Merge pull request #655 from degawa/feature/issue_647

fixed 32-bit integer overflow in stdlib_io_npy

Author: milancurcic

src/stdlib_io_npy_load.fypp

@@ -134,12 +134,12 @@ contains
 
         if (major > 1) then
             header_len = ichar(buf(1)) &
-                &      + ichar(buf(2)) * 2**8 &
-                &      + ichar(buf(3)) * 2**16 &
-                &      + ichar(buf(4)) * 2**32
+                &      + ichar(buf(2)) * 256**1 &
+                &      + ichar(buf(3)) * 256**2 &
+                &      + ichar(buf(4)) * 256**3
         else
             header_len = ichar(buf(1)) &
-                &      + ichar(buf(2)) * 2**8
+                &      + ichar(buf(2)) * 256**1
         end if
         allocate(character(header_len) :: dict, stat=stat)
         if (stat /= 0) return

src/stdlib_io_npy_save.fypp

@@ -60,10 +60,10 @@ contains
         !> String of bytes
         character(len=4) :: str
 
-        str = achar(mod(val, 2**8)) // &
-            & achar(mod(val, 2**16) / 2**8) // &
-            & achar(mod(val, 2**32) / 2**16) // &
-            & achar(val / 2**32)
+        str = achar(mod(val, 256**1)) // &
+            & achar(mod(val, 256**2) / 256**1) // &
+            & achar(mod(val, 256**3) / 256**2) // &
+            & achar(val / 256**3)
     end function to_bytes_i4