Z80Byte load[]=
    {
	0x08,			/* EX AF,AF'		*/
    	0xed, LOAD_PATCH,	/* ED illegal op	*/
	0xc9,			/* RET 			*/
	0xff			/* End of patch		*/
    };

    int f;

    for(f=0;save[f]!=0xff;f++)
    	mem[ROM_SAVE+f]=save[f];

    for(f=0;load[f]!=0xff;f++)
    	mem[ROM_LOAD+f]=load[f];
}


Z80Byte SPECPeek(Z80 *cpu, Z80Word addr)
{
    return mem[addr];
}


Z80Byte SnapPeek(Z80Word addr)
{
    return mem[addr];
}


void SPECPoke(Z80 *cpu, Z80Word addr, Z80Byte val)
{
    if (addr>=ROMLEN)
      mem[addr]=val;
}


void SnapPoke(Z80Word addr, Z80Byte val)
{
    if (addr>=ROMLEN)
      mem[addr]=val;
}


static int EDCallback(Z80 *z80, Z80Val data)
{
    Z80State state;

    switch((Z80Byte)data)
    {
    	case SAVE_PATCH:
	    state.AF&=~eZ80_Carry;
	    Z80SetState(z80,&state);
	    break;

    	case LOAD_PATCH:
	    Z80GetState(z80,&state);

	    if (TAPLoad(HIBYTE(state.AF),
			&state.IX,
			&state.DE,
			SnapPoke))
	    {
		state.AF|=eZ80_Carry;
		state.BC=0xb001;
	    }
	    else
	    {
		state.AF&=~eZ80_Carry;
		state.BC=0xff01;
	    }

	    Z80SetState(z80,&state);

	    break;

	default:
	    break;
    }

    return TRUE;
}


static int CheckTimers(Z80 *z80, Z80Val val)
{
    if (val>FRAME_CYCLES)
    {
	Z80ResetCycles(z80,val-FRAME_CYCLES);

	flashctr++;

	if (flashctr==FLASH)
	{
	    flash^=1;
	    flashctr=0;
	}

	Z80Interrupt(z80,0xff);

	DrawScreen();

	/* TODO: Process sound emulation */

	return FALSE;
    }
    else
    {
	return TRUE;
    }
}


/* ---------------------------------------- EXPORTED INTERFACES
*/
void SPECInit(uint16 *v, Z80 *z80)
{
    vram=v;

    memcpy(mem,spec48_bin,ROMLEN);

    /* Patch the ROM
    */
    RomPatch();
    Z80LodgeCallback(z80,eZ80_EDHook,EDCallback);
    Z80LodgeCallback(z80,eZ80_Instruction,CheckTimers);

    SPECReset(z80);
}


void SPECHandleKey(SoftKey key, int is_pressed)
{
    if (key<=SK_SPACE)
    {
    	int row;
	int bit;

	row=key/5;

	if (row&1)
	{
	    bit=5-(key%5);
	}
	else
	{
	    bit=(key%5);
	}

	if (is_pressed)
	{
	    matrix[row]&=~bit;
	}
	else
	{
	    matrix[row]|=bit;
	}
    }
    else
    {
    	/* TODO: Joysticks! */
    }
}


Z80Byte SPECReadPort(Z80 *z80, Z80Word port)
{
    Z80Byte lo=port&0xff;
    Z80Byte hi=port>>8;
    Z80Byte b=0xff;
    int f;

    switch(lo)
    {
	case 0x1f:	/* Kempston joystick */
	    break;

	case 0x7f:	/* Fuller joystick */
	    break;

	case 0xfb:	/* ZX Printer */
	    break;

	default:	/* ULA */
	    if (!(lo&1))
	    {
		/* Key matrix
		*/
		b=0xff;

		for(f=0;f<8;f++)
		    if (!(hi&(1<<f)))
			b&=matrix[f];

		b|=0xa0;

		/* TODO: Emulation of contention? */
	    }
	    else
	    	b=0xff;
	    break;
    }

    return b;
}


void SPECWritePort(Z80 *z80, Z80Word port, Z80Byte val)
{
    Z80Byte lo=port&0xff;

    switch(lo)
    {
	case 0xfe:	/* ULA */
	    break;

	case 0xfb:	/* ZX Printer */
	    break;

	default:
	    break;
    }
}


void SPECReset(Z80 *z80)
{
    int f;
    int c;
    int r;

    /* Set up the keyboard
    */
    for(f=0;f<8;f++)
    {
    	matrix[f]=0x1f;
    }

    /* Set up the colours
    */
    for(f=0;f<16;f++)
    {
    	coltable[f].col=0x8000|RGB15(coltable[f].r,coltable[f].g,coltable[f].b);
    }

    flash=0;
    flashctr=0;

    /* Set up screen
    */
    c=0;
    r=0;
    for(f=0;f<SCR_H;f++)
    {
    	line[f]=mem+SCRDATA+(c*8*TXT_W)+(r*TXT_W);

	c++;

	if ((c%8)==0)
	{
	    if (++r==8)
	    	r=0;
	    else
	    	c-=8;
	}
    }

    Z80ResetCycles(z80,0);
    Z80Reset(z80);
}


/* END OF FILE */