user: What would the C source look like for the assembly code provided here?

```asm
<mkgmtime>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  mov    %rdi,-0x18(%rbp)
  movq   $0x0,-0x8(%rbp)
  mov    -0x18(%rbp),%rax
  mov    (%rax),%eax
  cmp    $0x46,%eax
  jle    L100
  movl   $0x46,-0xc(%rbp)
  jmp    L98
L8:
  addq   $0x1e13380,-0x8(%rbp)
  mov    -0xc(%rbp),%eax
  and    $0x3,%eax
  test   %eax,%eax
  jne    L146
  mov    -0xc(%rbp),%edx
  movslq %edx,%rax
  imul   $0x51eb851f,%rax,%rax
  shr    $0x20,%rax
  sar    $0x5,%eax
  mov    %edx,%ecx
  sar    $0x1f,%ecx
  sub    %ecx,%eax
  imul   $0x64,%eax,%ecx
  mov    %edx,%eax
  sub    %ecx,%eax
  test   %eax,%eax
  jne    L1
  mov    -0xc(%rbp),%eax
  movslq %eax,%rdx
  imul   $0x51eb851f,%rdx,%rdx
  shr    $0x20,%rdx
  sar    $0x7,%edx
  mov    %eax,%ecx
  sar    $0x1f,%ecx
  sub    %ecx,%edx
  imul   $0x190,%edx,%ecx
  sub    %ecx,%eax
  mov    %eax,%edx
  cmp    $0x64,%edx
  jne    L146
L1:
  addq   $0x15180,-0x8(%rbp)
L146:
  addl   $0x1,-0xc(%rbp)
L98:
  mov    -0x18(%rbp),%rax
  mov    (%rax),%eax
  cmp    %eax,-0xc(%rbp)
  jl     L8
  jmp    L75
L100:
  mov    -0x18(%rbp),%rax
  mov    (%rax),%eax
  cmp    $0x45,%eax
  jg     L75
  movl   $0x45,-0xc(%rbp)
  jmp    L53
L4:
  subq   $0x1e13380,-0x8(%rbp)
  mov    -0xc(%rbp),%eax
  and    $0x3,%eax
  test   %eax,%eax
  jne    L17
  mov    -0xc(%rbp),%edx
  movslq %edx,%rax
  imul   $0x51eb851f,%rax,%rax
  shr    $0x20,%rax
  sar    $0x5,%eax
  mov    %edx,%ecx
  sar    $0x1f,%ecx
  sub    %ecx,%eax
  imul   $0x64,%eax,%ecx
  mov    %edx,%eax
  sub    %ecx,%eax
  test   %eax,%eax
  jne    L27
  mov    -0xc(%rbp),%eax
  movslq %eax,%rdx
  imul   $0x51eb851f,%rdx,%rdx
  shr    $0x20,%rdx
  sar    $0x7,%edx
  mov    %eax,%ecx
  sar    $0x1f,%ecx
  sub    %ecx,%edx
  imul   $0x190,%edx,%ecx
  sub    %ecx,%eax
  mov    %eax,%edx
  cmp    $0x64,%edx
  jne    L17
L27:
  subq   $0x15180,-0x8(%rbp)
L17:
  subl   $0x1,-0xc(%rbp)
L53:
  mov    -0x18(%rbp),%rax
  mov    (%rax),%eax
  cmp    %eax,-0xc(%rbp)
  jge    L4
L75:
  mov    -0x18(%rbp),%rax
  mov    0x8(%rax),%rax
  lea    0x0(,%rax,8),%rdx
  lea    D1(%rip),%rax
  mov    (%rdx,%rax,1),%rax
  add    %rax,-0x8(%rbp)
  mov    -0x18(%rbp),%rax
  mov    0x8(%rax),%rax
  cmp    $0x1,%rax
  jbe    L58
  mov    -0x18(%rbp),%rax
  mov    (%rax),%eax
  and    $0x3,%eax
  test   %eax,%eax
  jne    L58
  mov    -0x18(%rbp),%rax
  mov    (%rax),%edx
  movslq %edx,%rax
  imul   $0x51eb851f,%rax,%rax
  shr    $0x20,%rax
  sar    $0x5,%eax
  mov    %edx,%ecx
  sar    $0x1f,%ecx
  sub    %ecx,%eax
  imul   $0x64,%eax,%ecx
  mov    %edx,%eax
  sub    %ecx,%eax
  test   %eax,%eax
  jne    L31
  mov    -0x18(%rbp),%rax
  mov    (%rax),%eax
  movslq %eax,%rdx
  imul   $0x51eb851f,%rdx,%rdx
  shr    $0x20,%rdx
  sar    $0x7,%edx
  mov    %eax,%ecx
  sar    $0x1f,%ecx
  sub    %ecx,%edx
  imul   $0x190,%edx,%ecx
  sub    %ecx,%eax
  mov    %eax,%edx
  cmp    $0x64,%edx
  jne    L58
L31:
  addq   $0x15180,-0x8(%rbp)
L58:
  mov    -0x18(%rbp),%rax
  mov    0x10(%rax),%eax
  lea    -0x1(%rax),%edx
  mov    %edx,%eax
  add    %eax,%eax
  add    %edx,%eax
  shl    $0x3,%eax
  mov    %eax,%edx
  mov    -0x18(%rbp),%rax
  mov    0x14(%rax),%eax
  add    %edx,%eax
  imul   $0x3c,%eax,%edx
  mov    -0x18(%rbp),%rax
  mov    0x18(%rax),%eax
  add    %edx,%eax
  imul   $0x3c,%eax,%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  mov    0x20(%rax),%rax
  add    %rdx,%rax
  add    %rax,-0x8(%rbp)
  mov    -0x8(%rbp),%rax
  pop    %rbp
  ret
```

assistant: ```c
time_t mkgmtime(struct tm *tm) {
  static long msec[] = {0, 2678400, 5097600, 7776000, 10368000, 13046400, 15638400, 18316800, 20995200, 23587200, 26265600, 28857600};
  time_t t;
  int i;
  t = 0;
  if (tm->tm_year > 70) {
    for (i = 70; i < tm->tm_year; i++) {
      t += 31536000;
      if ((i % 4 == 0 && (i % 100 != 0 || i % 400 == 100)))
        t += 86400;
    }
  } else if (tm->tm_year < 70) {
    for (i = 69; i >= tm->tm_year; i--) {
      t -= 31536000;
      if ((i % 4 == 0 && (i % 100 != 0 || i % 400 == 100)))
        t -= 86400;
    }
  }
  t += msec[tm->tm_mon];
  if (tm->tm_mon > 1 && (tm->tm_year % 4 == 0 && (tm->tm_year % 100 != 0 || tm->tm_year % 400 == 100)))
    t += 86400;
  t += (((tm->tm_mday - 1) * 24 + tm->tm_hour) * 60 + tm->tm_min) * 60 + tm->tm_sec;
  return t;
}
```