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

```asm
<bn_mul_normal>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  push   %rbx
  sub    $0x48,%rsp
  mov    %rdi,-0x38(%rbp)
  mov    %rsi,-0x40(%rbp)
  mov    %edx,-0x44(%rbp)
  mov    %rcx,-0x50(%rbp)
  mov    %r8d,-0x48(%rbp)
  mov    -0x44(%rbp),%eax
  cmp    -0x48(%rbp),%eax
  jge    L84
  mov    -0x44(%rbp),%eax
  mov    %eax,-0x24(%rbp)
  mov    -0x48(%rbp),%eax
  mov    %eax,-0x44(%rbp)
  mov    -0x24(%rbp),%eax
  mov    %eax,-0x48(%rbp)
  mov    -0x40(%rbp),%rax
  mov    %rax,-0x18(%rbp)
  mov    -0x50(%rbp),%rax
  mov    %rax,-0x40(%rbp)
  mov    -0x18(%rbp),%rax
  mov    %rax,-0x50(%rbp)
L84:
  mov    -0x44(%rbp),%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x38(%rbp),%rax
  add    %rdx,%rax
  mov    %rax,-0x20(%rbp)
  cmpl   $0x0,-0x48(%rbp)
  jg     L82
  mov    -0x44(%rbp),%edx
  mov    -0x40(%rbp),%rsi
  mov    -0x38(%rbp),%rax
  mov    $0x0,%ecx
  mov    %rax,%rdi
  call   <bn_mul_words@plt>
  jmp    L42
L82:
  mov    -0x50(%rbp),%rax
  mov    (%rax),%ecx
  mov    -0x44(%rbp),%edx
  mov    -0x40(%rbp),%rsi
  mov    -0x38(%rbp),%rax
  mov    %rax,%rdi
  call   <bn_mul_words@plt>
  mov    -0x20(%rbp),%rdx
  mov    %eax,(%rdx)
L20:
  subl   $0x1,-0x48(%rbp)
  cmpl   $0x0,-0x48(%rbp)
  jle    L4
  mov    -0x50(%rbp),%rax
  add    $0x4,%rax
  mov    (%rax),%ecx
  mov    -0x38(%rbp),%rax
  lea    0x4(%rax),%rdi
  mov    -0x20(%rbp),%rax
  lea    0x4(%rax),%rbx
  mov    -0x44(%rbp),%edx
  mov    -0x40(%rbp),%rax
  mov    %rax,%rsi
  call   <bn_mul_add_words@plt>
  mov    %eax,(%rbx)
  subl   $0x1,-0x48(%rbp)
  cmpl   $0x0,-0x48(%rbp)
  jle    L106
  mov    -0x50(%rbp),%rax
  add    $0x8,%rax
  mov    (%rax),%ecx
  mov    -0x38(%rbp),%rax
  lea    0x8(%rax),%rdi
  mov    -0x20(%rbp),%rax
  lea    0x8(%rax),%rbx
  mov    -0x44(%rbp),%edx
  mov    -0x40(%rbp),%rax
  mov    %rax,%rsi
  call   <bn_mul_add_words@plt>
  mov    %eax,(%rbx)
  subl   $0x1,-0x48(%rbp)
  cmpl   $0x0,-0x48(%rbp)
  jle    L66
  mov    -0x50(%rbp),%rax
  add    $0xc,%rax
  mov    (%rax),%ecx
  mov    -0x38(%rbp),%rax
  lea    0xc(%rax),%rdi
  mov    -0x20(%rbp),%rax
  lea    0xc(%rax),%rbx
  mov    -0x44(%rbp),%edx
  mov    -0x40(%rbp),%rax
  mov    %rax,%rsi
  call   <bn_mul_add_words@plt>
  mov    %eax,(%rbx)
  subl   $0x1,-0x48(%rbp)
  cmpl   $0x0,-0x48(%rbp)
  jle    L55
  mov    -0x50(%rbp),%rax
  add    $0x10,%rax
  mov    (%rax),%ecx
  mov    -0x38(%rbp),%rax
  lea    0x10(%rax),%rdi
  mov    -0x20(%rbp),%rax
  lea    0x10(%rax),%rbx
  mov    -0x44(%rbp),%edx
  mov    -0x40(%rbp),%rax
  mov    %rax,%rsi
  call   <bn_mul_add_words@plt>
  mov    %eax,(%rbx)
  addq   $0x10,-0x20(%rbp)
  addq   $0x10,-0x38(%rbp)
  addq   $0x10,-0x50(%rbp)
  jmp    L20
L4:
  nop
  jmp    L42
L106:
  nop
  jmp    L42
L66:
  nop
  jmp    L42
L55:
  nop
L42:
  mov    -0x8(%rbp),%rbx
  leave
  ret
```

assistant: ```c
void bn_mul_normal(unsigned int *r, unsigned int *a, int na, unsigned int *b, int nb) {
  unsigned int *rr;
  if (na < nb) {
    int itmp;
    unsigned int *ltmp;
    itmp = na;
    na = nb;
    nb = itmp;
    ltmp = a;
    a = b;
    b = ltmp;
  }
  rr = &(r[na]);
  if (nb <= 0) {
    (void)bn_mul_words(r, a, na, 0);
    return;
  } else
    rr[0] = bn_mul_words(r, a, na, b[0]);
  for (;;) {
    if (--nb <= 0)
      return;
    rr[1] = bn_mul_add_words(&(r[1]), a, na, b[1]);
    if (--nb <= 0)
      return;
    rr[2] = bn_mul_add_words(&(r[2]), a, na, b[2]);
    if (--nb <= 0)
      return;
    rr[3] = bn_mul_add_words(&(r[3]), a, na, b[3]);
    if (--nb <= 0)
      return;
    rr[4] = bn_mul_add_words(&(r[4]), a, na, b[4]);
    rr += 4;
    r += 4;
    b += 4;
  }
}
```