Refactor civilization flow reward calculations for improved accuracy and performance

world/owniverse/quantity_math.gd

@@ -303,6 +303,27 @@ static func split_arrays(remainders: Dictionary, key: String, count: Variant, id
 
 
 static func accumulate_rate(remainders: Dictionary, key: String, count: Variant, probability: Variant) -> Variant:
+    # Reward rates are floats while populations are exact whole values. Keep
+    # the product as quotient plus fractional carry instead of constructing an
+    # intermediate Exact Value and flooring it again.
+    if probability is float and is_finite(probability) and probability >= 0.0 and (count is int or (count is E.Value and count.fraction == 0.0)) and E.ge(count, 0):
+        var terms: Array = E.parts(probability)
+        if terms[2] > 0:
+            var population: Array = E._blocks(count)[0]
+            var whole_product: Array = E.Big.multiply(population, terms[0])
+            var qr: Array = E.Big.divmod(whole_product, terms[1])
+            var fractional: float = E._fraction_ratio(qr[1], terms[1])
+            var carry: float = E.approx(remainders.get(key, 0))
+            if carry >= 0.0 and carry < 1.0:
+                if qr[1] == [0]:
+                    remainders[key] = carry
+                    return E._compose(qr[0])
+                fractional += carry
+                if fractional > 0.5 and absf(fractional - roundf(fractional)) <= 1e-12:
+                    fractional = roundf(fractional)
+                var extra: int = floori(fractional)
+                remainders[key] = fractional - extra
+                return E.add(E._compose(qr[0]), extra)
     var product: Variant = E.multiply(count, E.maximum(0, probability))
     var carry: float = E.approx(remainders.get(key, 0))
     if carry >= 0.0 and carry < 1.0 and E.ge(product, 0):