rom/exec/allocabs.c

   1 /*
   2     Copyright © 1995-2015, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Allocate memory at address
   6     Lang: english
   7 */
   8
   9 #include <aros/debug.h>
  10 #include <exec/alerts.h>
  11 #include <exec/execbase.h>
  12 #include <exec/memory.h>
  13 #include <exec/memheaderext.h>
  14 #include <proto/exec.h>
  15
  16 #include "exec_intern.h"
  17 #include "exec_util.h"
  18 #include "memory.h"
  19 #include "mungwall.h"
  20
  21 /*****************************************************************************
  22
  23     NAME */
  24
  25         AROS_LH2(APTR, AllocAbs,
  26
  27 /*  SYNOPSIS */
  28         AROS_LHA(IPTR,  byteSize, D0),
  29         AROS_LHA(APTR,  location, A1),
  30
  31 /*  LOCATION */
  32         struct ExecBase *, SysBase, 34, Exec)
  33
  34 /*  FUNCTION
  35         Allocate some memory from the system memory pool at a given address.
  36         The memory must be freed with FreeMem().
  37
  38     INPUTS
  39         byteSize - Number of bytes you want to get
  40         location - Where you want to get the memory
  41
  42     RESULT
  43         A pointer to some memory including the requested bytes or NULL if
  44         the memory couldn't be allocated.
  45
  46     NOTES
  47
  48     EXAMPLE
  49
  50     BUGS
  51
  52     SEE ALSO
  53         FreeMem()
  54
  55     INTERNALS
  56         This function may trash memory right after the allocation if it builds
  57         a new MemChunk there. Additionally it will trash additional area before
  58         and after the allocated space if mungwall is turned on. The additional
  59         space will be used for mungwall service data.
  60
  61         We can't just disable mungwalling for this function because in this case
  62         FreeMem() on AllocAbs()ed region will crash (FreeMem() will expect mungwall
  63         header attached to the chunk and there's no way to tell which function was
  64         used to allocate it.
  65
  66 ******************************************************************************/
  67 {
  68     AROS_LIBFUNC_INIT
  69
  70     IPTR origSize = byteSize;
  71     APTR ret = NULL;
  72     struct TraceLocation tp = CURRENT_LOCATION("AllocAbs");
  73
  74     /* Zero bytes requested? May return everything ;-). */
  75     if(!byteSize)
  76         return NULL;
  77
  78     /* Make room for mungwall if needed */
  79     if (PrivExecBase(SysBase)->IntFlags & EXECF_MungWall)
  80     {
  81         location -= MUNGWALL_BLOCK_SHIFT;
  82         byteSize += MUNGWALL_TOTAL_SIZE;
  83     }
  84
  85     ret = InternalAllocAbs(location, byteSize, SysBase);
  86
  87     D(bug("[AllocAbs] Location: requested 0x%p, actual 0x%p\n", location, ret));
  88     D(bug("[AllocAbs] Length: requested %u, actual %u\n", origSize, origSize + location - ret));
  89     /*
  90      * Starting address may have been adjusted, in this case 'ret' will
  91      * differ from 'location', and allocation length was in fact increased
  92      * by this difference.
  93      * We also specify MEMF_CLEAR because we do not want to destroy original
  94      * memory contents.
  95      */
  96     return MungWall_Build(ret, NULL, origSize + location - ret, MEMF_CLEAR, &tp, SysBase);
  97
  98     AROS_LIBFUNC_EXIT
  99 } /* AllocAbs */