svn commit: r301445 - stable/10/lib/libc/stdlib

[Andrey A. Chernov]

Author: ache
Date: Sun Jun  5 14:31:36 2016
New Revision: 301445
URL: https://svnweb.freebsd.org/changeset/base/301445

Log:
  MFC: r300956
  
  1) Unifdef USE_WEAK_SEEDING since it is too obsolete to support and makes
  reading hard.
  
  2) Instead of doing range transformation in each and every function here,
  do it single time directly in do_rand(). One "mod" operation overhead is not
  a big deal, but the code looks nicer and possible future functions additions
  or PRNG change do not miss range transformations neither have unneeded ones.
  
  3) Use POSIX argument types for visible functions (cosmetic).

Modified:
  stable/10/lib/libc/stdlib/rand.c
Directory Properties:
  stable/10/   (props changed)

Modified: stable/10/lib/libc/stdlib/rand.c
==============================================================================
--- stable/10/lib/libc/stdlib/rand.c	Sun Jun  5 14:04:54 2016	(r301444)
+++ stable/10/lib/libc/stdlib/rand.c	Sun Jun  5 14:31:36 2016	(r301445)
@@ -49,14 +49,6 @@ __FBSDID("$FreeBSD$");
 static int
 do_rand(unsigned long *ctx)
 {
-#ifdef  USE_WEAK_SEEDING
-/*
- * Historic implementation compatibility.
- * The random sequences do not vary much with the seed,
- * even with overflowing.
- */
-	return ((*ctx = *ctx * 1103515245 + 12345) % ((u_long)RAND_MAX + 1));
-#else   /* !USE_WEAK_SEEDING */
 /*
  * Compute x = (7^5 * x) mod (2^31 - 1)
  * without overflowing 31 bits:
@@ -67,48 +59,34 @@ do_rand(unsigned long *ctx)
  */
 	long hi, lo, x;
 
-	/* Must be in [1, 0x7ffffffe] range at this point. */
-	hi = *ctx / 127773;
-	lo = *ctx % 127773;
+	/* Transform to [1, 0x7ffffffe] range. */
+	x = (*ctx % 0x7ffffffe) + 1;
+	hi = x / 127773;
+	lo = x % 127773;
 	x = 16807 * lo - 2836 * hi;
 	if (x < 0)
 		x += 0x7fffffff;
-	*ctx = x;
 	/* Transform to [0, 0x7ffffffd] range. */
-	return (x - 1);
-#endif  /* !USE_WEAK_SEEDING */
+	x--;
+	*ctx = x;
+	return (x);
 }
 
 
 int
-rand_r(unsigned int *ctx)
+rand_r(unsigned *ctx)
 {
 	u_long val;
 	int r;
 
-#ifdef  USE_WEAK_SEEDING
 	val = *ctx;
-#else
-	/* Transform to [1, 0x7ffffffe] range. */
-	val = (*ctx % 0x7ffffffe) + 1;
-#endif
 	r = do_rand(&val);
-
-#ifdef  USE_WEAK_SEEDING
-	*ctx = (unsigned int)val;
-#else
-	*ctx = (unsigned int)(val - 1);
-#endif
+	*ctx = (unsigned)val;
 	return (r);
 }
 
 
-static u_long next =
-#ifdef  USE_WEAK_SEEDING
-    1;
-#else
-    2;
-#endif
+static u_long next = 1;
 
 int
 rand(void)
@@ -117,13 +95,9 @@ rand(void)
 }
 
 void
-srand(u_int seed)
+srand(unsigned seed)
 {
 	next = seed;
-#ifndef USE_WEAK_SEEDING
-	/* Transform to [1, 0x7ffffffe] range. */
-	next = (next % 0x7ffffffe) + 1;
-#endif
 }
 
 
@@ -145,10 +119,6 @@ sranddev(void)
 	mib[0] = CTL_KERN;
 	mib[1] = KERN_ARND;
 	sysctl(mib, 2, (void *)&next, &len, NULL, 0);
-#ifndef USE_WEAK_SEEDING
-	/* Transform to [1, 0x7ffffffe] range. */
-	next = (next % 0x7ffffffe) + 1;
-#endif
 }