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+/*++
+
+Copyright (c) 1992  Microsoft Corporation
+
+Module Name:
+
+    suballoc.c
+
+Abstract:
+
+    This module contains code for managing a paritially commited address
+    space.  It handles allocation of chunks of memory smaller than the 
+    commit granularity.  It commits and decommits memory as needed using
+    the supplied function for committing and decommitting memory.  The 
+    structures used for tracking the address space are allocated outside
+    of the specified addresss space.
+
+Author:
+
+    Dave Hastings (daveh) creation-date 21-Jan-1994
+    
+Notes:
+
+    Since this package does not actually access memory in the address space
+    it is managing, it will work as well with real linear addresses or 
+    "Intel Addresses" such as would be encountered with the Insignia Emulator
+    on risc.
+
+Revision History:
+
+
+--*/
+
+//
+// Constants
+// 
+
+//
+// Smallest chunk that will be sub allocated
+// 1024 was chosen currently, because that is the
+// smallest chunk XMS will allocate.
+//
+#define SUBALLOC_GRANULARITY        1024
+
+//
+// The size of the character array require to hold the 
+// bits defining whether the individual allocation entities
+// in the commited chunk are allocated or free
+//
+// BUGBUG Assert that COMMIT_GRANULARITY is a multiple of SUBALLOC_GRANULARITY
+//
+#define SUBALLOC_BITFIELD_SIZE      COMMIT_GRANULARITY / SUBALLOC_GRANULARITY
+
+//
+// Types
+//
+
+//
+// Routine for committing a specific region of of the address
+// space.  Although the return type is NTSTATUS, the only value
+// that is checked is 0 (for STATUS_SUCCESS).  If STATUS_SUCCESS
+// is returned, it is assumed that the function worked. If not,
+// it is assumed that it failed.  No special meaning is attached to
+// particular non-zero values.
+//
+typedef
+NTSTATUS 
+(*PSACOMMITROUTINE)(
+    ULONG BaseAddress,
+    ULONG Size
+    );
+
+//
+// Structure for tracking the address space.  Each chunk of 
+// memory of SUBALLOC_GRANULARITY in size is represented by
+// a bit.  Each chunk of memory of COMMIT_GRANULARITY is 
+// represented by one element of the array of bitfields.
+// The FreeCheck array half of the union allows us to check
+// whether the entire committed chunk is free more quickly.
+//
+// ?? Should we add a field to indicate whether the chunk is 
+//    committed?  We can always check for all allocated bits
+//    zero, and use that as an indication that the chunk is 
+//    not committed.
+//
+// BUGBUG Assert that the bits fit into memory the way we think
+// they do.
+//
+typedef struct _SubAllocation {
+    PSACOMMITROUTINE CommitRoutine;
+    ULONG BaseAddress;
+    ULONG Size;
+    union {
+        //
+        // bitfield with one bit per chunk.  Bit set indicates
+        // allocated.  Bit clear indicates free.  All bits 
+        // clear indicates un committed
+        //
+        UINT Allocated[SUBALLOC_BITFIELD_SIZE] : 1;
+        //
+        // Hopefully a faster way to check all bits.
+        //
+        UINT FreeCheck[SUBALLOC_BITFIELD_SIZE / sizeof(UINT)];
+    } CommitedChunk;
+} SUBALLOCATIONDATA, *PSUBALLOCATIONDATA
+
+
+PVOID
+SAInitialize(
+    ULONG BaseAddress,
+    ULONG Size,
+    PSACOMMITROUTINE CommitRoutine
+    )
+/*++
+
+Routine Description:
+
+    This function performs initialization of the sub allocation package
+    for the specified addresss range.  It allocates the data structures
+    necessary to track the allocations
+
+Arguments:
+
+    BaseAddress -- Supplies the base address of the address space to
+        sub allocate.
+    Size -- Supplies the size in bytes of the address space to sub allocate.
+    CommitRoutine -- Supplies a pointer to the routine used to commit regions
+        of the address space.
+
+Return Value:
+
+    If the function was successful it returns a pointer to the sub-allocation
+    data structures.  Otherwise it returns NULL.
+    
+--*/
+{
+
+}
+
+BOOL 
+SAQueryFree(
+    PVOID SubAllocation,
+    PULONG FreeBytes
+    )    
+/*++
+
+Routine Description:
+
+    This routine returns the number of free bytes in the 
+    sub allocated address space.
+
+Arguments:
+    
+    SubAllocation -- Supplies the pointer returned by SAInitialize
+    FreeBytes -- Returns the number of free bytes
+   
+Return Value:
+
+    TRUE -- if successful, and FreeBytes contains the number of free bytes.
+    FALSE otherwise
+    
+--*/
+{
+
+}
+
+BOOL
+SAAllocate(
+    PVOID SubAllocation,
+    ULONG Size,
+    PULONG Address
+    )
+/*++
+
+Routine Description:
+
+    This function allocates a portion of the address space described by 
+    SubAllocation.  If necessary, it will commit additional blocks. Address is 
+    rounded down to the next lower SUBALLOC_GRANULARITY boundary.
+    size is rounded up to the next higher multiple of SUBALLOC_GRANULARITY.
+
+Arguments:
+
+    SubAllocation -- Supplies the pointer returned by SAInitialize.
+    Size -- Supplies the size in bytes of the region to allocate.
+    Address -- Returns the address of the region allocated.
+
+Return Value:
+
+    TRUE if successful.  If false is returned, no address is returned.
+    
+Notes:
+
+    Zero is a valid value for the returned address.
+
+--*/
+{
+
+}
+
+BOOL
+SAFree(
+    PVOID SubAllocation,
+    ULONG Size,
+    ULONG Address
+    )
+/*++
+
+Routine Description:
+
+    This routine frees a sub-allocated chunk of memory.  If the 
+    entire commited block (or blocks) that the specified chunk
+    belongs to are free, the chunks are decommitted.  Address is 
+    rounded down to the next lower SUBALLOC_GRANULARITY boundary.
+    size is rounded up to the next higher multiple of SUBALLOC_GRANULARITY.
+
+Arguments:
+
+    SubAllocation -- Supplies the pointer returned by SAInitialize.
+    Size -- Supplies the size in bytes of the region to free.
+    Address -- Supplies the address of the region to free.
+
+Return Value:
+
+    TRUE if successful.
+    
+Notes:
+
+    It is possible to free a different size at a particular 
+    address than was allocated.  This will not cause the 
+    SubAllocation package any problems.
+    
+--*/
+{
+
+}
+
+BOOL
+SAReallocate(
+    PVOID SubAllocation,
+    ULONG OriginalSize,
+    ULONG OriginalAddress,
+    ULONG NewSize,
+    PULONG NewAddress
+    )
+/*++
+
+Routine Description:
+
+    This routine reallocates a sub allocated block of memory.
+    The sizes are rounded up to the next SUBALLOC_GRANULARITY.
+    The Original address is rounded down to the next SUBALLOC_GRANULARITY
+    boundary.  Only min(OriginalSize, NewSize) bytes of data are copied to
+    the new block.  The block changed in place if possible.
+
+Arguments:
+
+    SubAllocation -- Supplies the pointer returned by SAInitialize.
+    OriginalSize -- Supplies the old size in bytes of the block.
+    OriginalAddress -- Supplies the old address of the block.
+    NewSize -- Supplies the new size in bytes of the block.
+    NewAddress -- Returns the new address of the block.
+
+Return Value:
+
+    True if successful.  If unsucessful, no allocation is changed.
+    
+Notes:
+
+    If the caller does not supply the correct original size for the block,
+    some memory may be lost, and the block may be moved unnecessarily.
+    
+--*/
+{
+
+}