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

```asm
<pd_add>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x38,%rsp
  mov    %rdi,%r12
  mov    %rsi,%r13
  mov    %rdx,%rbp
  mov    %fs:0x28,%rax
  mov    %rax,0x28(%rsp)
  xor    %eax,%eax
  lea    0x20(%rsp),%rbx
  movsd  0x20(%rdi),%xmm0
  mov    %rbx,%rdi
  movsd  0x20(%rsi),%xmm1
  call   <dd_two_sum@plt>
  movq   %xmm0,%r14
  pxor   %xmm0,%xmm0
  addsd  0x20(%rsp),%xmm0
  movsd  %xmm0,(%rsp)
  movsd  0x18(%r12),%xmm0
  mov    %rbx,%rdi
  movsd  0x18(%r13),%xmm1
  call   <dd_two_sum@plt>
  movq   %xmm0,%r15
  mov    %rbx,%rdi
  movsd  0x20(%rsp),%xmm1
  movq   %r14,%xmm0
  call   <dd_two_sum@plt>
  movq   %xmm0,%r14
  movsd  (%rsp),%xmm0
  addsd  0x20(%rsp),%xmm0
  movsd  %xmm0,(%rsp)
  movsd  0x10(%r12),%xmm0
  mov    %rbx,%rdi
  movsd  0x10(%r13),%xmm1
  call   <dd_two_sum@plt>
  movsd  %xmm0,0x8(%rsp)
  mov    %rbx,%rdi
  movsd  0x20(%rsp),%xmm1
  movq   %r15,%xmm0
  call   <dd_two_sum@plt>
  movq   %xmm0,%r15
  mov    %rbx,%rdi
  movsd  0x20(%rsp),%xmm1
  movq   %r14,%xmm0
  call   <dd_two_sum@plt>
  movq   %xmm0,%r14
  movsd  (%rsp),%xmm0
  addsd  0x20(%rsp),%xmm0
  movsd  %xmm0,(%rsp)
  movsd  0x8(%r12),%xmm0
  mov    %rbx,%rdi
  movsd  0x8(%r13),%xmm1
  call   <dd_two_sum@plt>
  movsd  %xmm0,0x10(%rsp)
  mov    %rbx,%rdi
  movsd  0x20(%rsp),%xmm1
  movsd  0x8(%rsp),%xmm0
  call   <dd_two_sum@plt>
  movsd  %xmm0,0x8(%rsp)
  mov    %rbx,%rdi
  movsd  0x20(%rsp),%xmm1
  movq   %r15,%xmm0
  call   <dd_two_sum@plt>
  movq   %xmm0,%r15
  mov    %rbx,%rdi
  movsd  0x20(%rsp),%xmm1
  movq   %r14,%xmm0
  call   <dd_two_sum@plt>
  movsd  %xmm0,0x18(%rsp)
  movsd  (%rsp),%xmm0
  addsd  0x20(%rsp),%xmm0
  movsd  %xmm0,(%rsp)
  mov    %rbx,%rdi
  movsd  0x0(%r13),%xmm1
  movsd  (%r12),%xmm0
  call   <dd_two_sum@plt>
  movq   %xmm0,%r14
  mov    %rbx,%rdi
  movsd  0x20(%rsp),%xmm1
  movsd  0x10(%rsp),%xmm0
  call   <dd_two_sum@plt>
  movq   %xmm0,%r12
  mov    %rbx,%rdi
  movsd  0x20(%rsp),%xmm1
  movsd  0x8(%rsp),%xmm0
  call   <dd_two_sum@plt>
  movq   %xmm0,%r13
  mov    %rbx,%rdi
  movsd  0x20(%rsp),%xmm1
  movq   %r15,%xmm0
  call   <dd_two_sum@plt>
  movq   %xmm0,%r15
  mov    %rbx,%rdi
  movsd  0x20(%rsp),%xmm1
  movsd  0x18(%rsp),%xmm0
  call   <dd_two_sum@plt>
  movapd %xmm0,%xmm4
  lea    0x18(%rbp),%rcx
  lea    0x10(%rbp),%rdx
  lea    0x8(%rbp),%rsi
  lea    0x20(%rbp),%r8
  mov    %rbp,%rdi
  movsd  (%rsp),%xmm5
  addsd  0x20(%rsp),%xmm5
  movq   %r15,%xmm3
  movq   %r13,%xmm2
  movq   %r12,%xmm1
  movq   %r14,%xmm0
  call   <pd_fast_renorm@plt>
  mov    0x28(%rsp),%rax
  sub    %fs:0x28,%rax
  jne    L2
  add    $0x38,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L2:
  call   <__stack_chk_fail@plt>
```

assistant: ```c
void pd_add(const double *a, const double *b, double *c) {
  double f0, f1, f2, f3, f4, f5, e;
  f5 = 0.0;
  f4 = dd_two_sum(a[4], b[4], &e);
  f5 = f5 + e;
  f3 = dd_two_sum(a[3], b[3], &e);
  f4 = dd_two_sum(f4, e, &e);
  f5 = f5 + e;
  f2 = dd_two_sum(a[2], b[2], &e);
  f3 = dd_two_sum(f3, e, &e);
  f4 = dd_two_sum(f4, e, &e);
  f5 = f5 + e;
  f1 = dd_two_sum(a[1], b[1], &e);
  f2 = dd_two_sum(f2, e, &e);
  f3 = dd_two_sum(f3, e, &e);
  f4 = dd_two_sum(f4, e, &e);
  f5 = f5 + e;
  f0 = dd_two_sum(a[0], b[0], &e);
  f1 = dd_two_sum(f1, e, &e);
  f2 = dd_two_sum(f2, e, &e);
  f3 = dd_two_sum(f3, e, &e);
  f4 = dd_two_sum(f4, e, &e);
  f5 = f5 + e;
  pd_fast_renorm(f0, f1, f2, f3, f4, f5, &c[0], &c[1], &c[2], &c[3], &c[4]);
}
```