Pi Boot (Rainbow colored screen like Raspberry Pi boot) | MSX-BASIC 3.0+ (MSX2+/turbo R) / z88dk https://msxjpn.jimdofree.com/%E3%83%97%E3%83%AD%E3%82%B0%E3%83%A9%E3%83%A0/yjk-%E8%A1%A8%E7%A4%BA/

piboot.c

/*
 Pi Boot (Rainbow colored screen like Raspberry Pi boot) | MSX2+ / z88dk
 Copyright (c) 2019-2024 BALLOON | FU-SEN
 The MIT License (MIT) - https://mit.balloon.net.eu.org/#2019-2024

 zcc +msx -lndos -create-app -subtype=disk -bn piboot piboot.c
 --> BLOAD"PIBOOT.MSX",R
*/

void ldirvm(int addr, int vaddr, int size)
{
#asm
    ld   ix,0
    add  ix,sp
    ld   c,(ix+2)       ; size
    ld   b,(ix+3)
    ld   e,(ix+4)       ; vaddr
    ld   d,(ix+5)
    ld   l,(ix+6)       ; addr
    ld   h,(ix+7)
    call 005ch          ; LDIRVM
#endasm
}

void cls()
{
#asm
    xor  a              ; Clear Z flag
    call 00c3h          ; CLS
#endasm
}

void chgclr(char forclr, char bakclr, char bdrclr)
{
#asm
    ld   ix,0
    add  ix,sp
    ld   a,(ix+2)       ; BDRCLR
    ld   (0f3ebh),a
    ld   a,(ix+4)       ; BAKCLR
    ld   (0f3eah),a
    ld   a,(ix+6)       ; FORCLR
    ld   (0f3e9h),a
    ld   ix,0111h       ; CHGCLR
    call 015fh          ; EXTROM
#endasm
}

void chgmdp(char mode)
{
#asm
    ld   a,l            ; mode
    ld   ix,01b5h       ; CHGMDP
    call 015fh          ; EXTROM
#endasm
}

void screen12()
{
#asm
    ld	 hl,0fffah      ; rg25sa
    res  4,(hl)
    set  3,(hl)
    ld   a,(hl)
    ld   b,a
    ld   c,25           ; R#25
    call 0047h          ; WRTVDP
#endasm
}

int gttrig(char num)
{
#asm
    ld   a,l            ; num
    call 00d8h          ; GTTRIG
    ld   l,a
    ld   h,0
#endasm
}

char buf[192] = { 0 };

void main()
{
    int c=15;

    chgmdp(8);
    screen12();

    chgclr(255, 0, 0);
    cls();

    c=c<<3;

    for (int x=0; x<192; x+=4) {
        int k=x*64/192-32;
        buf[x]  =c|k&7;
        buf[x+1]=c|k>>3&7;
    }

    for (int j=-32; j<32; j++) {
        int y=106-(j+1)*212/64;
        for (int x=0; x<192; x+=4) {
            buf[x+2]=c|j&7;
            buf[x+3]=c|j>>3&7;
        }
        ldirvm(buf,    y*256+32,192);
        ldirvm(buf,(y+1)*256+32,192);
        ldirvm(buf,(y+2)*256+32,192);
        ldirvm(buf,(y+3)*256+32,192);
    }
    while (! gttrig(0));
}