Add from weekdate functions.

src/tests/calconv.c

@@ -123,6 +123,43 @@ int try_neg_year(int year)
 
 
 
+int try_weeks(void)
+{
+    // starting position
+    int weekcount = 52, weekday = 5, isoyear = -1;
+    int y, wk, wd, ret = 0;
+    struct iso8601_date dt;
+    
+    for(dt.day = 0; dt.day < MAX_YEAR_COUNT * 366; ++dt.day) {
+        iso8601_to_week(&y, &wk, &wd, &dt);
+        if(wd == 1) {
+            if(weekday != 7) goto discont;
+            ++weekcount;
+            if(wk == 1) {
+                if(weekcount != 53 && weekcount != 54) goto discont;
+                weekcount = 1;
+                ++isoyear;
+            }
+        }
+        if(wk != weekcount || y != isoyear) goto discont;
+
+        weekday = wd;
+        continue;
+
+    discont:
+        printf("[weekdiscont     ] %04d-W%02d-%d ==> %04d-W%02d-%d (%d)\n",
+            isoyear, weekcount, weekday, y, wk, wd, dt.day);
+        isoyear = y;
+        weekcount = wk;
+        weekday = wd;
+        if(++ret > 20) return ret;
+    }
+
+    return ret;
+}
+
+
+
 int main(int argc, char* argv[])
 {
     int ret = 0, year;
@@ -142,6 +179,9 @@ int main(int argc, char* argv[])
         if(ret > 20) return ret;
     }
 
+    ret += try_weeks();
+    if(ret > 20) return ret;
+
     return ret;
 }