user: 下面的汇编指令对应的C源代码是什么：

```asm
<igbc_char_hex>:
  endbr64
  push   %rbp
  push   %rbx
  sub    $0x8,%rsp
  mov    %edi,%ebx
  mov    %edi,%ebp
  and    $0xf,%ebp
  mov    $0x2,%edi
  call   <malloc@plt>
  shr    $0x4,%bl
  movzbl %bl,%ebx
  lea    D13(%rip),%rcx
  movslq (%rcx,%rbx,4),%rdx
  add    %rcx,%rdx
  notrack jmp *%rdx
  movb   $0x30,(%rax)
L53:
  movzbl %bpl,%ebp
  lea    D17(%rip),%rcx
  movslq (%rcx,%rbp,4),%rdx
  add    %rcx,%rdx
  notrack jmp *%rdx
  movb   $0x31,(%rax)
  jmp    L53
  movb   $0x32,(%rax)
  jmp    L53
  movb   $0x33,(%rax)
  jmp    L53
  movb   $0x34,(%rax)
  jmp    L53
  movb   $0x35,(%rax)
  jmp    L53
  movb   $0x36,(%rax)
  jmp    L53
  movb   $0x37,(%rax)
  jmp    L53
  movb   $0x38,(%rax)
  jmp    L53
  movb   $0x39,(%rax)
  jmp    L53
  movb   $0x41,(%rax)
  jmp    L53
  movb   $0x42,(%rax)
  jmp    L53
  movb   $0x43,(%rax)
  jmp    L53
  movb   $0x44,(%rax)
  jmp    L53
  movb   $0x45,(%rax)
  jmp    L53
  movb   $0x46,(%rax)
  jmp    L53
  movb   $0x30,0x1(%rax)
L41:
  add    $0x8,%rsp
  pop    %rbx
  pop    %rbp
  ret
  movb   $0x31,0x1(%rax)
  jmp    L41
  movb   $0x32,0x1(%rax)
  jmp    L41
  movb   $0x33,0x1(%rax)
  jmp    L41
  movb   $0x34,0x1(%rax)
  jmp    L41
  movb   $0x35,0x1(%rax)
  jmp    L41
  movb   $0x36,0x1(%rax)
  jmp    L41
  movb   $0x37,0x1(%rax)
  jmp    L41
  movb   $0x38,0x1(%rax)
  jmp    L41
  movb   $0x39,0x1(%rax)
  jmp    L41
  movb   $0x41,0x1(%rax)
  jmp    L41
  movb   $0x42,0x1(%rax)
  jmp    L41
  movb   $0x43,0x1(%rax)
  jmp    L41
  movb   $0x44,0x1(%rax)
  jmp    L41
  movb   $0x45,0x1(%rax)
  jmp    L41
  movb   $0x46,0x1(%rax)
  jmp    L41
```

assistant: ```c
char *igbc_char_hex(char num) {
  char lower = num & 0x0F;
  char upper = (num >> 4) & 0x0F;
  char *out = (char *)malloc(2);
  switch (upper) {
  case 0x00:
    out[0] = '0';
    break;
  case 0x01:
    out[0] = '1';
    break;
  case 0x02:
    out[0] = '2';
    break;
  case 0x03:
    out[0] = '3';
    break;
  case 0x04:
    out[0] = '4';
    break;
  case 0x05:
    out[0] = '5';
    break;
  case 0x06:
    out[0] = '6';
    break;
  case 0x07:
    out[0] = '7';
    break;
  case 0x08:
    out[0] = '8';
    break;
  case 0x09:
    out[0] = '9';
    break;
  case 0x0A:
    out[0] = 'A';
    break;
  case 0x0B:
    out[0] = 'B';
    break;
  case 0x0C:
    out[0] = 'C';
    break;
  case 0x0D:
    out[0] = 'D';
    break;
  case 0x0E:
    out[0] = 'E';
    break;
  case 0x0F:
    out[0] = 'F';
    break;
  }
  switch (lower) {
  case 0x00:
    out[1] = '0';
    break;
  case 0x01:
    out[1] = '1';
    break;
  case 0x02:
    out[1] = '2';
    break;
  case 0x03:
    out[1] = '3';
    break;
  case 0x04:
    out[1] = '4';
    break;
  case 0x05:
    out[1] = '5';
    break;
  case 0x06:
    out[1] = '6';
    break;
  case 0x07:
    out[1] = '7';
    break;
  case 0x08:
    out[1] = '8';
    break;
  case 0x09:
    out[1] = '9';
    break;
  case 0x0A:
    out[1] = 'A';
    break;
  case 0x0B:
    out[1] = 'B';
    break;
  case 0x0C:
    out[1] = 'C';
    break;
  case 0x0D:
    out[1] = 'D';
    break;
  case 0x0E:
    out[1] = 'E';
    break;
  case 0x0F:
    out[1] = 'F';
    break;
  }
  return out;
}
```