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 #define PAGE_SIZE       0x1000  // Should be in mm_virt.h
  13
  14 // === STRUCTURES ===
  15 typedef struct sVFS_MMapPageBlock       tVFS_MMapPageBlock;
  16 struct sVFS_MMapPageBlock
  17 {
  18         tVFS_MMapPageBlock      *Next;
  19         Uint64  BaseOffset;     // Must be a multiple of MMAP_PAGES_PER_BLOCK*PAGE_SIZE
  20         tPAddr  PhysAddrs[MMAP_PAGES_PER_BLOCK];
  21 };
  22
  23 // === CODE ===
  24 void *VFS_MMap(int *ErrNo, void *DestHint, size_t Length, int Protection, int Flags, int FD, Uint64 Offset)
  25 {
  26         tVFS_Handle     *h;
  27         tVAddr  mapping_dest;
  28          int    npages, pagenum;
  29         tVFS_MMapPageBlock      *pb, *prev;
  30
  31         npages = ((Offset & (PAGE_SIZE-1)) + Length) / PAGE_SIZE;
  32         pagenum = Offset / PAGE_SIZE;
  33
  34         mapping_dest = DestHint;
  35
  36         // TODO: Locate space for the allocation
  37         if( Flags & MAP_ANONYMOUS )
  38         {
  39                 MM_Allocate(mapping_dest);
  40                 return (void*)mapping_dest;
  41         }
  42
  43         h = VFS_GetHandle(FD);
  44         if( !h || !h->Node )    return NULL;
  45
  46         // Search for existing mapping for each page
  47         // - Sorted list of 16 page blocks
  48         for(
  49                 pb = h->Node->MMapInfo, prev = NULL;
  50                 pb && pb->BaseOffset + MMAP_PAGES_PER_BLOCK < pagenum;
  51                 prev = pb, pb = pb->Next
  52                 );
  53
  54         if( !pb || pb->BaseOffset > pagenum )
  55         {
  56                 void    *old_pb = pb;
  57                 // Allocate if needed
  58                 pb = malloc( sizeof(tVFS_MMapPageBlock) );
  59                 if(!pb) return NULL;
  60                 pb->Next = old_pb;
  61                 pb->BaseOffset = pagenum - pagenum % MMAP_PAGES_PER_BLOCK;
  62                 memset(pb->PhysAddrs, 0, sizeof(pb->PhysAddrs));
  63                 if(prev)
  64                         prev->Next = pb;
  65                 else
  66                         h->Node->MMapInfo = pb;
  67         }
  68
  69         while( npages -- )
  70         {
  71                 if( pb->PhysAddrs[pagenum - pb->BaseOffset] == 0 )
  72                 {
  73                         if( h->Node->MMap )
  74                                 h->Node->MMap(h->Node, pagenum*PAGE_SIZE, PAGE_SIZE, (void*)mapping_dest);
  75                         else
  76                         {
  77                                 // Allocate pages and read data
  78                                 MM_Allocate(mapping_dest);
  79                                 h->Node->Read(h->Node, pagenum*PAGE_SIZE, PAGE_SIZE, (void*)mapping_dest);
  80                         }
  81                         pb->PhysAddrs[pagenum - pb->BaseOffset] = MM_GetPhysAddr( mapping_dest );
  82                 }
  83                 else
  84                 {
  85                         MM_Map( mapping_dest, pb->PhysAddrs[pagenum - pb->BaseOffset] );
  86                 }
  87                 pagenum ++;
  88                 mapping_dest += PAGE_SIZE;
  89
  90                 // Roll on to next block if needed
  91                 if(pagenum - pb->BaseOffset == MMAP_PAGES_PER_BLOCK)
  92                 {
  93                         if( pb->Next && pb->Next->BaseOffset == pagenum )
  94                                 pb = pb->Next;
  95                         else
  96                         {
  97                                 tVFS_MMapPageBlock      *oldpb = pb;
  98                                 pb = malloc( sizeof(tVFS_MMapPageBlock) );
  99                                 pb->Next = oldpb->Next;
 100                                 pb->BaseOffset = pagenum;
 101                                 memset(pb->PhysAddrs, 0, sizeof(pb->PhysAddrs));
 102                                 oldpb->Next = pb;
 103                         }
 104                         pagenum = 0;
 105                 }
 106         }
 107
 108         return NULL;
 109 }
 110
 111 int VFS_MUnmap(int *ErrNo, void *Addr, size_t Length)
 112 {
 113         return 0;
 114 }