bvis238 for TweetX86

bvis238.TweetX86.asm

; My favourite effect code formatted to be pasted here http://twt86.co/
; 386dx25.de
        mov     ax, 13h
        int     10h
        push    0A000h
        pop     es
MAINLOOP
        mov     di, VBUF+320
        mov     cx, 64000 - 2*320
CONV
        xor     ax, ax
        add     ax, [di-1]      ; Sum up kernel taps
        add     ax, [di+1]
        add     ax, [di-320]
        add     ax, [di+320]
        
        sub     ax, 4*31        ; Use VGA palette gradient between 31 and 95
       
        shr     ax, 2           ; Average (/4) for diffusion
        and     al, 63
        add     al, 31+1        ; Increment for dynamics, and shift to palette
        
        mov     [di], al        ; Update pixel at [di]
        inc     di
        loop    CONV

        mov     si, VBUF
        xor     di, di
        mov     cx, 64000 / 4
        rep     movsd
        
        in      al, 60h
        and     al, 127
        dec     al
        jnz     MAINLOOP

VBUF    db      "386dx25"

description.md

Run the code on twt86.co

Binary code in base64 encoding:

uBMAzRBoAKAHv4EBuYD3McADRf8DRQEDhcD+A4VAAYPofMHoAiQ/BCCIBUfi4b5BADH/uYA+82al5GAkf/7IdcgzODZkeDI1

Size-coding attempt:

• les trick
• no VBUF
• ds = es for direct video mem access via [di+x]
• no clean palette shift
• no escape ;-)

        mov     al, 13h
        int     10h
        les     bx, [0]
        push    es
        pop     ds
MAINLOOP
        mov     cx, 64000 - 2*320
CONV
        xor     ax, ax
        add     ax, [di-1]      ; Sum up kernel taps
        add     ax, [di+1]
        add     ax, [di-320]
        add     ax, [di+320]

        shr     ax, 2           ; Average (/4) for diffusion
        and     al, 63
        add     al, 33          ; Magic increment
        
        stosb                   ; Update pixel
        loop    CONV
        jmp     MAINLOOP

Run on twt86.co
Base64: sBPNEMQeAAAGH7mA9zHAA0X/A0UBA4XA/gOFQAHB6AIkPwQhquLm6+E=