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

```asm
<Tcl_Backslash>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x30,%rsp
  mov    %rdi,-0x28(%rbp)
  mov    %rsi,-0x30(%rbp)
  mov    %fs:0x28,%rax
  mov    %rax,-0x8(%rbp)
  xor    %eax,%eax
  mov    -0x28(%rbp),%rax
  add    $0x1,%rax
  mov    %rax,-0x10(%rbp)
  movl   $0x2,-0x1c(%rbp)
  mov    -0x10(%rbp),%rax
  movzbl (%rax),%eax
  movsbl %al,%eax
  cmp    $0x78,%eax
  jg     L15
  cmp    $0x61,%eax
  jge    L50
  test   %eax,%eax
  je     L120
  cmp    $0xa,%eax
  je     L205
  jmp    L15
L50:
  sub    $0x61,%eax
  cmp    $0x17,%eax
  ja     L15
  mov    %eax,%eax
  lea    0x0(,%rax,4),%rdx
  lea    D15(%rip),%rax
  mov    (%rdx,%rax,1),%eax
  cltq
  lea    D15(%rip),%rdx
  add    %rdx,%rax
  notrack jmp *%rax
  movb   $0x7,-0x1d(%rbp)
  jmp    L103
  movb   $0x8,-0x1d(%rbp)
  jmp    L103
  movb   $0xc,-0x1d(%rbp)
  jmp    L103
  movb   $0xa,-0x1d(%rbp)
  jmp    L103
  movb   $0xd,-0x1d(%rbp)
  jmp    L103
  movb   $0x9,-0x1d(%rbp)
  jmp    L103
  movb   $0xb,-0x1d(%rbp)
  jmp    L103
  mov    -0x10(%rbp),%rax
  add    $0x1,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  mov    %eax,%edi
  call   <isxdigit@plt>
  test   %eax,%eax
  je     L264
  mov    -0x10(%rbp),%rax
  lea    0x1(%rax),%rcx
  lea    -0x18(%rbp),%rax
  mov    $0x10,%edx
  mov    %rax,%rsi
  mov    %rcx,%rdi
  mov    $0x0,%eax
  call   <strtoul@plt>
  mov    %al,-0x1d(%rbp)
  mov    -0x18(%rbp),%rax
  sub    -0x28(%rbp),%rax
  mov    %eax,-0x1c(%rbp)
  jmp    L103
L264:
  movl   $0x2,-0x1c(%rbp)
  movb   $0x78,-0x1d(%rbp)
  jmp    L103
L234:
  nop
L205:
  addq   $0x1,-0x10(%rbp)
  mov    -0x10(%rbp),%rax
  movzbl (%rax),%eax
  cmp    $0x20,%al
  je     L234
  mov    -0x10(%rbp),%rax
  movzbl (%rax),%eax
  cmp    $0x9,%al
  je     L234
  movb   $0x20,-0x1d(%rbp)
  mov    -0x10(%rbp),%rax
  sub    -0x28(%rbp),%rax
  mov    %eax,-0x1c(%rbp)
  jmp    L103
L120:
  movb   $0x5c,-0x1d(%rbp)
  movl   $0x1,-0x1c(%rbp)
  jmp    L103
L15:
  mov    -0x10(%rbp),%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  sub    $0x30,%eax
  cmp    $0x9,%eax
  ja     L156
  mov    -0x10(%rbp),%rax
  movzbl (%rax),%eax
  sub    $0x30,%eax
  mov    %al,-0x1d(%rbp)
  addq   $0x1,-0x10(%rbp)
  mov    -0x10(%rbp),%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  sub    $0x30,%eax
  cmp    $0x9,%eax
  ja     L187
  movl   $0x3,-0x1c(%rbp)
  movzbl -0x1d(%rbp),%eax
  lea    0x0(,%rax,8),%edx
  mov    -0x10(%rbp),%rax
  movzbl (%rax),%eax
  add    %edx,%eax
  sub    $0x30,%eax
  mov    %al,-0x1d(%rbp)
  addq   $0x1,-0x10(%rbp)
  mov    -0x10(%rbp),%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  sub    $0x30,%eax
  cmp    $0x9,%eax
  ja     L268
  movl   $0x4,-0x1c(%rbp)
  movzbl -0x1d(%rbp),%eax
  lea    0x0(,%rax,8),%edx
  mov    -0x10(%rbp),%rax
  movzbl (%rax),%eax
  add    %edx,%eax
  sub    $0x30,%eax
  mov    %al,-0x1d(%rbp)
  jmp    L103
L156:
  mov    -0x10(%rbp),%rax
  movzbl (%rax),%eax
  mov    %al,-0x1d(%rbp)
  movl   $0x2,-0x1c(%rbp)
  jmp    L103
L187:
  nop
  jmp    L103
L268:
  nop
L103:
  cmpq   $0x0,-0x30(%rbp)
  je     L195
  mov    -0x30(%rbp),%rax
  mov    -0x1c(%rbp),%edx
  mov    %edx,(%rax)
L195:
  movzbl -0x1d(%rbp),%eax
  mov    -0x8(%rbp),%rdx
  sub    %fs:0x28,%rdx
  je     L87
  call   <__stack_chk_fail@plt>
L87:
  leave
  ret
```

assistant: ```c
char Tcl_Backslash(src, readPtr) const char *src;
int *readPtr;
{
  const char *p = src + 1;
  char result;
  int count;
  count = 2;
  switch (*p) {
  case 'a':
    result = 0x7;
    break;
  case 'b':
    result = 0x8;
    break;
  case 'f':
    result = 0xc;
    break;
  case 'n':
    result = 0xa;
    break;
  case 'r':
    result = 0xd;
    break;
  case 't':
    result = 0x9;
    break;
  case 'v':
    result = 0xb;
    break;
  case 'x':
    if (isxdigit(((unsigned char)(p[1])))) {
      char *end;
      result = (char)strtoul(p + 1, &end, 16);
      count = end - src;
    } else {
      count = 2;
      result = 'x';
    }
    break;
  case '\n':
    do {
      p++;
    } while ((*p == ' ') || (*p == '\t'));
    result = ' ';
    count = p - src;
    break;
  case 0:
    result = '\\';
    count = 1;
    break;
  default:
    if (isdigit(((unsigned char)(*p)))) {
      result = (char)(*p - '0');
      p++;
      if (!isdigit(((unsigned char)(*p)))) {
        break;
      }
      count = 3;
      result = (char)((result << 3) + (*p - '0'));
      p++;
      if (!isdigit(((unsigned char)(*p)))) {
        break;
      }
      count = 4;
      result = (char)((result << 3) + (*p - '0'));
      break;
    }
    result = *p;
    count = 2;
    break;
  }
  if (readPtr != 0) {
    *readPtr = count;
  }
  return result;
}
```