* Make mbed_error use bitwise MbedCRC call rather than local
implementation.
* Remove use of POLY_32BIT_REV_ANSI from LittleFS.
* Move some MbedCRC instances closer to use - construction cost is
trivial, and visibility aids compiler optimisation.
* Use compile-time detection of hardware CRC capability, so unneeded
code and tables do not go into the image.
* Add global JSON config option to allow choice between no tables,
16-entry tables or 256-entry tables for software CRC. Default set
to 16-entry, reducing ROM size from previous 256-entry.
* Allow manual override in template parameter to force software or
bitwise CRC for a particular instance.
* Micro-optimisations, particularly use of `RBIT` instruction and
optimising bitwise computation using inline assembler.
Incompatible changes:
* Remove special-case "POLY_32BIT_REV_ANSI" - users can use standard
POLY_32BIT_ANSI, which now uses the same 16-entry tables by default,
or can use hardware acceleration, which was disabled for
POLY_32BIT_REV_ANSI. MbedCRC<POLY_32BIT_ANSI, 32, CrcMode::TABLE> can
be used to force software like POLY_32BIT_REV_ANSI.
* The precomputed table for POLY_16BIT_IBM had errors - this has been
corrected, but software CRC results will be different from the previous
software calculation.
* < 8-bit CRC results are no longer are shifted up in the output value,
but placed in the lowest bits, like other sizes. This means that code
performing the SD command CRC will now need to use `(crc << 1) | 1`,
rather than `crc | 1`.
This fixes:
```
[Warning] SerialBase.h@351,22: 'mbed::SerialBase::_flow2' will be initialized after [-Wreorder]
[Warning] SerialBase.h@343,22: 'bool mbed::SerialBase::_rx_enabled' [-Wreorder]
[Warning] SerialBase.cpp@26,1: when initialized here [-Wreorder]
```
by using C++11 style initializer for SerialBase
Kudos to Kevin Bracey, as her his suggestion - we can drop the initializer
list if we just set the values directly in the SerialBase.h. No need to
worry about the "right order" after that.
It is now possible to temporarily suspend PWM and safely preserve the duty
cycle set. This functionality is needed to allow a device to enter deep
sleep as a PWM instance prevents deep sleep in order for the timer it
relies on to run so its output can be modified. The duty cycle configuration
can be restored upon resuming from deep sleep.
Existing code may a dependency on the old behavior of "-1" to
mean "no instruction". Therefore, update the typedef, and the value
of QSPI_NO_INST, to avoid breaking those uses.
Encourage the usage of consistent types (there are currently
a mix of `int` and `unsigned int` used for qspi instructions)
QSPI commands are limited to 8 bits, to this is a typdef to char
It is possible to temporarily suspend USB and safely preserve its
configuration. This is needed to allow a device to enter deep
sleep as a USBDevice instance prevents deep sleep. USB operation can be
suspended with `deinit` and restored with `connect`.
The QSPI spec allows alt to be any size that is a multiple of the
number of data lines. For example, Micron's N25Q128A uses only a
single alt cycle for all read modes (1, 2, or 4 bits depending on
how many data lines are in use).
Przemyslaw Stekiel
Martin Kojtal
Kevin Bracey
Janne Kiiskila
Sandeep Mistry
Hugues Kamba
Mike Naberezny
Sebastian Stockhammer
Kyle Kearney
Matthew Macovsky
jeromecoutant