user: 这段汇编代码用C语言表示是什么样的？

```asm
<downhi>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  mov    %rdi,-0x28(%rbp)
  mov    %esi,-0x2c(%rbp)
  mov    %rdx,-0x38(%rbp)
  mov    %ecx,-0x30(%rbp)
  mov    %r8,-0x40(%rbp)
  mov    -0x2c(%rbp),%eax
  mov    %eax,%edx
  shr    $0x1f,%edx
  add    %edx,%eax
  sar    %eax
  mov    %eax,-0xc(%rbp)
  mov    -0x30(%rbp),%eax
  mov    %eax,%edx
  shr    $0x1f,%edx
  add    %edx,%eax
  sar    %eax
  sub    $0x1,%eax
  mov    %eax,-0x1c(%rbp)
  mov    -0x1c(%rbp),%eax
  add    %eax,%eax
  lea    0x1(%rax),%edx
  mov    -0x30(%rbp),%eax
  lea    -0x1(%rax),%ecx
  mov    %edx,%eax
  sub    %ecx,%eax
  test   %eax,%eax
  jns    L89
  addl   $0x1,-0x1c(%rbp)
L89:
  mov    -0x1c(%rbp),%eax
  mov    %eax,-0x18(%rbp)
  jmp    L72
L82:
  pxor   %xmm0,%xmm0
  movsd  %xmm0,-0x8(%rbp)
  movl   $0x0,-0x14(%rbp)
  jmp    L33
L92:
  mov    -0x14(%rbp),%eax
  cltq
  lea    0x0(,%rax,8),%rdx
  mov    -0x38(%rbp),%rax
  add    %rdx,%rax
  movsd  (%rax),%xmm1
  mov    -0x18(%rbp),%eax
  add    %eax,%eax
  add    $0x1,%eax
  sub    -0x14(%rbp),%eax
  cltq
  lea    0x0(,%rax,8),%rdx
  mov    -0x28(%rbp),%rax
  add    %rdx,%rax
  movsd  (%rax),%xmm0
  mulsd  %xmm1,%xmm0
  movsd  -0x8(%rbp),%xmm1
  addsd  %xmm1,%xmm0
  movsd  %xmm0,-0x8(%rbp)
  addl   $0x1,-0x14(%rbp)
L33:
  mov    -0x14(%rbp),%eax
  cmp    -0x30(%rbp),%eax
  jl     L92
  mov    -0x18(%rbp),%eax
  cltq
  lea    0x0(,%rax,8),%rdx
  mov    -0x40(%rbp),%rax
  add    %rdx,%rax
  movsd  -0x8(%rbp),%xmm0
  movsd  %xmm0,(%rax)
  addl   $0x1,-0x18(%rbp)
L72:
  mov    -0x18(%rbp),%eax
  cmp    -0xc(%rbp),%eax
  jl     L82
  mov    -0x1c(%rbp),%eax
  cmp    -0xc(%rbp),%eax
  jle    L49
  mov    -0xc(%rbp),%eax
  mov    %eax,-0x1c(%rbp)
L49:
  movl   $0x0,-0x18(%rbp)
  jmp    L60
L55:
  pxor   %xmm0,%xmm0
  movsd  %xmm0,-0x8(%rbp)
  mov    -0x18(%rbp),%eax
  add    %eax,%eax
  add    $0x1,%eax
  mov    %eax,-0x10(%rbp)
  movl   $0x0,-0x14(%rbp)
  jmp    L59
L37:
  cmpl   $0x0,-0x10(%rbp)
  jns    L58
  mov    -0x2c(%rbp),%eax
  add    %eax,-0x10(%rbp)
L58:
  mov    -0x14(%rbp),%eax
  cltq
  lea    0x0(,%rax,8),%rdx
  mov    -0x38(%rbp),%rax
  add    %rdx,%rax
  movsd  (%rax),%xmm1
  mov    -0x10(%rbp),%eax
  cltq
  lea    0x0(,%rax,8),%rdx
  mov    -0x28(%rbp),%rax
  add    %rdx,%rax
  movsd  (%rax),%xmm0
  mulsd  %xmm1,%xmm0
  movsd  -0x8(%rbp),%xmm1
  addsd  %xmm1,%xmm0
  movsd  %xmm0,-0x8(%rbp)
  subl   $0x1,-0x10(%rbp)
  addl   $0x1,-0x14(%rbp)
L59:
  mov    -0x14(%rbp),%eax
  cmp    -0x30(%rbp),%eax
  jl     L37
  mov    -0x18(%rbp),%eax
  cltq
  lea    0x0(,%rax,8),%rdx
  mov    -0x40(%rbp),%rax
  add    %rdx,%rax
  movsd  -0x8(%rbp),%xmm0
  movsd  %xmm0,(%rax)
  addl   $0x1,-0x18(%rbp)
L60:
  mov    -0x18(%rbp),%eax
  cmp    -0x1c(%rbp),%eax
  jl     L55
  nop
  nop
  pop    %rbp
  ret
```

assistant: ```c
void downhi(x, n, hpf, m, y) double x[], hpf[], y[];
int n, m;
{
  int n2, mlo, i, h, j;
  double s;
  n2 = n / 2;
  mlo = m / 2 - 1;
  if (2 * mlo + 1 - (m - 1) < 0)
    mlo++;
  for (i = mlo; i < n2; i++) {
    s = 0.;
    for (h = 0; h < m; h++)
      s += hpf[h] * x[2 * i + 1 - h];
    y[i] = s;
  }
  if (mlo > n2)
    mlo = n2;
  for (i = 0; i < mlo; i++) {
    s = 0.;
    j = 2 * i + 1;
    for (h = 0; h < m; h++) {
      if (j < 0)
        j += n;
      s += hpf[h] * x[j];
      --j;
    }
    y[i] = s;
  }
}
```