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(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 = (tVAddr)DestHint;
  35
  36 #if 0
  37         // TODO: Locate space for the allocation
  38         if( Flags & MAP_ANONYMOUS )
  39         {
  40                 MM_Allocate(mapping_dest);
  41                 return (void*)mapping_dest;
  42         }
  43 #endif
  44
  45         h = VFS_GetHandle(FD);
  46         if( !h || !h->Node )    return NULL;
  47
  48         // Search for existing mapping for each page
  49         // - Sorted list of 16 page blocks
  50         for(
  51                 pb = h->Node->MMapInfo, prev = NULL;
  52                 pb && pb->BaseOffset + MMAP_PAGES_PER_BLOCK < pagenum;
  53                 prev = pb, pb = pb->Next
  54                 );
  55
  56         // - Allocate a block if needed
  57         if( !pb || pb->BaseOffset > pagenum )
  58         {
  59                 void    *old_pb = pb;
  60                 pb = malloc( sizeof(tVFS_MMapPageBlock) );
  61                 if(!pb) return NULL;
  62                 pb->Next = old_pb;
  63                 pb->BaseOffset = pagenum - pagenum % MMAP_PAGES_PER_BLOCK;
  64                 memset(pb->PhysAddrs, 0, sizeof(pb->PhysAddrs));
  65                 if(prev)
  66                         prev->Next = pb;
  67                 else
  68                         h->Node->MMapInfo = pb;
  69         }
  70
  71         // - Map (and allocate) pages
  72         while( npages -- )
  73         {
  74                 if( pb->PhysAddrs[pagenum - pb->BaseOffset] == 0 )
  75                 {
  76                         if( h->Node->MMap )
  77                                 h->Node->MMap(h->Node, pagenum*PAGE_SIZE, PAGE_SIZE, (void*)mapping_dest);
  78                         else
  79                         {
  80                                 // Allocate pages and read data
  81                                 if( MM_Allocate(mapping_dest) == 0 ) {
  82                                         // TODO: Unwrap
  83                                         return NULL;
  84                                 }
  85                                 h->Node->Read(h->Node, pagenum*PAGE_SIZE, PAGE_SIZE, (void*)mapping_dest);
  86                         }
  87                         pb->PhysAddrs[pagenum - pb->BaseOffset] = MM_GetPhysAddr( mapping_dest );
  88 //                      MM_SetPageInfo( pb->PhysAddrs[pagenum - pb->BaseOffset], h->Node, pagenum*PAGE_SIZE );
  89                 }
  90                 else
  91                 {
  92                         MM_Map( mapping_dest, pb->PhysAddrs[pagenum - pb->BaseOffset] );
  93                 }
  94                 pagenum ++;
  95                 mapping_dest += PAGE_SIZE;
  96
  97                 // Roll on to next block if needed
  98                 if(pagenum - pb->BaseOffset == MMAP_PAGES_PER_BLOCK)
  99                 {
 100                         if( pb->Next && pb->Next->BaseOffset == pagenum )
 101                                 pb = pb->Next;
 102                         else
 103                         {
 104                                 tVFS_MMapPageBlock      *oldpb = pb;
 105                                 pb = malloc( sizeof(tVFS_MMapPageBlock) );
 106                                 pb->Next = oldpb->Next;
 107                                 pb->BaseOffset = pagenum;
 108                                 memset(pb->PhysAddrs, 0, sizeof(pb->PhysAddrs));
 109                                 oldpb->Next = pb;
 110                         }
 111                         pagenum = 0;
 112                 }
 113         }
 114
 115         return NULL;
 116 }
 117
 118 int VFS_MUnmap(void *Addr, size_t Length)
 119 {
 120         return 0;
 121 }