C++如何实现sha256算法

#pragma once
#include "HP_Types.h"
#define HP_SHA256_HASH_LEN                                        32
class CHP_Sha256
{
public:
        static int CalcSha256(char *pData, unsigned int uiDataLen, unsigned char pucResult[HP_SHA256_HASH_LEN]);
        static int CalcHmacSha256(char *pKey, unsigned int uiKeyLen, char *pData, unsigned int uiDataLen, unsigned char pucResult[HP_SHA256_HASH_LEN]);
private:
        CHP_Sha256();
        ~CHP_Sha256();
        typedef struct _THPSha256Context
        {
                HP_U64 ui64Len;
                unsigned int puiState[8];
                unsigned int uiCurLen;
                unsigned char pucBuf[64];
        } THPSha256Context;
        static void Init(THPSha256Context *pContext);
        static void Update(THPSha256Context *pContext, void *pBuf, unsigned int uiBufLen);
        static void Final(THPSha256Context *pContext, unsigned char pucResult[HP_SHA256_HASH_LEN]);
        static void Transform(THPSha256Context *pContext, unsigned char *pucBuf);
        static int Hash(unsigned char *pX, unsigned int uiXLen, unsigned char *pY, unsigned int uiYLen, unsigned char *pOut, unsigned int uiOutLen);
        static void Sha256(char *pData, unsigned int uiDataLen, unsigned char *pResult, unsigned int uiResultLen);
};