demo2

Assets/Demos/Demo2/Domain/SaturatingMath.cs

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+#nullable enable
+
+using System;
+
+namespace Demo2.Domain
+{
+    public static class SaturatingMath
+    {
+        public const long Scale = 1000;
+
+        public static long Add(long left, long right)
+        {
+            if (right > 0 && left > long.MaxValue - right) return long.MaxValue;
+            if (right < 0 && left < long.MinValue - right) return long.MinValue;
+            return left + right;
+        }
+
+        public static long Multiply(long left, long right)
+        {
+            if (left == 0 || right == 0) return 0;
+            if (left == long.MinValue && right == -1) return long.MaxValue;
+            if (right == long.MinValue && left == -1) return long.MaxValue;
+            var negative = (left < 0) ^ (right < 0);
+            var a = AbsUnsigned(left);
+            var b = AbsUnsigned(right);
+            if (a > (ulong)long.MaxValue / b) return negative ? long.MinValue : long.MaxValue;
+            var value = (long)(a * b);
+            return negative ? -value : value;
+        }
+
+        public static long MultiplyScaled(long value, long multiplierMilli)
+        {
+            if (value == 0 || multiplierMilli == 0) return 0;
+            var product = Multiply(value, multiplierMilli);
+            if (product == long.MaxValue || product == long.MinValue) return product;
+            return product / Scale;
+        }
+
+        public static string Format(long value)
+        {
+            var abs = value == long.MinValue ? long.MaxValue : Math.Abs(value);
+            if (abs < 1_000_000_000) return value.ToString("N0");
+            var exponent = (int)Math.Floor(Math.Log10(abs));
+            var mantissa = value / Math.Pow(10, exponent);
+            return mantissa.ToString("0.##") + "e" + exponent;
+        }
+
+        private static ulong AbsUnsigned(long value) => value < 0 ? (ulong)(-(value + 1)) + 1UL : (ulong)value;
+    }
+}