implement fractions

src/util/CMakeLists.txt

@@ -56,6 +56,7 @@ strings.c
 translation.c
 umlaut.c
 unicode.c
+variant.c
 xml.c
 )
 FOREACH(_FILE ${_FILES})

src/util/variant.c

@@ -0,0 +1,36 @@
+#include "variant.h"
+#include <limits.h>
+
+static int lcd(int a, int b) {
+    return a * b;
+}
+
+variant frac_add(variant a, variant b)
+{
+    int num, den;
+    variant v;
+    den = lcd(a.sa[1], b.sa[1]);
+    num = a.sa[0] * lcd / a.sa[1] + b.sa[0] * lcd / b.sa[1];
+    assert(num >= SHRT_MIN && num <= SHRT_MAX);
+    assert(den >= SHRT_MIN && den <= SHRT_MAX);
+    v.sa[0] = (short)num;
+    v.sa[1] = (short)den;
+    return v;
+}
+
+variant frac_mul(variant a, variant b)
+{
+    variant v = a;
+    return v;
+}
+
+variant frac_div(variant a, variant b)
+{
+    variant v = a;
+    return v;
+}
+
+#ifdef __cplusplus
+}
+#endif
+#endif

src/util/variant.h

@@ -1,3 +1,5 @@
+#pragma once
+
 #ifndef STRUCT_VARIANT_H
 #define STRUCT_VARIANT_H
 #ifdef __cplusplus
@@ -19,6 +21,10 @@ extern "C" {
       VAR_FLOAT
   } variant_type;
 
+  variant frac_add(variant a, variant b);
+  variant frac_mul(variant a, variant b);
+  variant frac_div(variant a, variant b);
+
 #ifdef __cplusplus
 }
 #endif