From 2ebb9e5e4cd81f7f389600a475a6f3e4f8afc87f Mon Sep 17 00:00:00 2001
From: oetiker <oetiker@a5681a0c-68f1-0310-ab6d-d61299d08faa>
Date: Fri, 7 Mar 2008 08:57:01 +0000
Subject: [PATCH] a nan-safe add operator (ADDNAN) into rrd. I used it to add
 several incomplete graphs.

NaN + NaN => NaN
 x + NaN => x
 NaN + y => y
 x + y => x + y

-- Timo Stripf tstripf gmx.de



git-svn-id: svn://svn.oetiker.ch/rrdtool/trunk/program@1303 a5681a0c-68f1-0310-ab6d-d61299d08faa
---
 doc/rrdgraph_rpn.pod |  5 +++++
 src/rrd_rpncalc.c    | 15 +++++++++++++++
 src/rrd_rpncalc.h    |  2 +-
 3 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/doc/rrdgraph_rpn.pod b/doc/rrdgraph_rpn.pod
index 3718349..aabd738 100644
--- a/doc/rrdgraph_rpn.pod
+++ b/doc/rrdgraph_rpn.pod
@@ -99,6 +99,11 @@ B<+, -, *, /, %>
 
 Add, subtract, multiply, divide, modulo
 
+B<ADDNAN>
+
+NAN-safe addition. If one parameter is NAN/UNKNOWN it'll be treated as
+zero. If both parameters are NAN/UNKNOWN, NAN/UNKNOWN will be returned.
+
 B<SIN, COS, LOG, EXP, SQRT>
 
 Sine and cosine (input in radians), log and exp (natural logarithm),
diff --git a/src/rrd_rpncalc.c b/src/rrd_rpncalc.c
index ed08662..839643b 100644
--- a/src/rrd_rpncalc.c
+++ b/src/rrd_rpncalc.c
@@ -178,6 +178,7 @@ void rpn_compact2str(
             add_op(OP_DEG2RAD, DEG2RAD)
             add_op(OP_AVG, AVG)
             add_op(OP_ABS, ABS)
+            add_op(OP_ADDNAN, ADDNAN)
 #undef add_op
     }
     (*str)[offset] = '\0';
@@ -374,6 +375,7 @@ rpnp_t   *rpn_parse(
             match_op(OP_DEG2RAD, DEG2RAD)
             match_op(OP_AVG, AVG)
             match_op(OP_ABS, ABS)
+            match_op(OP_ADDNAN, ADDNAN)
 #undef match_op
             else if ((sscanf(expr, DEF_NAM_FMT "%n", vname, &pos) == 1)
                      && ((rpnp[steps].ptr = (*lookup) (key_hash, vname)) !=
@@ -543,6 +545,19 @@ short rpn_calc(
                 + rpnstack->s[stptr];
             stptr--;
             break;
+        case OP_ADDNAN:
+            stackunderflow(1);
+			if (isnan(rpnstack->s[stptr - 1])) {
+	            rpnstack->s[stptr - 1] = rpnstack->s[stptr];
+			} else if (isnan(rpnstack->s[stptr])) {
+	            //rpnstack->s[stptr - 1] = rpnstack->s[stptr - 1];
+			} else {
+ 	           rpnstack->s[stptr - 1] = rpnstack->s[stptr - 1]
+    	            + rpnstack->s[stptr];
+			}
+
+            stptr--;
+            break;
         case OP_SUB:
             stackunderflow(1);
             rpnstack->s[stptr - 1] = rpnstack->s[stptr - 1]
diff --git a/src/rrd_rpncalc.h b/src/rrd_rpncalc.h
index b178f05..3e4da4c 100644
--- a/src/rrd_rpncalc.h
+++ b/src/rrd_rpncalc.h
@@ -18,7 +18,7 @@ enum op_en { OP_NUMBER = 0, OP_VARIABLE, OP_INF, OP_PREV, OP_NEGINF,
     OP_UN, OP_END, OP_LTIME, OP_NE, OP_ISINF, OP_PREV_OTHER, OP_COUNT,
     OP_ATAN, OP_SQRT, OP_SORT, OP_REV, OP_TREND, OP_TRENDNAN,
     OP_ATAN2, OP_RAD2DEG, OP_DEG2RAD,
-    OP_AVG, OP_ABS
+    OP_AVG, OP_ABS, OP_ADDNAN
 };
 
 typedef struct rpnp_t {
-- 
2.11.0