user: 请从给定的汇编指令推导出C源代码：

```asm
<nfall0>:
  endbr64
  mov    %edi,%r8d
  cmp    $0x1,%esi
  je     L149
  cmp    $0x1,%edi
  je     L149
  push   %r15
  lea    -0x1(%rdi),%eax
  mov    %esi,%r9d
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x68,%rsp
  mov    %eax,0x24(%rsp)
  lea    -0x2(%rdi),%eax
  mov    %eax,0x2c(%rsp)
  lea    -0x3(%rdi),%eax
  mov    %eax,0x34(%rsp)
  lea    -0x4(%rdi),%eax
  mov    %eax,0x3c(%rsp)
  lea    -0x5(%rdi),%eax
  mov    %eax,0x44(%rsp)
  lea    -0x6(%rdi),%eax
  mov    %eax,0xc(%rsp)
  lea    -0x7(%rdi),%eax
  mov    %eax,0x10(%rsp)
  lea    -0x8(%rdi),%eax
  lea    -0x9(%rdi),%edi
  mov    %eax,0x14(%rsp)
  movl   $0x0,0x28(%rsp)
  mov    %r8d,0x4c(%rsp)
L57:
  mov    %r9d,0x8(%rsp)
  movl   $0x0,0x30(%rsp)
  mov    %r9d,0x50(%rsp)
L127:
  cmpl   $0x1,0x24(%rsp)
  je     L92
  movl   $0x0,0x38(%rsp)
  mov    0x8(%rsp),%r9d
L132:
  cmpl   $0x1,0x2c(%rsp)
  je     L44
  movl   $0x0,0x40(%rsp)
  mov    %r9d,%r15d
  mov    %edi,%r14d
  mov    %r9d,0x54(%rsp)
L47:
  cmpl   $0x1,0x34(%rsp)
  je     L41
  movl   $0x0,0x48(%rsp)
  mov    %r14d,%r12d
  mov    %r15d,%r14d
  mov    %r15d,0x58(%rsp)
L10:
  cmpl   $0x1,0x3c(%rsp)
  je     L31
  xor    %r13d,%r13d
  mov    %r14d,%r8d
  mov    %r12d,%edi
  mov    %r13d,%ecx
  mov    %r14d,%r13d
L109:
  cmpl   $0x1,0x44(%rsp)
  je     L63
  xor    %ebx,%ebx
  mov    %r13d,%ebp
  mov    %r13d,%edx
  mov    %ebx,%r13d
L93:
  cmpl   $0x1,0xc(%rsp)
  je     L108
  mov    %ebp,%ebx
  mov    %r13d,%r9d
  xor    %r12d,%r12d
  mov    %r8d,%r13d
  mov    %ebp,%r8d
  mov    %edi,%ebp
L120:
  cmpl   $0x1,0x10(%rsp)
  je     L183
  mov    %ebx,0x5c(%rsp)
  mov    %ebx,%r14d
  xor    %r15d,%r15d
  mov    %ecx,%ebx
L172:
  cmpl   $0x1,0x14(%rsp)
  je     L185
  mov    %r14d,%esi
  mov    %ebp,%edi
  mov    %r9d,0x20(%rsp)
  sub    $0x1,%r14d
  mov    %r8d,0x1c(%rsp)
  mov    %edx,0x18(%rsp)
  call   <nfall0>
  mov    0x18(%rsp),%edx
  mov    0x1c(%rsp),%r8d
  add    %eax,%r15d
  cmp    $0x1,%r14d
  mov    0x20(%rsp),%r9d
  jne    L172
L185:
  mov    %ebx,%ecx
  mov    0x5c(%rsp),%ebx
  add    0x14(%rsp),%r15d
  add    %r15d,%r12d
  sub    $0x1,%ebx
  cmp    $0x1,%ebx
  jne    L120
L183:
  mov    %ebp,%edi
  mov    %r8d,%ebp
  add    0x10(%rsp),%r12d
  mov    %r13d,%r8d
  sub    $0x1,%ebp
  mov    %r9d,%r13d
  add    %r12d,%r13d
  cmp    $0x1,%ebp
  jne    L93
L108:
  mov    %r13d,%ebx
  mov    %edx,%r13d
  add    0xc(%rsp),%ebx
  sub    $0x1,%r13d
  add    %ebx,%ecx
  cmp    $0x1,%r13d
  jne    L109
L63:
  mov    %r8d,%r14d
  mov    0x44(%rsp),%eax
  mov    %edi,%r12d
  sub    $0x1,%r14d
  lea    (%rax,%rcx,1),%r8d
  add    %r8d,0x48(%rsp)
  cmp    $0x1,%r14d
  jne    L10
L31:
  mov    0x58(%rsp),%r15d
  mov    0x48(%rsp),%r13d
  mov    %r12d,%r14d
  add    0x3c(%rsp),%r13d
  add    %r13d,0x40(%rsp)
  sub    $0x1,%r15d
  cmp    $0x1,%r15d
  jne    L47
L41:
  mov    0x54(%rsp),%r9d
  mov    %r14d,%edi
  mov    0x40(%rsp),%r14d
  add    0x34(%rsp),%r14d
  add    %r14d,0x38(%rsp)
  sub    $0x1,%r9d
  cmp    $0x1,%r9d
  jne    L132
L44:
  subl   $0x1,0x8(%rsp)
  mov    0x8(%rsp),%esi
  mov    0x38(%rsp),%eax
  add    0x2c(%rsp),%eax
  add    %eax,0x30(%rsp)
  cmp    $0x1,%esi
  jne    L127
L92:
  mov    0x50(%rsp),%r9d
  mov    0x30(%rsp),%eax
  add    0x24(%rsp),%eax
  add    %eax,0x28(%rsp)
  sub    $0x1,%r9d
  cmp    $0x1,%r9d
  jne    L57
  mov    0x4c(%rsp),%r8d
  add    0x28(%rsp),%r8d
  add    $0x68,%rsp
  pop    %rbx
  mov    %r8d,%eax
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L149:
  mov    %r8d,%eax
  ret
```

assistant: ```c
unsigned int nfall0(unsigned int k, unsigned int n) {
  if (n == 1)
    return k;
  if (k == 1)
    return 1;
  return nfall0(k - 1, n) + nfall0(k, n - 1);
}
```