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

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

examples/stm32/f4/Makefile.include

@@ -36,12 +36,13 @@ endif
 TOOLCHAIN_DIR := ../../../../..
 endif
 CFLAGS		+= -Os -g -Wall -Wextra -I$(TOOLCHAIN_DIR)/include \
-		   -fno-common -mcpu=cortex-m4 -mthumb -msoft-float -MD -DSTM32F4
+		   -fno-common -mcpu=cortex-m4 -mthumb \
+		   -mfloat-abi=hard -mfpu=fpv4-sp-d16 -MD -DSTM32F4
 LDSCRIPT	?= $(BINARY).ld
 LDFLAGS		+= --static -lc -lnosys -L$(TOOLCHAIN_DIR)/lib \
 			 -L$(TOOLCHAIN_DIR)/lib/stm32/f4 \
 		   -T$(LDSCRIPT) -nostartfiles -Wl,--gc-sections \
-		   -mthumb -mcpu=cortex-m4 -march=armv7 -mfix-cortex-m3-ldrd -msoft-float
+		   -mthumb -mcpu=cortex-m4 -mthumb -mfloat-abi=hard -mfpu=fpv4-sp-d16
 OBJS		+= $(BINARY).o
 
 OOCD		?= openocd

examples/stm32/f4/stm32f4-discovery/mandelbrot/Makefile

@@ -0,0 +1,25 @@
+##
+## This file is part of the libopencm3 project.
+##
+## Copyright (C) 2009 Uwe Hermann <uwe@hermann-uwe.de>
+##
+## This library is free software: you can redistribute it and/or modify
+## it under the terms of the GNU Lesser General Public License as published by
+## the Free Software Foundation, either version 3 of the License, or
+## (at your option) any later version.
+##
+## This library is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU Lesser General Public License for more details.
+##
+## You should have received a copy of the GNU Lesser General Public License
+## along with this library.  If not, see <http://www.gnu.org/licenses/>.
+##
+
+BINARY = mandel
+
+LDSCRIPT = ../stm32f4-discovery.ld
+
+include ../../Makefile.include
+

examples/stm32/f4/stm32f4-discovery/mandelbrot/README

@@ -0,0 +1,12 @@
+------------------------------------------------------------------------------
+README
+------------------------------------------------------------------------------
+
+This example program demonstrates the floating point coprocessor usage on
+the ST STM32F4DISCOVERY eval board.
+
+A mandelbrot fractal is calculated and sent as "ascii-art" image through
+the USART2.
+
+The terminal settings for the receiving device/PC are 38400 8n1.
+

examples/stm32/f4/stm32f4-discovery/mandelbrot/mandel.c

@@ -0,0 +1,127 @@
+/*
+ * This file is part of the libopencm3 project.
+ *
+ * Copyright (C) 2009 Uwe Hermann <uwe@hermann-uwe.de>
+ * Copyright (C) 2011 Stephen Caudle <scaudle@doceme.com>
+ * Copyright (C) 2012 Daniel Serpell <daniel.serpell@gmail.com>
+ *
+ * This library is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this library.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <libopencm3/stm32/f4/rcc.h>
+#include <libopencm3/stm32/f4/gpio.h>
+#include <libopencm3/stm32/usart.h>
+
+void clock_setup(void)
+{
+	/* Enable high-speed clock at 120MHz */
+	rcc_clock_setup_hse_3v3(&hse_8mhz_3v3[CLOCK_3V3_120MHZ]);
+
+	/* Enable GPIOD clock for LED & USARTs. */
+	rcc_peripheral_enable_clock(&RCC_AHB1ENR, RCC_AHB1ENR_IOPDEN);
+	rcc_peripheral_enable_clock(&RCC_AHB1ENR, RCC_AHB1ENR_IOPAEN);
+
+	/* Enable clocks for USART2. */
+	rcc_peripheral_enable_clock(&RCC_APB1ENR, RCC_APB1ENR_USART2EN);
+}
+
+void usart_setup(void)
+{
+	/* Setup USART2 parameters. */
+	usart_set_baudrate(USART2, 38400);
+	usart_set_databits(USART2, 8);
+	usart_set_stopbits(USART2, USART_STOPBITS_1);
+	usart_set_mode(USART2, USART_MODE_TX);
+	usart_set_parity(USART2, USART_PARITY_NONE);
+	usart_set_flow_control(USART2, USART_FLOWCONTROL_NONE);
+
+	/* Finally enable the USART. */
+	usart_enable(USART2);
+}
+
+void gpio_setup(void)
+{
+	/* Setup GPIO pin GPIO12 on GPIO port D for LED. */
+	gpio_mode_setup(GPIOD, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, GPIO12);
+
+	/* Setup GPIO pins for USART2 transmit. */
+	gpio_mode_setup(GPIOA, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO2);
+
+	/* Setup USART2 TX pin as alternate function. */
+	gpio_set_af(GPIOA, GPIO_AF7, GPIO2);
+}
+
+/* Maximum number of iterations for the escape-time calculation */
+#define maxIter 32
+/* This array converts the iteration count to a character representation. */
+static char color[maxIter+1] = " .:++xxXXX%%%%%%################";
+
+/* Main mandelbrot calculation */
+static int iterate(float px, float py)
+{
+	int it=0;
+	float x=0,y=0;
+	while(it<maxIter)
+	{
+		float nx = x*x;
+		float ny = y*y;
+		if( (nx + ny) > 4 )
+			return it;
+		// Zn+1 = Zn^2 + P
+		y = 2*x*y + py;
+		x = nx - ny + px;
+		it++;
+	}
+	return 0;
+}
+
+static void mandel(float cX, float cY, float scale)
+{
+	int x,y;
+	for(x=-60;x<60;x++)
+	{
+		for(y=-50;y<50;y++)
+		{
+			int i = iterate(cX+x*scale, cY+y*scale);
+			usart_send_blocking(USART2, color[i]);
+		}
+		usart_send_blocking(USART2, '\r');
+		usart_send_blocking(USART2, '\n');
+	}
+}
+
+int main(void)
+{
+	float scale = 0.25f, centerX = -0.5f, centerY = 0.0f;
+
+	clock_setup();
+	gpio_setup();
+	usart_setup();
+
+	while (1) {
+		/* Blink the LED (PD12) on the board with each fractal drawn. */
+		gpio_toggle(GPIOD, GPIO12);	/* LED on/off */
+		mandel(centerX,centerY,scale);	/* draw mandelbrot */
+
+		/* Change scale and center */
+		centerX += 0.175f * scale;
+		centerY += 0.522f * scale;
+		scale	*= 0.875f;
+
+		usart_send_blocking(USART2, '\r');
+		usart_send_blocking(USART2, '\n');
+	}
+
+	return 0;
+}

include/libopencm3/stm32/f4/scb.h

@@ -72,6 +72,63 @@
 /* AFSR: Auxiliary Fault Status Register */
 #define SCB_AFSR				MMIO32(SCB_BASE + 0x3C)
 
+/* ID_PFR0: Processor Feature Register 0 */
+#define SCB_ID_PFR0				MMIO32(SCB_BASE + 0x40)
+
+/* ID_PFR1: Processor Feature Register 1 */
+#define SCB_ID_PFR1				MMIO32(SCB_BASE + 0x44)
+
+/* ID_DFR0: Debug Features Register 0 */
+#define SCB_ID_DFR0				MMIO32(SCB_BASE + 0x48)
+
+/* ID_AFR0: Auxiliary Features Register 0 */
+#define SCB_ID_AFR0				MMIO32(SCB_BASE + 0x4C)
+
+/* ID_MMFR0: Memory Model Feature Register 0 */
+#define SCB_ID_MMFR0				MMIO32(SCB_BASE + 0x50)
+
+/* ID_MMFR1: Memory Model Feature Register 1 */
+#define SCB_ID_MMFR1				MMIO32(SCB_BASE + 0x54)
+
+/* ID_MMFR2: Memory Model Feature Register 2 */
+#define SCB_ID_MMFR2				MMIO32(SCB_BASE + 0x58)
+
+/* ID_MMFR3: Memory Model Feature Register 3 */
+#define SCB_ID_MMFR3				MMIO32(SCB_BASE + 0x5C)
+
+/* ID_ISAR0: Instruction Set Attributes Register 0 */
+#define SCB_ID_ISAR0				MMIO32(SCB_BASE + 0x60)
+
+/* ID_ISAR1: Instruction Set Attributes Register 1 */
+#define SCB_ID_ISAR1				MMIO32(SCB_BASE + 0x64)
+
+/* ID_ISAR2: Instruction Set Attributes Register 2 */
+#define SCB_ID_ISAR2				MMIO32(SCB_BASE + 0x68)
+
+/* ID_ISAR3: Instruction Set Attributes Register 3 */
+#define SCB_ID_ISAR3				MMIO32(SCB_BASE + 0x6C)
+
+/* ID_ISAR4: Instruction Set Attributes Register 4 */
+#define SCB_ID_ISAR4				MMIO32(SCB_BASE + 0x70)
+
+/* CPACR: Coprocessor Access Control Register */
+#define SCB_CPACR				MMIO32(SCB_BASE + 0x88)
+
+/* FPCCR: Floating-Point Context Control Register */
+#define SCB_FPCCR				MMIO32(SCB_BASE + 0x234)
+
+/* FPCAR: Floating-Point Context Address Register */
+#define SCB_FPCAR				MMIO32(SCB_BASE + 0x238)
+
+/* FPDSCR: Floating-Point Default Status Control Register */
+#define SCB_FPDSCR				MMIO32(SCB_BASE + 0x23C)
+
+/* MVFR0: Media and Floating-Point Feature Register 0 */
+#define SCB_MVFR0				MMIO32(SCB_BASE + 0x240)
+
+/* MVFR1: Media and Floating-Point Feature Register 1 */
+#define SCB_MVFR1				MMIO32(SCB_BASE + 0x244)
+
 /* --- SCB values ---------------------------------------------------------- */
 
 /* --- SCB_CPUID values ---------------------------------------------------- */
@@ -292,6 +349,18 @@
 
 /* BFAR [31:0]: Bus fault address */
 
+/* --- SCB_CPACR values ---------------------------------------------------- */
+
+/* CPACR CPn: Access privileges values */
+#define SCB_CPACR_NONE			0	/* Access denied */
+#define SCB_CPACR_PRIV			1	/* Privileged access only */
+#define SCB_CPACR_FULL			3	/* Full access */
+
+/* CPACR [20:21]: Access privileges for coprocessor 10 */
+#define SCB_CPACR_CP10			(1 << 20)
+/* CPACR [22:23]: Access privileges for coprocessor 11 */
+#define SCB_CPACR_CP11			(1 << 22)
+
 /* --- SCB functions ------------------------------------------------------- */
 
 BEGIN_DECLS

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;