Kernel/vfs/mmap.c

   1 /*
   2  * Acess2 VFS
   3  * - Open, Close and ChDir
   4  */
   5 #define DEBUG   0
   6 #include <acess.h>
   7 #include <vfs.h>
   8 #include <vfs_ext.h>
   9 #include <vfs_int.h>
  10
  11 #define MMAP_PAGES_PER_BLOCK    16
  12
  13 // === STRUCTURES ===
  14 typedef struct sVFS_MMapPageBlock
  15 {
  16         tVFS_MMapPageBlock      *Next;
  17         Uint64  BaseOffset;     // Must be a multiple of MMAP_PAGES_PER_BLOCK*PAGE_SIZE
  18         tPAddr  PhysAddrs[MMAP_PAGES_PER_BLOCK];
  19 } tVFS_MMapPageBlock;
  20
  21 // === CODE ===
  22 void *VFS_MMap(int *ErrNo, void *DestHint, size_t Length, int Protection, int Flags, int FD, Uint64 Offset)
  23 {
  24         tVFS_Handle     *h;
  25         void    *mapping_dest;
  26          int    npages, pagenum;
  27         tVFS_MMapPageBlock      *pb, *prev;
  28
  29         npages = ((Offset & (PAGE_SIZE-1)) + Length) / PAGE_SIZE;
  30         pagenum = Offset / PAGE_SIZE;
  31
  32         mapping_dest = DestHint;
  33
  34         // TODO: Locate space for the allocation
  35         if( Flags & MAP_ANONYMOUS )
  36         {
  37                 MM_Allocate(mapping_dest);
  38                 return mapping_dest;
  39         }
  40
  41         h = VFS_GetHandle(FD);
  42         if( !h || !h->Node )    return NULL;
  43
  44         // Search for existing mapping for each page
  45         // - Sorted list of 16 page blocks
  46         for(
  47                 pb = h->Node->MMapInfo, prev = NULL;
  48                 pb && pb->BaseOffset + MMAP_PAGES_PER_BLOCK < pagenum;
  49                 prev = pb, pb = pb->Next
  50                 );
  51
  52         if( !pb || pb->BaseOffset > pagenum )
  53         {
  54                 void    *old_pb = pb;
  55                 // Allocate if needed
  56                 pb = malloc( sizeof(tVFS_MMapPageBlock) );
  57                 if(!pb) return NULL;
  58                 pb->Next = old_pb;
  59                 pb->BaseOffset = pagenum - pagenum % MMAP_PAGES_PER_BLOCK;
  60                 memset(pb->PhysAddrs, 0, sizeof(pb->PhysAddrs));
  61                 if(prev)
  62                         prev->Next = pb;
  63                 else
  64                         h->Node->MMapInfo = pb;
  65         }
  66
  67         while( npages -- )
  68         {
  69                 if( pb->PhysAddrs[pagenum - pb->BaseOffset] == 0 )
  70                 {
  71                         if( h->Node->MMap )
  72                                 h->Node->MMap(h->Node, pagenum*PAGE_SIZE, PAGE_SIZE, mapping_dest);
  73                         else
  74                         {
  75                                 // Allocate pages and read data
  76                                 MM_Allocate(mapping_dest);
  77                                 h->Node->Read(h->Node, pagenum*PAGE_SIZE, PAGE_SIZE, mapping_dest);
  78                         }
  79                         pb->PhysAddrs[pagenum -> pb->BaseOffset] = MM_GetPhysAddr( mapping_dest );
  80                 }
  81                 else
  82                 {
  83                         MM_Map( mapping_dest, pb->PhysAddrs[pagenum - pb->BaseOffset] );
  84                 }
  85                 pagenum ++;
  86                 mapping_dest += PAGE_SIZE;
  87
  88                 // Roll on to next block if needed
  89                 if(pagenum - pb->BaseOffset == MMAP_PAGES_PER_BLOCK)
  90                 {
  91                         if( pb->Next && pb->Next->BaseOffset == pagenum )
  92                                 pb = pb->Next;
  93                         else
  94                         {
  95                                 tVFS_MMapPageBlock      *oldpb = pb;
  96                                 pb = malloc( sizeof(tVFS_MMapPageBlock) );
  97                                 pb->Next = oldpb->Next;
  98                                 pb->BaseOffset = pagenum;
  99                                 memset(pb->PhysAddrs, 0, sizeof(pb->PhysAddrs));
 100                                 oldpb->Next = pb;
 101                         }
 102                         pagenum = 0;
 103                 }
 104         }
 105
 106         return NULL;
 107 }
 108
 109 int VFS_MUnmap(int *ErrNo, void *Addr, size_t Length)
 110 {
 111         return 0;
 112 }