makefiles/utils/ansi: Refactor ansi codes into their own file.

The escape codes and special chars now live in their own module. The
color module is only concerned with detecting whether to use colors or
not.

Additional variables are defined with hard a coded ESC char, a tab and a
newline. This removes the need for echo or printf.

Makefile.include

@@ -171,6 +171,7 @@ include $(RIOTMAKE)/utils/checks.mk
 include $(RIOTMAKE)/docker.inc.mk
 
 # include color echo macros
+include $(RIOTMAKE)/utils/ansi.mk
 include $(RIOTMAKE)/color.inc.mk
 
 # include concurrency helpers

makefiles/color.inc.mk

@@ -14,12 +14,11 @@ ifneq ($(CC_NOCOLOR),1)
   IS_TERMINAL = $(if $(MAKE_TERMOUT),$(MAKE_TERMERR),)
   # Check if terminal support colored output
   ifneq ($(IS_TERMINAL),)
-    _ANSI_ESC := $(shell printf "\033")
-    COLOR_GREEN  := $(_ANSI_ESC)[1;32m
-    COLOR_RED    := $(_ANSI_ESC)[1;31m
-    COLOR_YELLOW := $(_ANSI_ESC)[1;33m
-    COLOR_PURPLE := $(_ANSI_ESC)[1;35m
-    COLOR_RESET  := $(_ANSI_ESC)[0m
+    COLOR_GREEN  := $(ANSI_GREEN)
+    COLOR_RED    := $(ANSI_RED)
+    COLOR_YELLOW := $(ANSI_YELLOW)
+    COLOR_PURPLE := $(ANSI_PURPLE)
+    COLOR_RESET  := $(ANSI_RESET)
     ifeq ($(OS),Darwin)
       COLOR_ECHO   := echo -e
       SHELL=bash

makefiles/utils/ansi.mk

@@ -0,0 +1,11 @@
+# ANSI Terminal codes and other escape sequences.
+# The objective of this definitions is to be able to write special characters
+# without resorting to shell commands like echo.
+
+include $(RIOTMAKE)/utils/ansi_special.mk
+
+ANSI_GREEN  := $(ANSI_ESC)[1;32m
+ANSI_RED    := $(ANSI_ESC)[1;31m
+ANSI_YELLOW := $(ANSI_ESC)[1;33m
+ANSI_PURPLE := $(ANSI_ESC)[1;35m
+ANSI_RESET  := $(ANSI_ESC)[0m

makefiles/utils/ansi_special.mk

@@ -0,0 +1,16 @@
+# Make does not recognize escaped characters (e.g. \t, \033, etc).
+# The following variables contain the characters themselves.
+# This file is inherently fragile (i.e. your editor could destroy the tab
+# without you realizing, to be careful when editing this.
+
+# To generate this: $ printf "ANSI_ESC := \033# comment"
+ANSI_ESC := # you may or may not be able to see that character in your editor
+
+# The third parameter to the subst is a tab - be careful not to replace it with
+# spaces!
+TAB := $(subst ,,	)
+
+define NEWLINE
+
+
+endef