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

```asm
<fir_stereo>:
  endbr64
  mov    %edx,%eax
  mov    %rdi,%r9
  push   %r12
  sar    $0x1f,%eax
  push   %rbp
  shr    $0x1d,%eax
  push   %rbx
  mov    %rcx,%rbx
  lea    (%rdx,%rax,1),%r11d
  and    $0x7,%r11d
  sub    %eax,%r11d
  test   %edx,%edx
  lea    0x7(%rdx),%eax
  cmovns %edx,%eax
  and    $0xfffffff8,%eax
  cltq
  lea    (%rsi,%rax,4),%rdi
  cmp    %rdi,%rsi
  je     L35
  mov    %rsi,%r10
  mov    %rsi,%rdx
  mov    %r9,%rax
  xor    %ecx,%ecx
  xor    %ebp,%ebp
  nopl   0x0(%rax,%rax,1)
L31:
  mov    (%rdx),%esi
  mov    (%rax),%r12d
  add    $0x40,%rax
  add    $0x20,%rdx
  imul   %esi,%r12d
  imul   -0x3c(%rax),%esi
  add    %ebp,%r12d
  mov    -0x38(%rax),%ebp
  add    %ecx,%esi
  mov    -0x1c(%rdx),%ecx
  imul   %ecx,%ebp
  imul   -0x34(%rax),%ecx
  add    %r12d,%ebp
  mov    -0x30(%rax),%r12d
  add    %ecx,%esi
  mov    -0x18(%rdx),%ecx
  imul   %ecx,%r12d
  imul   -0x2c(%rax),%ecx
  add    %ebp,%r12d
  mov    -0x28(%rax),%ebp
  add    %ecx,%esi
  mov    -0x14(%rdx),%ecx
  imul   %ecx,%ebp
  imul   -0x24(%rax),%ecx
  add    %r12d,%ebp
  mov    -0x20(%rax),%r12d
  add    %ecx,%esi
  mov    -0x10(%rdx),%ecx
  imul   %ecx,%r12d
  imul   -0x1c(%rax),%ecx
  add    %ebp,%r12d
  mov    -0x18(%rax),%ebp
  add    %ecx,%esi
  mov    -0xc(%rdx),%ecx
  imul   %ecx,%ebp
  imul   -0x14(%rax),%ecx
  add    %r12d,%ebp
  mov    -0x10(%rax),%r12d
  add    %ecx,%esi
  mov    -0x8(%rdx),%ecx
  imul   %ecx,%r12d
  imul   -0xc(%rax),%ecx
  add    %ebp,%r12d
  mov    -0x8(%rax),%ebp
  add    %ecx,%esi
  mov    -0x4(%rdx),%ecx
  imul   %ecx,%ebp
  add    %r12d,%ebp
  imul   -0x4(%rax),%ecx
  add    %esi,%ecx
  cmp    %rdx,%rdi
  jne    L31
  mov    %rdi,%rax
  sub    %r10,%rax
  sub    $0x20,%rax
  shr    $0x5,%rax
  add    $0x1,%rax
  shl    $0x6,%rax
  add    %rax,%r9
L40:
  movslq %r11d,%r11
  lea    (%rdi,%r11,4),%rsi
  cmp    %rsi,%rdi
  je     L18
  nopl   0x0(%rax)
L16:
  mov    (%rdi),%eax
  mov    (%r9),%edx
  add    $0x8,%r9
  add    $0x4,%rdi
  imul   %eax,%edx
  imul   -0x4(%r9),%eax
  add    %edx,%ebp
  add    %eax,%ecx
  cmp    %rdi,%rsi
  jne    L16
L18:
  mov    %ebp,(%rbx)
  pop    %rbx
  mov    %ecx,(%r8)
  pop    %rbp
  pop    %r12
  ret
  nopl   0x0(%rax,%rax,1)
L35:
  xor    %ecx,%ecx
  xor    %ebp,%ebp
  jmp    L40
```

assistant: ```c
void fir_stereo(int *inp, int *coep, int firlen, int *out1p, int *out2p) {
  register int akku1 = 0, akku2 = 0, *endp;
  int n1 = (firlen / 8) * 8, n0 = firlen % 8;
  endp = coep + n1;
  while (coep != endp) {
    akku1 += *inp++ * *coep;
    akku2 += *inp++ * *coep++;
    akku1 += *inp++ * *coep;
    akku2 += *inp++ * *coep++;
    akku1 += *inp++ * *coep;
    akku2 += *inp++ * *coep++;
    akku1 += *inp++ * *coep;
    akku2 += *inp++ * *coep++;
    akku1 += *inp++ * *coep;
    akku2 += *inp++ * *coep++;
    akku1 += *inp++ * *coep;
    akku2 += *inp++ * *coep++;
    akku1 += *inp++ * *coep;
    akku2 += *inp++ * *coep++;
    akku1 += *inp++ * *coep;
    akku2 += *inp++ * *coep++;
  }
  endp = coep + n0;
  while (coep != endp) {
    akku1 += *inp++ * *coep;
    akku2 += *inp++ * *coep++;
  }
  *out1p = akku1;
  *out2p = akku2;
}
```