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

```asm
<hex_to_base4>:
  endbr64
  push   %r15
  mov    $0x8,%edx
  lea    D81(%rip),%r15
  push   %r14
  lea    D171(%rip),%r14
  push   %r13
  xor    %r13d,%r13d
  push   %r12
  lea    D139(%rip),%r12
  push   %rbp
  mov    %rsi,%rbp
  xor    %esi,%esi
  push   %rbx
  mov    %rdi,%rbx
  mov    %rbp,%rdi
  sub    $0x8,%rsp
  call   <memset@plt>
  nop
L65:
  mov    %rbx,%rdi
  call   <strlen@plt>
  cmp    %r13d,%eax
  jle    L75
  movzbl (%rbx,%r13,1),%eax
  sub    $0x30,%eax
  cmp    $0x36,%al
  ja     L43
  movzbl %al,%eax
  movslq (%r12,%rax,4),%rax
  add    %r12,%rax
  notrack jmp *%rax
  cs nopw 0x0(%rax,%rax,1)
L75:
  add    $0x8,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nop
L43:
  mov    %r15,%rdi
  call   <printf@plt>
  nopl   0x0(%rax,%rax,1)
L57:
  add    $0x1,%r13
  jmp    L65
  cs nopw 0x0(%rax,%rax,1)
  mov    %r14,%rsi
  mov    %rbp,%rdi
  call   <strcat@plt>
  jmp    L57
  nopl   (%rax)
  lea    D0(%rip),%rsi
  mov    %rbp,%rdi
  call   <strcat@plt>
  jmp    L57
  nopl   0x0(%rax)
  lea    D133(%rip),%rsi
  mov    %rbp,%rdi
  call   <strcat@plt>
  jmp    L57
  nopl   0x0(%rax)
  lea    D174(%rip),%rsi
  mov    %rbp,%rdi
  call   <strcat@plt>
  jmp    L57
  nopl   0x0(%rax)
  lea    D161(%rip),%rsi
  mov    %rbp,%rdi
  call   <strcat@plt>
  jmp    L57
  nopl   0x0(%rax)
  lea    D126(%rip),%rsi
  mov    %rbp,%rdi
  call   <strcat@plt>
  jmp    L57
  nopl   0x0(%rax)
  lea    D7(%rip),%rsi
  mov    %rbp,%rdi
  call   <strcat@plt>
  jmp    L57
  nopl   0x0(%rax)
  lea    D82(%rip),%rsi
  mov    %rbp,%rdi
  call   <strcat@plt>
  jmp    L57
  nopl   0x0(%rax)
  lea    D165(%rip),%rsi
  mov    %rbp,%rdi
  call   <strcat@plt>
  jmp    L57
  nopl   0x0(%rax)
  lea    D25(%rip),%rsi
  mov    %rbp,%rdi
  call   <strcat@plt>
  jmp    L57
  nopl   0x0(%rax)
  lea    D59(%rip),%rsi
  mov    %rbp,%rdi
  call   <strcat@plt>
  jmp    L57
  nopl   0x0(%rax)
  lea    D159(%rip),%rsi
  mov    %rbp,%rdi
  call   <strcat@plt>
  jmp    L57
  nopl   0x0(%rax)
  lea    D92(%rip),%rsi
  mov    %rbp,%rdi
  call   <strcat@plt>
  jmp    L57
  nopl   0x0(%rax)
  lea    D53(%rip),%rsi
  mov    %rbp,%rdi
  call   <strcat@plt>
  jmp    L57
  nopl   0x0(%rax)
  lea    D113(%rip),%rsi
  mov    %rbp,%rdi
  call   <strcat@plt>
  jmp    L57
  nopl   0x0(%rax)
  lea    D15(%rip),%rsi
  mov    %rbp,%rdi
  call   <strcat@plt>
  jmp    L57
```

tool_calls: name: disassemble_data
arguments: label: D81
datatype: string
name: disassemble_data
arguments: label: D171
datatype: string
name: disassemble_data
arguments: label: D0
datatype: string
name: disassemble_data
arguments: label: D133
datatype: string
name: disassemble_data
arguments: label: D174
datatype: string
name: disassemble_data
arguments: label: D161
datatype: string
name: disassemble_data
arguments: label: D126
datatype: string
name: disassemble_data
arguments: label: D7
datatype: string
name: disassemble_data
arguments: label: D82
datatype: string
name: disassemble_data
arguments: label: D165
datatype: string
name: disassemble_data
arguments: label: D25
datatype: string
name: disassemble_data
arguments: label: D59
datatype: string
name: disassemble_data
arguments: label: D159
datatype: string
name: disassemble_data
arguments: label: D92
datatype: string
name: disassemble_data
arguments: label: D53
datatype: string
name: disassemble_data
arguments: label: D113
datatype: string
name: disassemble_data
arguments: label: D15
datatype: string

tool: D81: Some wierd number is in the key 


tool: D171: 33

tool: D0: 32

tool: D133: 31

tool: D174: 30

tool: D161: 23

tool: D126: 22

tool: D7: 21

tool: D82: 20

tool: D165: 13

tool: D25: 12

tool: D59: 11

tool: D159: 10

tool: D92: 03

tool: D53: 02

tool: D113: 01

tool: D15: 00

assistant: ```c
void hex_to_base4(char *hexstr, char *base4str) {
  int i = 0;
  memset(base4str, 0, sizeof(base4str));
  for (i = 0; i < strlen(hexstr); i++) {
    switch (hexstr[i]) {
    case '0':
      strcat(base4str, "00");
      break;
    case '1':
      strcat(base4str, "01");
      break;
    case '2':
      strcat(base4str, "02");
      break;
    case '3':
      strcat(base4str, "03");
      break;
    case '4':
      strcat(base4str, "10");
      break;
    case '5':
      strcat(base4str, "11");
      break;
    case '6':
      strcat(base4str, "12");
      break;
    case '7':
      strcat(base4str, "13");
      break;
    case '8':
      strcat(base4str, "20");
      break;
    case '9':
      strcat(base4str, "21");
      break;
    case 'a':
      strcat(base4str, "22");
      break;
    case 'b':
      strcat(base4str, "23");
      break;
    case 'c':
      strcat(base4str, "30");
      break;
    case 'd':
      strcat(base4str, "31");
      break;
    case 'e':
      strcat(base4str, "32");
      break;
    case 'f':
      strcat(base4str, "33");
      break;
    default:
      printf("Some wierd number is in the key \n");
      break;
    }
  }
}
```