user: What is the c source code of the assembly code below:

```asm
<hex2bin>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x20,%rsp
  mov    %rdi,-0x18(%rbp)
  mov    %rsi,-0x20(%rbp)
  movl   $0x0,-0x4(%rbp)
  jmp    L67
L61:
  movl   $0x0,-0x8(%rbp)
  jmp    L58
L168:
  mov    -0x8(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movsbl %al,%eax
  sub    $0x30,%eax
  cmp    $0x36,%eax
  ja     L99
  mov    %eax,%eax
  lea    0x0(,%rax,4),%rdx
  lea    D175(%rip),%rax
  mov    (%rdx,%rax,1),%eax
  cltq
  lea    D175(%rip),%rdx
  add    %rdx,%rax
  notrack jmp *%rax
  mov    -0x20(%rbp),%rax
  lea    D136(%rip),%rdx
  mov    %rdx,%rsi
  mov    %rax,%rdi
  call   <strcat@plt>
  jmp    L207
  mov    -0x20(%rbp),%rax
  lea    D141(%rip),%rdx
  mov    %rdx,%rsi
  mov    %rax,%rdi
  call   <strcat@plt>
  jmp    L207
  mov    -0x20(%rbp),%rax
  lea    D77(%rip),%rdx
  mov    %rdx,%rsi
  mov    %rax,%rdi
  call   <strcat@plt>
  jmp    L207
  mov    -0x20(%rbp),%rax
  lea    D70(%rip),%rdx
  mov    %rdx,%rsi
  mov    %rax,%rdi
  call   <strcat@plt>
  jmp    L207
  mov    -0x20(%rbp),%rax
  lea    D75(%rip),%rdx
  mov    %rdx,%rsi
  mov    %rax,%rdi
  call   <strcat@plt>
  jmp    L207
  mov    -0x20(%rbp),%rax
  lea    D145(%rip),%rdx
  mov    %rdx,%rsi
  mov    %rax,%rdi
  call   <strcat@plt>
  jmp    L207
  mov    -0x20(%rbp),%rax
  lea    D66(%rip),%rdx
  mov    %rdx,%rsi
  mov    %rax,%rdi
  call   <strcat@plt>
  jmp    L207
  mov    -0x20(%rbp),%rax
  lea    D144(%rip),%rdx
  mov    %rdx,%rsi
  mov    %rax,%rdi
  call   <strcat@plt>
  jmp    L207
  mov    -0x20(%rbp),%rax
  lea    D104(%rip),%rdx
  mov    %rdx,%rsi
  mov    %rax,%rdi
  call   <strcat@plt>
  jmp    L207
  mov    -0x20(%rbp),%rax
  lea    D30(%rip),%rdx
  mov    %rdx,%rsi
  mov    %rax,%rdi
  call   <strcat@plt>
  jmp    L207
  mov    -0x20(%rbp),%rax
  lea    D153(%rip),%rdx
  mov    %rdx,%rsi
  mov    %rax,%rdi
  call   <strcat@plt>
  jmp    L207
  mov    -0x20(%rbp),%rax
  lea    D47(%rip),%rdx
  mov    %rdx,%rsi
  mov    %rax,%rdi
  call   <strcat@plt>
  jmp    L207
  mov    -0x20(%rbp),%rax
  lea    D121(%rip),%rdx
  mov    %rdx,%rsi
  mov    %rax,%rdi
  call   <strcat@plt>
  jmp    L207
  mov    -0x20(%rbp),%rax
  lea    D117(%rip),%rdx
  mov    %rdx,%rsi
  mov    %rax,%rdi
  call   <strcat@plt>
  jmp    L207
  mov    -0x20(%rbp),%rax
  lea    D86(%rip),%rdx
  mov    %rdx,%rsi
  mov    %rax,%rdi
  call   <strcat@plt>
  jmp    L207
  mov    -0x20(%rbp),%rax
  lea    D10(%rip),%rdx
  mov    %rdx,%rsi
  mov    %rax,%rdi
  call   <strcat@plt>
  jmp    L207
L99:
  mov    -0x8(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movsbl %al,%eax
  mov    %eax,%esi
  lea    D138(%rip),%rax
  mov    %rax,%rdi
  call   <printf@plt>
  mov    $0x0,%eax
  jmp    L44
L207:
  addl   $0x1,-0x8(%rbp)
L58:
  cmpl   $0xf,-0x8(%rbp)
  jle    L168
  addl   $0x1,-0x4(%rbp)
L67:
  cmpl   $0x6,-0x4(%rbp)
  jle    L61
  mov    $0x1,%eax
L44:
  leave
  ret
```

tool_calls: name: extract_symbolic_data
arguments: data_label: D136
type: string
name: extract_symbolic_data
arguments: data_label: D141
type: string
name: extract_symbolic_data
arguments: data_label: D77
type: string
name: extract_symbolic_data
arguments: data_label: D70
type: string
name: extract_symbolic_data
arguments: data_label: D75
type: string
name: extract_symbolic_data
arguments: data_label: D145
type: string
name: extract_symbolic_data
arguments: data_label: D66
type: string
name: extract_symbolic_data
arguments: data_label: D144
type: string
name: extract_symbolic_data
arguments: data_label: D104
type: string
name: extract_symbolic_data
arguments: data_label: D30
type: string
name: extract_symbolic_data
arguments: data_label: D153
type: string
name: extract_symbolic_data
arguments: data_label: D47
type: string
name: extract_symbolic_data
arguments: data_label: D121
type: string
name: extract_symbolic_data
arguments: data_label: D117
type: string
name: extract_symbolic_data
arguments: data_label: D86
type: string
name: extract_symbolic_data
arguments: data_label: D10
type: string
name: extract_symbolic_data
arguments: data_label: D138
type: string

tool: D136: 0000

tool: D141: 0001

tool: D77: 0010

tool: D70: 0011

tool: D75: 0100

tool: D145: 0101

tool: D66: 0110

tool: D144: 0111

tool: D104: 1000

tool: D30: 1001

tool: D153: 1010

tool: D47: 1011

tool: D121: 1100

tool: D117: 1101

tool: D86: 1110

tool: D10: 1111

tool: D138: 
 Invalid hex digit %c 

assistant: ```c
int hex2bin(char *hex, char *bin) {
  int i, j;
  for (j = 0; j < 7; j++)
    for (i = 0; i < 16; i++) {
      switch (hex[i]) {
      case '0':
        strcat(bin, "0000");
        break;
      case '1':
        strcat(bin, "0001");
        break;
      case '2':
        strcat(bin, "0010");
        break;
      case '3':
        strcat(bin, "0011");
        break;
      case '4':
        strcat(bin, "0100");
        break;
      case '5':
        strcat(bin, "0101");
        break;
      case '6':
        strcat(bin, "0110");
        break;
      case '7':
        strcat(bin, "0111");
        break;
      case '8':
        strcat(bin, "1000");
        break;
      case '9':
        strcat(bin, "1001");
        break;
      case 'a':
        strcat(bin, "1010");
        break;
      case 'b':
        strcat(bin, "1011");
        break;
      case 'c':
        strcat(bin, "1100");
        break;
      case 'd':
        strcat(bin, "1101");
        break;
      case 'e':
        strcat(bin, "1110");
        break;
      case 'f':
        strcat(bin, "1111");
        break;
      default:
        printf("\n Invalid hex digit %c ", hex[i]);
        return 0;
      }
    }
  return 1;
}
```