user: 提供的汇编代码用C语言表示会是什么样子:

```asm
<permute>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  mov    %rdx,%r13
  push   %r12
  mov    %esi,%r12d
  push   %rbp
  push   %rbx
  mov    %edi,%ebx
  sub    $0x38,%rsp
  mov    %fs:0x28,%rax
  mov    %rax,0x28(%rsp)
  mov    (%rdx),%rax
  mov    (%rcx),%rdx
  mov    %rdx,0x20(%rsp)
  mov    %rax,0x18(%rsp)
  test   %rax,%rax
  je     L28
L55:
  cmp    $0x1,%ebx
  je     L71
  test   %ebx,%ebx
  jle    L119
  movslq %ebx,%r13
  lea    -0x1(%rbx),%edi
  and    $0x1,%ebx
  shl    $0x2,%r13
  mov    %ebx,0xc(%rsp)
  lea    0x20(%rsp),%rbp
  xor    %ebx,%ebx
  lea    -0x4(%r13),%r14
  lea    0x18(%rsp),%r15
L12:
  mov    %r15,%rdx
  mov    %rbp,%rcx
  mov    %r12d,%esi
  mov    %edi,0x8(%rsp)
  call   <permute>
  mov    0xc(%rsp),%edx
  mov    0x20(%rsp),%rax
  mov    0x8(%rsp),%edi
  test   %edx,%edx
  jne    L114
  lea    (%rax,%rbx,1),%rdx
  add    %r14,%rax
  mov    (%rdx),%esi
  mov    (%rax),%r8d
  mov    %r8d,(%rdx)
  mov    %esi,(%rax)
L5:
  add    $0x4,%rbx
  cmp    %r13,%rbx
  jne    L12
L119:
  mov    0x28(%rsp),%rax
  sub    %fs:0x28,%rax
  jne    L13
  add    $0x38,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nop
L114:
  lea    (%rax,%r14,1),%rdx
  mov    (%rax),%esi
  mov    (%rdx),%r8d
  mov    %r8d,(%rax)
  mov    %esi,(%rdx)
  jmp    L5
L71:
  mov    0x18(%rsp),%rcx
  mov    $0x1,%eax
  cmpq   $0x0,(%rcx)
  lea    0x8(%rcx),%rdx
  je     L137
  nopl   0x0(%rax,%rax,1)
L131:
  mov    %rdx,%rbx
  add    $0x1,%rax
  lea    0x8(%rdx),%rdx
  cmpq   $0x0,(%rbx)
  jne    L131
  shl    $0x3,%rax
L21:
  movq   $0x0,(%rcx,%rax,1)
  shl    $0x2,%r12d
  mov    %r12d,%edi
  call   <malloc@plt>
  mov    %rax,(%rbx)
  mov    %rax,%rdi
  mov    0x28(%rsp),%rax
  sub    %fs:0x28,%rax
  jne    L13
  mov    0x20(%rsp),%rsi
  add    $0x38,%rsp
  mov    %r12d,%edx
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  jmp    10a0 <memcpy@plt>
  xchg   %ax,%ax
L28:
  mov    %rcx,%rbp
  call   <factorial@plt>
  lea    0x8(,%rax,8),%edi
  call   <malloc@plt>
  lea    0x0(,%rbx,4),%edi
  mov    %rax,0x0(%r13)
  movq   $0x0,(%rax)
  mov    %rax,0x18(%rsp)
  call   <malloc@plt>
  lea    -0x1(%rbx),%esi
  xor    %edx,%edx
  mov    %rax,0x20(%rsp)
  test   %ebx,%ebx
  jle    L109
  xchg   %ax,%ax
L74:
  mov    %rdx,%rcx
  mov    %edx,(%rax,%rdx,4)
  add    $0x1,%rdx
  cmp    %rsi,%rcx
  jne    L74
L109:
  mov    %rax,0x0(%rbp)
  mov    %ebx,%r12d
  jmp    L55
  nopl   0x0(%rax,%rax,1)
L137:
  mov    %rcx,%rbx
  mov    $0x8,%eax
  jmp    L21
L13:
  call   <__stack_chk_fail@plt>
```

assistant: ```c
void permute(int n, int m, int ***perms_p, int **a_p) {
  int i;
  int **perms = *perms_p;
  int *a = *a_p;
  if (perms == NULL) {
    perms = malloc((factorial((unsigned int)n) + 1) * sizeof(int *));
    *perms_p = perms;
    perms[0] = NULL;
    a = malloc(n * sizeof(int));
    for (i = 0; i < n; i++)
      a[i] = i;
    *a_p = a;
    m = n;
  }
  if (n == 1) {
    for (i = 0;; i++) {
      if (perms[i] == NULL) {
        perms[i + 1] = NULL;
        perms[i] = malloc(m * sizeof(int));
        memcpy(perms[i], a, m * sizeof(int));
        break;
      }
    }
  } else {
    for (i = 0; i < n; i++) {
      permute(n - 1, m, &perms, &a);
      int swap;
      if (n % 2 == 1) {
        swap = a[0];
        a[0] = a[n - 1];
        a[n - 1] = swap;
      } else {
        swap = a[i];
        a[i] = a[n - 1];
        a[n - 1] = swap;
      }
    }
  }
}
```