Handle negative pointers in MGDPTR

Negative pointers may appear when the address of the `Mem` common block is larger than the handled address. In this case, the `mod()` function may return a negative result, which is then corrected by this patch.
iraf-community · Oct 15, 2017 · 8a3e8cb · 8a3e8cb
1 parent e390f7e
commit 8a3e8cb
Showing 1 changed file with 2 additions and 0 deletions.
diff --git a/sys/nmemio/mgdptr.x b/sys/nmemio/mgdptr.x
@@ -23,6 +23,8 @@ begin
 	bufadr = fwa + (5 * SZ_INT)
 
 	modulus = mod (bufadr - fwa_align, sz_align)
+	if (modulus < 0)
+	    modulus = modulus + sz_align
 	if (modulus != 0)
 	    bufadr = bufadr + (sz_align - modulus)