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

```asm
<longestPalindrome>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  mov    %rdi,%r12
  push   %rbp
  push   %rbx
  sub    $0x28,%rsp
  mov    %fs:0x28,%rax
  mov    %rax,0x18(%rsp)
  xor    %eax,%eax
  call   <strlen@plt>
  movl   $0x0,0x10(%rsp)
  movl   $0x0,0x14(%rsp)
  test   %eax,%eax
  jle    L180
  movl   $0x0,0xc(%rsp)
  mov    %eax,%r13d
  xor    %ebx,%ebx
  xor    %ebp,%ebp
  lea    0x14(%rsp),%r15
  lea    0x10(%rsp),%r14
  nopl   0x0(%rax,%rax,1)
L191:
  mov    %ebx,%edx
  mov    %r15,%r8
  mov    %r14,%rcx
  mov    %r13d,%esi
  mov    %r12,%rdi
  call   <expand@plt>
  mov    0x10(%rsp),%edx
  mov    0x14(%rsp),%eax
  sub    %edx,%eax
  cmp    %ebp,%eax
  jl     L77
  mov    %edx,0xc(%rsp)
  lea    0x1(%rax),%ebp
L77:
  add    $0x1,%ebx
  cmp    %ebx,%r13d
  jne    L191
  test   %ebp,%ebp
  je     L180
  lea    0x1(%rbp),%edi
  mov    $0x1,%esi
  call   <calloc@plt>
  mov    %rax,%r8
  test   %ebp,%ebp
  jle    L110
  movslq 0xc(%rsp),%rdx
  mov    %r8,%rcx
  mov    %ebp,%esi
  lea    -0x1(%rbp),%eax
  lea    0x1(%r12,%rdx,1),%rdi
  sub    %rdi,%rcx
  cmp    $0xe,%rcx
  jbe    L125
  cmp    $0x6,%eax
  jbe    L125
  cmp    $0xe,%eax
  jbe    L143
  mov    %ebp,%ecx
  add    %r12,%rdx
  xor    %eax,%eax
  shr    $0x4,%ecx
  shl    $0x4,%rcx
  nop
L218:
  movdqu (%rdx,%rax,1),%xmm0
  movups %xmm0,(%r8,%rax,1)
  add    $0x10,%rax
  cmp    %rax,%rcx
  jne    L218
  mov    %ebp,%eax
  and    $0xfffffff0,%eax
  add    %eax,0xc(%rsp)
  mov    %eax,%ecx
  cmp    %eax,%ebp
  je     L110
  mov    %ebp,%esi
  sub    %eax,%esi
  lea    -0x1(%rsi),%edi
  cmp    $0x6,%edi
  jbe    L60
L166:
  mov    (%rdx,%rax,1),%rdx
  mov    %rdx,(%r8,%rax,1)
  mov    %esi,%eax
  and    $0xfffffff8,%eax
  add    %eax,0xc(%rsp)
  add    %eax,%ecx
  cmp    %eax,%esi
  je     L110
L60:
  movslq 0xc(%rsp),%rax
  movzbl (%r12,%rax,1),%esi
  mov    %rax,%rdi
  lea    0x1(%rax),%edx
  movslq %ecx,%rax
  mov    %sil,(%r8,%rax,1)
  lea    0x1(%rcx),%eax
  cmp    %eax,%ebp
  jle    L110
  movslq %edx,%rdx
  cltq
  lea    0x2(%rdi),%esi
  movzbl (%r12,%rdx,1),%edx
  mov    %dl,(%r8,%rax,1)
  lea    0x2(%rcx),%eax
  cmp    %eax,%ebp
  jle    L110
  movslq %esi,%rsi
  cltq
  lea    0x3(%rdi),%edx
  movzbl (%r12,%rsi,1),%esi
  mov    %sil,(%r8,%rax,1)
  lea    0x3(%rcx),%eax
  cmp    %eax,%ebp
  jle    L110
  movslq %edx,%rdx
  cltq
  lea    0x4(%rdi),%esi
  movzbl (%r12,%rdx,1),%edx
  mov    %dl,(%r8,%rax,1)
  lea    0x4(%rcx),%eax
  cmp    %eax,%ebp
  jle    L110
  movslq %esi,%rsi
  cltq
  lea    0x5(%rdi),%edx
  movzbl (%r12,%rsi,1),%esi
  mov    %sil,(%r8,%rax,1)
  lea    0x5(%rcx),%eax
  cmp    %eax,%ebp
  jle    L110
  movslq %edx,%rdx
  add    $0x6,%edi
  cltq
  add    $0x6,%ecx
  movzbl (%r12,%rdx,1),%edx
  movslq %edi,%r13
  mov    %dl,(%r8,%rax,1)
  cmp    %ecx,%ebp
  jle    L110
  movzbl (%r12,%r13,1),%eax
  movslq %ecx,%rcx
  mov    %al,(%r8,%rcx,1)
  cs nopw 0x0(%rax,%rax,1)
L110:
  mov    0x18(%rsp),%rax
  sub    %fs:0x28,%rax
  jne    L214
  add    $0x28,%rsp
  mov    %r8,%rax
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nopw   0x0(%rax,%rax,1)
L180:
  xor    %r8d,%r8d
  jmp    L110
  nopl   (%rax)
L125:
  xor    %eax,%eax
  add    %r12,%rdx
  nopl   (%rax)
L126:
  movzbl (%rdx,%rax,1),%ecx
  mov    %cl,(%r8,%rax,1)
  add    $0x1,%rax
  cmp    %rbp,%rax
  jne    L126
  jmp    L110
L143:
  xor    %eax,%eax
  xor    %ecx,%ecx
  add    %r12,%rdx
  jmp    L166
L214:
  call   <__stack_chk_fail@plt>
```

assistant: ```c
char *longestPalindrome(char *s) {
  int len = strlen(s);
  int start = 0, end = 0;
  int m_start = 0, m_end = 0;
  int max = 0;
  int i = 0;
  char *result = NULL;
  for (i = 0; i < len; i++) {
    expand(s, len, i, &start, &end);
    if (max < (end - start + 1)) {
      max = end - start + 1;
      m_start = start;
      m_end = end;
    }
  }
  if (max) {
    result = calloc(max + 1, sizeof(char));
    for (i = 0; i < max; i++) {
      result[i] = s[m_start++];
    }
  }
  return result;
}
```