user: 请将这段汇编代码片段转换成等效的C代码:

```asm
<strtobignum>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x20,%rsp
  mov    %rdi,-0x18(%rbp)
  mov    %rsi,-0x20(%rbp)
  jmp    L99
L47:
  addq   $0x1,-0x18(%rbp)
L99:
  mov    -0x18(%rbp),%rax
  movzbl (%rax),%eax
  cmp    $0x30,%al
  je     L47
  mov    -0x18(%rbp),%rax
  movzbl (%rax),%eax
  test   %al,%al
  jne    L60
  mov    -0x20(%rbp),%rax
  movl   $0x1,(%rax)
  mov    -0x20(%rbp),%rax
  add    $0x4,%rax
  movl   $0x0,(%rax)
  jmp    L11
L60:
  mov    -0x18(%rbp),%rax
  mov    %rax,%rdi
  call   <strlen@plt>
  mov    %eax,-0x4(%rbp)
  mov    -0x4(%rbp),%eax
  sub    $0x1,%eax
  lea    0x3(%rax),%edx
  test   %eax,%eax
  cmovs  %edx,%eax
  sar    $0x2,%eax
  lea    0x1(%rax),%edx
  mov    -0x20(%rbp),%rax
  mov    %edx,(%rax)
  movl   $0x1,-0x8(%rbp)
  jmp    L87
L13:
  mov    -0x8(%rbp),%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x20(%rbp),%rax
  add    %rdx,%rax
  movl   $0x0,(%rax)
  mov    -0x8(%rbp),%eax
  lea    0x0(,%rax,4),%edx
  mov    -0x4(%rbp),%eax
  sub    %edx,%eax
  mov    %eax,-0xc(%rbp)
  jmp    L42
L85:
  mov    -0x8(%rbp),%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x20(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%edx
  mov    %edx,%eax
  shl    $0x2,%eax
  add    %edx,%eax
  add    %eax,%eax
  mov    %eax,%ecx
  mov    -0xc(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movsbl %al,%eax
  lea    (%rcx,%rax,1),%edx
  mov    -0x8(%rbp),%eax
  cltq
  lea    0x0(,%rax,4),%rcx
  mov    -0x20(%rbp),%rax
  add    %rcx,%rax
  sub    $0x30,%edx
  mov    %edx,(%rax)
  addl   $0x1,-0xc(%rbp)
L42:
  mov    -0x8(%rbp),%eax
  sub    $0x1,%eax
  lea    0x0(,%rax,4),%edx
  mov    -0x4(%rbp),%eax
  sub    %edx,%eax
  cmp    %eax,-0xc(%rbp)
  jl     L85
  addl   $0x1,-0x8(%rbp)
L87:
  mov    -0x20(%rbp),%rax
  mov    (%rax),%eax
  cmp    %eax,-0x8(%rbp)
  jl     L13
  mov    -0x8(%rbp),%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x20(%rbp),%rax
  add    %rdx,%rax
  movl   $0x0,(%rax)
  movl   $0x0,-0xc(%rbp)
  jmp    L83
L1:
  mov    -0x8(%rbp),%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x20(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%edx
  mov    %edx,%eax
  shl    $0x2,%eax
  add    %edx,%eax
  add    %eax,%eax
  mov    %eax,%ecx
  mov    -0xc(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movsbl %al,%eax
  lea    (%rcx,%rax,1),%edx
  mov    -0x8(%rbp),%eax
  cltq
  lea    0x0(,%rax,4),%rcx
  mov    -0x20(%rbp),%rax
  add    %rcx,%rax
  sub    $0x30,%edx
  mov    %edx,(%rax)
  addl   $0x1,-0xc(%rbp)
L83:
  mov    -0x8(%rbp),%eax
  sub    $0x1,%eax
  lea    0x0(,%rax,4),%edx
  mov    -0x4(%rbp),%eax
  sub    %edx,%eax
  cmp    %eax,-0xc(%rbp)
  jl     L1
L11:
  leave
  ret
```

assistant: ```c
void strtobignum(char *s, int *d) {
  int a, l, t, i;
  while (*s == '0')
    s++;
  if (*s == '\0') {
    d[0] = 1;
    d[1] = 0;
    return;
  }
  l = strlen(s);
  d[0] = (l - 1) / 4 + 1;
  for (i = 1; i < d[0]; i++)
    for (d[i] = 0, a = l - 4 * i; a < l - 4 * (i - 1); a++)
      d[i] = d[i] * 10 + s[a] - '0';
  for (d[i] = 0, a = 0; a < l - 4 * (i - 1); a++)
    d[i] = d[i] * 10 + s[a] - '0';
}
```