temperature converter: Replace division with multiplication. This makes the code faster

stm-firmware/Makefile

@@ -14,7 +14,7 @@ LIBRARIES = -larm_cortexM4lf_math -lm
 
 DEFINES = -DSTM32F407xx -DSTM32F4XX -DARM_MATH_CM4 -DHSE_VALUE=8000000UL
 MAPFILE_BASE = memory-mapping
-LINKER_SCRIPT=stm32f407vet6_flash.ld 
+LINKER_SCRIPT=stm32f407vet6_flash.ld
 
 export GIT_VER = $(shell git describe --always --dirty --tags)
 DEFINES += -DGIT_VER=$(GIT_VER)
@@ -149,8 +149,16 @@ disassemble: $(target).elf
 objcopy: $(target).bin $(target).hex
 
 mrproper: clean
-	@echo "Purging project files..."
+ifneq ($(DEBUGBUILD),true)
+	@echo "Purging RELEASE project files"
+else
+	@echo "Purging DEBUG project files"
+endif
 	$(QUIET)rm -f $(target).pro $(target).creator $(target).files $(target).cflags $(target).cxxflags $(target).includes $(target).config
+ifneq ($(DEBUGBUILD),true)
+	$(QUIET)$(MAKE) DEBUGBUILD=true mrproper
+endif
+
 
 clean:
 	@echo -n "Cleaning up derived files for "

stm-firmware/temp-converter.c

@@ -68,7 +68,7 @@ int temp_converter_convert_resistance_to_temp(float resistance, float *temp_out)
 	diff_to_low_resistance = resistance - (float)(TEMP_CONVERSION_MIN_RES + TEMP_CONVERSION_RES_STEP * lower_idx);
 
 	/* Calculate output temperature */
-	*temp_out = (diff_to_low_resistance / TEMP_CONVERSION_RES_STEP) * diff_high_low + low;
+	*temp_out = (diff_to_low_resistance * (1.0f / TEMP_CONVERSION_RES_STEP)) * diff_high_low + low;
 
 return_ret_val:
 	return ret_val;