void prepareMapping(char mapEncodeToDecode[]) {
  char encodeToDecodeStr[] = "`1234567890-=QWERTYUIOP[]\\ASDFGHJKL;'ZXCVBNM,./";
  int i;
  for (i = 0; i < 256; i++)
    mapEncodeToDecode[i] = i;
  for (i = 1; encodeToDecodeStr[i] != '\0'; i++) {
    if (encodeToDecodeStr[i] == 'Q' || encodeToDecodeStr[i] == 'A' ||
        encodeToDecodeStr[i] == 'Z')
      continue;
    mapEncodeToDecode[(int)encodeToDecodeStr[i]] = encodeToDecodeStr[i - 1];
  }
}


x86 assembly (clang, -O0):
<prepareMapping>:
push   %rbp
mov    %rsp,%rbp
sub    $0x50,%rsp
mov    %rdi,-0x8(%rbp)
lea    -0x40(%rbp),%rdi
lea    0xed9(%rip),%rsi
mov    $0x30,%edx
call   1030 <memcpy@plt>
movl   $0x0,-0x44(%rbp)
cmpl   $0x100,-0x44(%rbp)
jge    1163 <prepareMapping+0x53>
mov    -0x44(%rbp),%eax
mov    %al,%dl
mov    -0x8(%rbp),%rax
movslq -0x44(%rbp),%rcx
mov    %dl,(%rax,%rcx,1)
mov    -0x44(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0x44(%rbp)
jmp    1138 <prepareMapping+0x28>
movl   $0x1,-0x44(%rbp)
movslq -0x44(%rbp),%rax
movsbl -0x40(%rbp,%rax,1),%eax
cmp    $0x0,%eax
je     11e4 <prepareMapping+0xd4>
movslq -0x44(%rbp),%rax
movsbl -0x40(%rbp,%rax,1),%eax
cmp    $0x51,%eax
je     11b2 <prepareMapping+0xa2>
movslq -0x44(%rbp),%rax
movsbl -0x40(%rbp,%rax,1),%eax
cmp    $0x41,%eax
je     11b2 <prepareMapping+0xa2>
movslq -0x44(%rbp),%rax
movsbl -0x40(%rbp,%rax,1),%eax
cmp    $0x5a,%eax
jne    11b7 <prepareMapping+0xa7>
jmp    11d6 <prepareMapping+0xc6>
mov    -0x44(%rbp),%eax
sub    $0x1,%eax
cltq
mov    -0x40(%rbp,%rax,1),%dl
mov    -0x8(%rbp),%rax
movslq -0x44(%rbp),%rcx
movsbl -0x40(%rbp,%rcx,1),%ecx
movslq %ecx,%rcx
mov    %dl,(%rax,%rcx,1)
mov    -0x44(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0x44(%rbp)
jmp    116a <prepareMapping+0x5a>
add    $0x50,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<prepareMapping>:
movaps 0xef9(%rip),%xmm0
movups %xmm0,(%rdi)
movaps 0xeff(%rip),%xmm0
movups %xmm0,0x10(%rdi)
movaps 0xf04(%rip),%xmm0
movups %xmm0,0x20(%rdi)
movaps 0xf09(%rip),%xmm0
movups %xmm0,0x30(%rdi)
movaps 0xf0e(%rip),%xmm0
movups %xmm0,0x40(%rdi)
movaps 0xf13(%rip),%xmm0
movups %xmm0,0x50(%rdi)
movaps 0xf18(%rip),%xmm0
movups %xmm0,0x60(%rdi)
movaps 0xf1d(%rip),%xmm0
movups %xmm0,0x70(%rdi)
movaps 0xf22(%rip),%xmm0
movups %xmm0,0x80(%rdi)
movaps 0xf24(%rip),%xmm0
movups %xmm0,0x90(%rdi)
movaps 0xf26(%rip),%xmm0
movups %xmm0,0xa0(%rdi)
movaps 0xf28(%rip),%xmm0
movups %xmm0,0xb0(%rdi)
movaps 0xf2a(%rip),%xmm0
movups %xmm0,0xc0(%rdi)
movaps 0xf2c(%rip),%xmm0
movups %xmm0,0xd0(%rdi)
movaps 0xf2e(%rip),%xmm0
movups %xmm0,0xe0(%rdi)
movaps 0xf30(%rip),%xmm0
movups %xmm0,0xf0(%rdi)
mov    $0x2,%eax
lea    0x104d(%rip),%r8
lea    0xfb2(%rip),%r9
lea    0xf1f(%rip),%r10
jmp    1202 <prepareMapping+0x102>
cs nopw 0x0(%rax,%rax,1)
nopl   (%rax)
movsbq (%rax,%r8,1),%rcx
movzbl -0x1(%rax,%r8,1),%edx
mov    %dl,(%rdi,%rcx,1)
add    $0x2,%rax
lea    -0x1(%rax),%rcx
lea    -0xd(%rcx),%edx
cmp    $0x22,%edx
ja     1217 <prepareMapping+0x117>
movslq (%r10,%rdx,4),%rdx
add    %r10,%rdx
jmp    *%rdx
movsbq -0x1(%rax,%r8,1),%rsi
movzbl -0x2(%rax,%r8,1),%edx
mov    %dl,(%rdi,%rsi,1)
add    $0xfffffff4,%ecx
cmp    $0x22,%ecx
ja     11f0 <prepareMapping+0xf0>
movslq (%r9,%rcx,4),%rcx
add    %r9,%rcx
jmp    *%rcx
ret

LLVM IR (-O0):
@__const.prepareMapping.encodeToDecodeStr = [48 x i8] c"`1234567890-=QWERTYUIOP[]\\ASDFGHJKL;'ZXCVBNM,./\00"
define void @prepareMapping(i8* %0) {
%2 = alloca i8*
%3 = alloca [48 x i8]
%4 = alloca i32
store i8* %0, i8** %2
%5 = bitcast [48 x i8]* %3 to i8*
store i32 0, i32* %4
br label %6
6: ; preds = %16, %1
%7 = load i32, i32* %4
%8 = icmp slt i32 %7, 256
br i1 %8, label %9, label %19
9: ; preds = %6
%10 = load i32, i32* %4
%11 = trunc i32 %10 to i8
%12 = load i8*, i8** %2
%13 = load i32, i32* %4
%14 = sext i32 %13 to i64
%15 = getelementptr inbounds i8, i8* %12, i64 %14
store i8 %11, i8* %15
br label %16
16: ; preds = %9
%17 = load i32, i32* %4
%18 = add nsw i32 %17, 1
store i32 %18, i32* %4
br label %6
19: ; preds = %6
store i32 1, i32* %4
br label %20
20: ; preds = %63, %19
%21 = load i32, i32* %4
%22 = sext i32 %21 to i64
%23 = getelementptr inbounds [48 x i8], [48 x i8]* %3, i64 0, i64 %22
%24 = load i8, i8* %23
%25 = sext i8 %24 to i32
%26 = icmp ne i32 %25, 0
br i1 %26, label %27, label %66
27: ; preds = %20
%28 = load i32, i32* %4
%29 = sext i32 %28 to i64
%30 = getelementptr inbounds [48 x i8], [48 x i8]* %3, i64 0, i64 %29
%31 = load i8, i8* %30
%32 = sext i8 %31 to i32
%33 = icmp eq i32 %32, 81
br i1 %33, label %48, label %34
34: ; preds = %27
%35 = load i32, i32* %4
%36 = sext i32 %35 to i64
%37 = getelementptr inbounds [48 x i8], [48 x i8]* %3, i64 0, i64 %36
%38 = load i8, i8* %37
%39 = sext i8 %38 to i32
%40 = icmp eq i32 %39, 65
br i1 %40, label %48, label %41
41: ; preds = %34
%42 = load i32, i32* %4
%43 = sext i32 %42 to i64
%44 = getelementptr inbounds [48 x i8], [48 x i8]* %3, i64 0, i64 %43
%45 = load i8, i8* %44
%46 = sext i8 %45 to i32
%47 = icmp eq i32 %46, 90
br i1 %47, label %48, label %49
48: ; preds = %41, %34, %27
br label %63
49: ; preds = %41
%50 = load i32, i32* %4
%51 = sub nsw i32 %50, 1
%52 = sext i32 %51 to i64
%53 = getelementptr inbounds [48 x i8], [48 x i8]* %3, i64 0, i64 %52
%54 = load i8, i8* %53
%55 = load i8*, i8** %2
%56 = load i32, i32* %4
%57 = sext i32 %56 to i64
%58 = getelementptr inbounds [48 x i8], [48 x i8]* %3, i64 0, i64 %57
%59 = load i8, i8* %58
%60 = sext i8 %59 to i32
%61 = sext i32 %60 to i64
%62 = getelementptr inbounds i8, i8* %55, i64 %61
store i8 %54, i8* %62
br label %63
63: ; preds = %49, %48
%64 = load i32, i32* %4
%65 = add nsw i32 %64, 1
store i32 %65, i32* %4
br label %20
66: ; preds = %20
ret void
}

LLVM IR (-O2):
@__const.prepareMapping.encodeToDecodeStr = [48 x i8] c"`1234567890-=QWERTYUIOP[]\\ASDFGHJKL;'ZXCVBNM,./\00"
define void @prepareMapping(i8* nocapture writeonly %0) {
%2 = bitcast i8* %0 to <16 x i8>*
store <16 x i8> <i8 0, i8 1, i8 2, i8 3, i8 4, i8 5, i8 6, i8 7, i8 8, i8 9, i8 10, i8 11, i8 12, i8 13, i8 14, i8 15>, <16 x i8>* %2
%3 = getelementptr inbounds i8, i8* %0, i64 16
%4 = bitcast i8* %3 to <16 x i8>*
store <16 x i8> <i8 16, i8 17, i8 18, i8 19, i8 20, i8 21, i8 22, i8 23, i8 24, i8 25, i8 26, i8 27, i8 28, i8 29, i8 30, i8 31>, <16 x i8>* %4
%5 = getelementptr inbounds i8, i8* %0, i64 32
%6 = bitcast i8* %5 to <16 x i8>*
store <16 x i8> <i8 32, i8 33, i8 34, i8 35, i8 36, i8 37, i8 38, i8 39, i8 40, i8 41, i8 42, i8 43, i8 44, i8 45, i8 46, i8 47>, <16 x i8>* %6
%7 = getelementptr inbounds i8, i8* %0, i64 48
%8 = bitcast i8* %7 to <16 x i8>*
store <16 x i8> <i8 48, i8 49, i8 50, i8 51, i8 52, i8 53, i8 54, i8 55, i8 56, i8 57, i8 58, i8 59, i8 60, i8 61, i8 62, i8 63>, <16 x i8>* %8
%9 = getelementptr inbounds i8, i8* %0, i64 64
%10 = bitcast i8* %9 to <16 x i8>*
store <16 x i8> <i8 64, i8 65, i8 66, i8 67, i8 68, i8 69, i8 70, i8 71, i8 72, i8 73, i8 74, i8 75, i8 76, i8 77, i8 78, i8 79>, <16 x i8>* %10
%11 = getelementptr inbounds i8, i8* %0, i64 80
%12 = bitcast i8* %11 to <16 x i8>*
store <16 x i8> <i8 80, i8 81, i8 82, i8 83, i8 84, i8 85, i8 86, i8 87, i8 88, i8 89, i8 90, i8 91, i8 92, i8 93, i8 94, i8 95>, <16 x i8>* %12
%13 = getelementptr inbounds i8, i8* %0, i64 96
%14 = bitcast i8* %13 to <16 x i8>*
store <16 x i8> <i8 96, i8 97, i8 98, i8 99, i8 100, i8 101, i8 102, i8 103, i8 104, i8 105, i8 106, i8 107, i8 108, i8 109, i8 110, i8 111>, <16 x i8>* %14
%15 = getelementptr inbounds i8, i8* %0, i64 112
%16 = bitcast i8* %15 to <16 x i8>*
store <16 x i8> <i8 112, i8 113, i8 114, i8 115, i8 116, i8 117, i8 118, i8 119, i8 120, i8 121, i8 122, i8 123, i8 124, i8 125, i8 126, i8 127>, <16 x i8>* %16
%17 = getelementptr inbounds i8, i8* %0, i64 128
%18 = bitcast i8* %17 to <16 x i8>*
store <16 x i8> <i8 -128, i8 -127, i8 -126, i8 -125, i8 -124, i8 -123, i8 -122, i8 -121, i8 -120, i8 -119, i8 -118, i8 -117, i8 -116, i8 -115, i8 -114, i8 -113>, <16 x i8>* %18
%19 = getelementptr inbounds i8, i8* %0, i64 144
%20 = bitcast i8* %19 to <16 x i8>*
store <16 x i8> <i8 -112, i8 -111, i8 -110, i8 -109, i8 -108, i8 -107, i8 -106, i8 -105, i8 -104, i8 -103, i8 -102, i8 -101, i8 -100, i8 -99, i8 -98, i8 -97>, <16 x i8>* %20
%21 = getelementptr inbounds i8, i8* %0, i64 160
%22 = bitcast i8* %21 to <16 x i8>*
store <16 x i8> <i8 -96, i8 -95, i8 -94, i8 -93, i8 -92, i8 -91, i8 -90, i8 -89, i8 -88, i8 -87, i8 -86, i8 -85, i8 -84, i8 -83, i8 -82, i8 -81>, <16 x i8>* %22
%23 = getelementptr inbounds i8, i8* %0, i64 176
%24 = bitcast i8* %23 to <16 x i8>*
store <16 x i8> <i8 -80, i8 -79, i8 -78, i8 -77, i8 -76, i8 -75, i8 -74, i8 -73, i8 -72, i8 -71, i8 -70, i8 -69, i8 -68, i8 -67, i8 -66, i8 -65>, <16 x i8>* %24
%25 = getelementptr inbounds i8, i8* %0, i64 192
%26 = bitcast i8* %25 to <16 x i8>*
store <16 x i8> <i8 -64, i8 -63, i8 -62, i8 -61, i8 -60, i8 -59, i8 -58, i8 -57, i8 -56, i8 -55, i8 -54, i8 -53, i8 -52, i8 -51, i8 -50, i8 -49>, <16 x i8>* %26
%27 = getelementptr inbounds i8, i8* %0, i64 208
%28 = bitcast i8* %27 to <16 x i8>*
store <16 x i8> <i8 -48, i8 -47, i8 -46, i8 -45, i8 -44, i8 -43, i8 -42, i8 -41, i8 -40, i8 -39, i8 -38, i8 -37, i8 -36, i8 -35, i8 -34, i8 -33>, <16 x i8>* %28
%29 = getelementptr inbounds i8, i8* %0, i64 224
%30 = bitcast i8* %29 to <16 x i8>*
store <16 x i8> <i8 -32, i8 -31, i8 -30, i8 -29, i8 -28, i8 -27, i8 -26, i8 -25, i8 -24, i8 -23, i8 -22, i8 -21, i8 -20, i8 -19, i8 -18, i8 -17>, <16 x i8>* %30
%31 = getelementptr inbounds i8, i8* %0, i64 240
%32 = bitcast i8* %31 to <16 x i8>*
store <16 x i8> <i8 -16, i8 -15, i8 -14, i8 -13, i8 -12, i8 -11, i8 -10, i8 -9, i8 -8, i8 -7, i8 -6, i8 -5, i8 -4, i8 -3, i8 -2, i8 -1>, <16 x i8>* %32
br label %33
33: ; preds = %54, %1
%34 = phi i64 [ 1, %1 ], [ %55, %54 ]
%35 = trunc i64 %34 to i32
switch i32 %35, label %36 [
i32 47, label %56
i32 13, label %44
i32 26, label %44
i32 37, label %44
]
36: ; preds = %33
%37 = getelementptr inbounds [48 x i8], [48 x i8]* @__const.prepareMapping.encodeToDecodeStr, i64 0, i64 %34
%38 = load i8, i8* %37
%39 = add nsw i64 %34, -1
%40 = getelementptr inbounds [48 x i8], [48 x i8]* @__const.prepareMapping.encodeToDecodeStr, i64 0, i64 %39
%41 = load i8, i8* %40
%42 = sext i8 %38 to i64
%43 = getelementptr inbounds i8, i8* %0, i64 %42
store i8 %41, i8* %43
br label %44
44: ; preds = %33, %33, %33, %36
%45 = add nuw nsw i64 %34, 1
%46 = trunc i64 %45 to i32
switch i32 %46, label %47 [
i32 47, label %56
i32 13, label %54
i32 26, label %54
i32 37, label %54
]
47: ; preds = %44
%48 = getelementptr inbounds [48 x i8], [48 x i8]* @__const.prepareMapping.encodeToDecodeStr, i64 0, i64 %45
%49 = load i8, i8* %48
%50 = getelementptr inbounds [48 x i8], [48 x i8]* @__const.prepareMapping.encodeToDecodeStr, i64 0, i64 %34
%51 = load i8, i8* %50
%52 = sext i8 %49 to i64
%53 = getelementptr inbounds i8, i8* %0, i64 %52
store i8 %51, i8* %53
br label %54
54: ; preds = %47, %44, %44, %44
%55 = add nuw nsw i64 %34, 2
br label %33
56: ; preds = %44, %33
ret void
}