Add F16C() macro for defining values without float support.

Implementation by Jonas Zeiger.

3 files changed, 201 insertions, 1 deletions

diff --git a/libfixmath/fix16.h b/libfixmath/fix16.h
index 6f3599b..35e101d 100644
--- a/libfixmath/fix16.h
+++ b/libfixmath/fix16.h
@@ -228,6 +228,89 @@ extern void fix16_to_str(fix16_t value, char *buf, int decimals);
  */

 extern fix16_t fix16_from_str(const char *buf);

 

+/** Helper macro for F16C. Replace token with its number of characters/digits. */

+#define FIXMATH_TOKLEN(token) ( sizeof( #token ) - 1 )

+

+/** Helper macro for F16C. Handles pow(10, n) for n from 0 to 8. */

+#define FIXMATH_CONSTANT_POW10(times) ( \

+  (times == 0) ? 1ULL \

+        : (times == 1) ? 10ULL \

+            : (times == 2) ? 100ULL \

+                : (times == 3) ? 1000ULL \

+                    : (times == 4) ? 10000ULL \

+                        : (times == 5) ? 100000ULL \

+                            : (times == 6) ? 1000000ULL \

+                                : (times == 7) ? 10000000ULL \

+                                    : 100000000ULL \

+)

+

+

+/** Helper macro for F16C, the type uint64_t is only used at compile time and

+ *  shouldn't be visible in the generated code.

+ *

+ * @note We do not use fix16_one instead of 65536ULL, because the

+ *       "use of a const variable in a constant expression is nonstandard in C".

+ */

+#define FIXMATH_CONVERT_MANTISSA(m) \

+( (unsigned) \

+    ( \

+        ( \

+            ( \

+                (uint64_t)( ( ( 1 ## m ## ULL ) - FIXMATH_CONSTANT_POW10(FIXMATH_TOKLEN(m)) ) * FIXMATH_CONSTANT_POW10(5 - FIXMATH_TOKLEN(m)) ) \

+                * 100000ULL * 65536ULL \

+            ) \

+            + 5000000000ULL /* rounding: + 0.5 */ \

+        ) \

+        / \

+        10000000000LL \

+    ) \

+)

+

+

+#define FIXMATH_COMBINE_I_M(i, m) \

+( \

+    ( \

+        (    i ) \

+        << 16 \

+    ) \

+    | \

+    ( \

+        FIXMATH_CONVERT_MANTISSA(m) \

+        & 0xFFFF \

+    ) \

+)

+

+

+/** Create int16_t (Q16.16) constant from separate integer and mantissa part.

+ *

+ * Only tested on 32-bit ARM Cortex-M0 / x86 Intel.

+ *

+ * This macro is needed when compiling with options like "--fpu=none",

+ * which forbid all and every use of float and related types and

+ * would thus make it impossible to have fix16_t constants.

+ *

+ * Just replace uses of F16() with F16C() like this:

+ *   F16(123.1234) becomes F16C(123,1234)

+ *

+ * @warning Specification of any value outside the mentioned intervals

+ *          WILL result in undefined behavior!

+ *

+ * @note Regardless of the specified minimum and maximum values for i and m below,

+ *       the total value of the number represented by i and m MUST be in the interval

+ *       ]-32768.00000:32767.99999[ else usage with this macro will yield undefined behavior.

+ *

+ * @param i Signed integer constant with a value in the interval ]-32768:32767[.

+ * @param m Positive integer constant in the interval ]0:99999[ (fractional part/mantissa).

+ */

+#define F16C(i, m) \

+( (fix16_t) \

+    ( \

+      (( #i[0] ) == '-') \

+        ? -FIXMATH_COMBINE_I_M((unsigned)( ( (i) * -1) ), m) \

+        : FIXMATH_COMBINE_I_M(i, m) \

+    ) \

+)

+

 #ifdef __cplusplus

 }

 #include "fix16.hpp"

diff --git a/unittests/Makefile b/unittests/Makefile
index 14dac10..329caf4 100644
--- a/unittests/Makefile
+++ b/unittests/Makefile
@@ -8,7 +8,7 @@ CFLAGS = -g -O0 -I../libfixmath -Wall -Wextra -Werror
 FIX16_SRC = ../libfixmath/fix16.c ../libfixmath/fix16_sqrt.c ../libfixmath/fix16_str.c \
 	../libfixmath/fix16_exp.c ../libfixmath/fix16.h
 
-all: run_fix16_unittests run_fix16_exp_unittests run_fix16_str_unittests
+all: run_fix16_unittests run_fix16_exp_unittests run_fix16_str_unittests run_fix16_macros_unittests
 
 clean:
 	rm -f fix16_unittests_????
@@ -63,3 +63,10 @@ run_fix16_str_unittests: fix16_str_unittests
 fix16_str_unittests: fix16_str_unittests.c $(FIX16_SRC)
 	$(CC) $(CFLAGS) $(DEFINES) -o $@ $^ -lm
 
+# Tests for literal macros, run only in default config
+run_fix16_macros_unittests: fix16_macros_unittests
+	./fix16_macros_unittests > /dev/null
+
+fix16_macros_unittests: fix16_macros_unittests.c $(FIX16_SRC)
+	$(CC) $(CFLAGS) $(DEFINES) -o $@ $^ -lm
+
diff --git a/unittests/fix16_macros_unittests.c b/unittests/fix16_macros_unittests.c
new file mode 100644
index 0000000..cdfcfaf
--- /dev/null
+++ b/unittests/fix16_macros_unittests.c
@@ -0,0 +1,110 @@
+/* This test checks that the F16() and F16C() macros work correctly. */
+
+#include <fix16.h>
+#include <stdio.h>
+#include <math.h>
+#include <stdbool.h>
+#include "unittests.h"
+
+#define DO_TEST(i,m) \
+  TEST(F16(i ## . ## m) == F16C(i,m)) \
+  TEST(F16(i ## . ## m) == fix16_from_dbl(i ## . ## m))
+
+int main()
+{
+  int status = 0;
+
+  /* Corner cases */
+  DO_TEST(1,234)
+  DO_TEST(0,0)
+  DO_TEST(1,0)
+  DO_TEST(-1,0)
+  DO_TEST(1,5)
+  DO_TEST(-1,5)
+  DO_TEST(000000,00000)
+  DO_TEST(0,00001)
+  DO_TEST(0,00010)
+  DO_TEST(0,1)
+  DO_TEST(0,10001)
+  DO_TEST(0,11000)
+  DO_TEST(25,133)
+  DO_TEST(32767,00000)
+  DO_TEST(32767,00001)
+  DO_TEST(32767,99999)
+  DO_TEST(0,25)
+  DO_TEST(0,99555)
+  DO_TEST(0,99998)
+  DO_TEST(0,99999)
+  DO_TEST(-1,1)
+  DO_TEST(-25,133)
+  DO_TEST(-32767,00001)
+  DO_TEST(-32768,00000)
+  
+  /* Random values */
+  DO_TEST(   0,02267)
+  DO_TEST(   1,49887)
+  DO_TEST(   0,27589)
+  DO_TEST(   0,38393)
+  DO_TEST(   0,08934)
+  DO_TEST(   0,95820)
+  DO_TEST(   0,95596)
+  DO_TEST(  72,10642)
+  DO_TEST(   0,48939)
+  DO_TEST(   3,37797)
+  DO_TEST(   1,09194)
+  DO_TEST(   0,08605)
+  DO_TEST(   3,04349)
+  DO_TEST(   3,95401)
+  DO_TEST(  15,36292)
+  DO_TEST(  56,09242)
+  DO_TEST(   0,54071)
+  DO_TEST(  27,08953)
+  DO_TEST(   0,03913)
+  DO_TEST(   1,32707)
+  DO_TEST(   4,50117)
+  DO_TEST(   0,24990)
+  DO_TEST(  44,77319)
+  DO_TEST(   2,59139)
+  DO_TEST(   0,16279)
+  DO_TEST(  17,14712)
+  DO_TEST(  11,54281)
+  DO_TEST(   0,02768)
+  DO_TEST(   0,39278)
+  DO_TEST(   0,19369)
+  DO_TEST(  -0,04534)
+  DO_TEST(  -0,00349)
+  DO_TEST(  -2,30380)
+  DO_TEST(  -0,03061)
+  DO_TEST(  -7,50065)
+  DO_TEST(  -3,97050)
+  DO_TEST(  -0,43898)
+  DO_TEST(  -3,49876)
+  DO_TEST(  -1,35942)
+  DO_TEST( -10,81154)
+  DO_TEST(  -0,26676)
+  DO_TEST(  -9,52134)
+  DO_TEST(  -0,42592)
+  DO_TEST(  -0,05424)
+  DO_TEST(  -0,62461)
+  DO_TEST(  -0,21562)
+  DO_TEST(  -0,22366)
+  DO_TEST(  -0,09074)
+  DO_TEST(  -1,29527)
+  DO_TEST(  -4,98427)
+  DO_TEST(  -0,10721)
+  DO_TEST( -11,39446)
+  DO_TEST(-451,53916)
+  DO_TEST(  -0,04279)
+  DO_TEST(  -3,36543)
+  DO_TEST(  -0,01003)
+  DO_TEST( -12,08326)
+  DO_TEST(  -1,07143)
+  DO_TEST(  -1,07737)
+  DO_TEST(  -0,22957)
+    
+  if (status != 0)
+    fprintf(stdout, "\n\nSome tests FAILED!\n");
+  
+  return status;
+}
+