Use float-enabled printf implementation

I hadn't realised there is a float-enabled printf implementation in AVR libc,
so let's use that instead of our own hack.

7 files changed, 17 insertions, 28 deletions

diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..694f6ad
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "BMP3-Sensor-API"]
+	path = BMP3-Sensor-API
+	url = https://github.com/BoschSensortec/BMP3-Sensor-API
diff --git a/BMP3-Sensor-API b/BMP3-Sensor-API
new file mode 160000
+Subproject 5c13e49e7649099696ff6ca5f5fe3ad4ab3f5d9
diff --git a/Makefile b/Makefile
index 3c15800..bb26ce1 100644
--- a/Makefile
+++ b/Makefile
@@ -5,8 +5,13 @@ QEMU_AVR ?= qemu-system-avr
 
 MCU ?= atmega32u4
 SIM_MCU ?= atmega2560
-CFLAGS += -Wall -Wextra -DF_CPU=16000000UL -mmcu=$(MCU) -O3
-SIM_CFLAGS += -Wall -Wextra -DF_CPU=16000000UL -mmcu=$(SIM_MCU) -g3 -gdwarf-2 -DWDT_DISABLE
+COMMON_CFLAGS += -Wall -Wextra -DF_CPU=16000000UL
+CFLAGS += $(COMMON_CFLAGS) -mmcu=$(MCU) -O3
+SIM_CFLAGS += $(COMMON_CFLAGS) -mmcu=$(SIM_MCU) -g3 -gdwarf-2 -DWDT_DISABLE
+
+COMMON_LDFLAGS += -Wl,-u,vfprintf -lprintf_flt
+LDFLAGS += $(COMMON_LDFLAGS) -mmcu=$(MCU)
+SIM_LDFLAGS += $(COMMON_LDFLAGS) -mmcu=$(SIM_MCU)
 
 $(shell mkdir -p build/{real,sim})
 
@@ -26,14 +31,14 @@ build/altimeter.elf: \
 	build/real/display_sim.o \
 	build/real/altimeter.o \
 	build/real/util.o
-	$(CC) -o $@ $^ $(CFLAGS)
+	$(CC) -o $@ $^ $(LDFLAGS)
 
 build/altimeter_sim.elf: \
 	build/sim/barometer_sim.o \
 	build/sim/display_sim.o \
 	build/sim/altimeter.o \
 	build/sim/util.o
-	$(CC) -o $@ $^ $(SIM_CFLAGS)
+	$(CC) -o $@ $^ $(SIM_LDFLAGS)
 
 include config.mk
 
diff --git a/altimeter.c b/altimeter.c
index 429976c..acaa95e 100644
--- a/altimeter.c
+++ b/altimeter.c
@@ -24,7 +24,6 @@
 ISR(TIMER1_COMPA_vect)
 {
 	PORTD ^= 1 << 5;
-	int tcnt1_start = TCNT1;
 	static volatile float setting = 1040.21; /* FIXME volatile for gdb hacks */
 	static float last_height = 0;
 	float pressure = 0;
@@ -46,36 +45,26 @@ ISR(TIMER1_COMPA_vect)
 
 	char line[LCD_WIDTH+1];
 	/* line 1 */
-	int alt_m_int;
-	float alt_m_float;
-	split_float(height_m, &alt_m_int, &alt_m_float);
-	snprintf(line, sizeof(line), "%d.%d m %c%d m/s", alt_m_int, (int)(round(alt_m_float*10)), rate_sym, abs(rate_m_s));
+	snprintf(line, sizeof(line), "%.1f m %c%d m/s", height_m, rate_sym, abs(rate_m_s));
 	blank_to_eol(line, sizeof(line));
 	display_set_cursor(0, 0);
 	display_write(line);
 
 
 	/* line 2 */
-	int pressure_hpa_int;
-	float pressure_hpa_float;
-	split_float(pressure, &pressure_hpa_int, &pressure_hpa_float);
-	snprintf(line, sizeof(line), "%d.%d hPa", pressure_hpa_int, (int)(round(pressure_hpa_float*100)));
+	snprintf(line, sizeof(line), "%.2f hPa", pressure);
 	blank_to_eol(line, sizeof(line));
 	display_set_cursor(0, 1);
 	display_write(line);
 
 	/* line 3 */
-	int setting_hpa_int;
-	float setting_hpa_float;
-	split_float(setting, &setting_hpa_int, &setting_hpa_float);
-	snprintf(line, sizeof(line), "SET %d.%d hPa", setting_hpa_int, (int)(round(setting_hpa_float*100)));
+	snprintf(line, sizeof(line), "SET %.2f hPa", setting);
 	blank_to_eol(line, sizeof(line));
 	display_set_cursor(0, 2);
 	display_write(line);
 
-	int tcnt1_end = TCNT1;
 	/* line 4 */
-	snprintf(line, sizeof(line), "TCNT1 delta %u", tcnt1_end - tcnt1_start);
+	snprintf(line, sizeof(line), "%.1f ""\xdf""C", 12.3f);
 	blank_to_eol(line, sizeof(line));
 	display_set_cursor(0, 3);
 	display_write(line);
diff --git a/display_sim.c b/display_sim.c
index 4737981..c87329e 100644
--- a/display_sim.c
+++ b/display_sim.c
@@ -104,7 +104,7 @@ void display_write(const char *text)
 	while (cursor_x < LCD_WIDTH && *text) {
 		c = *(text++);
 		/* 0-7 are custom chars in CGRAM on real LCD */
-		if (c < 8)
+		if ((unsigned int)c < 8)
 			c = '_';
 		display[cursor_y][cursor_x++] = c;
 	}
diff --git a/util.c b/util.c
index 794eea7..bd3f71f 100644
--- a/util.c
+++ b/util.c
@@ -16,10 +16,3 @@ void blank_to_eol(char *line, size_t len)
 	}
 	line[i] = '\0';
 }
-
-void split_float(float input, int *integer_part, float *float_part)
-{
-	*integer_part = (int)input;
-	*float_part = fabs(input - *integer_part);
-}
-
diff --git a/util.h b/util.h
index 49812b9..71adadf 100644
--- a/util.h
+++ b/util.h
@@ -4,4 +4,3 @@
 
 float pressure_to_metres_asl(float real, float setting);
 void blank_to_eol(char *line, size_t len);
-void split_float(float input, int *integer_part, float *float_part);