user: 请从给定的汇编指令推导出C源代码：

```asm
<julius_regular_involution>:
  endbr64
  push   %r15
  pxor   %xmm0,%xmm0
  push   %r14
  push   %r13
  mov    %rdi,%r13
  push   %r12
  mov    %rsi,%r12
  mov    %rcx,%rsi
  push   %rbp
  mov    %rcx,%rbp
  push   %rbx
  mov    %rdx,%rbx
  sub    $0x68,%rsp
  mov    %fs:0x28,%rax
  mov    %rax,0x58(%rsp)
  xor    %eax,%eax
  lea    0x40(%rsp),%r14
  movaps %xmm0,0x40(%rsp)
  lea    0x20(%rsp),%r15
  mov    %r14,%rdi
  call   <aes_128_encrypt@plt>
  lea    0x10(%rsp),%r8
  mov    %r12,%rcx
  mov    %r13,%rdx
  mov    %r8,%rdi
  shr    $0x4,%rcx
  mov    %r14,%rsi
  mov    %r8,0x8(%rsp)
  call   <evaluate_by_delta@plt>
  mov    0x8(%rsp),%rsi
  mov    $0x10,%edx
  mov    %r15,%rdi
  call   <memcpy@plt>
  mov    %rbp,%rsi
  mov    %r15,%rdi
  lea    0x30(%rsp),%rbp
  call   <aes_128_encrypt@plt>
  mov    %r12,%rax
  mov    $0x10,%edx
  mov    %r15,%rsi
  sub    %rbx,%rax
  mov    %rbp,%rdi
  test   $0x10,%al
  jne    L46
  call   <memcpy@plt>
  cmp    %rbx,%r12
  jbe    L4
  nopl   0x0(%rax)
L50:
  lea    0x0(%r13,%rbx,1),%rdi
  mov    %rbp,%rsi
  add    $0x10,%rbx
  call   <add_to_first@plt>
  mov    %r14,%rsi
  mov    %rbp,%rdi
  call   <mul_by_delta@plt>
  cmp    %rbx,%r12
  ja     L50
L4:
  mov    0x58(%rsp),%rax
  sub    %fs:0x28,%rax
  jne    L74
  add    $0x68,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nopl   0x0(%rax)
L46:
  call   <memcpy@plt>
  lea    0x0(%r13,%rbx,1),%rdi
  mov    %rbp,%rsi
  call   <add_to_first@plt>
  lea    0x10(%rbx),%rdx
  cmp    %rdx,%r12
  jbe    L4
  mov    %r14,%rsi
  mov    %rbp,%rdi
  mov    %rdx,0x8(%rsp)
  add    $0x20,%rbx
  call   <mul_by_delta@plt>
  mov    0x8(%rsp),%rdx
  mov    %rbp,%rsi
  lea    0x0(%r13,%rdx,1),%rdi
  mov    %rdi,0x8(%rsp)
  call   <add_to_first@plt>
  mov    0x8(%rsp),%rdi
  mov    %r15,%rsi
  call   <add_to_first@plt>
  cmp    %rbx,%r12
  jbe    L4
L15:
  lea    0x0(%r13,%rbx,1),%rdi
  mov    %rbp,%rsi
  add    $0x10,%rbx
  call   <add_to_first@plt>
  mov    %r14,%rsi
  mov    %rbp,%rdi
  call   <mul_by_delta@plt>
  cmp    %rbx,%r12
  ja     L15
  jmp    L4
L74:
  call   <__stack_chk_fail@plt>
```

assistant: ```c
void julius_regular_involution(unsigned char *pad, unsigned long long padlen, unsigned long long reg_index, unsigned long expanded_key[44]) {
  int i;
  unsigned long long cur;
  unsigned char seed[16];
  unsigned char mu[16];
  unsigned char tmp_mask[16];
  unsigned char delta[16];
  for (i = 0; i < 16; i++) {
    delta[i] = 0;
  }
  aes_128_encrypt(delta, expanded_key);
  evaluate_by_delta(seed, delta, pad, padlen / 16);
  memcpy(mu, seed, 16);
  aes_128_encrypt(mu, expanded_key);
  if (((padlen - reg_index) / 16) % 2 == 0) {
    cur = reg_index;
    memcpy(tmp_mask, mu, 16);
    for (cur = reg_index; cur < padlen; cur = cur + 16) {
      add_to_first(&pad[cur], tmp_mask);
      mul_by_delta(tmp_mask, delta);
    }
  } else {
    cur = reg_index;
    memcpy(tmp_mask, mu, 16);
    add_to_first(&pad[cur], tmp_mask);
    cur = cur + 16;
    if (cur < padlen) {
      mul_by_delta(tmp_mask, delta);
      add_to_first(&pad[cur], tmp_mask);
      add_to_first(&pad[cur], mu);
      cur = cur + 16;
    }
    for (; cur < padlen; cur = cur + 16) {
      add_to_first(&pad[cur], tmp_mask);
      mul_by_delta(tmp_mask, delta);
    }
  }
}
```