PR10632: simplify randint() implementation

* tapset/random.stp (randint): Make it 1-arity (imply min=0).
  Document with kerneldoc.
* doc/Systemtap_Tapset_Reference/tapsets.tmpl: Extract the docs.
* runtime/arith.c (_stp_random_pm_u): Rename without _pm.
  (_stp_random_pm): Rewrite in terms of ..._u.
* testsuite/random.stp: Adapt & simplify.

1 files changed, 10 insertions, 24 deletions

diff --git a/runtime/arith.c b/runtime/arith.c
index 4b0e6c9e..4c818a76 100644
--- a/runtime/arith.c
+++ b/runtime/arith.c
@@ -84,48 +84,34 @@ static int64_t _stp_mod64 (const char **error, int64_t x, int64_t y)
 }
 
 
-#ifndef _STP_TEST_
-/** Return a random integer between -n and n.
+/** Return a random integer between 0 and n - 1.
  * @param n how far from zero to go.  Make it positive but less than a million or so.
  */
-static int _stp_random_pm (int n)
+static unsigned long _stp_random_u (unsigned long n)
 {
 	static unsigned long seed;
 	static int initialized_p = 0;
-	
+
 	if (unlikely (! initialized_p)) {
 		seed = (unsigned long) jiffies;
 		initialized_p = 1;
 	}
-	
+
 	/* from glibc rand man page */
 	seed = seed * 1103515245 + 12345;
-	
-	return (seed % (2*n+1)-n);
+
+	return (n == 0 ? 0 : seed % n);
 }
-#endif /* _STP_TEST_ */
 
 
-#ifndef _STP_TEST_
-/** Return a random integer between 0 and n - 1.
+/** Return a random integer between -n and n.
  * @param n how far from zero to go.  Make it positive but less than a million or so.
  */
-static int _stp_random_pm_u (int n)
+static int _stp_random_pm (unsigned n)
 {
-	static unsigned long seed;
-	static int initialized_p = 0;
-
-	if (unlikely (! initialized_p)) {
-		seed = (unsigned long) jiffies;
-		initialized_p = 1;
-	}
-
-	/* from glibc rand man page */
-	seed = seed * 1103515245 + 12345;
-
-	return (seed % n);
+        return -(int)n + (int)_stp_random_u (2*n + 1);
 }
-#endif /* _STP_TEST_ */
+
 
 
 #if defined (__i386__) || defined (__arm__)