rnd

diff --git a/bootcard.asm b/bootcard.asm
index 1288c4a..4a2f3e4 100644 (file)
--- a/bootcard.asm
+++ b/bootcard.asm
@@ -9,6 +9,7 @@
 nticks equ 7e00h
 tmoffs equ 7e04h
 musptr equ 7e08h
+ppos   equ 7e0ch
 
 %macro setcur 2
        mov dx, %1 | (%2 << 8)
@@ -42,7 +43,7 @@ start:        xor ax, ax
        mov sp, 7c00h
 
        mov di, nticks
-       mov cx, 6
+       mov cx, 8
        rep stosw
 
        mov word [32], tintr
@@ -75,6 +76,8 @@ mainloop:
 
        call drawbg
 
+       call psys
+
        jmp mainloop
 
 drawbg:
@@ -115,6 +118,28 @@ drawbg:
        
        ret
 
+psys:  cmp word [ppos + 2], 0
+       ja .skipspawn
+
+       call rnd
+       add ax, 128
+       mov [ppos + 2], ax
+       call rnd
+       add ax, 32
+       mov [ppos], ax
+.skipspawn:
+       dec word [ppos + 2]
+       mov ax, [ppos + 2]
+       shr ax, 2
+       imul bx, ax, 320
+       add bx, [ppos]
+       mov byte [es:bx], 0eh
+
+rnd:   in al, 40h
+       mov ah, al
+       in al, 40h
+       shr ax, 8
+       ret
 
 textout:
        mov al, [si]