qdosmsq:traps:trap_1:rehp

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qdosmsq:traps:trap_1:rehp [2009/01/30 11:44]
norman created
qdosmsq:traps:trap_1:rehp [2009/02/12 09:51] (current)
george.gwilt LINKFR corrected to LNKFR
Line 1: Line 1:
 +====== MT_LNKFR/SMS_REHP ======
 +This trap frees previously allocated space in a user heap. 
  
 +^Call Parameters^^Return Parameters^^
 +|D0.B|$0D|D0.L|Corrupted?|
 +|D1.L|Size of area to be linked (back) in to the user heap. |D1.L|Corrupted.|
 +|D2.L|Unused. |D2.L| Corrupted.|
 +|D3.L|Unused. |D3.L| Corrupted.|
 +|A0.L|Address of the area of heap/memory to link (back) in to the user heap (Relative A6). |A0.L|Corrupted.|
 +|A1.L|Pointer to pointer to free space (Relative A6) or zero. |A1.L| Corrupted.|
 +|A2.L|Unused. |A2.L| Corrupted.|
 +
 +===== Errors =====
 +No errors are returned by this trap.
 +
 +===== Notes =====
 +
 +  * All registers not shown above are not used on entry and are preserved
 +on exit.
 +
 +  * A user heap is an area of memory, maybe in the common heap, set aside for use
 +by a single job. The job can allocate areas of this user heap for its own needs, and
 +deallocate them as required. This stops, or reduces fragmentation of the common heap which
 +is used by every task in the system. [[qdosmsq:memory:heaps|See here]] for more information on heaps.
 +
 +  * If the long word at (A1,A6) is zero, then this trap will create a new user heap at the address in A1.
 +
 +  * If (A1,A6) is not zero, then you are assumed to be releasing a previously allocated
 +chunk of user heap back into the user heap's free space.
 +
 +===== Example =====
 +[[qdosmsq:traps:trap_1:heaps|This example]] show the use of this, and other, heap
 +manipulation traps.
  • qdosmsq/traps/trap_1/rehp.txt
  • Last modified: 2009/02/12 09:51
  • by george.gwilt