user: Converte this assembly snippet into its equivalent C code:

```asm
<crypto_aead_decrypt>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  mov    %rsi,%r12
  push   %rbp
  push   %rbx
  sub    $0x98,%rsp
  mov    %rdi,0x10(%rsp)
  mov    0xd0(%rsp),%r13
  mov    %rcx,0x8(%rsp)
  mov    0xd8(%rsp),%rsi
  mov    %r8,0x18(%rsp)
  mov    0xe0(%rsp),%rdi
  mov    %r9,0x20(%rsp)
  mov    %fs:0x28,%rax
  mov    %rax,0x88(%rsp)
  xor    %eax,%eax
  cmp    $0xf,%r8
  jbe    L22
  lea    0x30(%rsp),%rbp
  mov    %r9,%r14
  mov    %rbp,%rdx
  call   <aegis256_initialization@plt>
  cmp    $0xf,%r13
  jbe    L74
  mov    $0x10,%ebx
  lea    0x60(%rsp),%r15
  sub    $0x10,%r14
  nopl   0x0(%rax)
L67:
  lea    (%r14,%rbx,1),%rdi
  mov    %rbp,%rdx
  mov    %r15,%rsi
  call   <aegis256_enc_aut_step@plt>
  mov    %rbx,%r9
  add    $0x10,%rbx
  cmp    %rbx,%r13
  jae    L67
L88:
  mov    %r13,%r14
  and    $0xf,%r14d
  jne    L108
L43:
  mov    0x18(%rsp),%rax
  sub    $0x10,%rax
  mov    %rax,(%r12)
  cmp    $0xf,%rax
  jbe    L131
  mov    0x8(%rsp),%rax
  mov    $0x10,%ebx
  lea    -0x10(%rax),%r15
  mov    0x10(%rsp),%rax
  lea    -0x10(%rax),%r14
  cs nopw 0x0(%rax,%rax,1)
L138:
  lea    (%r15,%rbx,1),%rsi
  lea    (%r14,%rbx,1),%rdi
  mov    %rbp,%rdx
  call   <aegis256_dec_aut_step@plt>
  mov    (%r12),%rax
  mov    %rbx,%rcx
  add    $0x10,%rbx
  cmp    %rbx,%rax
  jae    L138
L130:
  test   $0xf,%al
  jne    L2
L109:
  mov    (%r12),%rdi
  lea    0x70(%rsp),%rbx
  mov    %rbp,%r8
  mov    %r13,%rsi
  mov    %rbx,%rcx
  mov    $0x10,%edx
  call   <aegis256_tag_generation@plt>
  mov    0x8(%rsp),%rbp
  xor    %ecx,%ecx
  xor    %eax,%eax
  add    (%r12),%rbp
  nopl   0x0(%rax)
L85:
  movzbl 0x0(%rbp,%rax,1),%edx
  xor    (%rbx,%rax,1),%dl
  add    $0x1,%rax
  or     %edx,%ecx
  cmp    $0x10,%rax
  jne    L85
  neg    %cl
  sbb    %eax,%eax
L101:
  mov    0x88(%rsp),%rdx
  sub    %fs:0x28,%rdx
  jne    L37
  add    $0x98,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nopl   0x0(%rax)
L108:
  lea    0x50(%rsp),%r15
  xor    %esi,%esi
  mov    $0x10,%edx
  mov    %r9,0x28(%rsp)
  mov    %r15,%rdi
  call   <memset@plt>
  mov    0x20(%rsp),%rsi
  mov    %r14,%rdx
  mov    %r15,%rdi
  mov    0x28(%rsp),%r9
  add    %r9,%rsi
  call   <memcpy@plt>
  lea    0x60(%rsp),%rsi
  mov    %rbp,%rdx
  mov    %r15,%rdi
  call   <aegis256_enc_aut_step@plt>
  jmp    L43
  cs nopw 0x0(%rax,%rax,1)
L2:
  lea    0x60(%rsp),%r15
  mov    $0x10,%edx
  xor    %esi,%esi
  mov    %rcx,0x18(%rsp)
  mov    %r15,%rdi
  lea    0x50(%rsp),%r14
  call   <memset@plt>
  mov    0x18(%rsp),%rcx
  mov    (%r12),%rdx
  mov    %r15,%rdi
  mov    0x8(%rsp),%rax
  and    $0xf,%edx
  lea    (%rax,%rcx,1),%rsi
  call   <memcpy@plt>
  mov    %rbp,%rdx
  mov    %r15,%rsi
  mov    %r14,%rdi
  call   <aegis256_dec_aut_step@plt>
  mov    0x18(%rsp),%rcx
  mov    (%r12),%rdx
  mov    %r14,%rsi
  mov    0x10(%rsp),%rdi
  and    $0xf,%edx
  add    %rcx,%rdi
  call   <memcpy@plt>
  mov    (%r12),%rdx
  xor    %esi,%esi
  mov    %r14,%rdi
  and    $0xf,%edx
  call   <memset@plt>
  mov    %r14,%rdi
  call   <_mm_load_si128@plt>
  mov    0x30(%rsp),%edi
  mov    %eax,%esi
  call   <_mm_xor_si128@plt>
  mov    %eax,0x30(%rsp)
  jmp    L109
L74:
  xor    %r9d,%r9d
  jmp    L88
L131:
  xor    %ecx,%ecx
  jmp    L130
L22:
  mov    $0xffffffff,%eax
  jmp    L101
L37:
  call   <__stack_chk_fail@plt>
```

assistant: ```c
int crypto_aead_decrypt(unsigned char *m, unsigned long long *mlen, unsigned char *nsec, const unsigned char *c, unsigned long long clen, const unsigned char *ad, unsigned long long adlen, const unsigned char *npub, const unsigned char *k) {
  unsigned long long i;
  unsigned char plaintextblock[16], ciphertextblock[16];
  unsigned char tag[16];
  unsigned char check = 0;
  __m128i aegis256_state[6];
  if (clen < 16)
    return -1;
  aegis256_initialization(k, npub, aegis256_state);
  for (i = 0; (i + 16) <= adlen; i += 16) {
    aegis256_enc_aut_step(ad + i, ciphertextblock, aegis256_state);
  }
  if ((adlen & 0xf) != 0) {
    memset(plaintextblock, 0, 16);
    memcpy(plaintextblock, ad + i, adlen & 0xf);
    aegis256_enc_aut_step(plaintextblock, ciphertextblock, aegis256_state);
  }
  *mlen = clen - 16;
  for (i = 0; (i + 16) <= *mlen; i += 16) {
    aegis256_dec_aut_step(m + i, c + i, aegis256_state);
  }
  if ((*mlen & 0xf) != 0) {
    memset(ciphertextblock, 0, 16);
    memcpy(ciphertextblock, c + i, *mlen & 0xf);
    aegis256_dec_aut_step(plaintextblock, ciphertextblock, aegis256_state);
    memcpy(m + i, plaintextblock, *mlen & 0xf);
    memset(plaintextblock, 0, *mlen & 0xf);
    aegis256_state[0] = _mm_xor_si128(aegis256_state[0], _mm_load_si128((__m128i *)plaintextblock));
  }
  aegis256_tag_generation(*mlen, adlen, 16, tag, aegis256_state);
  for (i = 0; i < 16; i++)
    check |= (tag[i] ^ c[i + *mlen]);
  if (check == 0)
    return 0;
  else
    return -1;
}
```