disableUsbDevice(){
  #disable usb
  [ -f "/sys/devices/sunxi_usb/usb_role" ] || return 1
  echo 0 > "/sys/devices/sunxi_usb/usb_role"
}

switchToUsbDevice(){
  [ -f "/sys/devices/sunxi_usb/usb_role" ] || return 1
  disableUsbDevice
  # enable device mode
  echo 2 > "/sys/devices/sunxi_usb/usb_role"
  # make sure the usb gadgets are disabled
  echo 0 > "/sys/devices/virtual/android_usb/android0/enable"
}

switchToUsbHost(){
  [ -f "/sys/devices/sunxi_usb/usb_role" ] || return 1
  # make sure the usb gadgets are disabled
  [ -f "/sys/devices/virtual/android_usb/android0/enable" ] && \
  echo 0 > "/sys/devices/virtual/android_usb/android0/enable"
  disableUsbDevice
  # enable host mode
  echo 1 > "/sys/devices/sunxi_usb/usb_role"
}

getUsbStorageIds(){
  find "/dev/bus/usb" -type c | while read device
  do
    hexdump -n 1 -s 32 "$device" -C | grep -e '^00000020  08' && echo "$device"
  done
}

waitForStorageDevice(){
  local blockDevice="$1"
  [ -z "$timeout" ] && local timeout=5
  while [ $timeout -gt 0 ] && ! [ -b "$blockDevice" ]; do
    echo "waiting for $blockDevice $timeout"
    let timeout=timeout-1
    sleep 1
  done
  [ -b "$blockDevice" ]
}

waitForUsbDevice(){
  [ -z "$(getUsbStorageIds)" ] && return 1
  waitForStorageDevice ${1+"$@"}
}

waitForMmcDevice(){
  [ -f "/key-file" ] && return 1
  waitForStorageDevice ${1+"$@"}
}

checkStorageDevice(){
  local blockDevice="$1"
  [ -b "$blockDevice" ] || return 1

  local ro="defaults,nosuid,nodev,noatime,ro"
  local rw="defaults,nosuid,nodev,noatime,rw"
  local saves="$modname/saves"

  if ! [ "$cfg_usb_rw" == "y" ]; then
    mount -o $ro "$blockDevice" "$mountpoint/media" || return 1
  fi

  local need_repair=""
  [ -d "$mountpoint/media/$games" ] && ! [ -z "$(find $mountpoint/media/$games -name .repair.flag -maxdepth 2)" ] && need_repair=y

  if [ -d "$mountpoint/media/$saves" ] || [ -d "$mountpoint/media/$modname/transfer" ] || [ "$cfg_usb_rw" == "y" ] || [ "$need_repair" == "y" ]; then
    umount "$mountpoint/media" 2>/dev/null
    mount -o $rw "$blockDevice" "$mountpoint/media" || return 1
  fi

  if ! [ -d "$mountpoint/media/$modname" ]; then
    umount "$mountpoint/media"
    return 1
  fi

  [ -d "$mountpoint/media/$saves" ] && mount_bind "$mountpoint/media/$saves" "$mountpoint$profilepath"

  local bootlogo0="boot.png"
  local bootlogo1="$mountpoint/media/$modname/$bootlogo0"
  local bootlogo2="$rootfs/etc/$bootlogo0"
  if [ -f "$bootlogo1" ]; then
    rsync -ac "$bootlogo1" "$bootlogo2"
    showImage "$bootlogo2"
    cfg_boot_logo=''
  else
    [ -f "$bootlogo2" ] && rm -f "$bootlogo2" && source "$preinit.d/p7010_bootlogo"
  fi

  local bootsound0="boot.wav"
  local bootsound1="$mountpoint/media/$modname/$bootsound0"
  local bootsound2="$rootfs/etc/$bootsound0"
  if [ -f "$bootsound1" ]; then
    [ -f "$bootsound2" ] || playSound "$bootsound1"
    rsync -ac "$bootsound1" "$bootsound2"
  else
    rm -f "$bootsound2"
  fi

  return 0
}

checkExtStorage(){
  local di
  local d
  local p
  local timeout=5
  local blockDevice="/dev/sd"
  waitForUsbDevice "${blockDevice}a1"
  for di in $(seq 97 99); do
    d="$(printf "\\$(printf %o $di)\n")"
    for p in $(seq 1 9); do
      checkStorageDevice "$blockDevice$d$p" && return 0
    done
  done
  [ $timeout -gt 2 ] && timeout=2
  blockDevice="/dev/mmcblk0p"
  waitForMmcDevice "${blockDevice}1"
  for p in $(seq 1 9); do
    checkStorageDevice "$blockDevice$p" && return 0
  done
  return 1
}