From 30ff685094ea75ab116c44e1438621a63dea949d Mon Sep 17 00:00:00 2001
From: "Michael I. Bushnell" <mib@gnu.org>
Date: Mon, 28 Mar 1994 17:46:49 +0000
Subject: Formerly primes.c.~4~

---
 proc/primes.c | 66 ++++++++++++++++++++++++++++-------------------------------
 1 file changed, 31 insertions(+), 35 deletions(-)

(limited to 'proc')

diff --git a/proc/primes.c b/proc/primes.c
index b5e24d3e..1071e116 100644
--- a/proc/primes.c
+++ b/proc/primes.c
@@ -38,50 +38,42 @@ initprimes ()
   primes[1] = 3;
 }
 
-/* Make the array of primes larger than it is right now.  */
-void
-growprimes ()
+/* Return the next prime greater than or equal to n. */
+int 
+nextprime (int n)
 {
+  int p;
+  int low, high;
   int *iscomp;
   int nints;
   int lastprime = primes[nprimes - 1];
   int i, j;
   
-  nints = lastprime * lastprime;
-  iscomp = alloca (sizeof (int) * nints);
-  bzero (iscomp, sizeof (int) * nints);
-
-  
-
-  for (i = 0; i < nprimes; i++)
-    for (j = primes[i] * 2; j < nints; j += primes[i])
-      iscomp[j] = 1;
+  if (n < primes[0])
+    return primes[0];
 
-  for (i = lastprime; i < nints; i++)
+  while (n > primes[nprimes - 1])
     {
-      if (nprimes == primessize)
+      nints = lastprime * lastprime;
+      iscomp = alloca (sizeof (int) * nints);
+      bzero (iscomp, sizeof (int) * nints);
+      
+      for (i = 0; i < nprimes; i++)
+	for (j = primes[i] * 2; j < nints; j += primes[i])
+	  iscomp[j] = 1;
+
+      for (i = lastprime; i < nints; i++)
 	{
-	  primes = realloc (primes, primessize * sizeof (int) * 2);
-	  primessize *= 2;
+	  if (nprimes == primessize)
+	    {
+	      primes = realloc (primes, primessize * sizeof (int) * 2);
+	      primessize *= 2;
+	    }
+	  if (!iscomp[i])
+	    primes[nprimes++] = i;
 	}
-      if (!iscomp[i])
-	primes[nprimes++] = i;
     }
-}  
-
-/* Return the next prime greater than or equal to n. */
-int 
-nextprime (int n)
-{
-  int p;
-  int low, high;
   
-  if (n < primes[0])
-    return primes[0];
-
-  while (n > primes[nprimes - 1])
-    growprimes ();
-
   /* Binary search */
   low = 0;
   high = nprimes - 1;
@@ -100,9 +92,13 @@ nextprime (int n)
   return primes[p];
 }
 
-  
 
+main ()
+{
+  int i;
 
+  initprimes();
   
-    
-  
+  for (i = 0; i < 100; i++)
+    printf ("%d\t%d\n", i, nextprime(i));
+}
-- 
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