prepare for the release of rrdtool-1.2.9

[rrdtool.git] / src / rrd_diff.c

diff --git a/src/rrd_diff.c b/src/rrd_diff.c
index 0e04de6..24d144d 100644 (file)
--- a/src/rrd_diff.c
+++ b/src/rrd_diff.c
@@ -1,5 +1,5 @@
 /*****************************************************************************
- * RRDtool 1.1.x  Copyright Tobias Oetiker, 1999
+ * RRDtool 1.2.9  Copyright by Tobi Oetiker, 1997-2005
  * This code is stolen from rateup (mrtg-2.x) by Dave Rand
  *****************************************************************************
  * diff calculate the difference between two very long integers available as
@@ -7,6 +7,14 @@
  *****************************************************************************
  * $Id$
  * $Log$
+ * Revision 1.4  2003/03/10 00:30:34  oetiker
+ * handle cases with two negative numbers
+ * --  Sasha Mikheev <sasha@avalon-net.co.il>
+ *
+ * Revision 1.3  2002/04/01 18:31:22  oetiker
+ * "!" takes a higher preference than "||" this means rrd_update N:: would
+ * segfault -- Oliver Cook <ollie@uk.clara.net>
+ *
  * Revision 1.2  2002/02/01 20:34:49  oetiker
  * fixed version number and date/time
  *
@@ -34,21 +42,31 @@ rrd_diff(char *a, char *b)
 {
     char res[LAST_DS_LEN+1], *a1, *b1, *r1, *fix;
     int c,x,m;
-    
-    while (!isdigit((int)*a) || *a==0)
+    char a_neg=0, b_neg=0;
+    double result;
+   
+    while (!(isdigit((int)*a) || *a==0)) {
+        if(*a=='-') 
+           a_neg = 1;
         a++;
+    }
     fix=a;
     while (isdigit((int)*fix)) 
        fix++;
     *fix = 0; /* maybe there is some non digit data in the string */ 
-    while (!isdigit((int)*b) || *b==0)
+    while (!(isdigit((int)*b) || *b==0)) {
+       if(*b=='-') 
+           b_neg = 1;  
         b++;
+    }
     fix=b;
     while (isdigit((int)*fix)) 
        fix++;
     *fix = 0; /* maybe there is some non digit data in the string */ 
     if(!isdigit((int)*a) || !isdigit((int)*b))
        return DNAN;
+    if(a_neg+b_neg == 1) /* can not handle numbers with different signs yet */
+       return DNAN;
     a1 = &a[strlen(a)-1];
     m = max(strlen(a),strlen(b));
     if (m > LAST_DS_LEN) return DNAN; /* result string too short */
@@ -89,7 +107,12 @@ rrd_diff(char *a, char *b)
                 c=0;
             }
         }
-        return(-atof(res));
+        result = -atof(res);
     } else
-        return(atof(res));
+        result = atof(res);
+
+    if(a_neg+b_neg==2) /* both are negatives, reverse sign */
+        result = -result;
+    
+    return result;
 }