add the code to initalize the RNG w/ SRAM..

Makefile

@@ -1,25 +1,48 @@
 ARMCC?= arm-none-eabi-gcc
+ARMOBJDUMP?= arm-none-eabi-objdump
 ARMTARGET?= -mcpu=cortex-m3 -mthumb -DSTROBE_SINGLE_THREAD=1
 
-CFLAGS = -Istrobe
+PROG = lora.irr
+PROGEXT = .elf
+
+SRCS = main.c
+SRCS+= strobe_rng_init.c
+
 CFLAGS+= -DNDEBUG
 
-SRCS = \
-	strobe/strobe.c strobe/x25519.c
+# Strobe
+.PATH: $(.CURDIR)/strobe
+CFLAGS = -I$(.CURDIR)/strobe
+SRCS+= strobe.c \
+	x25519.c
+
+# Microcontroller
+STM32=$(.CURDIR)/stm32
+.PATH: $(STM32)/l151ccux
+LINKER_SCRIPT=$(STM32)/l151ccux/STM32L151CCUX_FLASH.ld
+SRCS+=	startup_stm32l151ccux.s \
+	system_stm32l1xx.c
+
+CFLAGS+= -I$(STM32)
+CFLAGS+= -I$(STM32)/l151ccux
+CFLAGS+= -DSTM32L151xC
 
-.OBJDIR = build
+OBJS = $(SRCS:C/.c$/.o/)
 
 .PHONY: all
-all: $(BUILDDIR)/strobe.o $(BUILDDIR)/x25519.o
+all: $(PROG)$(PROGEXT) $(PROG).list
+
+$(PROG)$(PROGEXT): $(OBJS)
+	$(ARMCC) $(ARMTARGET) -o $@ $(.ALLSRC) -T$(LINKER_SCRIPT) --specs=nosys.specs -Wl,--gc-sections -static --specs=nano.specs -Wl,--start-group -lc -lm -Wl,--end-group
+
+$(PROG).list: $(PROG)$(PROGEXT)
+	$(ARMOBJDUMP) -h -S $(.ALLSRC) > $@
 
 .PHONY: runtests
 runtests:
 	ls *.py | entr sh -c 'python -m coverage run -m unittest lora && coverage report --omit=p/\* -m -i'
 
-$(BUILDDIR):
-	mkdir -p $@
-
-$(BUILDDIR)/%.o : %.c
+.c.o:
 	$(ARMCC) $(ARMTARGET) $(CFLAGS) -c $< -o $@
 
 STROBE_REPO = https://git.code.sf.net/p/strobe/code

main.c

@@ -0,0 +1,8 @@
+#include <strobe_rng_init.h>
+
+int
+main(void)
+{
+
+	strobe_rng_init();
+}

stm32/l151ccux/STM32L151CCUX_FLASH.ld

@@ -57,6 +57,7 @@ _estack = ORIGIN(RAM) + LENGTH(RAM);	/* end of "RAM" Ram type memory */
 
 _Min_Heap_Size = 0x200 ;	/* required amount of heap  */
 _Min_Stack_Size = 0x400 ;	/* required amount of stack */
+rng_save_len = 32 ;		/* length of RNG state save space */
 
 /* Memories definition */
 MEMORY
@@ -177,6 +178,14 @@ SECTIONS
     __bss_end__ = _ebss;
   } >RAM
 
+  ._rng_state :
+  {
+    . = ALIGN(4);
+    PROVIDE ( rng_save = .);
+    . = . + rng_save_len;
+    . = ALIGN(4);
+  } >RAM
+
   /* User_heap_stack section, used to check that there is enough "RAM" Ram  type memory left */
   ._user_heap_stack :
   {

strobe_rng_init.c

@@ -0,0 +1,16 @@
+#include <strobe.h>
+
+#include <strobe_rng_init.h>
+
+extern char rng_save;
+extern int rng_save_len;
+
+void
+strobe_rng_init(void)
+{
+	int r;
+
+	strobe_seed_prng(&rng_save, 2*1024);
+
+	r = strobe_randomize(&rng_save, rng_save_len);
+}

strobe_rng_init.h

@@ -0,0 +1,2 @@
+
+void strobe_rng_init(void);