The "spacing" of "buffer structure" is confusing, use the "channel count"
instead.
Testing performed on nrf52840 feather:
Play stereo and mono, 8- and 16-bit, 8kHz RawSamples representing 333.33Hz
square waves.
Use both mono and stereo PWMAudioOut instances.
Scope the RC-filtered signal and use the scope's frequency
measurement function, verify the frequency is 333 or 334Hz in all tested
cases.
In the "stereo output" cases, verify both the L and R channels. Verify
the output amplitude is the same in both channels.
In the "stereo output" cases, run a second test where the L channel's
amplitude is attenuated 50%. Verify the output amplitude is correct
in each channel.
If a translation only has unicode code points 255 and below, the "values"
array can be 8 bits instead of 16 bits. This reclaims some code size,
e.g., in a local build, trinket_m0 / en_US reclaimed 112 bytes and de_DE
reclaimed 104 bytes. However, languages like zh_Latn_pinyin, which use
code points above 255, did not benefit.
By treating each unicode code-point as a single entity for huffman
compression, the overall compression rate can be somewhat improved
without changing the algorithm. On the decompression side, when
compressed values above 127 are encountered, they need to be
converted from a 16-bit Unicode code point into a UTF-8 byte
sequence.
Doing this returns approximately 1.5kB of flash storage with the
zh_Latn_pinyin translation. (292 -> 1768 bytes remaining in my build
of trinket_m0)
Other "more ASCII" translations benefit less, and in fact
zh_Latn_pinyin is no longer the most constrained translation!
(de_DE 1156 -> 1384 bytes free in flash, I didn't check others
before pushing for CI)
English is slightly pessimized, 2840 -> 2788 bytes, probably mostly
because the "values" array was changed from uint8_t to uint16_t,
which is strictly not required for an all-ASCII translation. This
could probably be avoided in this case, but as English is not the
most constrained translation it doesn't really matter.
Testing performed: built for feather nRF52840 express and trinket m0
in English and zh_Latn_pinyin; ran and verified the localized
messages such as
Àn xià rènhé jiàn jìnrù REPL. Shǐyòng CTRL-D chóngxīn jiāzài.
and
Press any key to enter the REPL. Use CTRL-D to reload.
were properly displayed.
.. inline-unit-growth was the same across all boards, and the highest
max-inline-insns-auto parameter was shared across 2 of 5 boards, so it's
worth a little work to follow the DRY principle
When adding the ability for boards to turn on the `@micropython.native`, `viper`, and `asm_thumb` decorators it was pointed out that it's somewhat awkward to write libraries and drivers that can take advantage of this since the decorators raise `SyntaxErrors` if they aren't enabled. In the case of `viper` and `asm_thumb` this behavior makes sense as they require writing non-normative code. Drivers could have a normal and viper/thumb implementation and implement them as such:
```python
try:
import _viper_impl as _impl
except SyntaxError:
import _python_impl as _impl
def do_thing():
return _impl.do_thing()
```
For `native`, however, this behavior and the pattern to work around it is less than ideal. Since `native` code should also be valid Python code (although not necessarily the other way around) using the pattern above means *duplicating* the Python implementation and adding `@micropython.native` in the code. This is an unnecessary maintenance burden.
This commit *modifies* the behavior of the `@micropython.native` decorator. On boards with `CIRCUITPY_ENABLE_MPY_NATIVE` turned on it operates as usual. On boards with it turned off it does *nothing*- it doesn't raise a `SyntaxError` and doesn't apply optimizations. This means we can write our drivers/libraries once and take advantage of speedups on boards where they are enabled.
We weren't correctly collecting the start and stop sequences. As
a result, the GC would free the space and allocate other info
there.
Thanks to JacobT on Discord for the bug report!
