improved performance

index.js

@@ -14,6 +14,13 @@ module.exports =
   , d2g: d2g
   }
 
+/*
+  Jalaali years starting the 33-year rule.
+*/
+var breaks =  [ -61, 9, 38, 199, 426, 686, 756, 818, 1111, 1181, 1210
+  , 1635, 2060, 2097, 2192, 2262, 2324, 2394, 2456, 3178
+  ]
+
 /*
   Converts a Gregorian date to Jalaali.
 */
@@ -46,7 +53,7 @@ function isValidJalaaliDate(jy, jm, jd) {
   Is this a leap year or not?
 */
 function isLeapJalaaliYear(jy) {
-  return jalCal(jy).leap === 0
+  return jalCalLeap(jy) === 0
 }
 
 /*
@@ -59,26 +66,61 @@ function jalaaliMonthLength(jy, jm) {
   return 29
 }
 
+/*
+    This function determines if the Jalaali (Persian) year is
+    leap (366-day long) or is the common year (365 days)
+
+    @param jy Jalaali calendar year (-61 to 3177)
+    @returns number of years since the last leap year (0 to 4)
+ */
+function jalCalLeap(jy) {  
+  var bl = breaks.length        
+    , jp = breaks[0]
+    , jm
+    , jump
+    , leap    
+    , n
+    , i
+
+  if (jy < jp || jy >= breaks[bl - 1])
+    throw new Error('Invalid Jalaali year ' + jy)
+
+  for (i = 1; i < bl; i += 1) {
+    jm = breaks[i]
+    jump = jm - jp
+    if (jy < jm)
+      break    
+    jp = jm
+  }
+  n = jy - jp
+
+  if (jump - n < 6)
+    n = n - jump + div(jump + 4, 33) * 33
+  leap = mod(mod(n + 1, 33) - 1, 4)
+  if (leap === -1) {
+    leap = 4
+  }  
+
+  return leap
+}
+
 /*
   This function determines if the Jalaali (Persian) year is
   leap (366-day long) or is the common year (365 days), and
   finds the day in March (Gregorian calendar) of the first
   day of the Jalaali year (jy).
 
   @param jy Jalaali calendar year (-61 to 3177)
+  @param withoutLeap when don't need leap (true or false) default is false
   @return
     leap: number of years since the last leap year (0 to 4)
     gy: Gregorian year of the beginning of Jalaali year
     march: the March day of Farvardin the 1st (1st day of jy)
   @see: http://www.astro.uni.torun.pl/~kb/Papers/EMP/PersianC-EMP.htm
   @see: http://www.fourmilab.ch/documents/calendar/
 */
-function jalCal(jy) {
-  // Jalaali years starting the 33-year rule.
-  var breaks =  [ -61, 9, 38, 199, 426, 686, 756, 818, 1111, 1181, 1210
-                , 1635, 2060, 2097, 2192, 2262, 2324, 2394, 2456, 3178
-                ]
-    , bl = breaks.length
+function jalCal(jy, withoutLeap) {  
+  var bl = breaks.length
     , gy = jy + 621
     , leapJ = -14
     , jp = breaks[0]
@@ -117,11 +159,13 @@ function jalCal(jy) {
   march = 20 + leapJ - leapG
 
   // Find how many years have passed since the last leap year.
-  if (jump - n < 6)
-    n = n - jump + div(jump + 4, 33) * 33
-  leap = mod(mod(n + 1, 33) - 1, 4)
-  if (leap === -1) {
-    leap = 4
+  if(!withoutLeap){
+    if (jump - n < 6)
+      n = n - jump + div(jump + 4, 33) * 33
+    leap = mod(mod(n + 1, 33) - 1, 4)
+    if (leap === -1) {
+      leap = 4
+    }
   }
 
   return  { leap: leap
@@ -139,7 +183,7 @@ function jalCal(jy) {
   @return Julian Day number
 */
 function j2d(jy, jm, jd) {
-  var r = jalCal(jy)
+  var r = jalCal(jy, true)
   return g2d(r.gy, 3, r.march) + (jm - 1) * 31 - div(jm, 7) * (jm - 7) + jd - 1
 }
 
@@ -155,7 +199,7 @@ function j2d(jy, jm, jd) {
 function d2j(jdn) {
   var gy = d2g(jdn).gy // Calculate Gregorian year (gy).
     , jy = gy - 621
-    , r = jalCal(jy)
+    , r = jalCal(jy, false)
     , jdn1f = g2d(gy, 3, r.march)
     , jd
     , jm

package.json

@@ -1,6 +1,6 @@
 {
   "name": "jalaali-js",
-  "version": "1.1.1",
+  "version": "1.1.2",
   "description": "Converts Gregorian and Jalaali calendars to each other",
   "main": "index.js",
   "repository": {