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

```asm
<ddot>:
  endbr64
  mov    %edi,%eax
  test   %edi,%edi
  jle    L135
  cmp    $0x1,%edx
  jne    L142
  cmp    $0x1,%r8d
  jne    L142
  movslq %edi,%rdx
  sar    $0x1f,%edi
  imul   $0x66666667,%rdx,%rdx
  sar    $0x21,%rdx
  sub    %edi,%edx
  lea    (%rdx,%rdx,4),%edi
  mov    %eax,%edx
  sub    %edi,%edx
  je     L117
  cmp    $0x1,%edx
  je     L132
  movupd (%rsi),%xmm1
  movupd (%rcx),%xmm6
  pxor   %xmm0,%xmm0
  mov    %edx,%edi
  shr    %edi
  mulpd  %xmm6,%xmm1
  addsd  %xmm1,%xmm0
  unpckhpd %xmm1,%xmm1
  addsd  %xmm1,%xmm0
  cmp    $0x2,%edi
  je     L53
  cmp    $0x2,%edx
  je     L56
  mov    $0x2,%edi
L144:
  movsd  (%rcx,%rdi,8),%xmm1
  mulsd  (%rsi,%rdi,8),%xmm1
  addsd  %xmm1,%xmm0
L56:
  cmp    $0x4,%eax
  jg     L61
  ret
  nopl   0x0(%rax)
L142:
  xor    %r9d,%r9d
  test   %edx,%edx
  js     L37
  xor    %edi,%edi
  test   %r8d,%r8d
  js     L165
L103:
  movslq %edx,%rdx
  movslq %r9d,%r9
  movslq %r8d,%r8
  movslq %edi,%rdi
  lea    (%rsi,%r9,8),%r9
  shl    $0x3,%rdx
  lea    (%rcx,%rdi,8),%rsi
  shl    $0x3,%r8
  xor    %ecx,%ecx
  pxor   %xmm0,%xmm0
L183:
  movsd  (%r9),%xmm1
  mulsd  (%rsi),%xmm1
  add    $0x1,%ecx
  add    %rdx,%r9
  add    %r8,%rsi
  addsd  %xmm1,%xmm0
  cmp    %ecx,%eax
  jne    L183
  ret
  nopl   0x0(%rax,%rax,1)
L135:
  pxor   %xmm0,%xmm0
L21:
  ret
  nopl   (%rax)
L117:
  pxor   %xmm0,%xmm0
L61:
  lea    -0x1(%rax),%edi
  mov    $0xcccccccd,%r8d
  sub    %edx,%edi
  mov    %edi,%r9d
  imul   %r8,%r9
  mov    $0x1,%r8d
  shr    $0x22,%r9
  add    $0x1,%r9d
  cmp    %eax,%edx
  cmovge %r8d,%r9d
  cmp    $0x4,%edi
  jbe    L143
  cmp    %eax,%edx
  jge    L143
  mov    %r9d,%r8d
  movslq %edx,%rax
  shr    %r8d
  shl    $0x3,%rax
  sub    $0x1,%r8d
  lea    (%rcx,%rax,1),%rdi
  add    %rsi,%rax
  lea    (%r8,%r8,4),%r10
  lea    0x50(%rdi),%r8
  shl    $0x4,%r10
  add    %r8,%r10
  jmp    L36
  nopl   0x0(%rax)
L59:
  add    $0x50,%r8
L36:
  movupd (%rax),%xmm7
  movupd (%rdi),%xmm2
  add    $0x50,%rax
  movupd -0x40(%rax),%xmm6
  movupd 0x10(%rdi),%xmm1
  mulpd  %xmm7,%xmm2
  movupd 0x20(%rdi),%xmm4
  movupd -0x30(%rax),%xmm7
  mulpd  %xmm6,%xmm1
  movupd 0x30(%rdi),%xmm3
  movupd -0x20(%rax),%xmm6
  mulpd  %xmm7,%xmm4
  movupd 0x40(%rdi),%xmm5
  movupd -0x10(%rax),%xmm7
  mov    %r8,%rdi
  mulpd  %xmm6,%xmm3
  mulpd  %xmm7,%xmm5
  addsd  %xmm2,%xmm0
  unpckhpd %xmm2,%xmm2
  addsd  %xmm0,%xmm2
  movapd %xmm1,%xmm0
  unpckhpd %xmm1,%xmm1
  addsd  %xmm2,%xmm0
  addsd  %xmm0,%xmm1
  movapd %xmm4,%xmm0
  unpckhpd %xmm4,%xmm4
  addsd  %xmm1,%xmm0
  addsd  %xmm0,%xmm4
  movapd %xmm3,%xmm0
  unpckhpd %xmm3,%xmm3
  addsd  %xmm4,%xmm0
  addsd  %xmm0,%xmm3
  movapd %xmm5,%xmm0
  unpckhpd %xmm5,%xmm5
  addsd  %xmm3,%xmm0
  addsd  %xmm5,%xmm0
  cmp    %r8,%r10
  jne    L59
  mov    %r9d,%eax
  and    $0xfffffffe,%eax
  lea    (%rax,%rax,4),%edi
  add    %edi,%edx
  cmp    %r9d,%eax
  je     L21
L143:
  movslq %edx,%rdx
  movsd  (%rcx,%rdx,8),%xmm1
  mulsd  (%rsi,%rdx,8),%xmm1
  lea    0x0(,%rdx,8),%rax
  addsd  %xmm0,%xmm1
  movsd  0x8(%rcx,%rax,1),%xmm0
  mulsd  0x8(%rsi,%rax,1),%xmm0
  addsd  %xmm0,%xmm1
  movsd  0x10(%rcx,%rax,1),%xmm0
  mulsd  0x10(%rsi,%rax,1),%xmm0
  addsd  %xmm0,%xmm1
  movsd  0x18(%rcx,%rax,1),%xmm0
  mulsd  0x18(%rsi,%rax,1),%xmm0
  addsd  %xmm0,%xmm1
  movsd  0x20(%rcx,%rax,1),%xmm0
  mulsd  0x20(%rsi,%rax,1),%xmm0
  addsd  %xmm1,%xmm0
  ret
  nopw   0x0(%rax,%rax,1)
L53:
  movupd 0x10(%rcx),%xmm1
  movupd 0x10(%rsi),%xmm7
  mulpd  %xmm7,%xmm1
  addsd  %xmm1,%xmm0
  unpckhpd %xmm1,%xmm1
  addsd  %xmm1,%xmm0
  jmp    L56
  nop
L165:
  mov    $0x1,%edi
  sub    %eax,%edi
  imul   %r8d,%edi
  jmp    L103
L37:
  mov    $0x1,%r9d
  xor    %edi,%edi
  sub    %eax,%r9d
  imul   %edx,%r9d
  test   %r8d,%r8d
  jns    L103
  jmp    L165
L132:
  xor    %edi,%edi
  pxor   %xmm0,%xmm0
  jmp    L144
```

assistant: ```c
double ddot(int n, double dx[], int incx, double dy[], int incy) {
  double dtemp;
  int i, ix, iy, m, mp1;
  mp1 = 0;
  m = 0;
  dtemp = 0.0e0;
  if (n <= 0)
    return (0.0e0);
  if (incx != 1 || incy != 1) {
    ix = 0;
    iy = 0;
    if (incx < 0)
      ix = (-n + 1) * incx;
    if (incy < 0)
      iy = (-n + 1) * incy;
    for (i = 0; i < n; i++) {
      dtemp = dtemp + dx[ix] * dy[iy];
      ix = ix + incx;
      iy = iy + incy;
    }
    return (dtemp);
  }
  m = n % 5;
  if (m != 0) {
    for (i = 0; i < m; i++)
      dtemp = dtemp + dx[i] * dy[i];
    if (n < 5)
      return (dtemp);
  }
  for (i = m; i < n; i = i + 5) {
    dtemp = dtemp + dx[i] * dy[i] + dx[i + 1] * dy[i + 1] + dx[i + 2] * dy[i + 2] + dx[i + 3] * dy[i + 3] + dx[i + 4] * dy[i + 4];
  }
  return (dtemp);
}
```