Can Anyone tell me why this doesn't work?

Hi All,


This is a bita Vesa(256) code to get a line of pixels - it works fine
in protected mode but hangs mysteriously in real mode - I'm fairly new
to asm & wressling with the segment registers and I can't see what it
is that I'm doing wrong - all suggestions welcome (Jason?)

:) Phil


procedure gline8(x1,x2,y :word;var Buff :pointer);assembler;
 {hangs in real mode , fine in prot}
 asm
          cld
          mov di, offset Buff
          mov cx,x1

@[EMAIL PROTECTED]
  push cx

          mov     bx,y
          shl     bx,2
          DB $66
          mov     si,word ptr LineOffsets[bx]
          DB $66
          mov     ax,cx
          DB $66
          add     si,ax
          DB $66
          mov bx,si
          DB $66
          shr bx,16
        { the above should be shld ebx,esi,16 but I don't know the
opcodes :)}
          cmp     bx,CurReadBank
          je @[EMAIL PROTECTED]
          mov     CurReadBank,bx  ; { reset to new page }
          add     bx,bx
          DB $66
          mov     dx,word ptr BankVals[bx]
          xor     bx,bx
          call    dword ptr switchbank
         { same as mov     ax,$4F05
          int     10H or WinfuncPtr in real mode}

          mov     bx,ReadWindow
          test    bx,bx
          jnz     @[EMAIL PROTECTED]
          mov     bx,CurReadBank
          mov     CurWriteBank,bx

@[EMAIL PROTECTED]
          push ds
          mov ds,SegA000
          movsb
          pop ds

@[EMAIL PROTECTED]
          pop cx
          inc cx
          cmp cx,x2
          jc @[EMAIL PROTECTED]
 end;