blue-pill: start the startup code

no idea if this works yet

.gitignore

@@ -41,3 +41,7 @@ ods/src/ch??ex??
 *.la
 *_bench
 misc/kf/kf
+*.elf
+*.bin
+blue-pill/*/*.d
+core

blue-pill/draugr/Makefile

@@ -1,5 +1,5 @@
 # configurables
-OBJS :=		
+OBJS :=		startup.o
 TARGET :=	blink
 OBJS += $(TARGET).o
 
@@ -9,18 +9,17 @@ BIN :=		$(TARGET).bin
 
 # toolchain setup
 ARMTC :=	arm-none-eabi
-ARMCC :=	$(ARMTC)-gcc
+AS :=		$(ARMTC)-as
-ARMCXX :=	$(ARMTC)-g++
+CC :=		$(ARMTC)-gcc
-CC :=		$(ARMCC)
+CXX :=		$(ARMTC)-g++
-CXX :=		$(ARMCXX)
+LD :=		$(ARMTC)-ld
-LD :=		$(ARMCXX)
 ARMSIZE :=	$(ARMTC)-size
 OBJCOPY :=	$(ARMTC)-objcopy
 
 # compiler options
 CPUFLAGS :=	-mcpu=cortex-m3 -mthumb
 CFLAGS :=	-Wall -Wextra -Os -MD $(CPUFLAGS)
-CXXFLAGS :=	-Wall -Wextra -Os -MD $(CPUFLAGS) -std=c++14
+CXXFLAGS :=	$(CFLAGS) -std=c++14 -fno-rtti -fno-exceptions -ffunction-sections -fdata-sections -fno-builtin
 LDFLAGS :=	$(CPUFLAGS) -nostartfiles -Wl,-T,stm32f103.ld
 LDLIBS :=	-lc -lnosys
 
@@ -33,7 +32,7 @@ STARTMEM :=	0x8000000
 all: $(BIN)
 
 $(ELF): $(OBJS)
-	$(ARMCC) $(LDFLAGS) -o $@ $(OBJS) $(LDLIBS)
+	$(CC) $(LDFLAGS) -o $@ $(OBJS) $(LDLIBS)
 	$(ARMSIZE) -A $@
 
 $(BIN): $(ELF)

blue-pill/draugr/blink.cc

@@ -2,48 +2,20 @@
 
 #define LED_PIN	13
 
-void 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 = {
-	initial_sp_value : (unsigned int *)0x100,
-	reset : reset_handler,
-};
-
-static inline void
-delay(unsigned long ms)
-{
-	for (unsigned long i = 0; i < ms; ++i) __asm__("nop");
-}
-
 // void __attribute__ ((weak, naked)) reset_handler(void) {
-void reset_handler() {
+int
-    *RCC |= (1 << 4); /* enable port C clock */
+main() {
-    GPIO_C->output_mode(LED_PIN, OUTPUT_GPP, OUTPUT_MAX_2MHZ);
+    GPIO_C->enable_clock();
+    GPIO_C->pin_mode(LED_PIN, true, OUTPUT_GPP, OUTPUT_MAX_2MHZ);
 
     while(1) {
-	    GPIO_C->clear_pin(LED_PIN);
+	    GPIO_C->pin_clear(LED_PIN);
 	    delay(1000000);
-	    GPIO_C->set_pin(LED_PIN);
+	    GPIO_C->pin_set(LED_PIN);
 	    delay(100000);
-	    GPIO_C->clear_pin(LED_PIN);
+	    GPIO_C->pin_clear(LED_PIN);
 	    delay(100000);
-	    GPIO_C->set_pin(LED_PIN);
+	    GPIO_C->pin_set(LED_PIN);
 	    delay(100000);
     }
 }

blue-pill/draugr/bluepill.h

@@ -4,4 +4,10 @@
 #include "bluepill/gpio.h"
 #include "bluepill/rcc.h"
 
+static inline void
+delay(unsigned long ms)
+{
+	for (unsigned long i = 0; i < ms; ++i) __asm__("nop");
+}
+
 #endif // __BLUEPILL_H__

blue-pill/draugr/bluepill/gpio.h

@@ -2,6 +2,7 @@
 #define __BLUEPILL_GPIO_H__
 
 #include <stdint.h>
+#include "rcc.h"
 
 constexpr volatile unsigned int	*PORTA = reinterpret_cast<volatile unsigned int *>(0x40010800);
 constexpr volatile unsigned int	*PORTB = reinterpret_cast<volatile unsigned int *>(0x40010c00);
@@ -11,9 +12,10 @@ constexpr volatile unsigned int	*PORTE = reinterpret_cast<volatile unsigned int
 
 class GPIO {
 public:
-	void	set_pin(uint32_t pin) { this->BSRR |= ((1 << pin) << 16); }
+	void	pin_set(uint32_t pin) { this->BSRR |= ((1 << pin) << 16); }
-	void	clear_pin(uint32_t pin) { this->BSRR |= (1 << pin); }
+	void	pin_clear(uint32_t pin) { this->BSRR |= (1 << pin); }
-	void	output_mode(uint32_t pin, uint32_t mode, uint32_t max) {
+	void	pin_mode(uint32_t pin, bool output, uint32_t mode, uint32_t max) {
+		if (output) {
 			if (pin > 7) {
 				pin = ((pin - 8) * 4);
 				this->CRH |= (max << pin);
@@ -25,6 +27,17 @@ public:
 				this->CRL |= (mode << (pin + 2));
 			}
 		}
+	}
+
+	uint32_t	port_index(void) {
+		/* Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn. */
+		return (((unsigned int)this) - ((unsigned int)PORTA)) >> 10;
+	}
+
+	void enable_clock(void) {
+		*RCC |= (1 << (this->port_index() + 2));
+	}
+
 
 private:
 	uint32_t	CRL;	/* configuration register low */

blue-pill/draugr/startup.s

@@ -0,0 +1,27 @@
+/*
+ * Startup code for the STM32F103-based blue pill board.
+ *
+ * TODO: revisit stack pointer
+ * TODO: is the IRQv buffer actually needed right now?
+ */
+
+.globl	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   0x110			/* remaining / IRQ vectors */
+
+.globl	reset_handler
+reset_handler:
+	bl	main