

### Overview of Licenses in GBDK-2020

See the relevant licensing files in the LICENSES folder for details on the entries below


### For the End User
Q: What license information is required when distributing the compiled ROM (binary) of my game?

A: There is no requirement to include or credit any of the GBDK-2020 licenses or authors, although credit of GBDK-2020 is appreciated.
   This is different and separate from redistributing the GBDK-2020 dev environment itself (or the GBDK-2020 sources) which does require the licenses.

If zx0 decompression from the GBDK library is used then credit should be included per the requirements of it's BSD 3-Clause license. See the LICENSE folder for details.




### GBDK Library & Makefiles, SDCC:
GPLv2+LE (linking exception). Some files from SDCC, some from the historical GBDK that were originally LGPL and have been relicensed to GPLv2+LE (linking exception) to match the SDCC ones in 2022 by permission of original authors.
- LICENSE_SDCC
- LICENSE_GPLV2_LE

When patches are used for some SDCC tools they can be found at:
https://github.com/gbdk-2020/gbdk-2020-sdcc


### Optional Crash handler in the GBDK Library
zlib License: https://github.com/ISSOtm/gb-starter-kit/
- LICENSE_crashhandler


### makebin:
zlib/libpng License
According to: http://sdcc.sourceforge.net/


### bankpack, ihxcheck, gbcompress, makecom:
Public Domain. @bbbbbr is the original author


### zx0 compression in gbcompress
The zx0 salvador code is available under the Zlib license, except for matchfinder.c which is placed under the Creative Commons CC0 license.
Please consult LICENSE.zlib.md and LICENSE.CC0.md for more information.

### zx0 compression in the library
BSD 3-Clause, Einar Saukas


### png2asset:
MIT License. @Zal0 is the original author + additional contributors


### LCC front end / compiler driver:
LCC License, traditionally named as the "CPYRIGHT" file


### png2hicolorgb:
Public Domain. Glen Cook and others are the original authors, @bbbbbr authored the cross platform console port



### Note about historical license changes:

(some edits for brevity)

August 4, 2022 (bbbbbr)

Re-licensing of GBDK Library & Makefiles

As mentioned above, the way forward is to re-license the library code to GPLV2 + LE to match the parts from SDCC so that all library code uses the same license.

To that end:

- This is from Jon Fuge @jf1452 when asked about re-licensing his contributions to GPL or GPLv2 with a Linking Exception (to have the same licenses as the SDCC library code):

    "Yes, completely happy to re-license the code to make it more accessible and link to my GitHub account."

- This is from Pascal Felber when asked about re-licensing his contributions to GPL or GPLv2 with a Linking Exception (to have the same licenses as the SDCC library code):

    "Yes, absolutely."

- Earlier in this issues @nzmichaelh mentioned being ok with re-licensing to MIT or BSD2. However instead of MIT or BSD2, I'd like to get final specific agreement from @nzmichaelh as well for GPLv2 + LE (linking exception) if that is acceptable (for the reasons mentioned above).

    nzmichaelh, Michael Hope: "GPLv2 + LE SGTM, go for it."

...

Great!
We've got the required signoff so I'll start the repo changes and we're good to go.
Thank you so much Michael, Pascal and Jon for allowing the re-license. We really appreciate the time you've taken to help resolve this issue and clear up any license ambiguity.
