sys: require float_math feature where needed

In some modules some functions are disabled when no floating point
arithmetics is available instead of blocking the whole module. The API
doc has been extended, so that users know why a function may fail to
link.

Author: maribu

sys/Makefile.dep

@@ -29,6 +29,10 @@ ifneq (,$(filter auto_init_sock_dns,$(USEMODULE)))
   endif
 endif
 
+ifneq (,$(filter color,$(USEMODULE)))
+  FEATURES_REQUIRED += float_math
+endif
+
 ifneq (,$(filter congure_%,$(USEMODULE)))
   USEMODULE += congure
 endif
@@ -259,6 +263,10 @@ ifneq (,$(filter posix_sockets,$(USEMODULE)))
   USEMODULE += posix_headers
 endif
 
+ifneq (,$(filter printf_float,$(USEMODULE)))
+  FEATURES_REQUIRED += float_math
+endif
+
 ifneq (,$(filter shell_cmd%,$(USEMODULE)))
   # each and every command is a submodule of shell_cmds
   USEMODULE += shell_cmds

sys/analog_util/adc_util.c

@@ -66,7 +66,10 @@ int32_t adc_util_map(int sample, adc_res_t res, int32_t min, int32_t max)
     return (min + scaled);
 }
 
+/* only pro adc_util_mapf if float_math is in use */
+#if MODULE_FLOAT_MATH
 float adc_util_mapf(int sample, adc_res_t res, float min, float max)
 {
     return ((((max - min) * sample) / ((int32_t)1L << _adc_res_bits(res))) + min);
 }
+#endif

sys/analog_util/dac_util.c

@@ -27,7 +27,10 @@ uint16_t dac_util_map(int value, int min, int max)
     return (uint16_t)(((value - min) * UINT16_MAX) / (max - min));
 }
 
+/* only provide dac_util_mapf when floating point arithmetics is available */
+#if MODULE_FLOAT_MATH
 uint16_t dac_util_mapf(float value, float min, float max)
 {
     return (uint16_t)(((value - min) * UINT16_MAX) / (max - min));
 }
+#endif

sys/fmt/fmt.c

@@ -37,19 +37,6 @@ extern ssize_t stdio_write(const void* buffer, size_t len);
 NONSTRING
 static const char _hex_chars[16] = "0123456789ABCDEF";
 
-static const uint32_t _tenmap[] = {
-    0,
-    10LU,
-    100LU,
-    1000LU,
-    10000LU,
-    100000LU,
-    1000000LU,
-    10000000LU,
-};
-
-#define TENMAP_SIZE  ARRAY_SIZE(_tenmap)
-
 static inline char _to_lower(char c)
 {
     return 'a' + (c - 'A');
@@ -377,6 +364,21 @@ size_t fmt_s32_dfp(char *out, int32_t val, int scale)
 
     return pos;
 }
+
+#if MODULE_FLOAT_MATH
+static const uint32_t _tenmap[] = {
+    0,
+    10LU,
+    100LU,
+    1000LU,
+    10000LU,
+    100000LU,
+    1000000LU,
+    10000000LU,
+};
+
+#define TENMAP_SIZE  ARRAY_SIZE(_tenmap)
+
 /* this is very probably not the most efficient implementation, as it at least
  * pulls in floating point math.  But it works, and it's always nice to have
  * low hanging fruits when optimizing. (Kaspar)
@@ -415,6 +417,7 @@ size_t fmt_float(char *out, float f, unsigned precision)
 
     return res;
 }
+#endif
 
 size_t fmt_lpad(char *out, size_t in_len, size_t pad_len, char pad_char)
 {

sys/include/analog_util.h

@@ -47,6 +47,9 @@ int32_t adc_util_map(int sample, adc_res_t res, int32_t min, int32_t max);
  * @brief   Map a sampled ADC value to a given range (using floating point
  *          arithmetic)
  *
+ * @warning This function is only available when the features `float_math`
+ *          is used.
+ *
  * @see adc_util_map
  *
  * @param[in] sample        sampled ADC value
@@ -75,6 +78,9 @@ uint16_t dac_util_map(int value, int min, int max);
 /**
  * @brief Helper function to map a given float value range to a valid DAC value.
  *
+ * @warning This function is only available when the features `float_math`
+ *          is used.
+ *
  * @see dac_util_map
  *
  * @param[in] value        value to map to a DAC set value

sys/include/fmt.h

@@ -326,6 +326,9 @@ size_t fmt_s32_dfp(char *out, int32_t val, int scale);
 /**
  * @brief Format float to string
  *
+ * @warning This function is only available when the features `float_math`
+ *          is used.
+ *
  * Converts float value @p f to string
  *
  * If @p out is NULL, will only return the number of characters that would have

sys/senml/Makefile.dep

@@ -1,3 +1,5 @@
+FEATURES_REQUIRED += float_math
+
 ifneq (,$(filter senml_saul,$(USEMODULE)))
   USEMODULE += senml_cbor
   USEMODULE += senml_phydat