From 84709d49f53e9169b7325b53588e7ee28b8e2f3c Mon Sep 17 00:00:00 2001
From: Travis Geiselbrecht <geist@foobox.com>
Date: Sat, 30 Jan 2016 14:41:36 -0800
Subject: [PATCH] [make] add a quick in dirty help target for the build system

make help: a quick overview of how to use the build system
make list: a list of all the buildable projects
---
 engine.mk    |  5 ++++-
 make/help.mk | 53 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 57 insertions(+), 1 deletion(-)
 create mode 100644 make/help.mk

diff --git a/engine.mk b/engine.mk
index 75beb7ba..47e8f248 100644
--- a/engine.mk
+++ b/engine.mk
@@ -31,6 +31,9 @@ make-make:
 endif
 endif
 
+# some additional rules to print some help
+include make/help.mk
+
 ifeq ($(do-nothing),)
 
 ifeq ($(PROJECT),)
@@ -38,7 +41,7 @@ ifeq ($(PROJECT),)
 ifneq ($(DEFAULT_PROJECT),)
 PROJECT := $(DEFAULT_PROJECT)
 else
-$(error No project specified.  Use "make projectname" or put "PROJECT := projectname" in local.mk)
+$(error No project specified. Use 'make list' for a list of projects or 'make help' for additional help)
 endif
 endif
 
diff --git a/make/help.mk b/make/help.mk
new file mode 100644
index 00000000..d4402bed
--- /dev/null
+++ b/make/help.mk
@@ -0,0 +1,53 @@
+# routines and rules to print some helpful stuff
+
+
+#$(warning MAKECMDGOALS = $(MAKECMDGOALS))
+
+# print some help and exit
+ifeq ($(firstword $(MAKECMDGOALS)),help)
+do-nothing=1
+
+.PHONY: help
+help:
+	@echo "LK build system quick help\n" \
+	"Individual projects are built into a build-<project> directory\n" \
+	"Output binary is located at build-<project>/lk.bin\n" \
+	"Environment or command line variables controlling build:\n" \
+	"PROJECT = <project name>\n" \
+	"TOOLCHAIN_PREFIX = <absolute path to toolchain or relative path with prefix>\n" \
+	"\n" \
+	"Special make targets:\n" \
+	"make help: This help\n" \
+	"make list: List of buildable projects\n" \
+	"make clean: cleans build of current project\n" \
+	"make spotless: removes all build directories\n" \
+	"make <project>: try to build project named <project>\n" \
+	"\n" \
+	"Examples:\n" \
+	"PROJECT=testproject make\n" \
+	"PROJECT=testproject make clean\n" \
+	"make testproject\n" \
+	"make testproject clean\n" \
+	"\n" \
+	"output will be in build-testproject/\n" \
+
+endif
+
+# list projects
+ifeq ($(firstword $(MAKECMDGOALS)),list)
+do-nothing=1
+
+# get a list of all the .mk files in the top level project directories
+PROJECTS:=$(basename $(strip $(foreach d,$(LKINC),$(wildcard $(d)/project/*.mk))))
+PROJECTS:=$(shell basename $(PROJECTS))
+
+.PHONY: list
+list:
+	@echo 'List of all buildable projects: (look in project/ directory)'; \
+	for p in $(PROJECTS); do \
+		echo $$p; \
+	done
+
+endif
+
+# vim: set syntax=make noexpandtab