See CHANGELOG.md for a summary of the changes.
Change-Id: I7a3ebb336958a61ea9e0ad02fb9c844960847ebb

beurdouc authored May 13, 2025 and Kevin Mooney committed May 13, 2025

Fixes issue #6 

In the rate matching function, the starting position of bit selection `k0` is calculated in the way instructed by 3GPP TS 38.212 and then used to copy the selected part of the encoder output.
But, this `k0` is the starting position of bit selection in the encoder output **including the filler bits**. While bits are selected from a buffer `in_bits` **where filler bits were previously removed**.
The result is that if `k0` falls within or after the filler bits then bits selection starts at the wrong position which introduces an offset in the bit selection output with regard to the expected output.

This commit fixes this behavior in the library at `src/UpperPHY/LDPC/arm_ldpc_rate_matching.cpp` but also in the reference implementation at `test/UpperPHY/LDPC/RateMatching/main.cpp`.
The fix is to test where k0 falls relatively to the filler bits and reduce it accordingly before proceeding with bit selection.

## Checklist

* [x] [Contribution meets RAL's licence terms](https://gitlab.arm.com/networking/ral/-/blob/main/CONTRIBUTING.md#user-content-licensing-information)
* [x] [New functions adhere to RAL's naming scheme](https://gitlab.arm.com/networking/ral/-/blob/main/CONTRIBUTING.md#user-content-function-naming)
* [x] [Contribution conforms to RAL's directory structure](https://gitlab.arm.com/networking/ral/-/blob/main/CONTRIBUTING.md#user-content-directory-structure)
* [] [Documentation updated](https://gitlab.arm.com/networking/ral/-/blob/main/CONTRIBUTING.md#user-content-documentation) -> not relevant
* [x] ["Unreleased" section of the Changelog updated](https://gitlab.arm.com/networking/ral/-/blob/main/CHANGELOG.md#unreleased)
* [x] [`clang-format` and `clang-tidy` run and changes included (C/C++ code)](https://gitlab.arm.com/networking/ral/-/blob/main/CONTRIBUTING.md#user-content-cc-code-style)
* [] [`flake8` run and changes included (Python code)](https://gitlab.arm.com/networking/ral/-/blob/main/CONTRIBUTING.md#user-content-python-code-style) -> no python code, only c
* [x] [`cmake-format` run and changes included (CMake code)](https://gitlab.arm.com/networking/ral/-/blob/main/CONTRIBUTING.md#user-content-cmake-code-style) -> no CMake code, only c
* [x] [Tests added or updated](https://gitlab.arm.com/networking/ral/-/blob/main/CONTRIBUTING.md#user-content-writing-tests)
* [x] [Tests pass when run with AddressSanitizer](https://gitlab.arm.com/networking/ral/-/blob/main/CONTRIBUTING.md?ref_type=heads#user-content-testing-with-addresssanitizer)
* [] [Benchmarks added or updated](https://gitlab.arm.com/networking/ral/-/blob/main/CONTRIBUTING.md#user-content-writing-benchmarks) -> not relevant

See CHANGELOG.md for a summary of the changes.

Change-Id: If1b8f7f2010de93e1328524b761dbb216960a60f

A poster on our forum observed that the accuracy of our LDPC decoder
was very much worse than that of other implementations.

The cause is that we do all our calculations in int8_t fixed-point,
which quickly saturates. The fix is to do all intermediate
calculations in int16_t fixed-point.

On average this causes a performance regression of between 1.2x and
1.3x across all ArmRAL benchmarks.

Co-Authored-By: Radu Salavat <radu.salavat@arm.com>
Co-Authored-By: Rosie Sumpter <rosie.sumpter@arm.com>
Co-Authored-By: Amy Wignall <amy.wignall@arm.com>

Co-Authored-By: Nick Dingle <nick.dingle@arm.com>
Co-Authored-By: Amy Wignall <amy.wignall@arm.com>
Co-Authored-By: Radu Salavat <radu.salavat@arm.com>

Co-Authored-By: Rosie Sumpter <rosie.sumpter@arm.com>
Co-Authored-By: Ryo Suzuki <ryo.suzuki@arm.com>

This will allow Gitlab to automatically detect it and link to it from
the front page of the project, which will make it more visible to
users.

Also update the list of third party licenses (currently empty) to
match and update the documentation to point to the new license files.

This collates all the change information from the Release Notes for
all releases into a single document. Subsequent releases will have
this information added in future.

We also update the Merge Request templates to tell contributors to
update the Changelog.