Stats

F4HWN firmware port for the UV-K1 and UV-K5 V3 using the PY32F071 MCU

This repository is a fork of the F4HWN custom firmware, who was a fork of Egzumer custom firmware. It extends the work done for the UV-K5 V1, based on the DP32G030 MCU, and adapts it to the newer UV-K1 and UV-K5 V3 built around the PY32F071 MCU. It is the result of the joint work of @muzkr and @armel.

A big thanks to DualTachyon, who paved the way by releasing the very first open-source firmware for the UV-K5 V1. None of this would have been possible without that initial work !

A note for developers who intend to fork this project

This firmware is distributed under the Apache 2.0 License, carrying forward the original copyright of DualTachyon, whose work laid the foundation for the UV-K5 open-source ecosystem. If you create a fork or a derived version, we strongly encourage you to keep your work open source.

Keeping your fork open:

• aligns with the intent and spirit of the Apache 2.0 License
• supports the amateur-radio and embedded-development community
• avoids unnecessary fragmentation
• allows others to study, audit and improve the firmware

It is also very much in line with the ham spirit: sharing knowledge, experimenting together and helping each other, rather than closing things off or claiming them as your own.

Maintaining an open-source fork is the best way to help build a healthy and sustainable ecosystem for everyone.

[!WARNING] EN - THIS FIRMWARE HAS NO REAL BRAIN. PLEASE USE YOUR OWN. Use this firmware at your own risk (entirely). There is absolutely no guarantee that it will work in any way shape or form on your radio(s), it may even brick your radio(s), in which case, you'd need to buy another radio. Anyway, have fun.

FR - CE FIRMWARE N'A PAS DE VÉRITABLE CERVEAU. VEUILLEZ UTILISER LE VÔTRE. Utilisez ce firmware à vos risques et périls. Il n'y a absolument aucune garantie qu'il fonctionnera d'une manière ou d'une autre sur votre (vos) radio(s), il peut même bousiller votre (vos) radio(s), dans ce cas, vous devrez acheter une autre radio. Quoi qu'il en soit, amusez-vous bien.

[!NOTE] EN - About CHIRP, as with many other firmwares, you need to use a dedicated driver. The matching CHIRP driver is now bundled with each release of this repository, so you can download the firmware and its driver together from the Releases page.

FR - A propos de CHIRP, comme pour beaucoup d'autres firmwares, vous devez utiliser un pilote dédié. Le driver CHIRP correspondant est désormais fourni avec chaque release de ce dépôt, ce qui permet de récupérer ensemble le firmware et son pilote depuis la page des Releases.

[!CAUTION] EN - I recommend backing up your calibration data with UV Studio immediately after flashing this firmware. It is a good habit to adopt.

FR - Je recommande de sauvegarder vos données de calibration avec UV Studio juste après avoir flashé ce firmware. C'est un bon réflexe à adopter.

Donations

Special thanks to Jean-Cyrille F6IWW (3 times), Fabrice 14RC123, Olivier 14RC206, Frédéric F4ESO, Stéphane F5LGW (2 times), Jorge Ornelas (4 times), Laurent F4AXK, Christophe Morel, Clayton W0LED, Pierre Antoine F6FWB, Jean-Claude 14FRS3306, Thierry F4GVO, Eric F1NOU, PricelessToolkit, Ady M6NYJ, Tom McGovern (4 times), Joseph Roth, Pierre-Yves Colin, Frank DJ7FG, Marcel Testaz, Brian Frobisher, Paolo Bussola, Dirk DL8DF, Levente Szőke (2 times), Bernard-Michel Herrera, Jérôme Saintespes, Paul Davies, RS (3 times), Johan F4WAT, Robert Wörle, Rafael Sundorf, Paul Harker, Peter Fintl, Pascal F4ICR (2 times), Mike DL2MF (3 times), Eric KI1C / F4WFS (3 times), Phil G0ELM, Jérôme Lambert, Eliot Vedel, Alfonso EA7KDF, Jean-François F1EVM, Robert DC1RDB (2 times), Ian KE2CHJ, Daryl VK3AWA, Roberto Brunelli, Robert Boardman, Stephen Oliver, Nicolas F4INE, William Bruno, Daniel OK2VLK, Tayler Chew, Peter DL7RFP, Philippe Kopp, Rune LA6YMA, Jeremy Luna, Steef Wagenaar (2 times), Zhuo BG7SGA, Jamie M0JLB, Antoine LIBERT, Vince K0DKR, Julia DF7JA, Ken 2E0UMK, Victor TI2SYS, Tobi DG9LAY, Deaglan K4DFQ, Catherine PALMER, Brian WA6JFK, Stéphane Hintzy, Roger F1HCN, Marcin Kusaj, Flavio Cottarelli, Bob N1MLZ, Carlos EA1IJ, Brian M7YLF, Giuseppe IT9LLH, 邓 月, Jon M1JRH, Antonios Chouchoumis, Cédric Thomas, Justin White, Gordon Campbell, Per Georg Fostad, Edward Phillips, Peter Kintscher, Jerome Lambert and Andy G0FTD for their donations. That’s so kind of them. Thanks so much 🙏🏻

Table of Contents

• Main features and improvements from F4HWN
• Main Features from Egzumer
• Manual
• Compiling and Building from Docker
• Flashing the Firmware with UV Studio
• Credits
• Other sources of information
• License

Main features and improvements from F4HWN

Fusion edition

Fusion is the generic reference edition for the UV-K1 and UV-K5 V3. It is intended for everyday use and is the base inherited by the specialized editions. It includes:

• Fagci's spectrum analyzer,
• broadcast FM radio and VOX,
• UV Studio with integrated K5Viewer screen mirroring, screenshots and remote keyboard control,
• advanced RX audio profiles and Audio Scope,
• automatic RX/TX activity logging with RF Log,
• Full Watch across VFO A, VFO B and up to two priority channels,
• Multiboot with one protected Main backup and four user firmware slots,
• independent Multiconfig banks, switchable at runtime through SetCfg.

Fusion also includes the overlay-apps platform: applications are loaded from external Flash and run in a 4 KiB RAM overlay. The additional presets are:

• Service, which adds AirCopy, BEAM and external-Flash service operations.
• Custom, a manually configured build based directly on the hidden technical default.

Multiboot and Multiconfig

Multiboot uses the radio's external Flash to keep one automatically maintained Main firmware backup and four additional firmware slots. Each image is validated before it is restored to internal Flash, and the selector displays the edition and version stored in every valid slot.

To open the Multiboot selector, power off the radio, hold MENU, power it on, then release the key when the selector appears. Use UP and DOWN to choose a slot, MENU to restore it and EXIT to leave without making changes.

[!CAUTION] Never power off the radio while a firmware slot is being restored.

Multiconfig provides one independent configuration bank for Main and for each of the four user slots. A bank contains the memory channels and names, VFO settings, scan lists, radio settings and edition-specific settings. By default, each firmware slot uses the bank with the same number.

The SetCfg menu can select and apply another bank immediately, without restarting the radio or changing firmware. The status bar shows the active bank as CFG M or CFG 1 to CFG 4, so several operating configurations can be used with the same firmware and compatible configurations can be shared across editions.

A SetCfg override survives normal power cycles. It does not permanently redefine the default configuration bank of a firmware slot: selecting a firmware through Multiboot always restores the natural association between the selected slot and its bank (Main to CFG M, or slot N to CFG N). Select another bank with SetCfg again after switching firmware if required.

Full Watch

Full Watch extends the normal dual-watch cycle to monitor:

• VFO A,
• VFO B,
• priority channel 1,
• priority channel 2.

The priority channels come from the existing scan-list priority settings. Duplicates, invalid entries and channels already loaded in VFO A or B are ignored automatically.

The RxMode menu provides two Full Watch modes:

• FULL RX / RESPOND replies on the channel that opened the squelch,
• MAIN TX / FULL RX always transmits on the selected main VFO.

Animated chevrons show the background watch cycle while the normal VFO display remains available for navigation and operation.

Overlay applications and APRS

Fusion can store up to 64 applications from the current collection of 43 in external Flash. Each app is loaded into a dedicated 4 KiB RAM overlay only while it is running, while larger read-only assets such as text, fonts, bitmaps and lookup tables remain in external Flash.

The current app collection includes:

• radio tools: Broadcast FM, Fox Hunt, Beacon, Beam, Signal Finder, Spectrum3D and ToneCall,
• digital and signal apps: ACARS RX, AIS RX, ATIS RX, ATIS DSC RX, APRS RX, APRS TX, APRS Edit, APRS DIGI, KISS TNC, CW Decode, CW Keyer, CW Trainer, CW USB, SSTV, POCSAG RX, Sonde M10, Sonde M20, Sonde RS41, GeoNav and EPIRB 406,
• tools and diagnostics: AF Scope, AF Spectro, QR Map, Resistor, System Info and Flash Map,
• games and demos: Breakout, Cube3D, Hell Maze, Minesweeper, Plasma, Rapid Roll, Snake, Sokoban, Space Impact and Tetris.

APRS RX receives AX.25 UI frames using Bell 202 AFSK at 1200 baud, displays common position formats and Mic-E data, and keeps a five-frame history. APRS TX uses an editable callsign (with boot-message fallback) and transmits a position beacon; its companion APRS Edit app edits the callsign, SSID, digipeater path, position, symbol and 89-character comment. GeoNav reuses that APRS position as the home QTH and shows the bearing and distance to a position handed off by the RS41, M10 or M20 radiosonde app. APRS DIGI is a deliberately limited WIDE1-1 fill-in digipeater with path-independent duplicate suppression and channel-busy protection. KISS TNC makes the radio the TNC of APRSdroid (or any KISS client) over the USB-C cable: the phone runs the APRS application, the radio demodulates and transmits.

ACARS RX receives the 2400 bit/s AM-MSK aircraft data link, checks odd parity and CRC, and keeps a three-message history with aircraft address, flight ID, label and printable message text. AIS RX samples the raw discriminator at 38.4 kHz, validates HDLC frames and shows Class A/B position and static reports from AIS1 or AIS2, one channel at a time. Its Flipper Zero bench vectors stay on 433.650 MHz.

AF Scope and AF Spectro are one instrument for the demodulated RX audio, split in two apps that hand off to each other with MENU: AF Scope is an oscilloscope (frequency counter, peak detect, persistence) and a tuner (the frequency of a steady tone against the nearest known tone); AF Spectro shows the spectrum and a sonogram, the two main peaks and the level difference between two tones (DTMF, FSK, Bell 202...). Both work in FM, AM and USB.

[!IMPORTANT] Overlay apps, including APRS RX, APRS TX and APRS DIGI, are experimental parts of Fusion. Use the app files supplied with the same firmware release so their ABI and required capabilities match the installed firmware.

[!CAUTION] Transmitting apps must only be used on frequencies, power levels and modes permitted by your licence and local regulations.

Radio and signal handling

• Reworked output-power levels:
• Low 1: below approximately 20 mW,
• Low 2: approximately 125 mW,
• Low 3: approximately 250 mW,
• Low 4: approximately 500 mW,
• Low 5: approximately 1 W,
• Mid: approximately 2 W,
• High: approximately 5 W,
• User: configurable through SetPwr.
• S-meter calibrated according to the IARU Region 1 recommendation for VHF/UHF:
• fixed S0 to S9+ values replace the former EEPROM S-meter thresholds,
• Classic and Tiny display styles are available.
• Configurable 12.5 kHz or 6.25 kHz narrow-FM bandwidth.
• Per-channel TX lock.
• Adjustable RX audio volume.
• Advanced RX audio profiles for FM and AM reception.
• Regional frequency-lock profiles for amateur bands, PMR446, FRS, GMRS and MURS.
• Support for 1600, 2200 and 3500 mAh battery profiles.

Spectrum analyzer

• Channel names displayed in the spectrum view.
• Persistent spectrum settings.
• Faster and smoother spectrum rendering.
• Improved behavior when freezing the spectrum or disconnecting USB-C.
• Spectrum analyzer state can be restored automatically at startup.

Scanning

• Support for up to 24 named scan lists + 1 mixed list.
• Each memory channel can be assigned to:
• OFF,
• one scan list from 01 to 24,
• ALL.
• The ALL list scans every channel except those assigned to OFF.
• The MIX list combines any selected subset of the 24 named lists into one scan set.
• Automatic selection of the next valid list when the requested list is empty.
• Direct scan-list selection while scanning:
• 00 selects ALL,
• 01 to 24 select the corresponding list,
• 25 selects MIX.
• Long press on MENU while scanning to exclude the current memory channel.
• Up to 64 frequency exclusions.
• Very fast scanning mode, reaching approximately 150 frequencies per second.
• Scan progress, RSSI and detected CTCSS/DCS information.
• Configurable scan resume behavior.
• Scan state can be restored automatically at startup.

User interface

• Improved VFO screen with:
• Classic and Tiny S-meter styles,
• Classic and Tiny frequency-information layouts,
• MAIN ONLY, DUAL, FULL and CROSS display modes,
• RX activity indication on the active VFO,
• optional RX LED blinking,
• squelch, monitor, step and CTCSS/DCS information,
• last-RX indication,
• RX and TX timers.
• Improved status bar with updated fonts and icons.
• Menu index remains visible while editing an entry.
• Improved frequency and memory-channel input.
• Improved audio-level display.
• AirCopy progress percentage and gauge.
• Smooth backlight fading.
• Manual backlight controls for quickly switching between minimum and maximum brightness.
• Configurable contrast and inverted-display mode.
• Configurable navigation layout for the different radio models.
• Improved power-on message and optional startup logo.
• System-information pages for:
• firmware version and build information,
• battery information,
• Flash and SRAM usage,
• project and documentation QR codes.

Audio and transmission controls

• Classic and OnePush PTT modes.
• Configurable timeout-timer alerts:
• disabled,
• sound,
• visual,
• sound and visual.
• Configurable end-of-transmission alerts using the same modes.
• Audio Scope during RX and TX.
• Improved Audio Scope behavior with OnePush PTT, DTMF and the 1750 Hz tone.
• Configurable automatic deep-sleep timeout.
• Quick actions for:
• RX mode,
• main-VFO-only display,
• PTT,
• wide/narrow bandwidth,
• 1750 Hz tone,
• mute,
• RX audio profile,
• maximum power,
• offset removal.

Fox Hunt and Beacon

• Dedicated Fox Hunt receiver with:
• calibrated S-meter display,
• scrolling signal-history graph,
• peak, minimum and trend indicators,
• selectable RF attenuation,
• silent, Geiger-style and received-audio modes,
• long-press F keypad lock (attenuation stays adjustable with the arrow keys).
• Independent Morse Beacon transmitter with:
• MOE, MOI, MOS, MOH, MO5 and MO identifiers,
• optional callsign identification,
• configurable TX and idle periods,
• live TX and idle countdowns,
• persisted Beacon settings,
• interactive control during transmission,
• shared long-press F keypad lock,
• TX-lock, modulation and battery-safety checks.
• Fox Hunt and Beacon screens are mirrored to UV Studio's integrated K5Viewer.

RF Log

• Automatic logging of RX and TX activity when RF Log is enabled.
• Logs stored in the radio's external Flash memory.
• Recorded information includes:
• RX or TX direction,
• frequency and channel,
• channel name,
• activity duration,
• S-meter level,
• battery voltage.
• On-radio history with RX/TX filtering and detailed views.
• Live RF Log dashboard and history access through UV Studio.

Connectivity and data transfer

• Live screen streaming to UV Studio over a USB serial connection.
• Screenshot capture and download.
• Remote keyboard control through the integrated K5Viewer.
• Automatic reconnection after a USB disconnect.
• RF Log monitoring, analytics and CSV export.
• Firmware flashing, calibration backup and restore, and boot-logo management from the same interface.
• BEAM transfer of complete channel settings between compatible radios.

AirCopy (Service edition)

AirCopy can transfer one 128-channel bank, the radio settings, or all memory banks and settings in one operation. Version 6.1 adds a stop-and-wait protocol with acknowledgements in both directions:

• the receiver acknowledges CRC32 comparison frames and every stored data frame,
• a missing acknowledgement automatically triggers a retry, up to three times,
• invalid, out-of-sequence or mismatched selections are rejected instead of being applied silently,
• the progress screen reports retries or receive errors and distinguishes blocks that were already identical from blocks that were copied.

Before sending data, the two radios compare CRC32 values in groups of up to 24 blocks. The receiver returns a difference bitmap, so only blocks whose contents differ are transmitted. Each radio data frame can carry up to three consecutive 64-byte blocks, approximately doubling over-the-air throughput compared with the previous one-block framing.

Transfer also supports direct radio-to-radio cable cloning over UART at 460800 baud. Press * in AirCopy to switch between AIR COPY and CABLE COPY; use UP and DOWN to select a memory bank, Settings or All (Mem+Set), then MENU on the sender and EXIT on the receiver.

Cable mode additionally provides Flash 2M, which clones the complete 2 MiB external Flash. Sectors are compared by CRC32 and only different sectors are written. The device-specific calibration sector is never copied or erased, and the receiving radio must be restarted after a successful Flash clone.

[!IMPORTANT] The new AirCopy wire format is not compatible with earlier versions. Both radios must run the same firmware version.

Settings and controls

• New or extended menu entries:
• SetPwr: configurable User output power,
• SetPTT: Classic or OnePush PTT,
• SetTOT: timeout-timer alert,
• SetEOT: end-of-transmission alert,
• SetCtr: display contrast,
• SetInv: inverted display,
• SetLck: keypad or keypad-and-PTT lock,
• SetMet: S-meter style,
• SetGUI: VFO information style,
• SetRxA: RX audio profile,
• SetTmr: RX and TX timers,
• SetOff: automatic deep-sleep delay,
• SetNFM: narrow-FM bandwidth,
• SetVol: RX audio volume,
• SetScn: scan mode,
• SetNav: radio-specific navigation layout,
• SetCfg: apply another Multiconfig bank without restarting.
• Improved PonMsg, BackLt, TxTOut, ScnRev and KeyLck menus.
• Full VFO state restoration with a long press on EXIT.
• Squelch changes made with F + UP or F + DOWN are persisted.

Keyboard shortcuts and assignable actions

• F + UP or F + DOWN: adjust the squelch level.
• F + F1 or F + F2: adjust the frequency step.
• F + 8: temporarily switch the backlight between minimum and maximum brightness.
• F + 9: return to the configured backlight strategy.
• Configurable short- and long-press actions include:
• RX mode,
• main-VFO-only display,
• virtual PTT,
• wide/narrow bandwidth,
• 1750 Hz tone,
• mute,
• RX audio profile,
• maximum power,
• offset removal,
• BEAM,
• RF Log,
• Fox Hunt,
• Beacon,
• ToneCall (launches the ToneCall overlay app).

Reliability and optimization

• Improved squelch and S-meter behavior.
• Fixed DTMF overlay issues.
• Fixed scan-range limits.
• Cleaner startup display.
• Removed PWM-related audio noise.
• Improved serial and K5Viewer key handling.
• Improved VFO persistence and restoration.
• Extensive code refactoring and memory optimization.
• DTMF calling and the scrambler remain disabled in Fusion.
• Legacy AM Fix support has been removed.

Main features from Egzumer:

• many of OneOfEleven mods:
• long press buttons functions replicating F+ action
• fast scanning
• channel name editing in the menu
• channel name + frequency display option
• shortcut for scan-list assignment (long press 5 NOAA)
• scan-list toggle (long press * Scan while scanning)
• configurable button function selectable from menu
• battery percentage/voltage on status bar, selectable from menu
• longer backlight times
• mic bar
• RSSI s-meter
• more frequency steps
• squelch more sensitive
• fagci spectrum analyzer (F+5 to turn on)
• some other mods introduced by me:
• SSB demodulation (adopted from fagci)
• backlight dimming
• battery voltage calibration from menu
• better battery percentage calculation, selectable for 1600mAh or 2200mAh
• more configurable button functions
• long press MENU as another configurable button
• better DCS/CTCSS scanning in the menu (* SCAN while in RX DCS/CTCSS menu item)
• Piotr022 style s-meter
• restore initial freq/channel when scanning stopped with EXIT, remember last found transmission with MENU button
• reordered and renamed menu entries
• LCD interference crash fix
• many others...

## Manual

Up to date manual is available in the Wiki section

Radio performance

Please note that the Quansheng UV-Kx radios are not professional quality transceivers, their performance is strictly limited. The RX front end has no track-tuned band pass filtering at all, and so are wide band/wide open to any and all signals over a large frequency range.

Using the radio in high intensity RF environments will most likely make reception difficult, especially in AM mode. The receiver simply does not have a great dynamic range, so stronger signals can easily cause distortion, desensitization and poor AM audio. This is fundamentally a hardware limitation: firmware can improve behavior at the margins, but it cannot overcome the front-end design of the radio. In practice, AM reception will degrade first and most severely, while FM reception is generally more tolerant and should remain more usable.

But, they are nice toys for the price, fun to play with.

Compiling and Building from Docker

This project provides a Docker-based build system for the UV-K1 and UV-K5 V3. Everything is handled through the compile-firmware.sh helper script. Fusion is the default generic preset, while specialized builds are generated in their own build/<Preset> directories.

Prerequisites

• Docker installed on your system
• Bash environment (Linux, macOS, WSL, Git Bash on Windows)

Build Script Overview

The script compile-firmware.sh:

1. Builds the Docker image (uvk1-uvk5v3) if it does not already exist.
2. Configures the selected preset with cmake --fresh.
3. Builds the firmware and outputs matching .elf, .bin and .hex files.
4. Displays Flash and RAM usage; All keeps the individual build logs quiet.

Usage

./compile-firmware.sh [Preset] [extra CMake options]

The default preset is Fusion. Available presets are:

• Custom
• Fusion
• Service
• All (Fusion and Service)

Examples:

./compile-firmware.sh
./compile-firmware.sh Fusion
./compile-firmware.sh Service
./compile-firmware.sh All

Passing Additional CMake Options

You can pass extra configuration options after the preset name.
These are forwarded directly to cmake --preset inside the container.

Examples:

./compile-firmware.sh Service -DENABLE_VOX=OFF
./compile-firmware.sh Fusion -DENABLE_FEAT_F4HWN_GAME=ON
./compile-firmware.sh Fusion -DSQL_TONE=600

To prepare the rolling development firmware:

./compile-firmware.sh Fusion -DDEV=ON

This keeps the regular build output in build/Fusion and also updates archive/f4hwn.fusion.development.bin. The development build is identified as DEV in the firmware information screen. Publishing the updated archive file remains an explicit Git operation.

Notes

• The first run may take a few minutes while Docker builds the base image.
• Each build runs inside Docker, so your host environment remains clean.

Flashing the Firmware with UV Studio

You can flash the UV-K5 V3 and UV-K1 directly from your web browser using the Web Serial-based UV Studio.

UV Studio combines firmware flashing, calibration maintenance, boot-logo management, K5Viewer and RF Log in a single interface. It requires no application installation, server or account. Use a desktop browser with Web Serial support, such as Chrome, Brave, Edge, Opera or Firefox 151+.

Steps to flash the firmware

• Open the Flash Firmware view in UV Studio.
• Connect your radio to your computer using a compatible USB programming cable (USB-C or Baofeng/Kenwood like double jack USB cable).
• Make sure your radio is in DFU mode (flash mode).
• Select an official F4HWN Fusion release from the catalog or load a local .bin firmware file.
• Click on Flash Firmware, then select the serial port associated with your radio.
• The progress bar will guide you through the flashing steps.

Once finished, your radio restarts with the new firmware.

Steps to dump or restore calibration data

UV Studio can also dump and restore calibration data, which is highly recommended. It is best to create a dump immediately after installing the F4HWN firmware, and to restore it before installing another firmware or returning to the stock firmware.

Dump

• Open the Dump Calibration view in UV Studio.
• Power on your radio in normal mode.
• Click Dump Calibration Data.

When the process is complete, click Download calibration.dat to save the file to your computer.

[!NOTE] A good practice is to rename your calibration file using the serial number of your radio, which you can find on the label on the back of the device once you remove the battery. This helps avoid mixing up calibration files when you own multiple units.

Restore

• Open the Restore Calibration view in UV Studio.
• Power on your radio in normal mode.
• Select your calibration.dat file on your computer.

Click Restore Calibration Data and wait until the process fully completes.

Other sources of information

• k1-teardown

Credits

Many thanks to various people:

• Muzkr
• Mrkusypl
• Andrej
• Egzumer
• OneOfEleven
• DualTachyon
• Mikhail
• Manuel
• @wagner
• @Lohtse Shar
• @Matoz
• @Davide
• @Ismo OH2FTG
• OneOfEleven
• @d1ced95
• and others I forget

License

Copyright 2023 Dual Tachyon https://github.com/DualTachyon

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.