/*
 * Copyright 2019 Google LLC. All Rights Reserved. This file and proprietary
 * source code may only be used and distributed under the Widevine Master
 * License Agreement.
 */

#include "message.h"

#include <assert.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>

/* Round up address to the nearest 8 byte boundary */
#define align_8(addr) (((uintptr_t)(addr) + 7) & ~(uintptr_t)7)

struct _Message {
  uint8_t* base;
  size_t capacity;
  size_t size;
  size_t read_offset;
  MessageStatus status;
};

/*
 * The message structure, which is separate from the buffer,
 * is initialized to reference the buffer
 */
void InitMessage(Message* message, uint8_t* buffer, size_t capacity) {
  assert(message != NULL);
  assert(buffer != NULL);
  message->base = buffer;
  message->capacity = capacity;
  message->size = 0;
  message->read_offset = 0;
  message->status = MESSAGE_STATUS_OK;
}

/*
 * Cast pointer of Message from the input buffer. Since Message* is 8-byte
 * aligned on a 64-bit system, or 4-byte aligned on a 32-bit system, the input
 * buffer needs to be adjusted to 8-byte alignment before pointer casting, in
 * order to avoid misaligned pointer
 */
Message* CreateMessage(uint8_t* buffer, size_t buffer_size) {
  assert(buffer != NULL);
  uint8_t* const buffer_aligned = (uint8_t* const)align_8(buffer);
  assert(buffer_size >= sizeof(Message) + (size_t)(buffer_aligned - buffer));
  Message* const message = (Message* const)buffer_aligned;
  message->base = buffer_aligned + sizeof(Message);
  message->capacity =
      buffer_size - sizeof(Message) - (size_t)(buffer_aligned - buffer);
  message->size = 0;
  message->read_offset = 0;
  message->status = MESSAGE_STATUS_OK;
  return message;
}

void ClearMessage(Message* message) {
  assert(message != NULL);
  message->size = 0;
  message->read_offset = 0;
  message->status = MESSAGE_STATUS_OK;
}

void ResetMessage(Message* message) {
  assert(message != NULL);
  message->read_offset = 0;
  message->status = MESSAGE_STATUS_OK;
}

uint8_t* GetBase(Message* message) {
  assert(message != NULL);
  return message->base;
}

size_t GetCapacity(Message* message) {
  assert(message != NULL);
  return message->capacity;
}

size_t GetSize(Message* message) {
  assert(message != NULL);
  return message->size;
}

MessageStatus GetStatus(Message* message) {
  assert(message != NULL);
  return message->status;
}

void SetStatus(Message* message, MessageStatus status) {
  assert(message != NULL);
  message->status = status;
}

void SetSize(Message* message, size_t size) {
  assert(message != NULL);
  message->size = size;
}