blue-pill: convert blinky to startup.s boot.

blue-pill/blinky/Makefile

@@ -1,5 +1,5 @@
 # configurables
-OBJS :=		
+OBJS :=		startup.o
 TARGET :=	blinky
 OBJS +=		$(TARGET).o
 
@@ -9,9 +9,9 @@ BIN :=		$(TARGET).bin
 
 # toolchain setup
 ARMTC :=	arm-none-eabi
-ARMCC :=	$(ARMTC)-gcc
-CC :=		$(ARMCC)
-LD :=		$(ARMCC)
+CC :=		$(ARMTC)-gcc
+LD :=		$(ARMTC)-gcc
+AS :=		$(ARMTC)-as
 ARMSIZE :=	$(ARMTC)-size
 OBJCOPY :=	$(ARMTC)-objcopy
 
@@ -30,7 +30,7 @@ STARTMEM :=	0x8000000
 all: $(BIN)
 
 $(ELF): $(OBJS)
-	$(ARMCC) $(LDFLAGS) -o $@ $(OBJS) $(LDLIBS)
+	$(CC) $(LDFLAGS) -o $@ $(OBJS) $(LDLIBS)
 	$(ARMSIZE) $@
 
 .PHONY: strip

blue-pill/blinky/blinky.c

@@ -19,7 +19,9 @@ led_on() {
 	set_pin(GPIO_C, LED_PIN);
 }
 
-void __attribute__ ((weak, naked)) reset_handler(void) {
+int
+main(void)
+{
     *RCC |= (1 << 4); /* enable port C clock */
     output_mode(GPIO_C, LED_PIN, OUTPUT_GPP, OUTPUT_MAX_2MHZ);
 
@@ -35,22 +37,3 @@ void __attribute__ ((weak, naked)) reset_handler(void) {
     }
 }
 
-__attribute__ ((section(".vectors")))
-struct {
-    unsigned int *initial_sp_value;
-    void (*reset)(void);
-    void (*nmi)(void);
-    void (*hard_fault)(void);
-    void (*memory_manage_fault)(void);
-    void (*bus_fault)(void);
-    void (*usage_fault)(void);
-    void (*reserved_x001c[4])(void);
-    void (*sv_call)(void);
-    void (*debug_monitor)(void);
-    void (*reserved_x0034)(void);
-    void (*pend_sv)(void);
-    void (*systick)(void);
-    void (*irq[68])(void);
-} vector_table = {
-    .reset = reset_handler,
-};

blue-pill/blinky/startup.s

@@ -0,0 +1,28 @@
+/*
+ * Startup code for the STM32F103-based blue pill board.
+ *
+ * TODO: revisit stack pointer
+ * TODO: is the IRQv buffer actually needed right now?
+ */
+
+.globl	vectors
+vectors:
+.align	2
+.long	0x100			/* best guess at stack pointer */
+.long	reset_handler		/* reset handler */
+.long	0			/* NMI handler */
+.long	0			/* hard_fault_handler */
+.long	0			/* memory management handler */
+.long	0			/* bus fault handler */
+.long	0			/* usage fault handler */
+.skip	0x20			/* reserved */
+.long	0			/* svcall handler */
+.long	0			/* debug handler */
+.skip	4			/* reserved */
+.long	0			/* pendsv handler */
+.long	0			/* systick handler */
+.skip   0xf4			/* remaining / IRQ vectors */
+
+.globl	reset_handler
+reset_handler:
+	bl	main