user: 下面的汇编指令对应的C源代码是什么：

```asm
<des_encrypt>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  mov    %esi,%ebx
  sub    $0x48,%rsp
  mov    %fs:0x28,%rax
  mov    %rax,0x38(%rsp)
  xor    %eax,%eax
  test   %rdx,%rdx
  je     L132
  lea    -0x1(%rsi),%r12d
  neg    %r12d
  and    $0x7,%r12d
  lea    (%r12,%rsi,1),%eax
  cmp    $0x106,%eax
  jg     L16
  mov    %rdi,%r15
  xor    %eax,%eax
  lea    0x29(%rsp),%rdi
  mov    %r12d,%esi
  mov    %rdx,%rbp
  call   <des_random_get@plt>
  test   %r12d,%r12d
  je     L80
  lea    0x1(%rbx),%edx
  xor    %eax,%eax
  movslq %edx,%rdx
  nopl   (%rax)
L75:
  movzbl 0x29(%rsp,%rax,1),%eax
  mov    %edx,%r13d
  mov    %al,-0x1(%r15,%rdx,1)
  mov    %edx,%eax
  add    $0x1,%rdx
  sub    %ebx,%eax
  movswq %ax,%rax
  cmp    %eax,%r12d
  jg     L75
L59:
  lea    0x1(%r13),%eax
  movslq %r13d,%rsi
  movslq %eax,%rbx
  mov    %eax,0x14(%rsp)
  add    %r15,%rsi
  add    %r15,%rbx
  cmp    $0x2,%r13d
  jle    L39
  mov    $0x2,%eax
  xor    %edx,%edx
  nopl   0x0(%rax,%rax,1)
L27:
  movswq %ax,%rcx
  add    $0x1,%eax
  xor    (%r15,%rcx,1),%dl
  movswl %ax,%ecx
  cmp    %r13d,%ecx
  jl     L27
  mov    %dl,(%rsi)
  lea    0x30(%rsp),%rax
  mov    $0x8,%esi
  mov    %rax,0x18(%rsp)
  mov    %rax,%rdi
  xor    %eax,%eax
  call   <des_random_get@plt>
  mov    0x30(%rsp),%rax
  mov    %rax,(%rbx)
L8:
  lea    0x8(%rbp),%r14
  mov    $0x2,%r12d
  mov    $0x2,%eax
  lea    0x38(%rsp),%rbx
  nopw   0x0(%rax,%rax,1)
L72:
  mov    0x18(%rsp),%rdx
  add    %r15,%rax
L37:
  movzbl (%rdx),%ecx
  add    $0x1,%rdx
  xor    %cl,(%rax)
  add    $0x1,%rax
  cmp    %rdx,%rbx
  jne    L37
  movswq %r12w,%r8
  mov    $0x1,%ecx
  mov    $0x3,%edx
  xor    %eax,%eax
  add    %r15,%r8
  mov    %r14,%rsi
  mov    %rbp,%rdi
  add    $0x8,%r12d
  mov    %r8,0x8(%rsp)
  call   <EuroDes@plt>
  mov    0x8(%rsp),%r8
  mov    (%r8),%rax
  mov    %rax,0x30(%rsp)
  movswq %r12w,%rax
  cmp    0x14(%rsp),%eax
  jl     L72
L88:
  lea    0x9(%r13),%eax
L120:
  mov    0x38(%rsp),%rdx
  sub    %fs:0x28,%rdx
  jne    L31
  add    $0x48,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L132:
  mov    %esi,%eax
  jmp    L120
L80:
  mov    %ebx,%r13d
  jmp    L59
L39:
  movb   $0x0,(%rsi)
  lea    0x30(%rsp),%rax
  mov    $0x8,%esi
  mov    %rax,0x18(%rsp)
  mov    %rax,%rdi
  xor    %eax,%eax
  call   <des_random_get@plt>
  mov    0x30(%rsp),%rax
  cmpl   $0x2,0x14(%rsp)
  mov    %rax,(%rbx)
  jle    L88
  jmp    L8
  nop
L16:
  mov    $0xffffffff,%eax
  jmp    L120
L31:
  call   <__stack_chk_fail@plt>
```

assistant: ```c
int des_encrypt(unsigned char *buffer, int len, unsigned char *deskey) {
  unsigned char checksum = 0;
  unsigned char noPadBytes;
  unsigned char padBytes[7];
  char ivec[8];
  short i;
  if (!deskey)
    return len;
  noPadBytes = (8 - ((len - 1) % 8)) % 8;
  if (len + noPadBytes + 1 >= 272 - 8)
    return -1;
  des_random_get(padBytes, noPadBytes);
  for (i = 0; i < noPadBytes; i++)
    buffer[len++] = padBytes[i];
  for (i = 2; i < len; i++)
    checksum ^= buffer[i];
  buffer[len++] = checksum;
  des_random_get((unsigned char *)ivec, 8);
  memcpy(buffer + len, ivec, 8);
  for (i = 2; i < len; i += 8) {
    unsigned char j;
    const unsigned char flags = (1 << 0) | (1 << 1);
    for (j = 0; j < 8; j++)
      buffer[i + j] ^= ivec[j];
    EuroDes(deskey, deskey + 8, flags, 1, buffer + i);
    memcpy(ivec, buffer + i, 8);
  }
  len += 8;
  return len;
}
```