[goffice] Fix US 30/360 date calculations. [#631242][#630784]

[Andreas J. Guelzow <guelzow src gnome org>]

commit 64a3da87a54c2b85245a55624dab66a209907505
Author: Andreas J Guelzow <aguelzow pyrshep ca>
Date:   Sun Oct 3 12:12:56 2010 -0600

    Fix US 30/360 date calculations. [#631242][#630784]
    
    2010-10-03  Andreas J. Guelzow <aguelzow pyrshep ca>
    
    	* goffice/utils/datetime.c (days_between_GO_BASIS_MSRB_30_360):
    	  fix calculation, see 631242 and 630784.

 ChangeLog                |    5 +++++
 NEWS                     |    3 +++
 goffice/utils/datetime.c |   12 +++++++++---
 3 files changed, 17 insertions(+), 3 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index 405a3c0..91aeb16 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2010-10-03  Andreas J. Guelzow <aguelzow pyrshep ca>
+
+	* goffice/utils/datetime.c (days_between_GO_BASIS_MSRB_30_360):
+	  fix calculation, see 631242 and 630784.
+
 2010-10-01  Morten Welinder <terra gnome org>
 
 	* configure.in: Post-release bump.
diff --git a/NEWS b/NEWS
index c12c6b2..7a51ffa 100644
--- a/NEWS
+++ b/NEWS
@@ -1,5 +1,8 @@
 goffice 0.8.12:
 
+Andreas
+	* Fix US 30/360 date calculations. [#631242][#630784]
+
 --------------------------------------------------------------------------
 goffice 0.8.11:
 
diff --git a/goffice/utils/datetime.c b/goffice/utils/datetime.c
index 28941c7..b683c48 100644
--- a/goffice/utils/datetime.c
+++ b/goffice/utils/datetime.c
@@ -261,12 +261,18 @@ days_between_GO_BASIS_MSRB_30_360 (GDate const *from, GDate const *to)
 	m2 = g_date_get_month (to);
 	d2 = g_date_get_day (to);
 
-	if (m1 == 2 && g_date_is_last_of_month (from))
+	if (d1 == d2 && m1 == m2 && y1 == y2)
+		return 0;
+	if (d1 == 31)
 		d1 = 30;
-	if (d2 == 31 && d1 >= 30)
+	if (d2 == 31 && d1 == 30)
 		d2 = 30;
-	if (d1 == 31)
+
+	if (m1 == 2 && g_date_is_last_of_month (from)) {
+		if (m2 == 2 && g_date_is_last_of_month (to))
+			d2 = 30;
 		d1 = 30;
+	}
 
 	return (y2 - y1) * 360 + (m2 - m1) * 30 + (d2 - d1);
 }