user: 请将这段汇编代码片段转换成等效的C代码:

```asm
<tm_diffmonths>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  mov    %rsi,%rbp
  push   %rbx
  sub    $0x18,%rsp
  mov    0x70(%rsp),%r12
  mov    %rdi,0x8(%rsp)
  mov    0x78(%rsp),%r13
  mov    0x80(%rsp),%r14
  mov    0x88(%rsp),%r15
  push   0x68(%rsp)
  push   0x68(%rsp)
  push   0x68(%rsp)
  push   0x68(%rsp)
  call   <tm_getrepresentation@plt>
  add    $0x20,%rsp
  push   0x88(%rsp)
  mov    %rax,%rbx
  push   0x88(%rsp)
  push   0x88(%rsp)
  push   0x88(%rsp)
  call   <tm_getrepresentation@plt>
  add    $0x20,%rsp
  cmp    %rax,%rbx
  je     L1
  mov    D7(%rip),%rax
  mov    (%rax),%edx
  mov    D9(%rip),%rax
  mov    %edx,(%rax)
  add    $0x18,%rsp
  xor    %eax,%eax
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nopl   (%rax)
L1:
  push   0x88(%rsp)
  mov    $0x1,%ebx
  push   0x88(%rsp)
  push   0x88(%rsp)
  push   0x88(%rsp)
  push   0x88(%rsp)
  push   0x88(%rsp)
  push   0x88(%rsp)
  push   0x88(%rsp)
  call   <tm_diffseconds@plt>
  add    $0x40,%rsp
  test   %rax,%rax
  js     L25
L58:
  mov    %r12,0x70(%rsp)
  mov    %r13,0x78(%rsp)
  mov    %r14,0x80(%rsp)
  mov    %r15,0x88(%rsp)
  push   0x88(%rsp)
  push   0x88(%rsp)
  push   0x88(%rsp)
  push   0x88(%rsp)
  push   0x88(%rsp)
  push   0x88(%rsp)
  push   0x88(%rsp)
  push   0x88(%rsp)
  call   <tm_diffcalendarmonths@plt>
  add    $0x40,%rsp
  mov    %eax,%edx
  cmp    %r12,0x50(%rsp)
  jle    L62
L63:
  xor    %eax,%eax
  test   %edx,%edx
  setg   %al
  sub    %eax,%edx
L98:
  mov    0x8(%rsp),%r15
  test   %r15,%r15
  je     L95
  lea    0x50(%rsp),%rdi
  mov    %edx,%esi
  mov    %edx,0x8(%rsp)
  call   <tm_addmonths@plt>
  push   0x88(%rsp)
  mov    %rbp,%rdi
  push   0x88(%rsp)
  push   0x88(%rsp)
  push   0x88(%rsp)
  push   0x88(%rsp)
  push   0x88(%rsp)
  push   0x88(%rsp)
  push   0x88(%rsp)
  call   <tm_diffdays@plt>
  add    $0x40,%rsp
  mov    0x8(%rsp),%edx
  imul   %ebx,%eax
  test   %rbp,%rbp
  mov    %eax,(%r15)
  je     L95
  mov    0x0(%rbp),%eax
  imul   %ebx,%eax
  mov    %eax,0x0(%rbp)
L95:
  add    $0x18,%rsp
  mov    %ebx,%eax
  imul   %edx,%eax
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nopw   0x0(%rax,%rax,1)
L62:
  jne    L98
  cmp    %r13,0x58(%rsp)
  jg     L63
  jne    L98
  cmp    %r14,0x60(%rsp)
  jg     L63
  jne    L98
  cmp    %r15,0x68(%rsp)
  jle    L98
  jmp    L63
  nopl   0x0(%rax,%rax,1)
L25:
  mov    0x50(%rsp),%rax
  mov    0x58(%rsp),%rdx
  mov    %r12,0x50(%rsp)
  mov    $0xffffffff,%ebx
  mov    0x60(%rsp),%rcx
  mov    0x68(%rsp),%rsi
  mov    %r13,0x58(%rsp)
  mov    %r14,0x60(%rsp)
  mov    %rdx,%r13
  mov    %rax,%r12
  mov    %r15,0x68(%rsp)
  mov    %rcx,%r14
  mov    %rsi,%r15
  jmp    L58
```

assistant: ```c
int tm_diffmonths(struct tm debut, struct tm fin, int *days, int *seconds) {
  if (tm_getrepresentation(debut) != tm_getrepresentation(fin)) {
    errno = EINVAL;
    return 0;
  }
  int coeff = 1;
  if (tm_diffseconds(debut, fin) < 0) {
    struct tm tmp = debut;
    debut = fin;
    fin = tmp;
    coeff = -1;
  }
  int ret = tm_diffcalendarmonths(debut, fin);
  if (fin.tm_mday < debut.tm_mday || (fin.tm_mday == debut.tm_mday && fin.tm_hour < debut.tm_hour) || (fin.tm_mday == debut.tm_mday && fin.tm_hour == debut.tm_hour && fin.tm_min < debut.tm_min) || (fin.tm_mday == debut.tm_mday && fin.tm_hour == debut.tm_hour && fin.tm_min == debut.tm_min && fin.tm_sec < debut.tm_sec))
    if (ret > 0)
      ret--;
  if (days) {
    tm_addmonths(&debut, ret);
    *days = coeff * tm_diffdays(debut, fin, seconds);
    if (seconds)
      *seconds *= coeff;
  }
  return coeff * ret;
}
```