rom/exec/allocabs.c

   1 /*
   2     Copyright © 1995-2012, 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
  37     INPUTS
  38         byteSize - Number of bytes you want to get
  39         location - Where you want to get the memory
  40
  41     RESULT
  42         A pointer to some memory including the requested bytes or NULL if
  43         the memory couldn't be allocated
  44
  45     NOTES
  46
  47     EXAMPLE
  48
  49     BUGS
  50
  51     SEE ALSO
  52         FreeMem()
  53
  54     INTERNALS
  55         This function may trash memory right after the allocation if it builds
  56         a new MemChunk there. Additionally it will trash additional area before
  57         and after the allocated space if mungwall is turned on. The additional
  58         space will be used for mungwall service data.
  59
  60         We can't just disable mungwalling for this function because in this case
  61         FreeMem() on AllocAbs()ed region will crash (FreeMem() will expect mungwall
  62         header attached to the chunk and there's no way to tell which function was
  63         used to allocate it.
  64
  65 ******************************************************************************/
  66 {
  67     AROS_LIBFUNC_INIT
  68
  69     IPTR origSize = byteSize;
  70     APTR ret = NULL;
  71     struct TraceLocation tp = CURRENT_LOCATION("AllocAbs");
  72
  73     /* Zero bytes requested? May return everything ;-). */
  74     if(!byteSize)
  75         return NULL;
  76
  77     /* Make room for mungwall if needed */
  78     if (PrivExecBase(SysBase)->IntFlags & EXECF_MungWall)
  79     {
  80         location -= MUNGWALL_BLOCK_SHIFT;
  81         byteSize += MUNGWALL_TOTAL_SIZE;
  82     }
  83
  84     ret = InternalAllocAbs(location, byteSize, SysBase);
  85
  86     D(bug("[AllocAbs] Location: requested 0x%p, actual 0x%p\n", location, ret));
  87     D(bug("[AllocAbs] Length: requested %u, actual %u\n", origSize, origSize + location - ret));
  88     /*
  89      * Starting address may have been adjusted, in this case 'ret' will
  90      * differ from 'location', and allocation length was in fact increased
  91      * by this difference.
  92      * We also specify MEMF_CLEAR because we do not want to destroy original
  93      * memory contents.
  94      */
  95     return MungWall_Build(ret, NULL, origSize + location - ret, MEMF_CLEAR, &tp, SysBase);
  96
  97     AROS_LIBFUNC_EXIT
  98 } /* AllocAbs */