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

```asm
<internal_fiat_p448_sub>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  mov    %rsi,%r12
  mov    $0x8,%esi
  push   %rbp
  mov    %rdx,%rbp
  push   %rbx
  mov    %rdi,%rbx
  mov    %r12d,%edi
  sub    $0x68,%rsp
  call   <_br2_load@plt>
  lea    0x8(%r12),%edi
  mov    $0x8,%esi
  mov    %rax,0x8(%rsp)
  call   <_br2_load@plt>
  lea    0x10(%r12),%edi
  mov    $0x8,%esi
  mov    %rax,%r15
  call   <_br2_load@plt>
  lea    0x18(%r12),%edi
  mov    $0x8,%esi
  mov    %rax,0x10(%rsp)
  call   <_br2_load@plt>
  lea    0x20(%r12),%edi
  mov    $0x8,%esi
  mov    %rax,0x18(%rsp)
  call   <_br2_load@plt>
  lea    0x28(%r12),%edi
  mov    $0x8,%esi
  mov    %rax,0x20(%rsp)
  call   <_br2_load@plt>
  lea    0x30(%r12),%edi
  mov    $0x8,%esi
  mov    %rax,0x28(%rsp)
  call   <_br2_load@plt>
  lea    0x38(%r12),%edi
  mov    $0x8,%esi
  mov    %rax,0x30(%rsp)
  call   <_br2_load@plt>
  mov    %ebp,%edi
  mov    $0x8,%esi
  mov    %rax,0x38(%rsp)
  call   <_br2_load@plt>
  lea    0x8(%rbp),%edi
  mov    $0x8,%esi
  mov    %rax,%r12
  call   <_br2_load@plt>
  lea    0x10(%rbp),%edi
  mov    $0x8,%esi
  mov    %rax,%r14
  call   <_br2_load@plt>
  lea    0x18(%rbp),%edi
  mov    $0x8,%esi
  mov    %rax,%r13
  call   <_br2_load@plt>
  lea    0x20(%rbp),%edi
  mov    $0x8,%esi
  mov    %rax,0x58(%rsp)
  call   <_br2_load@plt>
  lea    0x28(%rbp),%edi
  mov    $0x8,%esi
  mov    %rax,0x50(%rsp)
  call   <_br2_load@plt>
  lea    0x30(%rbp),%edi
  mov    $0x8,%esi
  mov    %rax,0x48(%rsp)
  call   <_br2_load@plt>
  lea    0x38(%rbp),%edi
  mov    $0x8,%esi
  movabs $0x1fffffffffffffc,%rbp
  mov    %rax,0x40(%rsp)
  call   <_br2_load@plt>
  mov    0x58(%rsp),%r9
  mov    0x50(%rsp),%r8
  movabs $0x1fffffffffffffe,%rsi
  add    %rsi,%r15
  add    0x20(%rsp),%rbp
  mov    0x38(%rsp),%r10
  mov    %ebx,%edi
  sub    %r14,%r15
  mov    0x10(%rsp),%r14
  sub    %r8,%rbp
  mov    0x28(%rsp),%r8
  mov    0x48(%rsp),%rcx
  mov    0x40(%rsp),%rdx
  add    %rsi,%r10
  add    %rsi,%r14
  add    %rsi,%r8
  sub    %rax,%r10
  sub    %r13,%r14
  mov    0x18(%rsp),%r13
  sub    %rcx,%r8
  mov    %r10,0x10(%rsp)
  mov    %r8,0x20(%rsp)
  add    %rsi,%r13
  sub    %r9,%r13
  mov    0x30(%rsp),%r9
  add    %rsi,%r9
  add    0x8(%rsp),%rsi
  sub    %rdx,%r9
  sub    %r12,%rsi
  mov    $0x8,%edx
  mov    %r9,0x18(%rsp)
  call   <_br2_store@plt>
  lea    0x8(%rbx),%edi
  mov    %r15,%rsi
  mov    $0x8,%edx
  call   <_br2_store@plt>
  lea    0x10(%rbx),%edi
  mov    %r14,%rsi
  mov    $0x8,%edx
  call   <_br2_store@plt>
  lea    0x18(%rbx),%edi
  mov    %r13,%rsi
  mov    $0x8,%edx
  call   <_br2_store@plt>
  lea    0x20(%rbx),%edi
  mov    %rbp,%rsi
  mov    $0x8,%edx
  call   <_br2_store@plt>
  mov    0x20(%rsp),%rsi
  lea    0x28(%rbx),%edi
  mov    $0x8,%edx
  call   <_br2_store@plt>
  mov    0x18(%rsp),%rsi
  lea    0x30(%rbx),%edi
  mov    $0x8,%edx
  call   <_br2_store@plt>
  mov    0x10(%rsp),%rsi
  add    $0x68,%rsp
  lea    0x38(%rbx),%edi
  mov    $0x8,%edx
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  jmp    1060 <_br2_store@plt>
```

assistant: ```c
void internal_fiat_p448_sub(uintptr_t out0, uintptr_t in0, uintptr_t in1) {
  uintptr_t x0, x8, x1, x9, x2, x10, x3, x11, x4, x12, x5, x13, x6, x14, x7, x15, x16, x17, x18, x19, x20, x21, x22, x23, x24, x25, x26, x27, x28, x29, x30, x31;
  x0 = _br2_load((in0) + ((uintptr_t)0ULL), sizeof(uintptr_t));
  x1 = _br2_load((in0) + ((uintptr_t)8ULL), sizeof(uintptr_t));
  x2 = _br2_load((in0) + ((uintptr_t)16ULL), sizeof(uintptr_t));
  x3 = _br2_load((in0) + ((uintptr_t)24ULL), sizeof(uintptr_t));
  x4 = _br2_load((in0) + ((uintptr_t)32ULL), sizeof(uintptr_t));
  x5 = _br2_load((in0) + ((uintptr_t)40ULL), sizeof(uintptr_t));
  x6 = _br2_load((in0) + ((uintptr_t)48ULL), sizeof(uintptr_t));
  x7 = _br2_load((in0) + ((uintptr_t)56ULL), sizeof(uintptr_t));
  x8 = _br2_load((in1) + ((uintptr_t)0ULL), sizeof(uintptr_t));
  x9 = _br2_load((in1) + ((uintptr_t)8ULL), sizeof(uintptr_t));
  x10 = _br2_load((in1) + ((uintptr_t)16ULL), sizeof(uintptr_t));
  x11 = _br2_load((in1) + ((uintptr_t)24ULL), sizeof(uintptr_t));
  x12 = _br2_load((in1) + ((uintptr_t)32ULL), sizeof(uintptr_t));
  x13 = _br2_load((in1) + ((uintptr_t)40ULL), sizeof(uintptr_t));
  x14 = _br2_load((in1) + ((uintptr_t)48ULL), sizeof(uintptr_t));
  x15 = _br2_load((in1) + ((uintptr_t)56ULL), sizeof(uintptr_t));
  x16 = (((uintptr_t)144115188075855870ULL) + (x0)) - (x8);
  x17 = (((uintptr_t)144115188075855870ULL) + (x1)) - (x9);
  x18 = (((uintptr_t)144115188075855870ULL) + (x2)) - (x10);
  x19 = (((uintptr_t)144115188075855870ULL) + (x3)) - (x11);
  x20 = (((uintptr_t)144115188075855868ULL) + (x4)) - (x12);
  x21 = (((uintptr_t)144115188075855870ULL) + (x5)) - (x13);
  x22 = (((uintptr_t)144115188075855870ULL) + (x6)) - (x14);
  x23 = (((uintptr_t)144115188075855870ULL) + (x7)) - (x15);
  x24 = x16;
  x25 = x17;
  x26 = x18;
  x27 = x19;
  x28 = x20;
  x29 = x21;
  x30 = x22;
  x31 = x23;
  _br2_store((out0) + ((uintptr_t)0ULL), x24, sizeof(uintptr_t));
  _br2_store((out0) + ((uintptr_t)8ULL), x25, sizeof(uintptr_t));
  _br2_store((out0) + ((uintptr_t)16ULL), x26, sizeof(uintptr_t));
  _br2_store((out0) + ((uintptr_t)24ULL), x27, sizeof(uintptr_t));
  _br2_store((out0) + ((uintptr_t)32ULL), x28, sizeof(uintptr_t));
  _br2_store((out0) + ((uintptr_t)40ULL), x29, sizeof(uintptr_t));
  _br2_store((out0) + ((uintptr_t)48ULL), x30, sizeof(uintptr_t));
  _br2_store((out0) + ((uintptr_t)56ULL), x31, sizeof(uintptr_t));
  return;
}
```