user: What would the C source look like for the assembly code provided here?

```asm
<double_to_ieee_80>:
  endbr64
  push   %r13
  movapd %xmm0,%xmm2
  pxor   %xmm0,%xmm0
  push   %r12
  push   %rbp
  xor    %ebp,%ebp
  push   %rbx
  mov    %rdi,%rbx
  sub    $0x18,%rsp
  comisd %xmm2,%xmm0
  jbe    L39
  xorpd  D3(%rip),%xmm2
  mov    $0xffffff80,%ebp
L39:
  ucomisd %xmm0,%xmm2
  jp     L1
  jne    L1
  xor    %edx,%edx
  xor    %r10d,%r10d
  xor    %esi,%esi
  xor    %edi,%edi
  xor    %r13d,%r13d
  xor    %r11d,%r11d
  xor    %r8d,%r8d
  xor    %r9d,%r9d
  xor    %ecx,%ecx
L25:
  mov    %bpl,(%rbx)
  mov    %r13b,0x5(%rbx)
  mov    %cl,0x1(%rbx)
  mov    %r9b,0x2(%rbx)
  mov    %r8b,0x3(%rbx)
  mov    %r11b,0x4(%rbx)
  mov    %dil,0x6(%rbx)
  mov    %sil,0x7(%rbx)
  mov    %r10b,0x8(%rbx)
  mov    %dl,0x9(%rbx)
  add    $0x18,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  ret
  nopl   (%rax)
L1:
  movapd %xmm2,%xmm0
  movsd  %xmm2,0x8(%rsp)
  call   <log@plt>
  divsd  D56(%rip),%xmm0
  addsd  D6(%rip),%xmm0
  movsd  D15(%rip),%xmm1
  cvttsd2si %xmm0,%r13d
  pxor   %xmm0,%xmm0
  movswl %r13w,%eax
  cvtsi2sd %eax,%xmm0
  subsd  %xmm0,%xmm1
  movsd  D22(%rip),%xmm0
  call   <pow@plt>
  movsd  0x8(%rsp),%xmm2
  mulsd  %xmm0,%xmm2
  movapd %xmm2,%xmm0
  movsd  %xmm2,0x8(%rsp)
  call   <myDoubleToUlong@plt>
  mov    %rax,%rdi
  mov    %rax,%r12
  call   <myUlongToDouble@plt>
  pxor   %xmm0,%xmm0
  movsd  0x8(%rsp),%xmm2
  cvtsi2sd %rax,%xmm0
  subsd  %xmm0,%xmm2
  mulsd  D47(%rip),%xmm2
  movapd %xmm2,%xmm0
  call   <myDoubleToUlong@plt>
  mov    %r12,%r9
  mov    %r12,%r8
  mov    %r13d,%ecx
  shr    $0x18,%r9
  mov    %rax,%rdx
  mov    %r13d,%eax
  shr    $0x10,%r8
  sar    $0x8,%ax
  mov    %rdx,%rdi
  mov    %rdx,%rsi
  mov    %r12d,%r13d
  shr    $0x18,%rdi
  or     %eax,%ebp
  mov    %r12,%rax
  shr    $0x10,%rsi
  movzbl %ah,%eax
  mov    %rax,%r11
  movzbl %dh,%eax
  mov    %rax,%r10
  jmp    L25
```

tool_calls: name: unpack_data
arguments: label: D3
type_guessed: f32[4]
name: unpack_data
arguments: label: D56
type_guessed: byte[8]
name: unpack_data
arguments: label: D6
type_guessed: f64
name: unpack_data
arguments: label: D15
type_guessed: f32[2]
name: unpack_data
arguments: label: D22
type_guessed: f64
name: unpack_data
arguments: label: D47
type_guessed: f32[2]

tool: {"D3": [0.0,-0.0,0.0,0.0]}

tool: {"D56": [0xef,0x39,0xfa,0xfe,0x42,0x2e,0xe6,0x3f]}

tool: D6: 16383

tool: {"D15": [0.0,6.50091552734375]}

tool: D22: 2

tool: {"D47": [0.0,30.0]}

assistant: ```c
void double_to_ieee_80(double val, unsigned char *p) {
  char sign = 0;
  short exp = 0;
  unsigned long mant1 = 0;
  unsigned long mant0 = 0;
  if (val < 0.0) {
    sign = 1;
    val = -val;
  }
  if (val != 0.0) {
    exp = (short)(log(val) / log(2.0) + 16383.0);
    val *= pow(2.0, 31.0 + 16383.0 - (double)exp);
    mant1 = myDoubleToUlong(val);
    val -= myUlongToDouble(mant1);
    val *= pow(2.0, 32.0);
    mant0 = myDoubleToUlong(val);
  }
  *p++ = ((sign << 7) | (exp >> 8));
  *p++ = 0xFF & exp;
  *p++ = (char)(0xFF & (mant1 >> 24));
  *p++ = (char)(0xFF & (mant1 >> 16));
  *p++ = (char)(0xFF & (mant1 >> 8));
  *p++ = (char)(0xFF & (mant1));
  *p++ = (char)(0xFF & (mant0 >> 24));
  *p++ = (char)(0xFF & (mant0 >> 16));
  *p++ = (char)(0xFF & (mant0 >> 8));
  *p++ = (char)(0xFF & (mant0));
}
```