近日对农历计算感兴趣，在网上找了一些源码看了看，发现一个广为流传的源码，好像是汉王的人所写。但是这个源码不但参数表太大，并且运算速度很慢，不适合于用到嵌入式产品中。后来看到一个不错的版本(可能为台湾人所写)，于是对它的参数表进行了优化，得到了一个不错的程序，非常适合于嵌入式系统。
        参数表所占存储空间为：30 + 4×支持年数
        经在MSP430仿真测试，参数表占有154字节，代码占有622字节，执行一次的典型时间是1382个时钟周期。

// -----------------------------------------------------------------
//      农历计算：
//      Copy From "西历农历转换程式    黄晓鸣  1995,7,25"
//      Modify  : Blove
//      Date            : 16:02 2005-12-1
// -----------------------------------------------------------------
typedef         unsigned char   INT8U;
typedef         unsigned short  INT16U;
typedef         unsigned long   INT32U;

typedef struct _SolarDate_Tag_
{
        INT16U  wYear;
        INT8U   chMonth;
        INT8U   chDate;
}sSolarDateTag;

typedef struct _LunarDate_Tag_
{
        INT16U  wYear;
        INT8U   chMonth;
        INT8U   chDate;
        INT8U   chKan;
        INT8U   chChi;
}sLunarDateTag;

// -------------------------------------------------------------------
//      农历计算参数位定义：
//              31-25   7       : ( BaseDays    )到公历1月1日到农历正月初一的累积日数
//              24-20   5       : ( Intercalation)闰月月份. 0==此年没有闰月
//              19-13   7       : ( BaseKanChih  )此年公历1月1日之干支序号减 1
//              12- 0   13      : ( MonthDays    )此农历年每月之大小, 0==小月(29日), 1==大月(30日)
// -------------------------------------------------------------------
#define         LPARA_MASK_BASE_DAYS            0xFE000000
#define         LPARA_MASK_INTERCALATION        0x01F00000
#define         LPARA_MASK_BASE_KANCHI          0x000FE000
#define         LPARA_MASK_MONTH_DAYS           0x00001FFF

#define         LPARA_SHIFT_BASE_DAYS           25
#define         LPARA_SHIFT_INTERCALATION       20
#define         LPARA_SHIFT_BASE_KANCHI         13
#define         LPARA_SHIFT_MONTH_DAYS          0

#define         LPara_GetBaseDays(i)            ( (m_dwLunarParas[i]&LPARA_MASK_BASE_DAYS)>>LPARA_SHIFT_BASE_DAYS )
#define         LPara_GetIntercalation(i)       ( (m_dwLunarParas[i]&LPARA_MASK_INTERCALATION)>>LPARA_SHIFT_INTERCALATION )
#define         LPara_GetBaseKanChi(i)          ( (m_dwLunarParas[i]&LPARA_MASK_BASE_KANCHI)>>LPARA_SHIFT_BASE_KANCHI )
#define         LPara_GetMonthDays(wYear,chMonth)       \
                                ( (((m_dwLunarParas[wYear]&LPARA_MASK_MONTH_DAYS)>>LPARA_SHIFT_MONTH_DAYS)>>chMonth)&0x01 )

// -----------------------------------------------------------
//      农历计算参数表
// -----------------------------------------------------------
static  const   INT32U  m_dwLunarParas[] =
{
        0x2E47752B, 0x5400952B, 0x3E012A5B, 0x2A21D55A, 0x4E02956A,     // 2005
        0x38733B55, 0x6003DBA4, 0x4A047B49, 0x32553A93, 0x5805DA95,
        0x4206752D, 0x2C470AAD, 0x50004AAD, 0x3C90F5AA, 0x620195D2,     // 2015
        0x4C022DA5, 0x3662FD4A, 0x5C038D4A, 0x46042C95, 0x3044D52E,
        0x54059556, 0x3E062AB5, 0x2A26D5B2, 0x500776D2, 0x3860AEA5,     // 2025
        0x5E015725, 0x4801F64B, 0x32528C97, 0x56035CAB, 0x4203E55A,
        0x2C348AD6                                                                              // 2031
};

#define FIRSTYEAR       2001                                                    // 参数表中的第一年
#define YEAR_NUMS       ( sizeof(m_dwLunarParas) / sizeof(INT32U) )
#define LASTYEAR        ( FIRSTYEAR + YEAR_NUMS - 1 )           // 参数表中的最后一年

// -----------------------------------------------------------
//      公历年每月天数标记表
//              由高位到低位为12-1月：1表示31天，0表示30天，二月除外
//      月份： 12  11  10   9    8   7    6   5    4   3    2    1
//                31, 30, 31, 30, 31, 31, 30, 31, 30, 31, 28, 31
//                1    0    1    0   1    1    0    1   0   1    0   1
// -----------------------------------------------------------
static  const   INT16U  m_wSolarMonthDaysFlag = 0x0AD5;

// -----------------------------------------------------------
// 公历年每月累积天数, 平年与闰年
// -----------------------------------------------------------
static  const   INT16U m_wSolarDays[14] =
{ 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365, 396 };

// -----------------------------------------------------------
// 求此公历年是否为闰年, 返回 0 为平年, 1 为闰年
// -----------------------------------------------------------
BOOL    Lunar_IsIntercalation( INT16U   wYear )
{
        if ( wYear % 400 == 0 )
                return 1;
        else if ( wYear % 100 == 0 )
                return 0;
        else if ( wYear % 4 == 0 )
                return 1;
        else
                return 0;
}

// -----------------------------------------------------------
//      农历计算
// -----------------------------------------------------------
int Lunar_Cal( sSolarDateTag *psSolarDate, sLunarDateTag *psLunarDate )
{
        INT16U  wSolarMonth, wDaySum, wSolarDaysSum, im, wTmp1, wTmp2, i, wKanChiSum;
        BOOL    bLeapFlag;
        INT8U   chMonthDays, chYearIndex;

        // 输入参数的有效性检查
        if ( psSolarDate->wYear<=FIRSTYEAR || psSolarDate->wYear>LASTYEAR )
                return 1;

        wSolarMonth = psSolarDate->chMonth - 1;
        if ( wSolarMonth > 11 )
                return 2;

        bLeapFlag = Lunar_IsIntercalation( psSolarDate->wYear );
        if ( wSolarMonth == 1)
        // 二月
        {
                chMonthDays = bLeapFlag + 28;
        }
        else
        // 其他月份
        {
                chMonthDays = 30 + ((m_wSolarMonthDaysFlag>>wSolarMonth)&0x01);
        }

        if ( psSolarDate->chDate<1 || psSolarDate->chDate>chMonthDays )
                return 3;

        chYearIndex = psSolarDate->wYear - FIRSTYEAR;

        wSolarDaysSum = m_wSolarDays[wSolarMonth];
        if ( wSolarMonth > 1 )
                wSolarDaysSum += bLeapFlag;
        wDaySum = wSolarDaysSum + psSolarDate->chDate;

        wKanChiSum = wDaySum + LPara_GetBaseKanChi(chYearIndex);
        psLunarDate->chKan      = wKanChiSum % 10;
        psLunarDate->chChi      = wKanChiSum % 12;

        if ( wDaySum <= LPara_GetBaseDays(chYearIndex) )
        {
                chYearIndex--;
                psLunarDate->wYear      = psSolarDate->wYear - 1;
                bLeapFlag                       = Lunar_IsIntercalation( psLunarDate->wYear );
                wSolarMonth               += 12;

                wSolarDaysSum = m_wSolarDays[wSolarMonth];
                if ( wSolarMonth > 1 )
                        wSolarDaysSum += bLeapFlag;
                wDaySum = wSolarDaysSum + psSolarDate->chDate;
        }
        else
        {
                psLunarDate->wYear      = psSolarDate->wYear;
        }

        wTmp1 = LPara_GetBaseDays(chYearIndex);
        for ( i=0; i<13; i++ )
        {
                wTmp2 = wTmp1 + LPara_GetMonthDays( chYearIndex, i) + 29;
                if ( wDaySum <= wTmp2 )
                        break;
                wTmp1 = wTmp2;
        }

        psLunarDate->chMonth = i + 1;
        psLunarDate->chDate = wDaySum - wTmp1;

        im = LPara_GetIntercalation(chYearIndex);
        if ( im != 0 && psLunarDate->chMonth > im)
                psLunarDate->chMonth--;

        if ( psLunarDate->chMonth > 12)
                psLunarDate->chMonth -= 12;

        return 0;
}