1 files changed, 10 insertions, 17 deletions
diff --git a/date.go b/date.go
index 0531b6c..a5edcf8 100644
--- a/date.go
+++ b/date.go
@@ -17,11 +17,14 @@ import (
 )
 
 const (
+	nanosInADay    = float64((24 * time.Hour) / time.Nanosecond)
 	dayNanoseconds = 24 * time.Hour
 	maxDuration    = 290 * 364 * dayNanoseconds
 )
 
 var (
+	excel1900Epoc         = time.Date(1899, time.December, 30, 0, 0, 0, 0, time.UTC)
+	excel1904Epoc         = time.Date(1904, time.January, 1, 0, 0, 0, 0, time.UTC)
 	excelMinTime1900      = time.Date(1899, time.December, 31, 0, 0, 0, 0, time.UTC)
 	excelBuggyPeriodStart = time.Date(1900, time.March, 1, 0, 0, 0, 0, time.UTC).Add(-time.Nanosecond)
 )
@@ -131,12 +134,11 @@ func doTheFliegelAndVanFlandernAlgorithm(jd int) (day, month, year int) {
 // timeFromExcelTime provides a function to convert an excelTime
 // representation (stored as a floating point number) to a time.Time.
 func timeFromExcelTime(excelTime float64, date1904 bool) time.Time {
-	const MDD int64 = 106750 // Max time.Duration Days, aprox. 290 years
 	var date time.Time
-	var intPart = int64(excelTime)
+	var wholeDaysPart = int(excelTime)
 	// Excel uses Julian dates prior to March 1st 1900, and Gregorian
 	// thereafter.
-	if intPart <= 61 {
+	if wholeDaysPart <= 61 {
 		const OFFSET1900 = 15018.0
 		const OFFSET1904 = 16480.0
 		const MJD0 float64 = 2400000.5
@@ -148,23 +150,14 @@ func timeFromExcelTime(excelTime float64, date1904 bool) time.Time {
 		}
 		return date
 	}
-	var floatPart = excelTime - float64(intPart)
-	var dayNanoSeconds float64 = 24 * 60 * 60 * 1000 * 1000 * 1000
+	var floatPart = excelTime - float64(wholeDaysPart)
 	if date1904 {
-		date = time.Date(1904, 1, 1, 0, 0, 0, 0, time.UTC)
+		date = excel1904Epoc
 	} else {
-		date = time.Date(1899, 12, 30, 0, 0, 0, 0, time.UTC)
+		date = excel1900Epoc
 	}
-
-	// Duration is limited to aprox. 290 years
-	for intPart > MDD {
-		durationDays := time.Duration(MDD) * time.Hour * 24
-		date = date.Add(durationDays)
-		intPart = intPart - MDD
-	}
-	durationDays := time.Duration(intPart) * time.Hour * 24
-	durationPart := time.Duration(dayNanoSeconds * floatPart)
-	return date.Add(durationDays).Add(durationPart)
+	durationPart := time.Duration(nanosInADay * floatPart)
+	return date.AddDate(0, 0, wholeDaysPart).Add(durationPart)
 }
 
 // ExcelDateToTime converts a float-based excel date representation to a time.Time.