backbuffer + vsync

diff --git a/bootcard.asm b/bootcard.asm
index 434bf0b..5c63dfe 100644 (file)
--- a/bootcard.asm
+++ b/bootcard.asm
@@ -12,6 +12,8 @@ tmoffs                equ nticks + 4
 muscur         equ tmoffs + 4
 data_end       equ muscur + 4
 
+backbuf_seg    equ 1000h
+
 OSC_FREQ       equ 1193182
 PIT_DATA0      equ 40h
 PIT_CMD                equ 43h
@@ -65,7 +67,7 @@ start:        xor eax, eax
 
        mov ax, 13h
        int 10h
-       push 0a000h
+       push backbuf_seg
        pop es
 
        ; setup palette
@@ -88,7 +90,41 @@ start:       xor eax, eax
        out dx, al
        dec cx
        jnz .cmapsetup
-       
+       sti
+
+mainloop:
+       call drawbg
+
+       mov dx, 3dah
+.invb: in al, dx
+       and al, 8
+       jnz mainloop
+.novb: in al, dx
+       and al, 8
+       jz .novb
+
+       push ds
+       push es
+       push es
+       pop ds
+       push 0a000h
+       pop es
+       xor di, di
+       xor si, si
+       mov cx, 32000
+       rep movsw
+       pop es
+       pop ds
+
+       setcursor 10, 12
+       mov si, str1
+       call textout
+       setcursor 12, 13
+       mov si, str2
+       call textout
+
+       jmp mainloop
+
 drawbg:
        mov bx, 200
        xor di, di
@@ -100,19 +136,8 @@ drawbg:
        rep stosw
        dec bx
        jnz .fillgrad
+       ret
 
-       setcursor 10, 12
-       mov si, str1
-       call textout
-       setcursor 12, 13
-       mov si, str2
-       call textout
-
-       sti
-
-infloop:
-       hlt
-       jmp infloop
 
 textout:
        mov al, [si]