user: 这段汇编代码用C语言表示是什么样的：

```asm
<smix>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x48,%rsp
  mov    %rdi,0x38(%rsp)
  mov    %rsi,%r12
  mov    %edx,0x2c(%rsp)
  mov    %rcx,0x18(%rsp)
  mov    %r8,%rbx
  mov    %rsi,%rax
  shl    $0x7,%rax
  mov    %rax,0x10(%rsp)
  lea    (%r8,%rax,1),%rbp
  lea    0x0(%rbp,%rax,1),%r15
  mov    %rsi,%rax
  shl    $0x5,%rax
  mov    %rax,0x30(%rsp)
  je     L35
  mov    %rdi,%r14
  mov    $0x0,%r13d
  mov    %rbp,0x8(%rsp)
  mov    %rax,%rbp
L5:
  mov    %r14,%rdi
  call   <libcperciva_le32dec@plt>
  mov    %eax,(%rbx,%r13,4)
  add    $0x1,%r13
  add    $0x10,%r14
  cmp    %rbp,%r13
  jne    L5
  mov    0x8(%rsp),%rbp
  cmpl   $0x0,0x2c(%rsp)
  jle    L40
L70:
  mov    %r12d,%eax
  shl    $0x7,%eax
  mov    %eax,0x8(%rsp)
  mov    0x18(%rsp),%r13
  mov    0x2c(%rsp),%eax
  sub    $0x1,%eax
  and    $0xfffffffe,%eax
  add    $0x2,%eax
  mov    %eax,0x24(%rsp)
  mov    $0x0,%r14d
L49:
  mov    0x8(%rsp),%edx
  mov    %rbx,%rsi
  mov    %r13,%rdi
  call   <blkcpy@plt>
  mov    %r12,%rcx
  mov    %r15,%rdx
  mov    %rbp,%rsi
  mov    %rbx,%rdi
  call   <blockmix_salsa8@plt>
  add    0x10(%rsp),%r13
  mov    0x8(%rsp),%edx
  mov    %rbp,%rsi
  mov    %r13,%rdi
  call   <blkcpy@plt>
  mov    %r12,%rcx
  mov    %r15,%rdx
  mov    %rbx,%rsi
  mov    %rbp,%rdi
  call   <blockmix_salsa8@plt>
  mov    %r14d,%eax
  add    $0x2,%r14d
  add    0x10(%rsp),%r13
  cmp    0x24(%rsp),%r14d
  jne    L49
  mov    %eax,0x28(%rsp)
  mov    $0x0,%r13d
  mov    0x2c(%rsp),%r14d
  sub    $0x1,%r14d
  mov    %r14d,0x24(%rsp)
  mov    0x10(%rsp),%r14
L84:
  mov    %r12,%rsi
  mov    %rbx,%rdi
  call   <integerify@plt>
  and    0x24(%rsp),%eax
  movslq %eax,%rsi
  imul   %r14,%rsi
  add    0x18(%rsp),%rsi
  mov    0x8(%rsp),%edx
  mov    %rbx,%rdi
  call   <blkxor@plt>
  mov    %r12,%rcx
  mov    %r15,%rdx
  mov    %rbp,%rsi
  mov    %rbx,%rdi
  call   <blockmix_salsa8@plt>
  mov    %r12,%rsi
  mov    %rbp,%rdi
  call   <integerify@plt>
  and    0x24(%rsp),%eax
  movslq %eax,%rsi
  imul   %r14,%rsi
  add    0x18(%rsp),%rsi
  mov    0x8(%rsp),%edx
  mov    %rbp,%rdi
  call   <blkxor@plt>
  mov    %r12,%rcx
  mov    %r15,%rdx
  mov    %rbx,%rsi
  mov    %rbp,%rdi
  call   <blockmix_salsa8@plt>
  mov    %r13d,%eax
  add    $0x2,%r13d
  cmp    %eax,0x28(%rsp)
  jne    L84
  cmpq   $0x0,0x30(%rsp)
  je     L28
L40:
  mov    0x38(%rsp),%r12
  mov    $0x0,%ebp
  mov    0x30(%rsp),%r13
L13:
  mov    (%rbx,%rbp,4),%esi
  mov    %r12,%rdi
  call   <libcperciva_le32enc@plt>
  add    $0x1,%rbp
  add    $0x10,%r12
  cmp    %rbp,%r13
  jne    L13
L28:
  add    $0x48,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L35:
  cmpl   $0x0,0x2c(%rsp)
  jg     L70
  jmp    L28
```

assistant: ```c
void smix(uint8_t *B, size_t r, uint64_t N, uint32_t *V, uint32_t *XY) {
  uint32_t *X = XY;
  uint32_t *Y = &XY[32 * r];
  uint32_t *Z = &XY[64 * r];
  uint64_t i;
  uint64_t j;
  size_t k;
  for (k = 0; k < 32 * r; k++)
    X[k] = libcperciva_le32dec(&B[4 * k]);
  for (i = 0; i < N; i += 2) {
    blkcpy(&V[i * (32 * r)], X, 128 * r);
    blockmix_salsa8(X, Y, Z, r);
    blkcpy(&V[(i + 1) * (32 * r)], Y, 128 * r);
    blockmix_salsa8(Y, X, Z, r);
  }
  for (i = 0; i < N; i += 2) {
    j = integerify(X, r) & (N - 1);
    blkxor(X, &V[j * (32 * r)], 128 * r);
    blockmix_salsa8(X, Y, Z, r);
    j = integerify(Y, r) & (N - 1);
    blkxor(Y, &V[j * (32 * r)], 128 * r);
    blockmix_salsa8(Y, X, Z, r);
  }
  for (k = 0; k < 32 * r; k++)
    libcperciva_le32enc(&B[4 * k], X[k]);
}
```