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

```asm
<internal_fiat_p521_carry>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  mov    %rsi,%rbp
  mov    $0x8,%esi
  push   %rbx
  mov    %rdi,%rbx
  mov    %ebp,%edi
  sub    $0x38,%rsp
  call   <_br2_load@plt>
  lea    0x8(%rbp),%edi
  mov    $0x8,%esi
  mov    %rax,0x20(%rsp)
  call   <_br2_load@plt>
  lea    0x10(%rbp),%edi
  mov    $0x8,%esi
  mov    %rax,%r15
  call   <_br2_load@plt>
  lea    0x18(%rbp),%edi
  mov    $0x8,%esi
  mov    %rax,%r14
  call   <_br2_load@plt>
  lea    0x20(%rbp),%edi
  mov    $0x8,%esi
  mov    %rax,%r13
  call   <_br2_load@plt>
  lea    0x28(%rbp),%edi
  mov    $0x8,%esi
  mov    %rax,%r12
  call   <_br2_load@plt>
  lea    0x30(%rbp),%edi
  mov    $0x8,%esi
  mov    %rax,0x8(%rsp)
  call   <_br2_load@plt>
  lea    0x38(%rbp),%edi
  mov    $0x8,%esi
  mov    %rax,0x10(%rsp)
  call   <_br2_load@plt>
  lea    0x40(%rbp),%edi
  mov    $0x8,%esi
  movabs $0x3ffffffffffffff,%rbp
  mov    %rax,0x18(%rsp)
  call   <_br2_load@plt>
  mov    0x20(%rsp),%rdx
  mov    %rax,%r9
  mov    %rdx,%rdi
  and    %rbp,%rdx
  shr    $0x3a,%rdi
  add    %r15,%rdi
  mov    %rdi,%rcx
  and    %rbp,%rdi
  shr    $0x3a,%rcx
  mov    %rcx,%rax
  add    %r14,%rax
  mov    %rax,%r14
  shr    $0x3a,%r14
  add    %r13,%r14
  mov    %r14,%r15
  shr    $0x3a,%r15
  add    %r12,%r15
  mov    %r15,%rcx
  shr    $0x3a,%rcx
  add    0x8(%rsp),%rcx
  mov    %rcx,%r8
  mov    %rcx,0x28(%rsp)
  shr    $0x3a,%r8
  add    0x10(%rsp),%r8
  mov    %r8,%r13
  mov    %r8,0x20(%rsp)
  shr    $0x3a,%r13
  add    0x18(%rsp),%r13
  mov    %r13,%r12
  shr    $0x3a,%r12
  add    %r9,%r12
  mov    %r12,%rsi
  shr    $0x39,%rsi
  add    %rdx,%rsi
  mov    $0x8,%edx
  mov    %rsi,%r9
  shr    $0x3a,%r9
  add    %rdi,%r9
  mov    %ebx,%edi
  mov    %r9,%r10
  mov    %r9,0x10(%rsp)
  shr    $0x3a,%r10
  and    %rbp,%rax
  and    %rbp,%rsi
  add    %rax,%r10
  mov    %r10,0x8(%rsp)
  call   <_br2_store@plt>
  mov    0x10(%rsp),%rsi
  lea    0x8(%rbx),%edi
  mov    $0x8,%edx
  and    %rbp,%rsi
  call   <_br2_store@plt>
  mov    0x8(%rsp),%rsi
  lea    0x10(%rbx),%edi
  mov    $0x8,%edx
  call   <_br2_store@plt>
  mov    %r14,%rsi
  lea    0x18(%rbx),%edi
  mov    $0x8,%edx
  and    %rbp,%rsi
  call   <_br2_store@plt>
  mov    %r15,%rsi
  lea    0x20(%rbx),%edi
  mov    $0x8,%edx
  and    %rbp,%rsi
  call   <_br2_store@plt>
  mov    0x28(%rsp),%rcx
  lea    0x28(%rbx),%edi
  mov    $0x8,%edx
  and    %rbp,%rcx
  mov    %rcx,%rsi
  call   <_br2_store@plt>
  mov    0x20(%rsp),%rsi
  lea    0x30(%rbx),%edi
  mov    $0x8,%edx
  and    %rbp,%rsi
  call   <_br2_store@plt>
  mov    %r13,%rsi
  lea    0x38(%rbx),%edi
  mov    $0x8,%edx
  and    %rbp,%rsi
  call   <_br2_store@plt>
  add    $0x38,%rsp
  mov    %r12,%rsi
  lea    0x40(%rbx),%edi
  movabs $0x1ffffffffffffff,%rax
  pop    %rbx
  mov    $0x8,%edx
  pop    %rbp
  and    %rax,%rsi
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  jmp    1060 <_br2_store@plt>
```

assistant: ```c
void internal_fiat_p521_carry(uintptr_t out0, uintptr_t in0) {
  uintptr_t x0, x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x18, x19, x11, x12, x13, x14, x15, x16, x17, x20, x21, x22, x23, x24, x25, x26, x27, x28, x29, x30, x31, x32, x33, x34, x35, x36, x37;
  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((in0) + ((uintptr_t)64ULL), sizeof(uintptr_t));
  x9 = x0;
  x10 = ((x9) >> ((uintptr_t)58ULL)) + (x1);
  x11 = ((x10) >> ((uintptr_t)58ULL)) + (x2);
  x12 = ((x11) >> ((uintptr_t)58ULL)) + (x3);
  x13 = ((x12) >> ((uintptr_t)58ULL)) + (x4);
  x14 = ((x13) >> ((uintptr_t)58ULL)) + (x5);
  x15 = ((x14) >> ((uintptr_t)58ULL)) + (x6);
  x16 = ((x15) >> ((uintptr_t)58ULL)) + (x7);
  x17 = ((x16) >> ((uintptr_t)58ULL)) + (x8);
  x18 = ((x9) & ((uintptr_t)288230376151711743ULL)) + ((x17) >> ((uintptr_t)57ULL));
  x19 = ((x18) >> ((uintptr_t)58ULL)) + ((x10) & ((uintptr_t)288230376151711743ULL));
  x20 = (x18) & ((uintptr_t)288230376151711743ULL);
  x21 = (x19) & ((uintptr_t)288230376151711743ULL);
  x22 = ((x19) >> ((uintptr_t)58ULL)) + ((x11) & ((uintptr_t)288230376151711743ULL));
  x23 = (x12) & ((uintptr_t)288230376151711743ULL);
  x24 = (x13) & ((uintptr_t)288230376151711743ULL);
  x25 = (x14) & ((uintptr_t)288230376151711743ULL);
  x26 = (x15) & ((uintptr_t)288230376151711743ULL);
  x27 = (x16) & ((uintptr_t)288230376151711743ULL);
  x28 = (x17) & ((uintptr_t)144115188075855871ULL);
  x29 = x20;
  x30 = x21;
  x31 = x22;
  x32 = x23;
  x33 = x24;
  x34 = x25;
  x35 = x26;
  x36 = x27;
  x37 = x28;
  _br2_store((out0) + ((uintptr_t)0ULL), x29, sizeof(uintptr_t));
  _br2_store((out0) + ((uintptr_t)8ULL), x30, sizeof(uintptr_t));
  _br2_store((out0) + ((uintptr_t)16ULL), x31, sizeof(uintptr_t));
  _br2_store((out0) + ((uintptr_t)24ULL), x32, sizeof(uintptr_t));
  _br2_store((out0) + ((uintptr_t)32ULL), x33, sizeof(uintptr_t));
  _br2_store((out0) + ((uintptr_t)40ULL), x34, sizeof(uintptr_t));
  _br2_store((out0) + ((uintptr_t)48ULL), x35, sizeof(uintptr_t));
  _br2_store((out0) + ((uintptr_t)56ULL), x36, sizeof(uintptr_t));
  _br2_store((out0) + ((uintptr_t)64ULL), x37, sizeof(uintptr_t));
  return;
}
```