艾米丽的餐厅7:跪求！哪位高手帮我具体注释一下DES算法代码？

void SetKey(const char* Key, int len)
{
memset(deskey, 0, 16);
memcpy(deskey, Key, len>16?16:len);
SetSubKey(&SubKey[0], &deskey[0]);
Is3DES = len>8 ? (SetSubKey(&SubKey[1], &deskey[8]), true) : false;
}
void SDES(char Out[8], char In[8], const PSubKey pSubKey, bool Type)
{
static bool M[64], tmp[32], *Li=&M[0], *Ri=&M[32];
ByteToBit(M, In, 64);
Transform(M, M, IP_Table, 64);
if( Type == ENCRYPT )
{
for(int i=0; i<16; ++i)
{
memcpy(tmp, Ri, 32);
F_func(Ri, (*pSubKey)[i]);
Xor(Ri, Li, 32);
memcpy(Li, tmp, 32);
}
}
else
{
for(int i=15; i>=0; --i)
{
memcpy(tmp, Li, 32);
F_func(Li, (*pSubKey)[i]);
Xor(Li, Ri, 32);
memcpy(Ri, tmp, 32);
}
}
Transform(M, M, IPR_Table, 64);
BitToByte(Out, M, 64);
}
void SetSubKey(PSubKey pSubKey, const char Key[8])
{
static bool K[64], *KL=&K[0], *KR=&K[28];
ByteToBit(K, Key, 64);
Transform(K, K, PC1_Table, 56);
for(int i=0; i<16; ++i)
{
RotateL(KL, 28, LOOP_Table[i]);
RotateL(KR, 28, LOOP_Table[i]);
Transform((*pSubKey)[i], K, PC2_Table, 48);
}
}
void F_func(bool In[32], const bool Ki[48])
{
static bool MR[48];
Transform(MR, In, E_Table, 48);
Xor(MR, Ki, 48);
S_func(In, MR);
Transform(In, In, P_Table, 32);
}
void S_func(bool Out[32], const bool In[48])
{
for(char i=0,j,k; i<8; ++i,In+=6,Out+=4)
{
j = (In[0]<<1) + In[5];
k = (In[1]<<3) + (In[2]<<2) + (In[3]<<1) + In[4];
ByteToBit(Out, &S_Box[i][j][k], 4);
}
}
void Transform(bool *Out, bool *In, const char *Table, int len)
{
for(int i=0; i<len; ++i)
Tmp[i] = In[ Table[i]-1 ];
memcpy(Out, Tmp, len);
}
void Xor(bool *InA, const bool *InB, int len)
{
for(int i=0; i<len; ++i)
InA[i] ^= InB[i];
}
void RotateL(bool *In, int len, int loop)
{
memcpy(Tmp, In, loop);
memcpy(In, In+loop, len-loop);
memcpy(In+len-loop, Tmp, loop);
}
void ByteToBit(bool *Out, const char *In, int bits)
{
for(int i=0; i<bits; ++i)
Out[i] = (In[i>>3]>>(i&7)) & 1;
}
void BitToByte(char *Out, const bool *In, int bits)
{
memset(Out, 0, bits>>3);
for(int i=0; i<bits; ++i)
Out[i>>3] |= In[i]<<(i&7);
}