* Cleanup base64::encode functions
The implementation choice here using libb64 is generally good as it
is a relatively fast implementation, however the adaptation to
use PROGMEM for the translation function was a bad choice, as reading
randomly PROGMEM with byte-wide access is very very very slow.
Doing a naive if-snake is between 20% and 55% faster and uses less
flash (about 120 bytes less) and also for reasons I don't understand
8 bytes less data RAM (maybe the removal of static?).
In addition the base64::encode function was allocating for larger
input a huge amount of memory (twice the total size). we can reduce
that by doing a chunk-wise conversation to base64.
* Create authorisation base64 encoded string without newlines
Rather than first creating a string with newlines and then
stripping it away in the fast path of constructing the query,
we can call the right method and trust that the result does
not have newlines anymore.
This is another instance in the core library where we pass in read-only
parameters as pass-by-value, where in the case of String() that
is inefficient as it involves copy-constructor/temp string creations.
Remove and rewrite all the parts of the core/libraries using TIMER1
and consolidate into a single, shared waveform generation interrupt
structure. Tone, analogWrite(), Servo all now just call into this
shared resource to perform their tasks so are all compatible
and can be used simultaneously.
This setup enables multiple tones, analogWrites, servos, and stepper
motors to be controlled with reasonable accuracy. It uses both TIMER1
and the internal ESP cycle counter to handle timing of waveform edges.
TIMER1 is used in non-reload mode and only edges cause interrupts. The
interrupt is started and stopped as required, minimizing overhead when
these features are not being used.
A generic "startWaveform(pin, high-US, low-US, runtime-US)" and
"stopWaveform(pin)" allow for further types of interfaces. Minimum
high or low period is ~1 us.
Add a tone(float) method, useful when working with lower frequencies.
Fixes#4321. Fixes 4349.
