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

```asm
<_inner_vec_ddot>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  push   %rbx
  mov    %rdi,-0x10(%rbp)
  mov    %esi,-0x14(%rbp)
  mov    %rdx,-0x20(%rbp)
  mov    %rcx,-0x28(%rbp)
  mov    %r8d,-0x18(%rbp)
  movsd  %xmm0,-0x30(%rbp)
  mov    %r9d,-0x34(%rbp)
  pxor   %xmm6,%xmm6
  mov    $0x0,%ebx
  jmp    L22
L51:
  mov    -0x20(%rbp),%rax
  movsd  (%rax),%xmm1
  mov    -0x28(%rbp),%rax
  movsd  (%rax),%xmm0
  mulsd  %xmm1,%xmm0
  movapd %xmm0,%xmm2
  movapd %xmm6,%xmm7
  addsd  %xmm7,%xmm2
  mov    -0x20(%rbp),%rax
  add    $0x8,%rax
  movsd  (%rax),%xmm1
  mov    -0x18(%rbp),%eax
  cltq
  lea    0x0(,%rax,8),%rdx
  mov    -0x28(%rbp),%rax
  add    %rdx,%rax
  movsd  (%rax),%xmm0
  mulsd  %xmm1,%xmm0
  movapd %xmm0,%xmm3
  addsd  %xmm2,%xmm3
  mov    -0x20(%rbp),%rax
  add    $0x10,%rax
  movsd  (%rax),%xmm1
  mov    -0x18(%rbp),%eax
  add    %eax,%eax
  cltq
  lea    0x0(,%rax,8),%rdx
  mov    -0x28(%rbp),%rax
  add    %rdx,%rax
  movsd  (%rax),%xmm0
  mulsd  %xmm1,%xmm0
  movapd %xmm0,%xmm4
  addsd  %xmm3,%xmm4
  mov    -0x20(%rbp),%rax
  add    $0x18,%rax
  movsd  (%rax),%xmm1
  mov    -0x18(%rbp),%edx
  mov    %edx,%eax
  add    %eax,%eax
  add    %edx,%eax
  cltq
  lea    0x0(,%rax,8),%rdx
  mov    -0x28(%rbp),%rax
  add    %rdx,%rax
  movsd  (%rax),%xmm0
  mulsd  %xmm1,%xmm0
  addsd  %xmm4,%xmm0
  movapd %xmm0,%xmm6
  mov    -0x18(%rbp),%eax
  shl    $0x2,%eax
  cltq
  shl    $0x3,%rax
  add    %rax,-0x28(%rbp)
  addq   $0x20,-0x20(%rbp)
  add    $0x4,%ebx
L22:
  mov    -0x34(%rbp),%eax
  sub    $0x3,%eax
  cmp    %eax,%ebx
  jl     L51
  cmp    -0x34(%rbp),%ebx
  je     L12
  mov    -0x34(%rbp),%eax
  sub    $0x1,%eax
  cmp    %eax,%ebx
  jge    L21
  mov    -0x20(%rbp),%rax
  movsd  (%rax),%xmm1
  mov    -0x28(%rbp),%rax
  movsd  (%rax),%xmm0
  mulsd  %xmm1,%xmm0
  movapd %xmm0,%xmm5
  addsd  %xmm6,%xmm5
  mov    -0x20(%rbp),%rax
  add    $0x8,%rax
  movsd  (%rax),%xmm1
  mov    -0x18(%rbp),%eax
  cltq
  lea    0x0(,%rax,8),%rdx
  mov    -0x28(%rbp),%rax
  add    %rdx,%rax
  movsd  (%rax),%xmm0
  mulsd  %xmm1,%xmm0
  addsd  %xmm5,%xmm0
  movapd %xmm0,%xmm6
  mov    -0x18(%rbp),%eax
  add    %eax,%eax
  cltq
  shl    $0x3,%rax
  add    %rax,-0x28(%rbp)
  addq   $0x10,-0x20(%rbp)
  add    $0x2,%ebx
L21:
  cmp    -0x34(%rbp),%ebx
  jge    L20
  mov    -0x20(%rbp),%rax
  movsd  (%rax),%xmm1
  mov    -0x28(%rbp),%rax
  movsd  (%rax),%xmm0
  mulsd  %xmm1,%xmm0
  movapd %xmm6,%xmm7
  addsd  %xmm7,%xmm0
  movapd %xmm0,%xmm6
  mov    -0x18(%rbp),%eax
  cltq
  shl    $0x3,%rax
  add    %rax,-0x28(%rbp)
  add    $0x1,%ebx
  jmp    L44
L12:
  nop
  jmp    L44
L20:
  nop
L44:
  mov    -0x10(%rbp),%rax
  movsd  (%rax),%xmm1
  movapd %xmm6,%xmm0
  mulsd  -0x30(%rbp),%xmm0
  addsd  %xmm1,%xmm0
  mov    -0x10(%rbp),%rax
  movsd  %xmm0,(%rax)
  nop
  mov    -0x8(%rbp),%rbx
  leave
  ret
```

assistant: ```c
void _inner_vec_ddot(double *y0, int incY, const double *a0, const double *x0, int incX, double alpha, int nC) {
  register int i;
  register double ytmp;
  ytmp = 0.0;
  for (i = 0; i < nC - 3; i += 4) {
    ytmp += a0[0] * x0[0];
    ytmp += a0[1] * x0[incX];
    ytmp += a0[2] * x0[2 * incX];
    ytmp += a0[3] * x0[3 * incX];
    x0 += incX << 2;
    a0 += 4;
  }
  if (i == nC)
    goto update;
  if (i < nC - 1) {
    ytmp += a0[0] * x0[0];
    ytmp += a0[1] * x0[incX];
    x0 += incX << 1;
    a0 += 2;
    i += 2;
  }
  if (i < nC) {
    ytmp += a0[0] * x0[0];
    x0 += incX;
    i++;
  }
update:
  y0[0] += ytmp * alpha;
}
```