flat assembler - ERR directive - useful ??? Conditional ERR

Index > Compiler Internals > ERR directive - useful ??? Conditional ERR

Author

Thread

DOS386

Joined: 08 Dec 2006
Posts: 1900

DOS386 07 Apr 2009, 01:54

Code:

  macro mov op1,op2 {
    if op1 eq cs
      err "CS is not a valid destination"
    end if
    if op1 in <ds,es,fs,gs,ss> & op2 in <cs,ds,es,fs,gs,ss>
      push  op2
      pop   op1
    else
      mov   op1,op2
    end if
  } ; endmacro

  mov es,ax
  mov ds,cs
  mov cs,ds ; BUG !!!

When compiling this in the commandline, I get 2 offending lines listed:

Code:

  mov cs,ds ; BUG !!!
      err "CS is not a valid destination"

telling me what's wrong ... but this not really the effect of err - if I place anything other like abortcompilationhere , the effect will be pretty same.

OTOH in the IDE, only

Code:

  mov cs,ds ; BUG !!!

gets listed and no clue what's wrong, and no benefit from err again. Shouldn't err pass the string to become useful ?

Other possibility of improvement:

Code:

  if ($>$FFFF)
    err "You ran out of UNreal CS limit"
  end if

could become:

Code:

  err ($>$FFFF)

would crash only if the expression is true and report the offending expression. Idea

07 Apr 2009, 01:54

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20309
Location: In your JS exploiting you and your system

revolution 07 Apr 2009, 02:01

The idea of err is that it is always guaranteed to give an error. Kind of like Intel making UD2 as an encoding to never be used by a valid instruction.

Last edited by revolution on 07 Apr 2009, 02:06; edited 1 time in total

07 Apr 2009, 02:01

DOS386

Joined: 08 Dec 2006
Posts: 1900

DOS386 07 Apr 2009, 02:04

revolution wrote:

The idea of err is that is it always guaranteed to give an error. Kind of like Intel making UD2 as an encoding to never be used by a valid instruction.

while abortcompilationhere could become valid one day Laughing

Code:

  conderr ($>$FFFF)

07 Apr 2009, 02:04

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20309
Location: In your JS exploiting you and your system

revolution 07 Apr 2009, 02:09

abortcompilationhere is too long to be friendly to use.

07 Apr 2009, 02:09

Tomasz Grysztar

Joined: 16 Jun 2003
Posts: 8351
Location: Kraków, Poland

Tomasz Grysztar 07 Apr 2009, 05:10

And "abortcompilationhere" gives you a different error message, while ERR tells you that breaking the compilation was intended in that place.

07 Apr 2009, 05:10

< Last Thread | Next Thread >

Forum Rules:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum