__int64 __fastcall sub_82F(char *a1, int a2, _BYTE *a3, int *a4)
{
int v5;
int v6;
int v7;
char *v9;
int v10;
int i;

v9 = a1;
if ( !a1 || !a2 )
return 0xFFFFFFFFLL;
v10 = 0;
if ( a2 % 3 )
v10 = 3 - a2 % 3;
for ( i = 0; i < a2 + v10; i += 3 )
{
*a3 = byte_EC0[*v9 >> 2];
if ( i == a2 + v10 - 3 && v10 )
{
if ( v10 == 1 )
{
v5 = (char)sub_7FA((unsigned __int8)*v9, 6LL, 2LL);
a3[1] = byte_EC0[v5 + (char)sub_7FA((unsigned __int8)v9[1], 0LL, 4LL)];
a3[2] = byte_EC0[(char)sub_7FA((unsigned __int8)v9[1], 4LL, 2LL)];
a3[3] = 61;
}
else if ( v10 == 2 )
{
a3[1] = byte_EC0[(char)sub_7FA((unsigned __int8)*v9, 6LL, 2LL)];
a3[2] = 61;
a3[3] = 61;
}
}
else
{
v6 = (char)sub_7FA((unsigned __int8)*v9, 6LL, 2LL);
a3[1] = byte_EC0[v6 + (char)sub_7FA((unsigned __int8)v9[1], 0LL, 4LL)];
v7 = (char)sub_7FA((unsigned __int8)v9[1], 4LL, 2LL);
a3[2] = byte_EC0[v7 + (char)sub_7FA((unsigned __int8)v9[2], 0LL, 6LL)];
a3[3] = byte_EC0[v9[2] & 0x3F];
}
a3 += 4;
v9 += 3;
}
if ( a4 )
*a4 = 8 * (a2 + v10) / 6;
return 0LL;
}这段代码是什么加密 In your response, include at most 1 words that are fully capitalized to emphasize key points.
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