nuttx/boards/arm/s32k1xx/rddrone-uavcan146
chao.an b88561299b make/expression: improving up asm/C/C++ compile times
In the current compilation environment, the recursive assignment(=) for compile
flags will be delayed until every file is actually need to be compile.

For example:
--------------------------------------------------------------------------------
arch/arm/src/Makefile:

INCLUDES += ${shell $(INCDIR) "$(CC)" $(ARCH_SRCDIR)$(DELIM)chip}
INCLUDES += ${shell $(INCDIR) "$(CC)" $(ARCH_SRCDIR)$(DELIM)common}
INCLUDES += ${shell $(INCDIR) "$(CC)" $(ARCH_SRCDIR)$(DELIM)$(ARCH_SUBDIR)}
INCLUDES += ${shell $(INCDIR) "$(CC)" $(TOPDIR)$(DELIM)sched}

CPPFLAGS += $(INCLUDES) $(EXTRAFLAGS)
CFLAGS += $(INCLUDES) $(EXTRAFLAGS)
CXXFLAGS += $(INCLUDES) $(EXTRAFLAGS)
AFLAGS += $(INCLUDES) $(EXTRAFLAGS)
--------------------------------------------------------------------------------

All compilation options will be included recursively,
which will be delayed until the compilation options are actually used:

tools/Config.mk:

--------------------------------------------------------------------------------
define COMPILE
  @echo "CC: $1"
  $(Q) $(CC) -c $(CFLAGS) $($(strip $1)_CFLAGS) $1 -o $2
endef
--------------------------------------------------------------------------------

All compile flags to be reexecuted $(INCDIR) as long as one file needs to be compiled,
but in fact, the compilation options have not changed in the current directory.

So the we recommand to change the syntax of assignment
From
    Recursive (=)
To
    Simple    (:=)

In this way, we can ensure that all compilation options are expanded only once and reducing repeated works.

Signed-off-by: chao.an <anchao@xiaomi.com>
2020-11-02 07:53:53 -08:00
..
configs libc/stdio: Allocate file_struct dynamically 2020-09-11 17:58:17 +08:00
include NXStyle fixes 2020-06-15 08:07:19 -06:00
scripts make/expression: improving up asm/C/C++ compile times 2020-11-02 07:53:53 -08:00
src S32K1XX EEEPROM indentation fix 2020-06-30 12:46:50 -06:00
Kconfig S32K add support for Nxp drone boards (#224) 2020-02-07 04:53:40 -08:00
README.txt Ensure all source code end with one and only one newline 2020-02-08 07:25:56 -06:00

README
======

This directory holds the port to the NXP RDDRONE-UAVCAN board with S32K146 MCU.

Contents
========

  o Status

Status
======

  2020-01-23:  Configuration created (copy-paste from S32K146EVB).
    Tested: Serial console