content: /*
   * Copyright (C) 2018 The Android Open Source Project
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package android.hardware.hdmi;
  
  import android.annotation.IntDef;
  
  import java.lang.annotation.Retention;
  import java.lang.annotation.RetentionPolicy;
  
  /**
   * Various utilities related to HDMI CEC.
   *
   * TODO(b/110094868): unhide for Q
   * @hide
   */
  public final class HdmiUtils {
      /**
       * Return value of {@link #getLocalPortFromPhysicalAddress(int, int)}
       */
      static final int TARGET_NOT_UNDER_LOCAL_DEVICE = -1;
      static final int TARGET_SAME_PHYSICAL_ADDRESS = 0;
  
      private HdmiUtils() { /* cannot be instantiated */ }
  
      /**
       * Method to parse target physical address to the port number on the current device.
       *
       * <p>This check assumes target address is valid.
       *
       * @param targetPhysicalAddress is the physical address of the target device
       * @param myPhysicalAddress is the physical address of the current device
       * @return
       * If the target device is under the current device, return the port number of current device
       * that the target device is connected to. This also applies to the devices that are indirectly
       * connected to the current device.
       *
       * <p>If the target device has the same physical address as the current device, return
       * {@link #TARGET_SAME_PHYSICAL_ADDRESS}.
       *
       * <p>If the target device is not under the current device, return
       * {@link #TARGET_NOT_UNDER_LOCAL_DEVICE}.
       */
      public static int getLocalPortFromPhysicalAddress(
              int targetPhysicalAddress, int myPhysicalAddress) {
          if (myPhysicalAddress == targetPhysicalAddress) {
              return TARGET_SAME_PHYSICAL_ADDRESS;
          }
  
          int mask = 0xF000;
          int finalMask = 0xF000;
          int maskedAddress = myPhysicalAddress;
  
          while (maskedAddress != 0) {
              maskedAddress = myPhysicalAddress & mask;
              finalMask |= mask;
              mask >>= 4;
          }
  
          int portAddress = targetPhysicalAddress & finalMask;
          if ((portAddress & (finalMask << 4)) != myPhysicalAddress) {
              return TARGET_NOT_UNDER_LOCAL_DEVICE;
          }
  
          mask <<= 4;
          int port = portAddress & mask;
          while ((port >> 4) != 0) {
              port >>= 4;
          }
          return port;
      }
  
      /**
       * TODO(b/110094868): unhide for Q
       * @hide
       */
      @Retention(RetentionPolicy.SOURCE)
      @IntDef({HDMI_RELATIVE_POSITION_UNKNOWN, HDMI_RELATIVE_POSITION_DIRECTLY_BELOW,
              HDMI_RELATIVE_POSITION_BELOW, HDMI_RELATIVE_POSITION_SAME,
              HDMI_RELATIVE_POSITION_DIRECTLY_ABOVE, HDMI_RELATIVE_POSITION_ABOVE,
              HDMI_RELATIVE_POSITION_SIBLING, HDMI_RELATIVE_POSITION_DIFFERENT_BRANCH})
      public @interface HdmiAddressRelativePosition {}
      /**
       * HDMI relative position is not determined.
       * TODO(b/110094868): unhide for Q
       * @hide
       */
      public static final int HDMI_RELATIVE_POSITION_UNKNOWN = 0;
      /**
       * HDMI relative position: directly blow the device.
       * TODO(b/110094868): unhide for Q
       * @hide
       */
      public static final int HDMI_RELATIVE_POSITION_DIRECTLY_BELOW = 1;
      /**
       * HDMI relative position: indirectly below the device.
       * TODO(b/110094868): unhide for Q
       * @hide
       */
      public static final int HDMI_RELATIVE_POSITION_BELOW = 2;
      /**
       * HDMI relative position: the same device.
       * TODO(b/110094868): unhide for Q
       * @hide
       */
      public static final int HDMI_RELATIVE_POSITION_SAME = 3;
      /**
       * HDMI relative position: directly above the device.
       * TODO(b/110094868): unhide for Q
       * @hide
       */
      public static final int HDMI_RELATIVE_POSITION_DIRECTLY_ABOVE = 4;
      /**
       * HDMI relative position: indirectly above the device.
       * TODO(b/110094868): unhide for Q
       * @hide
       */
      public static final int HDMI_RELATIVE_POSITION_ABOVE = 5;
      /**
       * HDMI relative position: directly below a same device.
       * TODO(b/110094868): unhide for Q
       * @hide
       */
      public static final int HDMI_RELATIVE_POSITION_SIBLING = 6;
      /**
       * HDMI relative position: different branch.
       * TODO(b/110094868): unhide for Q
       * @hide
       */
      public static final int HDMI_RELATIVE_POSITION_DIFFERENT_BRANCH = 7;
  
      private static final int NPOS = -1;
  
      /**
       * Check if the given physical address is valid.
       *
       * @param address physical address
       * @return {@code true} if the given address is valid
       */
      public static boolean isValidPhysicalAddress(int address) {
          if (address < 0 || address >= 0xFFFF) {
              return false;
          }
          int mask = 0xF000;
          boolean hasZero = false;
          for (int i = 0; i < 4; i++) {
              if ((address & mask) == 0) {
                  hasZero = true;
              } else if (hasZero) {
                  // only 0s are valid after a 0.
                  // e.g. 0x1012 is not valid.
                  return false;
              }
              mask >>= 4;
          }
          return true;
      }
  
  
      /**
       * Returns the relative position of two physical addresses.
       */
      @HdmiAddressRelativePosition
      public static int getHdmiAddressRelativePosition(int src, int dest) {
          if (src == 0xFFFF || dest == 0xFFFF) {
              // address not assigned
              return HDMI_RELATIVE_POSITION_UNKNOWN;
          }
          try {
              int firstDiffPos = physicalAddressFirstDifferentDigitPos(src, dest);
              if (firstDiffPos == NPOS) {
                  return HDMI_RELATIVE_POSITION_SAME;
              }
              int mask = (0xF000 >> (firstDiffPos * 4));
              int nextPos = firstDiffPos + 1;
              if ((src & mask) == 0) {
                  // src is above dest
                  if (nextPos == 4) {
                      // last digits are different
                      return HDMI_RELATIVE_POSITION_DIRECTLY_ABOVE;
                  }
                  if (((0xF000 >> (nextPos * 4)) & dest) == 0) {
                      // next digit is 0
                      return HDMI_RELATIVE_POSITION_DIRECTLY_ABOVE;
                  }
                  return HDMI_RELATIVE_POSITION_ABOVE;
              }
  
              if ((dest & mask) == 0) {
                  // src is below dest
                  if (nextPos == 4) {
                      // last digits are different
                      return HDMI_RELATIVE_POSITION_DIRECTLY_BELOW;
                  }
                  if (((0xF000 >> (nextPos * 4)) & src) == 0) {
                      // next digit is 0
                      return HDMI_RELATIVE_POSITION_DIRECTLY_BELOW;
                  }
                  return HDMI_RELATIVE_POSITION_BELOW;
              }
              if (nextPos == 4) {
                  // last digits are different
                  return HDMI_RELATIVE_POSITION_SIBLING;
              }
              if (((0xF000 >> (nextPos * 4)) & src) == 0 && ((0xF000 >> (nextPos * 4)) & dest) == 0) {
                  return HDMI_RELATIVE_POSITION_SIBLING;
              }
              return HDMI_RELATIVE_POSITION_DIFFERENT_BRANCH;
          } catch (IllegalArgumentException e) {
              // invalid address
              return HDMI_RELATIVE_POSITION_UNKNOWN;
          }
      }
  
      private static int physicalAddressFirstDifferentDigitPos(int address1, int address2)
              throws IllegalArgumentException {
          if (!isValidPhysicalAddress(address1)) {
              throw new IllegalArgumentException(address1 + " is not a valid address.");
          }
          if (!isValidPhysicalAddress(address2)) {
              throw new IllegalArgumentException(address2 + " is not a valid address.");
          }
          int mask = 0xF000;
          for (int i = 0; i < 4; i++) {
              if ((address1 & mask) != (address2 & mask)) {
                  return i;
              }
              mask = mask >> 4;
          }
          return NPOS;
      }
  }
  