HASH: Rewrite internal xxh64() to accept pointer instead of array.

Signed-off-by: Grzegorz Kowal <grzegorz@amuncode.org>

sources/hash.F90

@@ -195,25 +195,22 @@ module hash
 !
   integer(kind=8) function digest(input, hash_type) result(hash)
 
-#ifdef XXHASH
     use iso_c_binding, only: c_loc
-#endif /* XXHASH */
 
     implicit none
 
     integer(kind=1), dimension(:), target, intent(in) :: input
     integer                              , intent(in) :: hash_type
 
-#ifdef XXHASH
     integer(kind=8) :: length
-#endif /* XXHASH */
 
 !-------------------------------------------------------------------------------
 !
     select case(hash_type)
     case(hash_xxh64)
 #ifndef XXHASH
-      hash   = xxh64(input)
+      length = size(input, kind=8)
+      hash   = xxh64(c_loc(input), length)
 #else /* XXHASH */
       length = size(input, kind=8)
       hash   = xxh64_lib(c_loc(input), length, 0_8)
@@ -354,24 +351,30 @@ module hash
 !
 !   Arguments:
 !
-!     input - the input sequence of bytes;
+!     buffer - the buffer pointer;
+!     length - the buffer length;
 !
 !===============================================================================
 !
-  integer(kind=8) function xxh64(input) result(hash)
+  integer(kind=8) function xxh64(buffer, length) result(hash)
+
+    use iso_c_binding, only: c_ptr, c_f_pointer
 
     implicit none
 
-    integer(kind=1), dimension(:), target, intent(in) :: input
+    type(c_ptr)    , intent(in) :: buffer
+    integer(kind=8), intent(in) :: length
 
-    integer(kind=8) :: length
     integer(kind=8) :: remaining, offset
 
     integer(kind=8), dimension(4) :: lane, chunk
 
+    integer(kind=1), dimension(:), pointer :: input
+
 !-------------------------------------------------------------------------------
 !
-    length    = size(input, kind=8)
+    call c_f_pointer(buffer, input, [ length ])
+
     hash      = 0_8
     offset    = 1_8
     remaining = length