user: 请从给定的汇编指令推导出C源代码:

```asm
<decode_integer>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  mov    %rdi,-0x18(%rbp)
  mov    %rsi,-0x20(%rbp)
  mov    -0x20(%rbp),%rax
  mov    (%rax),%eax
  lea    0x1(%rax),%edx
  mov    -0x20(%rbp),%rax
  mov    %edx,(%rax)
  mov    -0x20(%rbp),%rax
  mov    (%rax),%eax
  mov    %eax,%edx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  cmp    $0x4,%eax
  je     L13
  cmp    $0x4,%eax
  jg     L74
  cmp    $0x3,%eax
  je     L7
  cmp    $0x3,%eax
  jg     L74
  cmp    $0x1,%eax
  je     L25
  cmp    $0x2,%eax
  je     L68
  jmp    L74
L25:
  mov    -0x20(%rbp),%rax
  mov    (%rax),%eax
  lea    0x1(%rax),%edx
  mov    -0x20(%rbp),%rax
  mov    %edx,(%rax)
  mov    -0x20(%rbp),%rax
  mov    (%rax),%eax
  mov    %eax,%edx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  mov    %eax,-0x4(%rbp)
  jmp    L35
L68:
  mov    -0x20(%rbp),%rax
  mov    (%rax),%eax
  lea    0x1(%rax),%edx
  mov    -0x20(%rbp),%rax
  mov    %edx,(%rax)
  mov    -0x20(%rbp),%rax
  mov    (%rax),%eax
  mov    %eax,%edx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  mov    %eax,-0x4(%rbp)
  shll   $0x8,-0x4(%rbp)
  mov    -0x20(%rbp),%rax
  mov    (%rax),%eax
  lea    0x1(%rax),%edx
  mov    -0x20(%rbp),%rax
  mov    %edx,(%rax)
  mov    -0x20(%rbp),%rax
  mov    (%rax),%eax
  mov    %eax,%edx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  or     %eax,-0x4(%rbp)
  jmp    L35
L7:
  mov    -0x20(%rbp),%rax
  mov    (%rax),%eax
  lea    0x1(%rax),%edx
  mov    -0x20(%rbp),%rax
  mov    %edx,(%rax)
  mov    -0x20(%rbp),%rax
  mov    (%rax),%eax
  mov    %eax,%edx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  mov    %eax,-0x4(%rbp)
  shll   $0x8,-0x4(%rbp)
  mov    -0x20(%rbp),%rax
  mov    (%rax),%eax
  lea    0x1(%rax),%edx
  mov    -0x20(%rbp),%rax
  mov    %edx,(%rax)
  mov    -0x20(%rbp),%rax
  mov    (%rax),%eax
  mov    %eax,%edx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  or     %eax,-0x4(%rbp)
  shll   $0x8,-0x4(%rbp)
  mov    -0x20(%rbp),%rax
  mov    (%rax),%eax
  lea    0x1(%rax),%edx
  mov    -0x20(%rbp),%rax
  mov    %edx,(%rax)
  mov    -0x20(%rbp),%rax
  mov    (%rax),%eax
  mov    %eax,%edx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  or     %eax,-0x4(%rbp)
  jmp    L35
L13:
  mov    -0x20(%rbp),%rax
  mov    (%rax),%eax
  lea    0x1(%rax),%edx
  mov    -0x20(%rbp),%rax
  mov    %edx,(%rax)
  mov    -0x20(%rbp),%rax
  mov    (%rax),%eax
  mov    %eax,%edx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  mov    %eax,-0x4(%rbp)
  shll   $0x8,-0x4(%rbp)
  mov    -0x20(%rbp),%rax
  mov    (%rax),%eax
  lea    0x1(%rax),%edx
  mov    -0x20(%rbp),%rax
  mov    %edx,(%rax)
  mov    -0x20(%rbp),%rax
  mov    (%rax),%eax
  mov    %eax,%edx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  or     %eax,-0x4(%rbp)
  shll   $0x8,-0x4(%rbp)
  mov    -0x20(%rbp),%rax
  mov    (%rax),%eax
  lea    0x1(%rax),%edx
  mov    -0x20(%rbp),%rax
  mov    %edx,(%rax)
  mov    -0x20(%rbp),%rax
  mov    (%rax),%eax
  mov    %eax,%edx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  or     %eax,-0x4(%rbp)
  shll   $0x8,-0x4(%rbp)
  mov    -0x20(%rbp),%rax
  mov    (%rax),%eax
  lea    0x1(%rax),%edx
  mov    -0x20(%rbp),%rax
  mov    %edx,(%rax)
  mov    -0x20(%rbp),%rax
  mov    (%rax),%eax
  mov    %eax,%edx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  or     %eax,-0x4(%rbp)
  jmp    L35
L74:
  movl   $0x4,-0x4(%rbp)
  nop
L35:
  mov    -0x20(%rbp),%rax
  mov    (%rax),%eax
  lea    0x1(%rax),%edx
  mov    -0x20(%rbp),%rax
  mov    %edx,(%rax)
  mov    -0x4(%rbp),%eax
  pop    %rbp
  ret
```

assistant: ```c
int decode_integer(unsigned char *array, unsigned int *pointer) {
  unsigned int buffer;
  switch (array[++*pointer]) {
  case 0x01:
    buffer = array[++*pointer];
    break;
  case 0x02:
    buffer = array[++*pointer];
    buffer <<= 8;
    buffer |= array[++*pointer];
    break;
  case 0x03:
    buffer = array[++*pointer];
    buffer <<= 8;
    buffer |= array[++*pointer];
    buffer <<= 8;
    buffer |= array[++*pointer];
    break;
  case 0x04:
    buffer = array[++*pointer];
    buffer <<= 8;
    buffer |= array[++*pointer];
    buffer <<= 8;
    buffer |= array[++*pointer];
    buffer <<= 8;
    buffer |= array[++*pointer];
    break;
  default:
    buffer = 4;
    break;
  }
  ++*pointer;
  return buffer;
}
```