user: Please show me the C implementation that matches the assembly code listed below:

```asm
<cbguard2l>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  mov    %rdi,-0x18(%rbp)
  mov    %esi,-0x1c(%rbp)
  mov    %edx,-0x20(%rbp)
  mov    %ecx,-0x24(%rbp)
  mov    %r8d,-0x28(%rbp)
  movl   $0x0,-0x4(%rbp)
  jmp    L21
L17:
  mov    -0x24(%rbp),%eax
  imul   -0x4(%rbp),%eax
  mov    %eax,%edx
  mov    %edx,%eax
  add    %eax,%eax
  add    %edx,%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x18(%rbp),%rax
  add    %rax,%rdx
  mov    -0x24(%rbp),%eax
  imul   -0x4(%rbp),%eax
  mov    %eax,%ecx
  mov    -0x1c(%rbp),%eax
  add    %eax,%ecx
  mov    %ecx,%eax
  add    %eax,%eax
  add    %ecx,%eax
  cltq
  lea    0x0(,%rax,4),%rcx
  mov    -0x18(%rbp),%rax
  add    %rcx,%rax
  movss  (%rdx),%xmm0
  movss  %xmm0,(%rax)
  mov    -0x24(%rbp),%eax
  imul   -0x4(%rbp),%eax
  mov    %eax,%edx
  mov    %edx,%eax
  add    %eax,%eax
  add    %edx,%eax
  add    $0x1,%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x18(%rbp),%rax
  lea    (%rdx,%rax,1),%rcx
  mov    -0x1c(%rbp),%edx
  mov    %edx,%eax
  add    %eax,%eax
  add    %edx,%eax
  lea    0x1(%rax),%esi
  mov    -0x24(%rbp),%eax
  imul   -0x4(%rbp),%eax
  mov    %eax,%edx
  mov    %edx,%eax
  add    %eax,%eax
  add    %edx,%eax
  add    %esi,%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movss  (%rcx),%xmm0
  movss  %xmm0,(%rax)
  mov    -0x24(%rbp),%eax
  imul   -0x4(%rbp),%eax
  mov    %eax,%edx
  mov    %edx,%eax
  add    %eax,%eax
  add    %edx,%eax
  add    $0x2,%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x18(%rbp),%rax
  lea    (%rdx,%rax,1),%rcx
  mov    -0x1c(%rbp),%edx
  mov    %edx,%eax
  add    %eax,%eax
  add    %edx,%eax
  lea    0x2(%rax),%esi
  mov    -0x24(%rbp),%eax
  imul   -0x4(%rbp),%eax
  mov    %eax,%edx
  mov    %edx,%eax
  add    %eax,%eax
  add    %edx,%eax
  add    %esi,%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movss  (%rcx),%xmm0
  movss  %xmm0,(%rax)
  addl   $0x1,-0x4(%rbp)
L21:
  mov    -0x4(%rbp),%eax
  cmp    -0x20(%rbp),%eax
  jl     L17
  movl   $0x0,-0x8(%rbp)
  jmp    L22
L37:
  mov    -0x8(%rbp),%edx
  mov    %edx,%eax
  add    %eax,%eax
  add    %edx,%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x18(%rbp),%rax
  add    %rax,%rdx
  mov    -0x24(%rbp),%eax
  imul   -0x20(%rbp),%eax
  mov    %eax,%ecx
  mov    -0x8(%rbp),%eax
  add    %eax,%ecx
  mov    %ecx,%eax
  add    %eax,%eax
  add    %ecx,%eax
  cltq
  lea    0x0(,%rax,4),%rcx
  mov    -0x18(%rbp),%rax
  add    %rcx,%rax
  movss  (%rdx),%xmm0
  movss  %xmm0,(%rax)
  mov    -0x8(%rbp),%edx
  mov    %edx,%eax
  add    %eax,%eax
  add    %edx,%eax
  add    $0x1,%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x18(%rbp),%rax
  lea    (%rdx,%rax,1),%rcx
  mov    -0x8(%rbp),%edx
  mov    %edx,%eax
  add    %eax,%eax
  add    %edx,%eax
  lea    0x1(%rax),%esi
  mov    -0x24(%rbp),%eax
  imul   -0x20(%rbp),%eax
  mov    %eax,%edx
  mov    %edx,%eax
  add    %eax,%eax
  add    %edx,%eax
  add    %esi,%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movss  (%rcx),%xmm0
  movss  %xmm0,(%rax)
  mov    -0x8(%rbp),%edx
  mov    %edx,%eax
  add    %eax,%eax
  add    %edx,%eax
  add    $0x2,%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x18(%rbp),%rax
  lea    (%rdx,%rax,1),%rcx
  mov    -0x8(%rbp),%edx
  mov    %edx,%eax
  add    %eax,%eax
  add    %edx,%eax
  lea    0x2(%rax),%esi
  mov    -0x24(%rbp),%eax
  imul   -0x20(%rbp),%eax
  mov    %eax,%edx
  mov    %edx,%eax
  add    %eax,%eax
  add    %edx,%eax
  add    %esi,%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movss  (%rcx),%xmm0
  movss  %xmm0,(%rax)
  addl   $0x1,-0x8(%rbp)
L22:
  mov    -0x8(%rbp),%eax
  cmp    -0x1c(%rbp),%eax
  jl     L37
  mov    -0x24(%rbp),%eax
  imul   -0x20(%rbp),%eax
  mov    %eax,%edx
  mov    -0x1c(%rbp),%eax
  add    %eax,%edx
  mov    %edx,%eax
  add    %eax,%eax
  add    %edx,%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x18(%rbp),%rax
  add    %rax,%rdx
  mov    -0x18(%rbp),%rax
  movss  (%rax),%xmm0
  movss  %xmm0,(%rdx)
  mov    -0x1c(%rbp),%edx
  mov    %edx,%eax
  add    %eax,%eax
  add    %edx,%eax
  lea    0x1(%rax),%ecx
  mov    -0x24(%rbp),%eax
  imul   -0x20(%rbp),%eax
  mov    %eax,%edx
  mov    %edx,%eax
  add    %eax,%eax
  add    %edx,%eax
  add    %ecx,%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x18(%rbp),%rax
  add    %rax,%rdx
  mov    -0x18(%rbp),%rax
  movss  0x4(%rax),%xmm0
  movss  %xmm0,(%rdx)
  mov    -0x1c(%rbp),%edx
  mov    %edx,%eax
  add    %eax,%eax
  add    %edx,%eax
  lea    0x2(%rax),%ecx
  mov    -0x24(%rbp),%eax
  imul   -0x20(%rbp),%eax
  mov    %eax,%edx
  mov    %edx,%eax
  add    %eax,%eax
  add    %edx,%eax
  add    %ecx,%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x18(%rbp),%rax
  add    %rax,%rdx
  mov    -0x18(%rbp),%rax
  movss  0x8(%rax),%xmm0
  movss  %xmm0,(%rdx)
  nop
  pop    %rbp
  ret
```

assistant: ```c
void cbguard2l(float bxy[], int nx, int ny, int nxe, int nye) {
  int j, k;
  for (k = 0; k < ny; k++) {
    bxy[3 * nx + 3 * nxe * k] = bxy[3 * nxe * k];
    bxy[1 + 3 * nx + 3 * nxe * k] = bxy[1 + 3 * nxe * k];
    bxy[2 + 3 * nx + 3 * nxe * k] = bxy[2 + 3 * nxe * k];
  }
  for (j = 0; j < nx; j++) {
    bxy[3 * j + 3 * nxe * ny] = bxy[3 * j];
    bxy[1 + 3 * j + 3 * nxe * ny] = bxy[1 + 3 * j];
    bxy[2 + 3 * j + 3 * nxe * ny] = bxy[2 + 3 * j];
  }
  bxy[3 * nx + 3 * nxe * ny] = bxy[0];
  bxy[1 + 3 * nx + 3 * nxe * ny] = bxy[1];
  bxy[2 + 3 * nx + 3 * nxe * ny] = bxy[2];
  return;
}
```