Merging pull request #37 Adds hard-float support to stm32f4, with a nice mandelbrot example

Merge remote-tracking branch 'schodet/hard-float'

lib/stm32/f4/Makefile

@@ -24,7 +24,8 @@ PREFIX	?= arm-none-eabi
 CC		= $(PREFIX)-gcc
 AR		= $(PREFIX)-ar
 CFLAGS		= -Os -g -Wall -Wextra -I../../../include -fno-common \
-		  -mcpu=cortex-m3 -mthumb -Wstrict-prototypes \
+		  -mcpu=cortex-m4 -mthumb -mfloat-abi=hard -mfpu=fpv4-sp-d16 \
+		  -Wstrict-prototypes \
 		  -ffunction-sections -fdata-sections -MD -DSTM32F4
 # ARFLAGS	= rcsv
 ARFLAGS		= rcs

lib/stm32/f4/vector.c

@@ -18,6 +18,8 @@
  * along with this library.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <libopencm3/stm32/f4/scb.h>
+
 #define WEAK __attribute__ ((weak))
 
 /* Symbols exported by the linker script(s): */
@@ -224,6 +226,9 @@ void reset_handler(void)
 
 	__asm__("MSR msp, %0" : : "r"(&_stack));
 
+	/* Enable access to Floating-Point coprocessor. */
+	SCB_CPACR |= SCB_CPACR_FULL * (SCB_CPACR_CP10 | SCB_CPACR_CP11);
+
 	for (src = &_data_loadaddr, dest = &_data; dest < &_edata; src++, dest++)
 		*dest = *src;