/*

西曆農曆轉換程式 黃曉鳴 1995,7,25

prototype: int CalConv( struct ConvDate * );

struct ConvDate
{
int Source; ==0 則輸入日期為西曆, !=0 則輸入為農曆
int SolarYear; 輸出或輸入之西曆年份
int SolarMonth; 西曆月
int SolarDate; 西曆日
int LunarYear; 輸出或輸入之農曆年份
int LunarMonth; 農曆月
int LunarDate; 農曆日
int Weekday; 該日為星期幾 ( 0==星期日, 1==星期一, ... )
int Kan; 該日天干 ( 0==甲, 1==乙, ..., 9==癸 )
int Chih; 該日地支 ( 0==子, 1==丑, ..., 11==亥 )
};

呼叫時須設定 Souce 的值, 若為 0 則為西曆轉農曆, 否則為農曆轉西曆. 然後視
輸入為西曆或農曆來設定西曆或農曆的年月日. 轉換後的年月日會填入結構中( 農
曆或西曆 ), 以及該日為星期幾, 天干地支.
若函式的返回值為 0 表示沒有錯誤, 1 為輸入之年份錯誤, 2 為輸入之月份錯誤,
3 為輸入之日期錯誤.
輸入之西曆年須在 1937 - 2031 間
輸入之農曆年須在 1936 - 2030 間
若須擴充, 則增加 LunarCal[]

*/

#define FIRSTYEAR 1936 /* The first year in LunarCal[] */

struct ConvDate
{
int Source;
int SolarYear;
int SolarMonth;
int SolarDate;
int LunarYear;
int LunarMonth;
int LunarDate;
int Weekday;
int Kan;
int Chih;
};

struct tagLunarCal
{
int BaseDays; /* 到西曆 1 月 1 日到農曆正月初一的累積日數 */
int Intercalation; /* 閏月月份. 0==此年沒有閏月 */
int BaseWeekday; /* 此年西曆 1 月 1 日為星期幾再減 1 */
int BaseKanChih; /* 此年西曆 1 月 1 日之干支序號減 1 */
int MonthDays[13]; /* 此農曆年每月之大小, 0==小月(29日), 1==大月(30日) */
};

struct tagLunarCal LunarCal[] = {
{ 23, 3, 2, 17, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0 }, /* 1936 */
{ 41, 0, 4, 23, 1, 0, 0, 1, 0, 0, 1, 0, 1, 1, 1, 0, 1 },
{ 30, 7, 5, 28, 1, 1, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1 },
{ 49, 0, 6, 33, 1, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 1, 1 },
{ 38, 0, 0, 38, 1, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1 }, /* 1940 */
{ 26, 6, 2, 44, 1, 1, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 0 },
{ 45, 0, 3, 49, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0 },
{ 35, 0, 4, 54, 0, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1 },
{ 24, 4, 5, 59, 1, 0, 1, 0, 1, 0, 1, 0, 1, 1, 0, 1, 1 }, /* 1944 */
{ 43, 0, 0, 5, 0, 0, 1, 0, 0, 1, 0, 1, 1, 1, 0, 1, 1 },
{ 32, 0, 1, 10, 1, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 1 },
{ 21, 2, 2, 15, 1, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 1, 1 },
{ 40, 0, 3, 20, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1, 1 }, /* 1948 */
{ 28, 7, 5, 26, 1, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1 },
{ 47, 0, 6, 31, 0, 1, 1, 0, 1, 1, 0, 0, 1, 0, 1, 0, 1 },
{ 36, 0, 0, 36, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0 },
{ 26, 5, 1, 41, 0, 1, 0, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1 }, /* 1952 */
{ 44, 0, 3, 47, 0, 1, 0, 0, 1, 1, 0, 1, 1, 0, 1, 0, 1 },
{ 33, 0, 4, 52, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 1, 0 },
{ 23, 3, 5, 57, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1, 1, 1 },
{ 42, 0, 6, 2, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1, 1, 1 }, /* 1956 */
{ 30, 8, 1, 8, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1, 0 },
{ 48, 0, 2, 13, 1, 1, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1, 0 },
{ 38, 0, 3, 18, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1 },
{ 27, 6, 4, 23, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0 }, /* 1960 */
{ 45, 0, 6, 29, 1, 0, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0 },
{ 35, 0, 0, 34, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 1, 0, 1 },
{ 24, 4, 1, 39, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1, 1, 1, 0 },
{ 43, 0, 2, 44, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1, 1, 1, 0 }, /* 1964 */
{ 32, 0, 4, 50, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1 },
{ 20, 3, 5, 55, 1, 1, 1, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0 },
{ 39, 0, 6, 0, 1, 1, 0, 1, 1, 0, 0, 1, 0, 1, 0, 1, 0 },
{ 29, 7, 0, 5, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1 }, /* 1968 */
{ 47, 0, 2, 11, 0, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1 },
{ 36, 0, 3, 16, 1, 0, 0, 1, 0, 1, 1, 0, 1, 1, 0, 1, 0 },
{ 26, 5, 4, 21, 0, 1, 0, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1 },
{ 45, 0, 5, 26, 0, 1, 0, 0, 1, 0, 1, 0, 1, 1, 0, 1, 1 }, /* 1972 */
{ 33, 0, 0, 32, 1, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1 },
{ 22, 4, 1, 37, 1, 1, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1 },
{ 41, 0, 2, 42, 1, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 1 },
{ 30, 8, 3, 47, 1, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1 }, /* 1976 */
{ 48, 0, 5, 53, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1 },
{ 37, 0, 6, 58, 1, 0, 1, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1 },
{ 27, 6, 0, 3, 1, 0, 0, 1, 0, 1, 1, 0, 1, 1, 0, 1, 0 },
{ 46, 0, 1, 8, 1, 0, 0, 1, 0, 1, 0, 1, 1, 0, 1, 1, 0 }, /* 1980 */
{ 35, 0, 3, 14, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1 },
{ 24, 4, 4, 19, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 1, 1 },
{ 43, 0, 5, 24, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 1, 1 },
{ 32, 10, 6, 29, 1, 0, 1, 1, 0, 0, 1, 0, 0, 1, 0, 1, 1 }, /* 1984 */
{ 50, 0, 1, 35, 0, 1, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0 },
{ 39, 0, 2, 40, 0, 1, 1, 0, 1, 1, 0, 1, 0, 1, 0, 0, 1 },
{ 28, 6, 3, 45, 1, 0, 1, 0, 1, 1, 0, 1, 1, 0, 1, 0, 0 },
{ 47, 0, 4, 50, 1, 0, 1, 0, 1, 0, 1, 1, 0, 1, 1, 0, 1 }, /* 1988 */
{ 36, 0, 6, 56, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0 },
{ 26, 5, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 1, 1, 1 },
{ 45, 0, 1, 6, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 1, 1, 0 },
{ 34, 0, 2, 11, 0, 1, 1, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0 }, /* 1992 */
{ 22, 3, 4, 17, 0, 1, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0 },
{ 40, 0, 5, 22, 1, 1, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0 },
{ 30, 8, 6, 27, 0, 1, 1, 0, 1, 0, 1, 1, 0, 0, 1, 0, 1 },
{ 49, 0, 0, 32, 0, 1, 0, 1, 1, 0, 1, 0, 1, 1, 0, 0, 1 }, /* 1996 */
{ 37, 0, 2, 38, 1, 0, 1, 0, 1, 0, 1, 1, 0, 1, 1, 0, 1 },
{ 27, 5, 3, 43, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 0, 1 },
{ 46, 0, 4, 48, 1, 0, 0, 1, 0, 0, 1, 0, 1, 1, 1, 0, 1 },
{ 35, 0, 5, 53, 1, 1, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1 }, /* 2000 */
{ 23, 4, 0, 59, 1, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1 },
{ 42, 0, 1, 4, 1, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1 },
{ 31, 0, 2, 9, 1, 1, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 0 },
{ 21, 2, 3, 14, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1 }, /* 2004 */
{ 39, 0, 5, 20, 0, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1 },
{ 28, 7, 6, 25, 1, 0, 1, 0, 1, 0, 1, 0, 1, 1, 0, 1, 1 },
{ 48, 0, 0, 30, 0, 0, 1, 0, 0, 1, 0, 1, 1, 1, 0, 1, 1 },
{ 37, 0, 1, 35, 1, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 1 }, /* 2008 */
{ 25, 5, 3, 41, 1, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 1, 1 },
{ 44, 0, 4, 46, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1, 1 },
{ 33, 0, 5, 51, 1, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1 },
{ 22, 4, 6, 56, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0 }, /* 2012 */
{ 40, 0, 1, 2, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0 },
{ 30, 9, 2, 7, 0, 1, 0, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1 },
{ 49, 0, 3, 12, 0, 1, 0, 0, 1, 0, 1, 1, 1, 0, 1, 0, 1 },
{ 38, 0, 4, 17, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 1, 0 }, /* 2016 */
{ 27, 6, 6, 23, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1, 1, 1 },
{ 46, 0, 0, 28, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1, 1, 0 },
{ 35, 0, 1, 33, 0, 1, 1, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0 },
{ 24, 4, 2, 38, 0, 1, 1, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1 }, /* 2020 */
{ 42, 0, 4, 44, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1 },
{ 31, 0, 5, 49, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0 },
{ 21, 2, 6, 54, 0, 1, 0, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1 },
{ 40, 0, 0, 59, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 1, 0, 1 }, /* 2024 */
{ 28, 6, 2, 5, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1, 1, 1, 0 },
{ 47, 0, 3, 10, 1, 0, 1, 0, 0, 1, 0, 0, 1, 1, 1, 0, 1 },
{ 36, 0, 4, 15, 1, 1, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1 },
{ 25, 5, 5, 20, 1, 1, 1, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0 }, /* 2028 */
{ 43, 0, 0, 26, 1, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1 },
{ 32, 0, 1, 31, 1, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 0 },
{ 22, 3, 2, 36, 0, 1, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0 } };

#define LASTYEAR (FIRSTYEAR+sizeof(LunarCal)/sizeof(struct tagLunarCal)-1)

/* 西曆年每月之日數 */
int SolarCal[12] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };

/* 西曆年每月之累積日數, 平年與閏年 */
int SolarDays[2][14] = {
{ 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365, 396 },
{ 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366, 397 } };

/* 求此西曆年是否為閏年, 返回 0 為平年, 1 為閏年 */
int GetLeap( int year )
{
if ( year % 400 == 0 )
return 1;
else if ( year % 100 == 0 )
return 0;
else if ( year % 4 == 0 )
return 1;
else
return 0;
}

/* 西曆農曆轉換 */
int CalConv( struct ConvDate *cd )
{
int leap, d, sm, y, im, l1, l2, acc, i, lm, kc;
if ( cd->Source == 0 ) /* Solar */
{
if ( cd->SolarYear <= FIRSTYEAR || cd->SolarYear > LASTYEAR )
return 1;
sm = cd->SolarMonth - 1;
if ( sm < 0 || sm > 11 )
return 2;
leap = GetLeap( cd->SolarYear );
if ( sm == 1 )
d = leap + 28;
else
d = SolarCal[sm];
if ( cd->SolarDate < 1 || cd->SolarDate > d )
return 3;
y = cd->SolarYear - FIRSTYEAR;
acc = SolarDays[leap][sm] + cd->SolarDate;
cd->Weekday = ( acc + LunarCal[y].BaseWeekday ) % 7;
kc = acc + LunarCal[y].BaseKanChih;
cd->Kan = kc % 10;
cd->Chih = kc % 12;
if ( acc <= LunarCal[y].BaseDays )
{
y--;
cd->LunarYear = cd->SolarYear - 1;
leap = GetLeap( cd->LunarYear );
sm += 12;
acc = SolarDays[leap][sm] + cd->SolarDate;
}
else
cd->LunarYear = cd->SolarYear;
l1 = LunarCal[y].BaseDays;
for ( i=0; i<13; i++ )
{
l2 = l1 + LunarCal[y].MonthDays[i] + 29;
if ( acc <= l2 )
break;
l1 = l2;
}
cd->LunarMonth = i + 1;
cd->LunarDate = acc - l1;
im = LunarCal[y].Intercalation;
if ( im != 0 && cd->LunarMonth > im )
{
cd->LunarMonth--;
if ( cd->LunarMonth == im )
cd->LunarMonth = -im;
}
if ( cd->LunarMonth > 12 )
cd->LunarMonth -= 12;
}
else /* Lunar */
{
if ( cd->LunarYear < FIRSTYEAR || cd->LunarYear >= LASTYEAR )
return 1;
y = cd->LunarYear - FIRSTYEAR;
im = LunarCal[y].Intercalation;
lm = cd->LunarMonth;
if ( lm < 0 )
{
if ( lm != -im )
return 2;
}
else if ( lm < 1 || lm > 12 )
return 2;
if ( im != 0 )
{
if ( lm > im )
lm++;
else if ( lm == -im )
lm = im + 1;
}
lm--;
if ( cd->LunarDate > LunarCal[y].MonthDays[lm] + 29 )
return 3;
acc = LunarCal[y].BaseDays;
for ( i=0; i<lm; i++ )
acc += LunarCal[y].MonthDays[i] + 29;
acc += cd->LunarDate;
leap = GetLeap( cd->LunarYear );
for ( i=13; i>=0; i-- )
if ( acc > SolarDays[leap][i] )
break;
cd->SolarDate = acc - SolarDays[leap][i];
if ( i <= 11 )
{
cd->SolarYear = cd->LunarYear;
cd->SolarMonth = i + 1;
}
else
{
cd->SolarYear = cd->LunarYear + 1;
cd->SolarMonth = i - 11;
}
leap = GetLeap( cd->SolarYear );
y = cd->SolarYear - FIRSTYEAR;
acc = SolarDays[leap][cd->SolarMonth-1] + cd->SolarDate;
cd->Weekday = ( acc + LunarCal[y].BaseWeekday ) % 7;
kc = acc + LunarCal[y].BaseKanChih;
cd->Kan = kc % 10;
cd->Chih = kc % 12;
}
return 0;
}