user: 请从给定的汇编指令推导出C源代码:

```asm
<fib>:
  endbr64
  push   %r15
  mov    %rdi,%rax
  sub    $0x1,%rdi
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x98,%rsp
  mov    %rdi,(%rsp)
  movq   $0x0,0x18(%rsp)
  cmp    $0x1,%rax
  jbe    L54
  cmpq   $0x1,(%rsp)
  jbe    L19
L136:
  movq   $0x0,0x20(%rsp)
  mov    (%rsp),%rax
  sub    $0x1,%rax
  mov    %rax,0x8(%rsp)
  cmpq   $0x1,0x8(%rsp)
  mov    %rax,0x38(%rsp)
  je     L112
L123:
  movq   $0x0,0x28(%rsp)
  mov    0x8(%rsp),%rax
  sub    $0x1,%rax
  mov    %rax,0x10(%rsp)
  cmpq   $0x1,0x10(%rsp)
  mov    %rax,0x40(%rsp)
  je     L144
L201:
  movq   $0x0,0x30(%rsp)
  mov    0x10(%rsp),%rax
  sub    $0x1,%rax
  mov    %rax,0x50(%rsp)
  mov    %rax,%r11
L195:
  cmp    $0x1,%r11
  je     L38
  lea    -0x1(%r11),%rax
  xor    %ecx,%ecx
  mov    %rax,0x48(%rsp)
  mov    %rax,%rbp
L323:
  cmp    $0x1,%rbp
  je     L56
  lea    -0x1(%rbp),%rsi
  xor    %r12d,%r12d
  mov    %rsi,%rdx
L72:
  cmp    $0x1,%rdx
  je     L317
  lea    -0x2(%rdx),%r8
  xor    %r15d,%r15d
  mov    %r8,%r9
L214:
  lea    0x1(%r9),%rax
  mov    %r9,%rbx
  xor    %r13d,%r13d
  cmp    $0x1,%rax
  jbe    L285
  mov    %rbx,%r10
  xor    %r14d,%r14d
  cmp    $0x1,%rbx
  je     L226
  nopl   0x0(%rax,%rax,1)
L234:
  lea    -0x1(%r10),%rdi
  mov    %r8,0x88(%rsp)
  mov    %rsi,0x80(%rsp)
  mov    %r9,0x78(%rsp)
  mov    %rdx,0x70(%rsp)
  mov    %r11,0x68(%rsp)
  mov    %rcx,0x60(%rsp)
  mov    %r10,0x58(%rsp)
  call   <fib>
  mov    0x58(%rsp),%r10
  mov    0x60(%rsp),%rcx
  add    %rax,%r14
  mov    0x68(%rsp),%r11
  mov    0x70(%rsp),%rdx
  sub    $0x2,%r10
  mov    0x78(%rsp),%r9
  mov    0x80(%rsp),%rsi
  cmp    $0x1,%r10
  mov    0x88(%rsp),%r8
  ja     L234
  add    $0x1,%r14
L217:
  lea    -0x2(%rbx),%rax
  sub    $0x1,%rbx
  add    %r14,%r13
  cmp    $0x1,%rbx
  jbe    L300
  mov    %rax,%rbx
  xor    %r14d,%r14d
  mov    %rbx,%r10
  cmp    $0x1,%rbx
  jne    L234
L226:
  mov    $0x1,%r14d
  jmp    L217
L317:
  mov    $0x1,%r15d
  mov    $0xffffffffffffffff,%r8
L282:
  sub    $0x1,%rdx
  add    %r15,%r12
  cmp    $0x1,%rdx
  jbe    L79
  mov    %r8,%rdx
  jmp    L72
L79:
  add    $0x1,%r12
L175:
  add    %r12,%rcx
  sub    $0x2,%rbp
  cmp    $0x1,%rsi
  ja     L323
  add    $0x1,%rcx
L154:
  add    %rcx,0x30(%rsp)
  sub    $0x2,%r11
  cmpq   $0x1,0x48(%rsp)
  ja     L195
  mov    0x30(%rsp),%rax
  add    $0x1,%rax
L224:
  add    %rax,0x28(%rsp)
  mov    0x10(%rsp),%rax
  sub    $0x2,%rax
  cmpq   $0x1,0x50(%rsp)
  jbe    L268
  mov    %rax,0x10(%rsp)
  cmpq   $0x1,0x10(%rsp)
  jne    L201
L144:
  movq   $0x0,0x50(%rsp)
  mov    $0x1,%eax
  jmp    L224
  nopl   0x0(%rax)
L285:
  mov    $0x1,%r13d
L259:
  add    %r13,%r15
  lea    -0x2(%r9),%rax
  cmp    $0x1,%r9
  jbe    L269
  mov    %rax,%r9
  jmp    L214
  nopl   0x0(%rax,%rax,1)
L269:
  add    $0x1,%r15
  jmp    L282
  nopl   0x0(%rax)
L300:
  add    $0x1,%r13
  jmp    L259
L56:
  mov    $0x1,%r12d
  xor    %esi,%esi
  jmp    L175
L38:
  movq   $0x0,0x48(%rsp)
  mov    $0x1,%ecx
  jmp    L154
L268:
  mov    0x28(%rsp),%rax
  add    $0x1,%rax
L283:
  add    %rax,0x20(%rsp)
  mov    0x8(%rsp),%rax
  sub    $0x2,%rax
  cmpq   $0x1,0x40(%rsp)
  jbe    L239
  mov    %rax,0x8(%rsp)
  cmpq   $0x1,0x8(%rsp)
  jne    L123
L112:
  movq   $0x0,0x40(%rsp)
  mov    $0x1,%eax
  jmp    L283
L239:
  mov    0x20(%rsp),%rax
  add    $0x1,%rax
L221:
  add    %rax,0x18(%rsp)
  mov    (%rsp),%rax
  sub    $0x2,%rax
  cmpq   $0x1,0x38(%rsp)
  jbe    L203
  mov    %rax,(%rsp)
  cmpq   $0x1,(%rsp)
  ja     L136
L19:
  mov    (%rsp),%rdi
  mov    $0x1,%eax
  sub    $0x1,%rdi
  mov    %rdi,0x38(%rsp)
  jmp    L221
L203:
  mov    0x18(%rsp),%rax
  add    $0x1,%rax
L85:
  add    $0x98,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L54:
  mov    $0x1,%eax
  jmp    L85
```

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