/*
 * Copyright (c) Advanced Micro Devices, Inc., or its affiliates.
 *
 * SPDX-License-Identifier: MIT
 */

#include "utils/debug.hpp"
#include "top.hpp"
#include "utils/flags.hpp"

#include "devhcmessages.hpp"

#include <vector>
namespace amd {

enum {
  DESCRIPTOR_OFFSET_FLAG_BEGIN = 0,
  DESCRIPTOR_OFFSET_FLAG_END = 1,
  DESCRIPTOR_OFFSET_RESERVED0 = 2,
  DESCRIPTOR_OFFSET_LEN = 5,
  DESCRIPTOR_OFFSET_ID = 8
};

enum {
  DESCRIPTOR_WIDTH_FLAG_BEGIN = 1,
  DESCRIPTOR_WIDTH_FLAG_END = 1,
  DESCRIPTOR_WIDTH_RESERVED0 = 3,
  DESCRIPTOR_WIDTH_LEN = 3,
  DESCRIPTOR_WIDTH_ID = 56
};

struct Message {
  std::vector<uint64_t> data_;
  bool live_;
  uint64_t messageId_;

  void clear() {
    live_ = false;
    data_.clear();
  };

  void append(uint64_t* payload, uint8_t len) { data_.insert(data_.end(), payload, payload + len); }

  Message(uint64_t c) : live_(true), messageId_(c) {};
};

static uint64_t getField(uint64_t desc, uint8_t offset, uint8_t width) {
  return (desc >> offset) & ((1ULL << width) - 1);
}

static uint64_t setField(uint64_t desc, uint64_t value, uint8_t offset, uint8_t width) {
  uint64_t resetMask = ~(((1ULL << width) - 1) << offset);
  return (desc & resetMask) | (value << offset);
}

static uint64_t getLen(uint64_t desc) {
  return getField(desc, DESCRIPTOR_OFFSET_LEN, DESCRIPTOR_WIDTH_LEN);
}

static uint64_t getBeginFlag(uint64_t desc) {
  return getField(desc, DESCRIPTOR_OFFSET_FLAG_BEGIN, DESCRIPTOR_WIDTH_FLAG_BEGIN);
}

static uint64_t getEndFlag(uint64_t desc) {
  return getField(desc, DESCRIPTOR_OFFSET_FLAG_END, DESCRIPTOR_WIDTH_FLAG_END);
}

static uint64_t resetBeginFlag(uint64_t desc) {
  uint64_t resetMask = ~(1 << DESCRIPTOR_OFFSET_FLAG_BEGIN);
  return desc & resetMask;
}

static uint64_t getMessageId(uint64_t desc) {
  return getField(desc, DESCRIPTOR_OFFSET_ID, DESCRIPTOR_WIDTH_ID);
}

static uint64_t setMessageId(uint64_t desc, uint64_t id) {
  return setField(desc, id, DESCRIPTOR_OFFSET_ID, DESCRIPTOR_WIDTH_ID);
}

Message* MessageHandler::newMessage() {
  if (!freeSlots_.empty()) {
    auto c = freeSlots_.back();
    freeSlots_.pop_back();
    assert(c <= messageSlots_.size());
    Message* m = messageSlots_[c];
    assert(m);
    assert(m->messageId_ == c);
    assert(m->data_.empty());
    m->live_ = true;
    return m;
  }

  Message* m = new Message(messageSlots_.size());
  messageSlots_.push_back(m);
  return m;
}

MessageHandler::~MessageHandler() {
  for (auto M : messageSlots_) {
    delete M;
  }
}

Message* MessageHandler::getMessage(uint64_t messageId) {
  if (messageSlots_.size() <= messageId) {
    return nullptr;
  }

  auto m = messageSlots_[messageId];

  return m->live_ ? m : nullptr;
}

void MessageHandler::discardMessage(Message* message) {
  message->clear();
  freeSlots_.push_back(message->messageId_);
  // TODO: Consider reducing the number of message slots based on
  // some busy-ness heuristic.
}

// Defined in devhcprintf.cpp

void handlePrintf(uint64_t* output, const uint64_t* input, uint64_t len);


bool MessageHandler::handlePayload(uint32_t service, uint64_t* payload) {
  Message* message = nullptr;

  auto desc = payload[0];
  auto begin = getBeginFlag(desc);
  auto end = getEndFlag(desc);

  if (begin) {
    message = newMessage();
    desc = resetBeginFlag(desc);
    desc = setMessageId(desc, message->messageId_);
    payload[0] = desc;
  } else {
    auto messageId = getMessageId(desc);
    message = getMessage(messageId);
  }

  if (!message) {
    ClPrint(amd::LOG_ERROR, amd::LOG_ALWAYS, "Hostcall: No message found");
    return false;
  }

  auto len = getLen(desc);
  message->append(payload + 1, len);

  if (!end) {
    return true;
  }

  switch (service) {
    case SERVICE_PRINTF:
      amd::handlePrintf(payload, message->data_.data(), message->data_.size());
      break;
    default:
      ClPrint(amd::LOG_ERROR, amd::LOG_ALWAYS, "Hostcall: Messages not supported for service %d",
              service);
      return false;
  }
  discardMessage(message);
  return true;
}
}  // namespace amd