Subversion Repositories Shiroi

/* $Id: shiroi.c 1 2024-08-28 08:10:28Z nishi $ */

unsigned char inp(unsigned char);
void outp(unsigned char, unsigned char);
void write_vram(unsigned short);
void putchar(char);
void putstr(char*);
void scroll_y(void);
void beep(void);
void _beep(unsigned long howlong);
void init_cards(void);

unsigned short posx;
unsigned short posy;

short vdp_addr;
short vdp_data;
short psg_addr;
short psg_data;
short fpu_addr;
short fpu_data;

void main(void) {
        int i;

        posx = 0;
        posy = 0;

        vdp_addr = -1;
        psg_addr = -1;
        fpu_addr = -1;

        init_cards();

        if(vdp_addr == -1) {
                int i;
                for(i = 0; i < 3; i++) {
                        _beep(3L * 1024);
                        unsigned long j;
                        for(j = 0; j < 3L * 1024; j++)
                                ;
                }
                while(1)
                        ;
        }

        outp(vdp_addr, 0x00);
        outp(vdp_addr, 0x80);

        outp(vdp_addr, 0xd0);
        outp(vdp_addr, 0x81);

        outp(vdp_addr, 0x02);
        outp(vdp_addr, 0x82);

        outp(vdp_addr, 0x00);
        outp(vdp_addr, 0x84);

        outp(vdp_addr, 0xf4);
        outp(vdp_addr, 0x87);

        write_vram(0);
        for(i = 0; i < 0x800; i++) outp(vdp_data, *((unsigned char*)(0x2000 + i)));

        beep();

        putstr("Shiroi Microcomputer BASIC\r\n");
        if(fpu_addr == -1) {
                putstr("Math Card Mark I not present\r\n");
        } else {
                putstr("Math Card Mark I present\r\n");
        }
        if(psg_addr == -1) {
                putstr("Sound Card Mark I not present\r\n");
        } else {
                putstr("Sound Card Mark I present\r\n");
        }

        write_vram(0x800 + 40 * 12);
        for(i = 0; i < 0x100; i++) outp(vdp_data, i);

        while(1)
                ;
}

void init_cards(void) {
        int i;
        int port = 2;
        for(i = 0; i < 256 / 3; i++) {
                int t = inp(port);
                if(t != 0) {
                        if(t == 0x01) {
                                vdp_addr = port - 2;
                                vdp_data = port - 1;
                        } else if(t == 0x11) {
                                psg_addr = port - 2;
                                psg_data = port - 1;
                        } else if(t == 0x21) {
                                fpu_addr = port - 2;
                                fpu_data = port - 1;
                        }
                }
                port += 3;
        }
}

void beep(void) { _beep(3L * 1024); }

void _beep(unsigned long howlong) {
        if(psg_addr == -1) return;
        unsigned long i;

        outp(psg_addr, 8);
        outp(psg_data, 0x0f);

        outp(psg_addr, 0);
        outp(psg_data, 0xd6);

        outp(psg_addr, 1);
        outp(psg_data, 0x0);

        outp(psg_addr, 7);
        outp(psg_data, 0x3e);

        for(i = 0; i < howlong; i++)
                ;

        outp(psg_addr, 7);
        outp(psg_data, 0x3f);
}

void write_vram(unsigned short addr) {
        addr |= 0x4000;
        outp(vdp_addr, addr & 0x00ff);
        outp(vdp_addr, ((addr & 0xff00) >> 8));
}

void read_vram(unsigned short addr) {
        outp(vdp_addr, addr & 0x00ff);
        outp(vdp_addr, ((addr & 0xff00) >> 8));
}

void scroll_y(void) {
        int i;
        for(i = 0; i < 40 * 23; i++) {
                read_vram(0x800 + i + 40);
                unsigned char ch = inp(vdp_data);
                write_vram(0x800 + i);
                outp(vdp_data, ch);
        }
        for(i = 0; i < 40; i++) {
                outp(vdp_data, 0);
        }
}

void putchar(char c) {
        if(c == '\r') {
                posx = 0;
        } else if(c == '\n') {
                posy++;
        } else {
                write_vram(0x800 + posy * 40 + posx);
                outp(vdp_data, c);
                posx++;
                if(posx == 40) {
                        posx = 0;
                        posy++;
                }
        }
        if(posy == 24) {
                scroll_y();
                posy = 23;
                posx = 0;
        }
}

void putstr(char* str) {
        int i;
        for(i = 0; str[i] != 0; i++) putchar(str[i]);
}

unsigned char inp(unsigned char port) __naked { __asm ld hl, #2 add hl, sp ld c, (hl)in a, (c)ld l, a ld h, #0 ret __endasm; }

void outp(unsigned char port, unsigned char data) __naked { __asm push bc ld hl, #4 add hl, sp ld c, (hl)inc hl ld b, (hl)out(c), b pop bc ret __endasm; }