user: 请从给定的汇编指令推导出C源代码:

```asm
<fib>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x48,%rsp
  mov    %edi,0x20(%rsp)
  movl   $0x0,0x10(%rsp)
  cmp    $0x1,%edi
  jle    L94
  mov    %edi,0x4(%rsp)
L159:
  mov    0x4(%rsp),%eax
  movl   $0x0,0x14(%rsp)
  lea    -0x1(%rax),%edi
  mov    %edi,0x8(%rsp)
  cmp    $0x2,%eax
  je     L156
L42:
  mov    0x8(%rsp),%eax
  movl   $0x0,0x18(%rsp)
  lea    -0x1(%rax),%edi
  mov    %edi,0xc(%rsp)
  cmp    $0x2,%eax
  je     L69
L201:
  mov    0xc(%rsp),%eax
  movl   $0x0,0x1c(%rsp)
  lea    -0x1(%rax),%r11d
  cmp    $0x2,%eax
  je     L15
L96:
  lea    -0x1(%r11),%ebp
  xor    %edx,%edx
  mov    $0x1,%eax
  cmp    $0x2,%r11d
  je     L53
L85:
  lea    -0x1(%rbp),%r12d
  xor    %r13d,%r13d
  mov    $0x1,%eax
  cmp    $0x2,%ebp
  je     L14
L101:
  cmp    $0x2,%r12d
  je     L213
  lea    -0x3(%r12),%r15d
  lea    -0x6(%r12),%r8d
  xor    %ecx,%ecx
  mov    %r15d,%eax
  lea    -0x4(%r12),%r9d
  and    $0xfffffffe,%eax
  sub    %eax,%r8d
L79:
  lea    0x2(%r9),%ebx
  xor    %esi,%esi
  cmp    $0xffffffff,%r9d
  je     L22
L50:
  lea    -0x1(%rbx),%r10d
  xor    %r14d,%r14d
  mov    $0x1,%eax
  cmp    $0x2,%ebx
  je     L106
L78:
  lea    -0x1(%r10),%edi
  mov    %r9d,0x3c(%rsp)
  mov    %r8d,0x38(%rsp)
  mov    %esi,0x34(%rsp)
  mov    %ecx,0x30(%rsp)
  mov    %edx,0x2c(%rsp)
  mov    %r11d,0x28(%rsp)
  mov    %r10d,0x24(%rsp)
  call   <fib>
  mov    0x24(%rsp),%r10d
  mov    0x28(%rsp),%r11d
  add    %eax,%r14d
  mov    0x2c(%rsp),%edx
  mov    0x30(%rsp),%ecx
  sub    $0x2,%r10d
  mov    0x34(%rsp),%esi
  mov    0x38(%rsp),%r8d
  cmp    $0x1,%r10d
  mov    0x3c(%rsp),%r9d
  jg     L78
  lea    -0x3(%rbx),%eax
  and    $0x1,%eax
L106:
  sub    $0x2,%ebx
  cmp    $0x1,%eax
  sbb    $0xffffffff,%r14d
  add    %r14d,%esi
  cmp    $0x1,%ebx
  jg     L50
  mov    %r9d,%ebx
  and    $0x1,%ebx
L22:
  cmp    $0x1,%ebx
  sbb    $0xffffffff,%esi
  sub    $0x2,%r9d
  add    %esi,%ecx
  cmp    %r9d,%r8d
  jne    L79
  and    $0x1,%r15d
L246:
  sub    $0x2,%r12d
  cmp    $0x1,%r15d
  sbb    $0xffffffff,%ecx
  add    %ecx,%r13d
  cmp    $0x1,%r12d
  jg     L101
  lea    -0x3(%rbp),%eax
  and    $0x1,%eax
L14:
  sub    $0x2,%ebp
  cmp    $0x1,%eax
  sbb    $0xffffffff,%r13d
  add    %r13d,%edx
  cmp    $0x1,%ebp
  jg     L85
  lea    -0x3(%r11),%eax
  and    $0x1,%eax
L53:
  sub    $0x2,%r11d
  cmp    $0x1,%eax
  sbb    $0xffffffff,%edx
  add    %edx,0x1c(%rsp)
  cmp    $0x1,%r11d
  jg     L96
  mov    0xc(%rsp),%eax
  sub    $0x3,%eax
  and    $0x1,%eax
L194:
  subl   $0x2,0xc(%rsp)
  cmp    $0x1,%eax
  mov    0xc(%rsp),%edi
  mov    0x1c(%rsp),%eax
  sbb    $0xffffffff,%eax
  add    %eax,0x18(%rsp)
  cmp    $0x1,%edi
  jg     L201
  mov    0x8(%rsp),%eax
  sub    $0x3,%eax
  and    $0x1,%eax
L154:
  subl   $0x2,0x8(%rsp)
  cmp    $0x1,%eax
  mov    0x8(%rsp),%edi
  mov    0x18(%rsp),%eax
  sbb    $0xffffffff,%eax
  add    %eax,0x14(%rsp)
  cmp    $0x1,%edi
  jg     L42
  mov    0x4(%rsp),%eax
  sub    $0x3,%eax
  and    $0x1,%eax
L176:
  subl   $0x2,0x4(%rsp)
  cmp    $0x1,%eax
  mov    0x4(%rsp),%edi
  mov    0x14(%rsp),%eax
  sbb    $0xffffffff,%eax
  add    %eax,0x10(%rsp)
  cmp    $0x1,%edi
  jg     L159
  andl   $0x1,0x20(%rsp)
L94:
  mov    0x20(%rsp),%eax
  test   %eax,%eax
  je     L126
  cmp    $0x1,%eax
  je     L240
L126:
  mov    0x10(%rsp),%eax
  add    $0x48,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L213:
  xor    %ecx,%ecx
  mov    $0x1,%r15d
  jmp    L246
L15:
  mov    $0x1,%eax
  jmp    L194
L69:
  mov    $0x1,%eax
  jmp    L154
L156:
  mov    $0x1,%eax
  jmp    L176
L240:
  addl   $0x1,0x10(%rsp)
  jmp    L126
```

assistant: ```c
int fib(int n) {
  if (n > 1)
    return fib(n - 1) + fib(n - 2);
  else if (n == 0)
    return 0;
  else if (n == 1)
    return 1;
}
```