Kernel - Adding support for MMap (untested)

diff --git a/Kernel/include/vfs.h b/Kernel/include/vfs.h
index 248a1ac..73161a1 100644 (file)
--- a/Kernel/include/vfs.h
+++ b/Kernel/include/vfs.h
@@ -155,6 +155,7 @@ typedef struct sVFS_Node
        
        /**
         * \name VFS_Select() fields
+        * \note Used by the VFS internals, drivers should use VFS_Mark*
         * \{
         */
         int    DataAvaliable;
@@ -166,6 +167,15 @@ typedef struct sVFS_Node
        /**
         * \}
         */
+
+       /**
+        * \name VFS_MMap() fields
+        * \{
+        */
+       void    *MMapInfo;
+       /**
+        * \}
+        */
        
        /**
         * \name Common Functions

diff --git a/Kernel/include/vfs_int.h b/Kernel/include/vfs_int.h
index d4a533d..0d6b3b5 100644 (file)
--- a/Kernel/include/vfs_int.h
+++ b/Kernel/include/vfs_int.h
@@ -35,6 +35,11 @@ typedef struct sVFS_Proc {
        tVFS_Handle     Handles[];
 } tVFS_Proc;
 
+typedef struct sVFS_MMapPage {
+       Uint64  FileOffset;
+       tPAddr  PAddr;
+} tVFS_MMapPage;
+
 // === GLOBALS ===
 extern tVFS_Mount      *gVFS_Mounts;
 

diff --git a/Kernel/vfs/mmap.c b/Kernel/vfs/mmap.c
new file mode 100644 (file)
index 0000000..f8422bb
--- /dev/null
+++ b/Kernel/vfs/mmap.c
@@ -0,0 +1,112 @@
+/*
+ * Acess2 VFS
+ * - Open, Close and ChDir
+ */
+#define DEBUG  0
+#include <acess.h>
+#include <vfs.h>
+#include <vfs_ext.h>
+#include <vfs_int.h>
+
+#define MMAP_PAGES_PER_BLOCK   16
+
+// === STRUCTURES ===
+typedef struct sVFS_MMapPageBlock
+{
+       tVFS_MMapPageBlock      *Next;
+       Uint64  BaseOffset;     // Must be a multiple of MMAP_PAGES_PER_BLOCK*PAGE_SIZE
+       tPAddr  PhysAddrs[MMAP_PAGES_PER_BLOCK];
+} tVFS_MMapPageBlock;
+
+// === CODE ===
+void *VFS_MMap(int *ErrNo, void *DestHint, size_t Length, int Protection, int Flags, int FD, Uint64 Offset)
+{
+       tVFS_Handle     *h;
+       void    *mapping_dest;
+        int    npages, pagenum;
+       tVFS_MMapPageBlock      *pb, *prev;
+       
+       npages = ((Offset & (PAGE_SIZE-1)) + Length) / PAGE_SIZE;
+       pagenum = Offset / PAGE_SIZE;
+
+       mapping_dest = DestHint;        
+
+       // TODO: Locate space for the allocation
+       if( Flags & MAP_ANONYMOUS )
+       {
+               MM_Allocate(mapping_dest);
+               return mapping_dest;
+       }
+
+       h = VFS_GetHandle(FD);
+       if( !h || !h->Node )    return NULL;
+
+       // Search for existing mapping for each page
+       // - Sorted list of 16 page blocks
+       for(
+               pb = h->Node->MMapInfo, prev = NULL;
+               pb && pb->BaseOffset + MMAP_PAGES_PER_BLOCK < pagenum;
+               prev = pb, pb = pb->Next
+               );
+
+       if( !pb || pb->BaseOffset > pagenum )
+       {
+               void    *old_pb = pb;
+               // Allocate if needed
+               pb = malloc( sizeof(tVFS_MMapPageBlock) );
+               if(!pb) return NULL;
+               pb->Next = old_pb;
+               pb->BaseOffset = pagenum - pagenum % MMAP_PAGES_PER_BLOCK;
+               memset(pb->PhysAddrs, 0, sizeof(pb->PhysAddrs));
+               if(prev)
+                       prev->Next = pb;
+               else
+                       h->Node->MMapInfo = pb;
+       }
+
+       while( npages -- )
+       {
+               if( pb->PhysAddrs[pagenum - pb->BaseOffset] == 0 )
+               {
+                       if( h->Node->MMap )
+                               h->Node->MMap(h->Node, pagenum*PAGE_SIZE, PAGE_SIZE, mapping_dest);
+                       else
+                       {
+                               // Allocate pages and read data
+                               MM_Allocate(mapping_dest);
+                               h->Node->Read(h->Node, pagenum*PAGE_SIZE, PAGE_SIZE, mapping_dest);
+                       }
+                       pb->PhysAddrs[pagenum -> pb->BaseOffset] = MM_GetPhysAddr( mapping_dest );
+               }
+               else
+               {
+                       MM_Map( mapping_dest, pb->PhysAddrs[pagenum - pb->BaseOffset] );
+               }
+               pagenum ++;
+               mapping_dest += PAGE_SIZE;
+               
+               // Roll on to next block if needed
+               if(pagenum - pb->BaseOffset == MMAP_PAGES_PER_BLOCK)
+               {
+                       if( pb->Next && pb->Next->BaseOffset == pagenum )
+                               pb = pb->Next;
+                       else
+                       {
+                               tVFS_MMapPageBlock      *oldpb = pb;
+                               pb = malloc( sizeof(tVFS_MMapPageBlock) );
+                               pb->Next = oldpb->Next;
+                               pb->BaseOffset = pagenum;
+                               memset(pb->PhysAddrs, 0, sizeof(pb->PhysAddrs));
+                               oldpb->Next = pb;
+                       }
+                       pagenum = 0;
+               }
+       }
+       
+       return NULL;
+}
+
+int VFS_MUnmap(int *ErrNo, void *Addr, size_t Length)
+{
+       return 0;
+}