Add framework to let make automatically pick optimized asm implementations over generic C ones to firmware.

Example: for a file asm/foo.c, make will look for asm/arm/foo.[cS] and
compile it if found. If not found it'll fall back to asm/foo.c.

Also introduce new ARCH make variable. This is automatically detected by
configure. It is distinct from CPU since CPU defines the dir used for
the target tree (i.e. firmware/target/X, so it can be "hosted").
ARCH really has the target isa and can be x86 for sims/raaa too.

Change-Id: I18e5d2b7b7bbc2ad2be551a74a0fcae5ffbcbf8b

3 files changed, 30 insertions, 0 deletions

diff --git a/firmware/asm/SOURCES b/firmware/asm/SOURCES
new file mode 100644
index 0000000000..8b13789179
--- /dev/null
+++ b/firmware/asm/SOURCES
@@ -0,0 +1 @@
+
diff --git a/firmware/asm/asm.make b/firmware/asm/asm.make
new file mode 100644
index 0000000000..410cb6ca11
--- /dev/null
+++ b/firmware/asm/asm.make
@@ -0,0 +1,27 @@
+#             __________               __   ___.
+#   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+#   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+#   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+#   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+#                     \/            \/     \/    \/            \/
+# $Id$
+#
+
+# Collect dummy C files in firmware/asm
+ASM_DUMMY_SRC := $(notdir $(call preprocess, $(FIRMDIR)/asm/SOURCES))
+
+# Get the corresponding real source files under firmware/asm/$ARCH (C or ASM)
+ASM_C_SRC := $(addprefix $(FIRMDIR)/asm/$(ARCH)/,$(ASM_DUMMY_SRC))
+ASM_S_SRC := $(ASM_C_SRC:.c=.S)
+
+# ASM_SRC now contains only files that exist under $ARCH
+ASM_SRC := $(wildcard $(ASM_C_SRC))
+ASM_SRC += $(wildcard $(ASM_S_SRC))
+
+# GEN_SRC now contains a .c for each file in ASM_DUMMY_SRC that's not in ASM_SRC
+# I.e. fallback to a generic C source if no correspinding file in $ARCH is found
+GEN_SRC := $(filter-out $(notdir $(ASM_SRC:.S=.c)),$(ASM_DUMMY_SRC))
+GEN_SRC := $(addprefix $(FIRMDIR)/asm/,$(GEN_SRC))
+
+FIRMLIB_SRC += $(ASM_SRC)
+FIRMLIB_SRC += $(GEN_SRC)
diff --git a/firmware/firmware.make b/firmware/firmware.make
index aab735aa91..94747613ba 100644
--- a/firmware/firmware.make
+++ b/firmware/firmware.make
@@ -12,6 +12,8 @@ ifndef APP_TYPE
 INCLUDES += -I$(FIRMDIR)/libc/include
 endif
 
+include $(FIRMDIR)/asm/asm.make
+
 FIRMLIB_SRC += $(call preprocess, $(FIRMDIR)/SOURCES)
 FIRMLIB_OBJ := $(call c2obj, $(FIRMLIB_SRC))
 ifeq (,$(findstring -DARCHOS_PLAYER,$(TARGET)))