qdosmsq:traps:trap_3:trnc [QDOS Internals]

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====== FS_TRUNCATE/IOF_TRNC ======

This trap truncates a file to the current position.

^Call Parameters^^Return Parameters^^
|D0.B|$4B|D0.L|Error return.|
|D1.L| |D1.L|Corrupted.|
|D3.W|Timeout |D3.L|Preserved.|
|A0.L|Channel ID |A0.L|Preserved.|
|A1.L| |A1.L|Corrupted.|

===== Errors =====
Any sub system IO errors including
|ERR_NC|Not complete.|


===== Notes =====
  * All registers not shown above are not used on entry and are preserved on exit.
 

===== Example =====
The example below shows the use of this trap call to truncate a file to the position set in D1.L. It is assumed that A0 contains the file's ID.

<code>
trnc    moveq   #fs_posab,d0    ; $42
        moveq   #-1,d3          ; Timeout
        trap    #3              ; Set the position
        tst.l   d0              ; OK? . .
        bne     error           ; . . no!
        moveq   #fs_truncate,d0 ; $4B
        trap    #3              ; Truncate
        tst.l   d0              ; OK? . .
        bne     error           ; . . no!        
       
</code>