VDPアクセス例

既に作成したinp(),outp()I/O関数を用いてVDPを直接扱う。

VDPを直接設定し画面モードを切り替える場合は、BIOSと異なりレジスタの操作と画面初期化
などを必要とする。

新たに作成した関数はVDPレジスタアクセス、メモリーアドレス設定、フォント再設定の
三つの関数のみ。

VRAMへのアクセス方法は初めにアドレス(VMemadr)をセットし、後はI/Oダイレクト(outp/inp)に連続してリードライトする。

SCREEN8へ切り替えはVDPモードレジスタの設定だけでなく、CLS処理など
画面の初期化を行なう必要がある。

SCREEN8からテキストモードSCREEN0へ復帰する際は、9938/9958のフォントデータを
再セットアップする必要がある。
以下のサンプルコードは英数字のみ。

サンプル例はSCREEN0(WIDTH40)から、SCREEN8にモード切替え後、再びSCREEN0(40)へ戻る

サンプルソースコード。
vdpexample.c

//ALPHABET FONT
const unsigned char f[96][8]={ 
 {0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0},
 {0x20,0x20,0x20,0x20,0x0,0x0,0x20,0x0},
 {0x50,0x50,0x50,0x0,0x0,0x0,0x0,0x0},
 {0x50,0x50,0xF8,0x50,0xF8,0x50,0x50,0x0},
 {0x20,0x78,0xA0,0x70,0x28,0xF0,0x20,0x0},
 {0xC0,0xC8,0x10,0x20,0x40,0x98,0x18,0x0},
 {0x40,0xA0,0x40,0xA8,0x90,0x98,0x60,0x0},
 {0x10,0x20,0x40,0x0,0x0,0x0,0x0,0x0},
 {0x10,0x20,0x40,0x40,0x40,0x20,0x10,0x0},
 {0x40,0x20,0x10,0x10,0x10,0x20,0x40,0x0},
 {0x20,0xA8,0x70,0x20,0x70,0xA8,0x20,0x0},
 {0x0,0x20,0x20,0xF8,0x20,0x20,0x0,0x0},
 {0x0,0x0,0x0,0x0,0x0,0x20,0x20,0x40},
 {0x0,0x0,0x0,0x78,0x0,0x0,0x0,0x0},
 {0x0,0x0,0x0,0x0,0x0,0x60,0x60,0x0},
 {0x0,0x0,0x8,0x10,0x20,0x40,0x80,0x0},
 {0x70,0x88,0x98,0xA8,0xC8,0x88,0x70,0x0},
 {0x20,0x60,0xA0,0x20,0x20,0x20,0xF8,0x0},
 {0x70,0x88,0x8,0x10,0x60,0x80,0xF8,0x0},
 {0x70,0x88,0x8,0x30,0x8,0x88,0x70,0x0},
 {0x10,0x30,0x50,0x90,0xF8,0x10,0x10,0x0},
 {0xF8,0x80,0xE0,0x10,0x8,0x10,0xE0,0x0},
 {0x30,0x40,0x80,0xF0,0x88,0x88,0x70,0x0},
 {0xF8,0x88,0x10,0x20,0x20,0x20,0x20,0x0},
 {0x70,0x88,0x88,0x70,0x88,0x88,0x70,0x0},
 {0x70,0x88,0x88,0x78,0x8,0x10,0x60,0x0},
 {0x0,0x0,0x20,0x0,0x0,0x20,0x0,0x0},
 {0x0,0x0,0x20,0x0,0x0,0x20,0x20,0x40},
 {0x18,0x30,0x60,0xC0,0x60,0x30,0x18,0x0},
 {0x0,0x0,0xF8,0x0,0xF8,0x0,0x0,0x0},
 {0xC0,0x60,0x30,0x18,0x30,0x60,0xC0,0x0},
 {0x70,0x88,0x8,0x10,0x20,0x0,0x20,0x0},
 {0x70,0x88,0x8,0x68,0xA8,0xA8,0x70,0x0},
 {0x20,0x50,0x88,0x88,0xF8,0x88,0x88,0x0},
 {0xF0,0x48,0x48,0x70,0x48,0x48,0xF0,0x0},
 {0x30,0x48,0x80,0x80,0x80,0x48,0x30,0x0},
 {0xE0,0x50,0x48,0x48,0x48,0x50,0xE0,0x0},
 {0xF8,0x80,0x80,0xF0,0x80,0x80,0xF8,0x0},
 {0xF8,0x80,0x80,0xF0,0x80,0x80,0x80,0x0},
 {0x70,0x88,0x80,0xB8,0x88,0x88,0x70,0x0},
 {0x88,0x88,0x88,0xF8,0x88,0x88,0x88,0x0},
 {0x70,0x20,0x20,0x20,0x20,0x20,0x70,0x0},
 {0x38,0x10,0x10,0x10,0x90,0x90,0x60,0x0},
 {0x88,0x90,0xA0,0xC0,0xA0,0x90,0x88,0x0},
 {0x80,0x80,0x80,0x80,0x80,0x80,0xF8,0x0},
 {0x88,0xD8,0xA8,0xA8,0x88,0x88,0x88,0x0},
 {0x88,0xC8,0xC8,0xA8,0x98,0x98,0x88,0x0},
 {0x70,0x88,0x88,0x88,0x88,0x88,0x70,0x0},
 {0xF0,0x88,0x88,0xF0,0x80,0x80,0x80,0x0},
 {0x70,0x88,0x88,0x88,0xA8,0x90,0x68,0x0},
 {0xF0,0x88,0x88,0xF0,0xA0,0x90,0x88,0x0},
 {0x70,0x88,0x80,0x70,0x8,0x88,0x70,0x0},
 {0xF8,0x20,0x20,0x20,0x20,0x20,0x20,0x0},
 {0x88,0x88,0x88,0x88,0x88,0x88,0x70,0x0},
 {0x88,0x88,0x88,0x88,0x50,0x50,0x20,0x0},
 {0x88,0x88,0x88,0xA8,0xA8,0xD8,0x88,0x0},
 {0x88,0x88,0x50,0x20,0x50,0x88,0x88,0x0},
 {0x88,0x88,0x88,0x70,0x20,0x20,0x20,0x0},
 {0xF8,0x8,0x10,0x20,0x40,0x80,0xF8,0x0},
 {0x70,0x40,0x40,0x40,0x40,0x40,0x70,0x0},
 {0x88,0x50,0x20,0x70,0x20,0x70,0x20,0x0},
 {0x70,0x10,0x10,0x10,0x10,0x10,0x70,0x0},
 {0x20,0x50,0x88,0x0,0x0,0x0,0x0,0x0},
 {0x0,0x0,0x0,0x0,0x0,0x0,0xF8,0x0},
 {0x40,0x20,0x10,0x0,0x0,0x0,0x0,0x0},
 {0x0,0x0,0x70,0x8,0x78,0x88,0x78,0x0},
 {0x80,0x80,0xB0,0xC8,0x88,0xC8,0xB0,0x0},
 {0x0,0x0,0x70,0x88,0x80,0x88,0x70,0x0},
 {0x8,0x8,0x68,0x98,0x88,0x98,0x68,0x0},
 {0x0,0x0,0x70,0x88,0xF8,0x80,0x70,0x0},
 {0x10,0x28,0x20,0xF8,0x20,0x20,0x20,0x0},
 {0x0,0x0,0x68,0x98,0x98,0x68,0x8,0x70},
 {0x80,0x80,0xF0,0x88,0x88,0x88,0x88,0x0},
 {0x20,0x0,0x60,0x20,0x20,0x20,0x70,0x0},
 {0x10,0x0,0x30,0x10,0x10,0x10,0x90,0x60},
 {0x40,0x40,0x48,0x50,0x60,0x50,0x48,0x0},
 {0x60,0x20,0x20,0x20,0x20,0x20,0x70,0x0},
 {0x0,0x0,0xD0,0xA8,0xA8,0xA8,0xA8,0x0},
 {0x0,0x0,0xB0,0xC8,0x88,0x88,0x88,0x0},
 {0x0,0x0,0x70,0x88,0x88,0x88,0x70,0x0},
 {0x0,0x0,0xB0,0xC8,0xC8,0xB0,0x80,0x80},
 {0x0,0x0,0x68,0x98,0x98,0x68,0x8,0x8},
 {0x0,0x0,0xB0,0xC8,0x80,0x80,0x80,0x0},
 {0x0,0x0,0x78,0x80,0xF0,0x8,0xF0,0x0},
 {0x40,0x40,0xF0,0x40,0x40,0x48,0x30,0x0},
 {0x0,0x0,0x90,0x90,0x90,0x90,0x68,0x0},
 {0x0,0x0,0x88,0x88,0x88,0x50,0x20,0x0},
 {0x0,0x0,0x88,0xA8,0xA8,0xA8,0x50,0x0},
 {0x0,0x0,0x88,0x50,0x20,0x50,0x88,0x0},
 {0x0,0x0,0x88,0x88,0x98,0x68,0x8,0x70},
 {0x0,0x0,0xF8,0x10,0x20,0x40,0xF8,0x0},
 {0x18,0x20,0x20,0x40,0x20,0x20,0x18,0x0},
 {0x20,0x20,0x20,0x0,0x20,0x20,0x20,0x0},
 {0xC0,0x20,0x20,0x10,0x20,0x20,0xC0,0x0},
 {0x40,0xA8,0x10,0x0,0x0,0x0,0x0,0x0},
 {0,0,0,0,0,0,0,0}
};

extern unsigned char inp(unsigned char);
extern outp(unsigned char,unsigned char);

void VRegister(unsigned char reg, unsigned char data);
void VMemadr(long addr, char rw);
void Fontset(void);

void main(void){
	long i;
	int j; 

	//SCREEN8
	VRegister(0,0xE);
	VRegister(1,0x60);

	//VDP DISPSCAN BASE ADDRESS(PATTERN NAME TABLE)
	VRegister(2,0x1F);

	//SPRITE OFF
	VRegister(8,0xA);

	//SET ADDRESS,WRITE MODE
	VMemadr(0,1);

	//WRITE VMEM(I/O DIRECT)
	for(j=0; j<0xd3ff; j++){
		outp(0x98,0);
	}

	//WAIT
	for(i=0; i<300000; i++);

	//RETURN SCREEN0(40)
	VRegister(0,0);
	VRegister(1,0x70);

	//VDP DISPSCAN BASE ADDRESS
	VRegister(2,0x0);

	//SCREEN0(40) FONT RECOVER
	Fontset();
}

//function(Register number, Data)
void VRegister(unsigned char reg, unsigned char data){
	outp(0x99,data);
	outp(0x99,reg+0x80);
}

//function(VMem Address, 0-Read/1-Write)
void VMemadr(long addr,char rw){
	unsigned char low,mid,hi;

	low=addr & 0xff;
	mid=(addr >> 8) & 0x3f;
	hi=(addr >>14) & 0x7;

	//HI ADDR
	outp(0x99,hi);
	//R#14
	outp(0x99,0x8e);

	//LOW ADDR
	outp(0x99,low);
	//MID ADDR
	if (rw) {
		//WRITE
		outp(0x99,mid+0x40);
	}else{
		//READ
		outp(0x99,mid);
	}
}

void Fontset(){
	int i;
	int j;

	//CLEAR VFONT ALLOCATION
	VMemadr(0x800,1);
	for(i=0x800; i<0x1100; i++){
		outp(0x98,0);
	}

	//SET VFONT ADDRESS
	//(PATTERN GENERATOR TABLE,SCREEN0/WIDTH40)
	VMemadr(0x900,1);

	//WRITE FONT(ALPHABET ONLY)
	for(i=0; i<96; i++){
		for(j=0; j<8; j++){
		outp(0x98,f[i][j]);
		}
	}
}