user: What is the c source code of the assembly code below?

```asm
<f>:
  endbr64
  mov    %rdi,%rcx
  mov    %esi,%edx
  test   %esi,%esi
  jle    L86
  lea    -0x1(%rsi),%eax
  cmp    $0xe,%eax
  jbe    L177
  shr    $0x4,%esi
  pxor   %xmm1,%xmm1
  pxor   %xmm4,%xmm4
  mov    %rdi,%rax
  sub    $0x1,%esi
  pxor   %xmm3,%xmm3
  shl    $0x4,%rsi
  lea    0x10(%rdi,%rsi,1),%rsi
  nopl   0x0(%rax,%rax,1)
L17:
  movdqu (%rax),%xmm0
  add    $0x10,%rax
  movdqa %xmm0,%xmm2
  punpckhbw %xmm4,%xmm0
  punpcklbw %xmm4,%xmm2
  psllw  $0x8,%xmm0
  psllw  $0x8,%xmm2
  movdqa %xmm2,%xmm5
  punpckhwd %xmm3,%xmm2
  punpcklwd %xmm3,%xmm5
  paddd  %xmm5,%xmm1
  paddd  %xmm2,%xmm1
  movdqa %xmm0,%xmm2
  punpckhwd %xmm3,%xmm0
  punpcklwd %xmm3,%xmm2
  paddd  %xmm2,%xmm1
  paddd  %xmm0,%xmm1
  cmp    %rsi,%rax
  jne    L17
  movdqa %xmm1,%xmm0
  mov    %edx,%esi
  psrldq $0x8,%xmm0
  and    $0xfffffff0,%esi
  paddd  %xmm0,%xmm1
  movdqa %xmm1,%xmm0
  psrldq $0x4,%xmm0
  paddd  %xmm0,%xmm1
  movd   %xmm1,%eax
  test   $0xf,%dl
  je     L88
L43:
  movslq %esi,%rdi
  movzbl (%rcx,%rdi,1),%edi
  shl    $0x8,%edi
  add    %edi,%eax
  lea    0x1(%rsi),%edi
  cmp    %edi,%edx
  jle    L9
  movslq %edi,%rdi
  movzbl (%rcx,%rdi,1),%edi
  shl    $0x8,%edi
  add    %edi,%eax
  lea    0x2(%rsi),%edi
  cmp    %edi,%edx
  jle    L9
  movslq %edi,%rdi
  movzbl (%rcx,%rdi,1),%edi
  shl    $0x8,%edi
  add    %edi,%eax
  lea    0x3(%rsi),%edi
  cmp    %edi,%edx
  jle    L9
  movslq %edi,%rdi
  movzbl (%rcx,%rdi,1),%edi
  shl    $0x8,%edi
  add    %edi,%eax
  lea    0x4(%rsi),%edi
  cmp    %edi,%edx
  jle    L9
  movslq %edi,%rdi
  movzbl (%rcx,%rdi,1),%edi
  shl    $0x8,%edi
  add    %edi,%eax
  lea    0x5(%rsi),%edi
  cmp    %edi,%edx
  jle    L9
  movslq %edi,%rdi
  movzbl (%rcx,%rdi,1),%edi
  shl    $0x8,%edi
  add    %edi,%eax
  lea    0x6(%rsi),%edi
  cmp    %edi,%edx
  jle    L9
  movslq %edi,%rdi
  movzbl (%rcx,%rdi,1),%edi
  shl    $0x8,%edi
  add    %edi,%eax
  lea    0x7(%rsi),%edi
  cmp    %edi,%edx
  jle    L9
  movslq %edi,%rdi
  movzbl (%rcx,%rdi,1),%edi
  shl    $0x8,%edi
  add    %edi,%eax
  lea    0x8(%rsi),%edi
  cmp    %edi,%edx
  jle    L9
  movslq %edi,%rdi
  movzbl (%rcx,%rdi,1),%edi
  shl    $0x8,%edi
  add    %edi,%eax
  lea    0x9(%rsi),%edi
  cmp    %edi,%edx
  jle    L9
  movslq %edi,%rdi
  movzbl (%rcx,%rdi,1),%edi
  shl    $0x8,%edi
  add    %edi,%eax
  lea    0xa(%rsi),%edi
  cmp    %edi,%edx
  jle    L9
  movslq %edi,%rdi
  movzbl (%rcx,%rdi,1),%edi
  shl    $0x8,%edi
  add    %edi,%eax
  lea    0xb(%rsi),%edi
  cmp    %edi,%edx
  jle    L9
  movslq %edi,%rdi
  movzbl (%rcx,%rdi,1),%edi
  shl    $0x8,%edi
  add    %edi,%eax
  lea    0xc(%rsi),%edi
  cmp    %edi,%edx
  jle    L9
  movslq %edi,%rdi
  movzbl (%rcx,%rdi,1),%edi
  shl    $0x8,%edi
  add    %edi,%eax
  lea    0xd(%rsi),%edi
  cmp    %edi,%edx
  jle    L9
  movslq %edi,%rdi
  add    $0xe,%esi
  movzbl (%rcx,%rdi,1),%edi
  shl    $0x8,%edi
  add    %edi,%eax
  cmp    %esi,%edx
  jle    L9
  movslq %esi,%rsi
  movzbl (%rcx,%rsi,1),%edx
  shl    $0x8,%edx
  add    %edx,%eax
  ret
  xchg   %ax,%ax
L86:
  xor    %eax,%eax
L9:
  ret
L177:
  xor    %esi,%esi
  xor    %eax,%eax
  jmp    L43
L88:
  ret
```

assistant: ```c
int f(unsigned char *s, int n) {
  int sum = 0;
  int i;
  for (i = 0; i < n; i++)
    sum += 256 * s[i];
  return sum;
}
```