对下面的C语言伪代码函数进行分析推测关于该函数的使用环境和预期目的详细的函数功能等信息并为这个函数取一个新的名字 ) _BYTE *__fastcall sub_74918(int a1, int a2, int a3, int a4) { int v6; // r2 void *v7; // r0 void *v8; // r1 void *v9; // r3 int v10; // r10 char *v11; // r0 int v12; // r8 unsigned int v13; // r5 int i; // r1 unsigned int j; // r2 _BYTE *result; // r0 int v17; // r4 int v18; // r9 int k; // r6 char *v20; // r1 unsigned __int8 v22; // [sp+9h] [bp-27h] unsigned __int8 v23; // [sp+Ah] [bp-26h] unsigned __int8 v24; // [sp+Bh] [bp-25h] char v25; // [sp+Ch] [bp-24h] char v26; // [sp+Dh] [bp-23h] char v27; // [sp+Eh] [bp-22h] char v28; // [sp+Fh] [bp-21h] if ( a3 ) { v6 = 56; v7 = off_D7060; v8 = off_D7064; v9 = &unk_EA328; } else { v7 = off_D7068; v8 = off_D706C; v9 = &unk_EA329; v6 = 131; } v10 = ((int (__fastcall *)(void *, void *, int, void *, int))loc_74AC4)(v7, v8, v6, v9, a4); v11 = (char *)malloc(1u); if ( !v11 ) return 0; v12 = 0; LABEL_6: v13 = 0; while ( a2 != v13 ) { *(&v22 + v13) = *(_BYTE *)(a1 + v13); if ( ++v13 == 3 ) { v25 = v22 >> 2; v28 = v24 & 0x3F; v26 = (v23 >> 4) | (16 * (v22 & 3)); v27 = (v24 >> 6) | (4 * (v23 & 0xF)); v11 = (char *)realloc(v11, v12 + 4); a2 -= 3; a1 += 3; for ( i = 0; i != 4; ++i ) v11[v12 + i] = *(_BYTE *)(v10 + (unsigned __int8)*(&v25 + i)); v12 += 4; goto LABEL_6; } } if ( v13 ) { for ( j = v13; j <= 2; ++j ) *(&v22 + j) = 0; v25 = v22 >> 2; v28 = v24 & 0x3F; v26 = (v23 >> 4) | (16 * (v22 & 3)); v17 = 0; v27 = (v24 >> 6) | (4 * (v23 & 0xF)); while ( v13 + 1 != v17 ) { v11 = (char *)realloc(v11, v12 + v17 + 1); v11[v12 + v17] = *(_BYTE *)(v10 + (unsigned __int8)*(&v25 + v17)); ++v17; } v18 = v12 + v17; for ( k = 0; v13 + k <= 2; ++k ) { v11 = (char *)realloc(v11, v18 + k + 1); v20 = &v11[k]; v20[v12 + v17] = 61; } v12 = v18 + k; } result = realloc(v11, v12 + 1); result[v12] = 0; return result; }