O!
Of course.
I asked Google and found it for PHP :-)
Here the full version. Have backward also :-)

CLEAR 

DIMENSION g_days_in_month[12], j_days_in_month[12]
g_days_in_month[ 1] = 31
g_days_in_month[ 2] = 28
g_days_in_month[ 3] = 31
g_days_in_month[ 4] = 30
g_days_in_month[ 5] = 31
g_days_in_month[ 6] = 30
g_days_in_month[ 7] = 31
g_days_in_month[ 8] = 31
g_days_in_month[ 9] = 30
g_days_in_month[10] = 31
g_days_in_month[11] = 30
g_days_in_month[12] = 31

j_days_in_month[ 1] = 31
j_days_in_month[ 2] = 31
j_days_in_month[ 3] = 31
j_days_in_month[ 4] = 31
j_days_in_month[ 5] = 31
j_days_in_month[ 6] = 31
j_days_in_month[ 7] = 30
j_days_in_month[ 8] = 30
j_days_in_month[ 9] = 30
j_days_in_month[10] = 30
j_days_in_month[11] = 30
j_days_in_month[12] = 29

j_month_name    = ["Farvardin", "Ordibehesht", "Khordad", "Tir", "Mordad", "Shahrivar", "Mehr", "Aban", "Azar", "Dey", "Bahman", "Esfand"]


 ooo = gregorian_to_jalali(2012, 1, 21)
 ? ooo.Year, ooo.Month, ooo.Day
 ooo = jalaliToGregorian( ooo.Year, ooo.Month, ooo.Day)
? ooo.Year, ooo.Month, ooo.Day

function div(a, b)
return INT(a / b)
  
function gregorian_to_jalali(g_y, g_m, g_d)
   
   gy = g_y-1600
   gm = g_m-1
   gd = g_d-1

   g_day_no = 365*gy+div(gy+3,4)-div(gy+99,100)+div(gy+399,400);

   for i=1 TO gm
      g_day_no = g_day_no + g_days_in_month[i]
   NEXT
   
   if (gm > 1 AND ((gy%4==0 AND gy%100!=0) OR (gy%400==0)))
      g_day_no = g_day_no + 1
   ENDIF
   g_day_no = g_day_no + gd
 
   j_day_no = g_day_no-79
 
   j_np = div(j_day_no, 12053)
   j_day_no = j_day_no % 12053
 
   jy = 979+33*j_np+4*div(j_day_no,1461)

   j_day_no = j_day_no % 1461
 
   if (j_day_no >= 366)
      jy = jy + div(j_day_no-1, 365)
      j_day_no = (j_day_no-1)%365
   ENDIF
 
   for i = 1 TO 11
      IF j_day_no >= j_days_in_month[i]
         j_day_no = j_day_no - j_days_in_month[i]
      ELSE
         EXIT
      ENDIF
   NEXT
   jm = i
   jd = j_day_no+1

   oReturn = CREATEOBJECT([EMPTY])
   ADDPROPERTY(oReturn,[Year], jy)
   ADDPROPERTY(oReturn,[Month], jm)
   ADDPROPERTY(oReturn,[Day], jd)
RETURN oReturn


******** 
FUNCTION jalaliToGregorian(j_y, j_m, j_d) 
   jy = j_y-979
   jm = j_m-1
   jd = j_d-1

   j_day_no = 365*jy + div(jy, 33)*8 + div(jy%33+3, 4)
   for i=1 TO jm
      j_day_no = j_day_no + j_days_in_month[i] 
   NEXT

   j_day_no = j_day_no + jd

   g_day_no = j_day_no+79

   gy = 1600 + 400*div(g_day_no, 146097) &&/* 146097 = 365*400 + 400/4 - 400/100 + 400/400 */ 
   g_day_no = g_day_no % 146097

   leap = .t.
   if (g_day_no >= 36525) &&/* 36525 = 365*100 + 100/4 */ 
      g_day_no = g_day_no - 1
      gy = gy + 100*div(g_day_no,  36524) &&/* 36524 = 365*100 + 100/4 - 100/100 */ 
      g_day_no = g_day_no % 36524

      if (g_day_no >= 365) 
          g_day_no = g_day_no + 1
      else 
         leap = .f.
      ENDIF   
   ENDIF 

   gy = gy + 4*div(g_day_no, 1461) && /* 1461 = 365*4 + 4/4 */ 
   g_day_no = g_day_no % 1461 

   if (g_day_no >= 366)
      leap = .f.

      g_day_no = g_day_no - 1  
      gy = gy + div(g_day_no, 365)
      g_day_no = g_day_no % 365 
   ENDIF

   i = 1
   DO WHILE g_day_no >= g_days_in_month[i] + IIF(i == 2 AND leap, 1, 0)
      g_day_no = g_day_no - g_days_in_month[i] + IIF(i == 2 AND leap, 1, 0)
      i = i + 1
   ENDDO
   gm = i 
   gd = g_day_no+1 
   oReturn = CREATEOBJECT([EMPTY])
   ADDPROPERTY(oReturn,[Year], gy)
   ADDPROPERTY(oReturn,[Month], gm)
   ADDPROPERTY(oReturn,[Day], gd)
   
RETURN oReturn

And again NOT TESTED!!!!!