user: 请从给定的汇编指令推导出C源代码：

```asm
<draw_block4x4_rg11_eac>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x30,%rsp
  mov    %rdi,-0x18(%rbp)
  mov    %rsi,-0x20(%rbp)
  mov    %edx,-0x24(%rbp)
  mov    -0x18(%rbp),%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  mov    $0x38,%edx
  mov    %edx,%ecx
  shl    %cl,%eax
  mov    %eax,%esi
  mov    -0x18(%rbp),%rax
  add    $0x1,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  mov    $0x30,%edx
  mov    %edx,%ecx
  shl    %cl,%eax
  or     %eax,%esi
  mov    -0x18(%rbp),%rax
  add    $0x2,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  mov    $0x28,%edx
  mov    %edx,%ecx
  shl    %cl,%eax
  or     %eax,%esi
  mov    -0x18(%rbp),%rax
  add    $0x3,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  mov    $0x20,%edx
  mov    %edx,%ecx
  shl    %cl,%eax
  or     %eax,%esi
  mov    %esi,%edx
  mov    -0x18(%rbp),%rax
  add    $0x4,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  shl    $0x18,%eax
  or     %eax,%edx
  mov    -0x18(%rbp),%rax
  add    $0x5,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  shl    $0x10,%eax
  or     %eax,%edx
  mov    -0x18(%rbp),%rax
  add    $0x6,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  shl    $0x8,%eax
  or     %eax,%edx
  mov    -0x18(%rbp),%rax
  add    $0x7,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  or     %edx,%eax
  mov    %eax,-0x8(%rbp)
  mov    -0x20(%rbp),%rcx
  mov    -0x8(%rbp),%eax
  mov    $0x0,%edx
  mov    %rcx,%rsi
  mov    %eax,%edi
  call   <decode_block4x4_11bits@plt>
  mov    -0x18(%rbp),%rax
  add    $0x8,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  mov    $0x38,%edx
  mov    %edx,%ecx
  shl    %cl,%eax
  mov    %eax,%esi
  mov    -0x18(%rbp),%rax
  add    $0x9,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  mov    $0x30,%edx
  mov    %edx,%ecx
  shl    %cl,%eax
  or     %eax,%esi
  mov    -0x18(%rbp),%rax
  add    $0xa,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  mov    $0x28,%edx
  mov    %edx,%ecx
  shl    %cl,%eax
  or     %eax,%esi
  mov    -0x18(%rbp),%rax
  add    $0xb,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  mov    $0x20,%edx
  mov    %edx,%ecx
  shl    %cl,%eax
  or     %eax,%esi
  mov    %esi,%edx
  mov    -0x18(%rbp),%rax
  add    $0xc,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  shl    $0x18,%eax
  or     %eax,%edx
  mov    -0x18(%rbp),%rax
  add    $0xd,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  shl    $0x10,%eax
  or     %eax,%edx
  mov    -0x18(%rbp),%rax
  add    $0xe,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  shl    $0x8,%eax
  or     %eax,%edx
  mov    -0x18(%rbp),%rax
  add    $0xf,%rax
  movzbl (%rax),%eax
  movzbl %al,%eax
  or     %edx,%eax
  mov    %eax,-0x4(%rbp)
  mov    -0x20(%rbp),%rcx
  mov    -0x4(%rbp),%eax
  mov    $0x1,%edx
  mov    %rcx,%rsi
  mov    %eax,%edi
  call   <decode_block4x4_11bits@plt>
  mov    $0x1,%eax
  leave
  ret
```

assistant: ```c
int draw_block4x4_rg11_eac(const unsigned char *bitstring, unsigned int *image_buffer, int flags) {
  uint64_t red_qword = ((uint64_t)bitstring[0] << 56) | ((uint64_t)bitstring[1] << 48) | ((uint64_t)bitstring[2] << 40) | ((uint64_t)bitstring[3] << 32) | ((uint64_t)bitstring[4] << 24) | ((uint64_t)bitstring[5] << 16) | ((uint64_t)bitstring[6] << 8) | bitstring[7];
  decode_block4x4_11bits(red_qword, image_buffer, 0);
  uint64_t green_qword = ((uint64_t)bitstring[8] << 56) | ((uint64_t)bitstring[9] << 48) | ((uint64_t)bitstring[10] << 40) | ((uint64_t)bitstring[11] << 32) | ((uint64_t)bitstring[12] << 24) | ((uint64_t)bitstring[13] << 16) | ((uint64_t)bitstring[14] << 8) | bitstring[15];
  decode_block4x4_11bits(green_qword, image_buffer, 1);
  return 1;
}
```