? libc/stdlib/diff
Index: include/stdlib.h
===================================================================
RCS file: /home/cvs/avr-libc/avr-libc/include/stdlib.h,v
retrieving revision 1.5
diff -u -r1.5 stdlib.h
--- include/stdlib.h	9 Sep 2002 22:10:04 -0000	1.5
+++ include/stdlib.h	10 Sep 2002 10:27:15 -0000
@@ -71,8 +71,6 @@
 /** Comparision function type for qsort(), just for convenience. */
 typedef int (*__compar_fn_t)(const void *, const void *);
 
-#define	RAND_MAX 0x7FFFFFFF
-
 #ifndef DOXYGEN
 
 #ifndef __ATTR_CONST__
@@ -370,6 +368,33 @@
  */
 
 extern double strtod(const char *__nptr, char **__endptr);
+
+/** Highest number that can be generated by rand(). */
+#define	RAND_MAX 0x7FFF
+
+/**
+     The rand() function computes a sequence of pseudo-random integers in the
+     range of 0 to \c RAND_MAX (as defined by the header file <stdlib.h>).
+
+     The srand() function sets its argument \c seed as the seed for a new
+     sequence of pseudo-random numbers to be returned by rand().  These
+     sequences are repeatable by calling srand() with the same seed value.
+
+     If no seed value is provided, the functions are automatically seeded with
+     a value of 1.
+*/
+extern int rand(void);
+/**
+   Pseudo-random number generator seeding; see rand().
+*/
+extern void srand(unsigned int __seed);
+
+/**
+   Variant of rand() that stores the context in the user-supplied
+   variable located at \c ctx instead of a static library variable
+   so the function becomes re-entrant.
+*/
+extern int rand_r(unsigned long *ctx);
 /address@hidden/
 
 /address@hidden/
@@ -490,9 +515,7 @@
 extern int atexit(void (*)(void));
 extern double atof(const char *);
 extern void *calloc(size_t, size_t);
-extern int rand(void);
 extern void *realloc(void *, size_t);
-extern void srand(unsigned int);
 #endif
 
 #ifdef __cplusplus
Index: libc/stdlib/rand.c
===================================================================
RCS file: /home/cvs/avr-libc/avr-libc/libc/stdlib/rand.c,v
retrieving revision 1.1
diff -u -r1.1 rand.c
--- libc/stdlib/rand.c	5 Jul 2002 20:38:44 -0000	1.1
+++ libc/stdlib/rand.c	10 Sep 2002 10:27:15 -0000
@@ -27,38 +27,58 @@
  * SUCH DAMAGE.
  *
  * Posix rand_r function added May 1999 by Wes Peters <address@hidden>.
+ *
+ * $Id$
  */
 
-#if defined(LIBC_SCCS) && !defined(lint)
+/*
+ * From:
 static char sccsid[] = "@(#)rand.c	8.1 (Berkeley) 6/14/93";
-#endif /* LIBC_SCCS and not lint */
+*/
 
-#if 0
-#include <sys/types.h>
-#endif
 #include <stdlib.h>
 
-#ifdef TEST
-#include <stdio.h>
-#endif /* TEST */
-
 static int
 do_rand(unsigned long *ctx)
 {
-	return ((*ctx = *ctx * 1103515245 + 12345) % ((unsigned long int)RAND_MAX + 1));
+#ifdef  USE_WEAK_SEEDING
+/*
+ * Historic implementation compatibility.
+ * The random sequences do not vary much with the seed,
+ * even with overflowing.
+ */
+	return ((*ctx = *ctx * 1103515245L + 12345L) %
+		((unsigned long)RAND_MAX + 1));
+#else   /* !USE_WEAK_SEEDING */
+/*
+ * Compute x = (7^5 * x) mod (2^31 - 1)
+ * wihout overflowing 31 bits:
+ *      (2^31 - 1) = 127773 * (7^5) + 2836
+ * From "Random number generators: good ones are hard to find",
+ * Park and Miller, Communications of the ACM, vol. 31, no. 10,
+ * October 1988, p. 1195.
+ */
+	long hi, lo, x;
+
+	hi = *ctx / 127773L;
+	lo = *ctx % 127773L;
+	x = 16807L * lo - 2836L * hi;
+	if (x <= 0)
+		x += 0x7fffffffL;
+	return ((*ctx = x) % ((unsigned long)RAND_MAX + 1));
+#endif  /* !USE_WEAK_SEEDING */
 }
 
 
 int
-rand_r(unsigned int *ctx)
+rand_r(unsigned long *ctx)
 {
-	unsigned long int val = (unsigned long int) *ctx;
-	*ctx = do_rand(&val);
+	*ctx = do_rand(&ctx);
 	return (int) *ctx;
 }
 
 
-static unsigned long int next = 1;
+static unsigned long next = 1;
 
 int
 rand(void)
@@ -71,32 +91,4 @@
 {
 	next = seed;
 }
-
-#ifdef TEST
-
-main()
-{
-    int i;
-    unsigned myseed;
-
-    printf("seeding rand with 0x19610910: \n");
-    srand(0x19610910);
-
-    printf("generating three pseudo-random numbers:\n");
-    for (i = 0; i < 3; i++)
-    {
-	printf("next random number = %d\n", rand());
-    }
-
-    printf("generating the same sequence with rand_r:\n");
-    myseed = 0x19610910;
-    for (i = 0; i < 3; i++)
-    {
-	printf("next random number = %d\n", rand_r(&myseed));
-    }
-
-    return 0;
-}
-
-#endif /* TEST */