1 /*****************************************************************************
2 * RRDtool 1.2.14 Copyright by Tobi Oetiker, 1997-2006
3 * This code is stolen from rateup (mrtg-2.x) by Dave Rand
4 *****************************************************************************
5 * diff calculate the difference between two very long integers available as
7 *****************************************************************************
10 * Revision 1.4 2003/03/10 00:30:34 oetiker
11 * handle cases with two negative numbers
12 * -- Sasha Mikheev <sasha@avalon-net.co.il>
14 * Revision 1.3 2002/04/01 18:31:22 oetiker
15 * "!" takes a higher preference than "||" this means rrd_update N:: would
16 * segfault -- Oliver Cook <ollie@uk.clara.net>
18 * Revision 1.2 2002/02/01 20:34:49 oetiker
19 * fixed version number and date/time
21 * Revision 1.1.1.1 2001/02/25 22:25:05 oetiker
24 * Revision 1.1 1998/10/08 18:21:45 oetiker
27 * Revision 1.3 1998/02/06 21:10:52 oetiker
28 * removed max define .. it is now in rrd_tool.h
30 * Revision 1.2 1997/12/07 20:38:03 oetiker
33 * Revision 1.1 1997/11/28 23:31:59 oetiker
36 *****************************************************************************/
41 rrd_diff(char *a, char *b)
43 char res[LAST_DS_LEN+1], *a1, *b1, *r1, *fix;
45 char a_neg=0, b_neg=0;
48 while (!(isdigit((int)*a) || *a==0)) {
54 while (isdigit((int)*fix))
56 *fix = 0; /* maybe there is some non digit data in the string */
57 while (!(isdigit((int)*b) || *b==0)) {
63 while (isdigit((int)*fix))
65 *fix = 0; /* maybe there is some non digit data in the string */
66 if(!isdigit((int)*a) || !isdigit((int)*b))
68 if(a_neg+b_neg == 1) /* can not handle numbers with different signs yet */
71 m = max(strlen(a),strlen(b));
72 if (m > LAST_DS_LEN) return DNAN; /* result string too short */
75 for (b1 = res;b1 <= r1; b1++) *b1 = ' ';
77 r1[1] = 0; /* Null terminate result */
80 if (a1 >= a && b1 >= b) {
81 *r1 = ((*a1 - c) - *b1) + '0';
85 *r1 = ('0' - *b1 - c) + '0';
91 if (*r1 > '9') { /* 0 - 10 */
101 for (x=0; isdigit((int)*r1) && x<m; x++,r1--) {
102 *r1 = ('9' - *r1 + c) + '0';
114 if(a_neg+b_neg==2) /* both are negatives, reverse sign */