Syslog interrrupt buffer:  eliminate a warning about an uninitialized variable; simply some related logic.

libc/wchar: Versions mbrlen and mbsrtowcs taken and adapted from FreeBSD code (at https://github.com/freebsd/freebsd/)

libc/wchar: Versions mbrlen and mbsrtowcs taken and adapted from FreeBSD code (at https://github.com/freebsd/freebsd/)

Kconfig/deconfigs:  Add CONFIG_ARCH_TOOLCHAIN_GNU to indicate that the toolchain is based on GNU gcc/as/ld.  This is in addition to the CPU-specific versions of the same definition.

STM32F410.  Add support for STM32Fr10.  STM32F410 is a version of STM32F4 with 32 KB of RAM and 62 or 128 KB of flash.

kinetis:K66 GPIO and pin mux cleanup

Approved-by: Gregory Nutt <gnutt@nuttx.org>

Fix the libcanard link version to get it compiling without errors.

Approved-by: Gregory Nutt <gnutt@nuttx.org>

Signed-off-by: Alan Carvalho de Assis <acassis@gmail.com>

Bitbucket Issue 47: Some of last syslog changes needed to be condition on #ifdef CONFIG_SYSLOG_BUFFER in order to be built without syslog buffering enabled.

STM32L4: port stm32l4_serial_get_uart function from STM32F7

Approved-by: Gregory Nutt <gnutt@nuttx.org>

syslog:  There is yet another place where the output can get split.  That is in syslog_dev_write():  It will break up the stream to insert a CR before the LF.  This can that can be avoid be generating the CR-LF sequence in the buffer and then detecting and ignoring valid CR-LF sequences, rather than expecting syslog_dev_write() to insert the CR in this case.

I don't like the idea that syslog_dev_write() still scans the entire output buffer to expand CR-LF sequence.  This seems really wasteful, especially in this case where we can be sure that the is no CR or LF without a matching LF or CR.  Bu, I think, the existing behavior in syslog_dev_write() must be retained because it is needed in other contexts.

syslog: Avoid flushing syslog_stream buffer, if possible, until lib_vsprintf() completely parses the format.  This assures that the flush will flush the entire output, even data that may potentially follow the linefeed.  And, in that case, it cannot be interleaved with other devug output.  Suggested by Jussi Kivilinna.

mtd: fix some unallocated and NULL pointer issues.  rwb->wrflush and rwb->wrmaxblocks in rwbuffer could get unallocated values from ftl_initialize() in some configurations.  Also fixes related assert:

  up_assert: Assertion failed at file:rwbuffer.c line: 643

that can happen with the following configuration:

  CONFIG_FTL_WRITEBUFFER=y
  CONFIG_DRVR_WRITEBUFFER=y
  # CONFIG_FS_WRITABLE is not set

These problems are caused by CONFIG variable differences between the buffer layers. TODO: This is not a perfect solution. readahead support has similar issues.

When syslog message has addition characters after last new-line. With buffering those now get lost as vsyslog does not flush output after lib_sprintf. Additional trailing characters could be ANSI escape sequence to reset state that message setups. For example, macro here uses colors and resets state after actual message (including '\n'):

With flushing added to vsyslog, then there is problem that next syslog line might come from other task before reset sequence, causing wrong line getting color. This could be avoided by not flushing on '\n' but only if IOB is full and/or at end of vsyslog. Would this make sense?

STM32L4: Review of last PR + Move separate stm32l4_flash.h; move hardware-specific definitions to chip/stm32l4_flash.h

STM32L4: add internal flash write support

Approved-by: Gregory Nutt <gnutt@nuttx.org>