user: 这段汇编代码用C语言表示是什么样的:

```asm
<escape_char>:
  endbr64
  push   %r15
  xor    %r15d,%r15d
  push   %r14
  mov    %r9,%r14
  push   %r13
  mov    %rsi,%r13
  push   %r12
  mov    %ecx,%r12d
  push   %rbp
  mov    %rdi,%rbp
  mov    %rsi,%rdi
  push   %rbx
  xor    %ebx,%ebx
  sub    $0x38,%rsp
  mov    0x70(%rsp),%rax
  mov    %rdx,0x18(%rsp)
  mov    %r8,0x10(%rsp)
  mov    %rax,(%rsp)
  mov    %fs:0x28,%rax
  mov    %rax,0x28(%rsp)
  xor    %eax,%eax
  call   <assert@plt>
  lea    0x20(%rsp),%rax
  mov    %rax,0x8(%rsp)
  cmp    %rbp,%r13
  jne    L24
  jmp    L52
  nop
L82:
  xor    %r15d,%r15d
  test   %ecx,%ecx
  je     L103
  mov    D32(%rip),%rax
  mov    %ecx,%r15d
  mov    (%rax),%eax
  mov    %eax,(%r14)
L103:
  add    $0x1,%rbx
  cmp    %r13,%rbp
  je     L52
L24:
  movzbl 0x0(%rbp),%eax
  test   %al,%al
  je     L166
  add    $0x1,%rbp
  movsbl %al,%ecx
  cmp    $0x5c,%al
  je     L128
L78:
  test   %r12d,%r12d
  jne    L82
  mov    D27(%rip),%rax
  mov    %r15d,%edi
  mov    %r15d,%esi
  shl    $0x8,%edi
  mov    (%rax),%eax
  lea    (%rdi,%rcx,1),%r15d
  mov    %eax,%r8d
  shr    $0x8,%r8d
  cmp    %esi,%r8d
  jb     L65
  sub    %ecx,%eax
  cmp    %edi,%eax
  jae    L103
L65:
  mov    D32(%rip),%rax
  add    $0x1,%rbx
  mov    (%rax),%eax
  mov    %eax,(%r14)
  cmp    %r13,%rbp
  jne    L24
L52:
  cmpq   $0x0,0x10(%rsp)
  jne    L160
L117:
  mov    0x18(%rsp),%rax
  mov    %r13,(%rax)
  mov    0x28(%rsp),%rax
  sub    %fs:0x28,%rax
  jne    L15
  add    $0x38,%rsp
  mov    %r15d,%eax
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  cs nopw 0x0(%rax,%rax,1)
L128:
  cmp    %rbp,%r13
  je     L48
  mov    (%rsp),%r8
  mov    0x8(%rsp),%rsi
  mov    %r14,%rcx
  mov    %rbp,%rdi
  mov    %r12d,%edx
  call   <escape_char_1@plt>
  mov    0x20(%rsp),%rbp
  mov    %eax,%ecx
  jmp    L78
  nopl   0x0(%rax,%rax,1)
L166:
  cmpq   $0x0,0x10(%rsp)
  je     L110
  xor    %eax,%eax
  mov    0x10(%rsp),%rdx
  cmp    $0x1,%rbx
  seta   %al
  mov    %eax,(%rdx)
  cmp    %rbp,%r13
  je     L117
L110:
  lea    -0x1(%rbp),%r13
  jmp    L117
  nopw   0x0(%rax,%rax,1)
L160:
  xor    %eax,%eax
  mov    0x10(%rsp),%rdx
  cmp    $0x1,%rbx
  seta   %al
  mov    %eax,(%rdx)
  jmp    L117
  nopl   (%rax)
L48:
  mov    D31(%rip),%rax
  mov    (%rsp),%rdx
  cmpq   $0x0,0x10(%rsp)
  mov    (%rax),%eax
  mov    %eax,(%rdx)
  je     L117
  jmp    L160
L15:
  call   <__stack_chk_fail@plt>
```

assistant: ```c
int escape_char(char *start, char *limit, char **const end, int is_wide, int *const multi, int *const warn, int *const err) {
  int ret = 0;
  char *i;
  size_t n = 0;
  assert(limit);
  for (i = start; i != limit && *i; i++) {
    int this;
    if (*i == '\\') {
      char *escfin;
      i++;
      if (i == limit) {
        *err = EILSEQ;
        break;
      }
      this = escape_char_1(i, &escfin, is_wide, warn, err);
      i = escfin - 1;
    } else {
      this = *i;
    }
    if (is_wide) {
      ret = this;
      if (ret)
        *warn = E2BIG;
    } else {
      int of = 0;
      if ((unsigned)ret > UINT_MAX / 256u)
        of = 1;
      ret *= 256u;
      if ((unsigned)ret > UINT_MAX - this)
        of = 1;
      ret += this;
      if (of)
        *warn = E2BIG;
    }
    n++;
  }
  if (multi)
    *multi = n > 1;
  if (i == limit)
    *end = i;
  else
    *end = i - 1;
  return ret;
}
```