nuttx/boards/arm/xmc4/xmc4700-relax
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/nsh libc/stdio: Allocate file_struct dynamically 2020-09-11 17:58:17 +08:00
include boards/arm/xmc4: add initial support for the Infineon XMC4700 Relax board 2020-03-22 08:29:51 -06:00
scripts make/expression: improving up asm/C/C++ compile times 2020-11-02 07:53:53 -08:00
src drivers/led: Extend userled_set_t from 8bits to 32bits 2020-06-07 19:28:10 +01:00
Kconfig boards/arm/xmc4: add initial support for the Infineon XMC4700 Relax board 2020-03-22 08:29:51 -06:00
README.txt boards/arm/xmc4: add initial support for the Infineon XMC4700 Relax board 2020-03-22 08:29:51 -06:00

README for the XMC4700 Relax
============================

  The directory provides board support for the Infineon XMC4700 Relax Kit.

Status
======

  2020-03-21:   The XMC4700 Relax boots into NSH, provides the NSH prompt,
    and the LEDs are working.