From 614736cbb23fd71794d489a22a2a78a2d45e2a1b Mon Sep 17 00:00:00 2001
From: David Garske <david@wolfssl.com>
Date: Thu, 21 Sep 2017 11:09:44 -0700
Subject: [PATCH] Add code to detect if Cortex M series and disable
 architecture specific code in `armtarget.c`. Improved `Makefile.common` to
 include toolchain prefix.

---
 IDE/GCC-ARM/Makefile.common    | 31 ++++++++++++++++++++-----------
 IDE/GCC-ARM/README.md          |  6 +++++-
 IDE/GCC-ARM/Source/armtarget.c | 12 ++++++++++++
 3 files changed, 37 insertions(+), 12 deletions(-)

diff --git a/IDE/GCC-ARM/Makefile.common b/IDE/GCC-ARM/Makefile.common
index b64fc7c41..beab49806 100755
--- a/IDE/GCC-ARM/Makefile.common
+++ b/IDE/GCC-ARM/Makefile.common
@@ -3,7 +3,9 @@ CMD_ECHO =
 
 # Important directories
 BUILD_DIR = ./Build
-TOOLCHAIN_DIR = /opt/gcc-arm-none-eabi/bin
+
+# Toolchain location and prefix
+TOOLCHAIN = /opt/gcc-arm-none-eabi/bin/arm-none-eabi-
 
 INC = -I./Header \
 	  -I./Source \
@@ -26,9 +28,16 @@ CFLAGS = $(ARCHFLAGS) -std=gnu99 -Wall -Wno-cpp \
 		 -ffunction-sections -fdata-sections \
 		 -Os -flto $(DBGFLAGS)
 
-# LD: Remove unused sections, link with newlib-nano implementation, generate map
-LDFLAGS = $(ARCHFLAGS) -Wl,--gc-sections --specs=nano.specs --specs=nosys.specs
+# LD: Remove unused sections
+LDFLAGS = $(ARCHFLAGS) -Wl,--gc-sections
+
+# LD: Link with newlib-nano implementation
+LDFLAGS += --specs=nano.specs --specs=nosys.specs
+
+# LD: generate map
 LDFLAGS += -Wl,-Map=$(BUILD_DIR)/$(BIN).map $(DBGFLAGS)
+
+# LD: Entry point
 LDFLAGS += -Wl,-ereset_handler
 
 # Math lib (for DH)
@@ -42,14 +51,14 @@ OBJS_C = $(addprefix $(BUILD_DIR)/, $(FILENAMES_C:.c=.o))
 vpath %.c $(dir $(SRC_C))
 
 # Tools selection
-CC = $(TOOLCHAIN_DIR)/arm-none-eabi-gcc
-AS = $(TOOLCHAIN_DIR)/arm-none-eabi-gcc
-LD = $(TOOLCHAIN_DIR)/arm-none-eabi-gcc
-AR = $(TOOLCHAIN_DIR)/arm-none-eabi-ar
-NM = $(TOOLCHAIN_DIR)/arm-none-eabi-nm
-OBJCOPY = $(TOOLCHAIN_DIR)/arm-none-eabi-objcopy
-OBJDUMP = $(TOOLCHAIN_DIR)/arm-none-eabi-objdump
-SIZE = $(TOOLCHAIN_DIR)/arm-none-eabi-size
+CC = $(TOOLCHAIN)gcc
+AS = $(TOOLCHAIN)gcc
+LD = $(TOOLCHAIN)gcc
+AR = $(TOOLCHAIN)ar
+NM = $(TOOLCHAIN)nm
+OBJCOPY = $(TOOLCHAIN)objcopy
+OBJDUMP = $(TOOLCHAIN)objdump
+SIZE = $(TOOLCHAIN)size
 
 build_hex: $(BUILD_DIR) $(BUILD_DIR)/$(BIN).hex
 	@echo ""
diff --git a/IDE/GCC-ARM/README.md b/IDE/GCC-ARM/README.md
index 00eb0d26e..34119dc43 100755
--- a/IDE/GCC-ARM/README.md
+++ b/IDE/GCC-ARM/README.md
@@ -1,5 +1,7 @@
 # Example Project for GCC ARM
 
+This example is for Cortex M series, but can be adopted for other architectures.
+
 ## Design
 
 * All library options are defined in `Header/user_settings.h`.
@@ -10,7 +12,9 @@
 ## Building
 
 1. Make sure you have `gcc-arm-none-eabi` installed.
-2. Modify the `Makefile.common` to use correct toolchain directory `TOOLCHAIN_DIR` and architecture 'ARCHFLAGS' (default is cortex-m0 / thumb). See [GCC ARM Options](https://gcc.gnu.org/onlinedocs/gcc-4.7.3/gcc/ARM-Options.html) `-mcpu=name`.
+2. Modify the `Makefile.common`:
+  * Use correct toolchain path `TOOLCHAIN`.
+  * Use correct architecture 'ARCHFLAGS' (default is cortex-m0 / thumb). See [GCC ARM Options](https://gcc.gnu.org/onlinedocs/gcc-4.7.3/gcc/ARM-Options.html) `-mcpu=name`.
 3. Use `make` and it will build the static library and wolfCrypt test/benchmark and wolfSSL TLS client targets as `.elf` and `.hex` in `/Build`.
 
 Example:
diff --git a/IDE/GCC-ARM/Source/armtarget.c b/IDE/GCC-ARM/Source/armtarget.c
index c090f5a7e..13c830a39 100755
--- a/IDE/GCC-ARM/Source/armtarget.c
+++ b/IDE/GCC-ARM/Source/armtarget.c
@@ -28,6 +28,13 @@
 #include <stdarg.h>
 #include <string.h>
 
+/* Test to determine if ARM Cortex M */
+#if defined(__arm__) && defined(__ARM_ARCH) && (__ARM_ARCH == 6 || __ARM_ARCH == 7)
+    #define CORTEX_M_SERIES
+#endif
+
+
+#ifdef CORTEX_M_SERIES
 /* Memory initialization */
 extern uint32_t __data_load_start__[];
 extern uint32_t __data_start__[];
@@ -55,10 +62,12 @@ void meminit32(uint32_t* start, uint32_t* end)
         *start++ = 0;
     }
 }
+#endif /* CORTEX_M_SERIES */
 
 /* Entry Point */
 void reset_handler(void)
 {
+#ifdef CORTEX_M_SERIES
     /* Init sections */
     memcpy32(__data_load_start__, __data_start__, __data_end__);
     meminit32(__bss_start__, __bss_end__);
@@ -66,6 +75,7 @@ void reset_handler(void)
     /* Init heap */
     __heap_start__[0] = 0;
     __heap_start__[1] = ((uint32_t)__heap_end__ - (uint32_t)__heap_start__);
+#endif /* CORTEX_M_SERIES */
 
     /* Start main */
     extern int main(void);
@@ -75,6 +85,7 @@ void reset_handler(void)
     while(1);
 }
 
+#ifdef CORTEX_M_SERIES
 // Vector Exception/Interrupt Handlers
 static void Default_Handler(void)
 {
@@ -199,6 +210,7 @@ const vector_entry vectors[] __attribute__ ((section(".vectors"),used)) =
 
     /* remainder go below */
 };
+#endif /* CORTEX_M_SERIES */
 
 
 /* TIME CODE */