From f85aa977eba3daed645575cb927d8d969b14b8ad Mon Sep 17 00:00:00 2001
From: Ivan Hetman <Ihromant@users.noreply.github.com>
Date: Mon, 23 Sep 2024 16:46:05 +0300
Subject: [PATCH] classlib: add Math cell/floor div/mod versions, add exact
 versions of methods

---
 .../org/teavm/classlib/java/lang/TMath.java   | 80 ++++++++++++++++++-
 .../teavm/classlib/java/lang/MathTest.java    | 20 +++++
 2 files changed, 97 insertions(+), 3 deletions(-)

diff --git a/classlib/src/main/java/org/teavm/classlib/java/lang/TMath.java b/classlib/src/main/java/org/teavm/classlib/java/lang/TMath.java
index eb705a331..15f79502a 100644
--- a/classlib/src/main/java/org/teavm/classlib/java/lang/TMath.java
+++ b/classlib/src/main/java/org/teavm/classlib/java/lang/TMath.java
@@ -143,6 +143,13 @@ public final class TMath extends TObject {
         return (a ^ b) < 0 && div * b != a ? div - 1 : div;
     }
 
+    public static int floorDivExact(int a, int b) {
+        if (a == Integer.MIN_VALUE && b == -1) {
+            throw new ArithmeticException();
+        }
+        return floorDiv(a, b);
+    }
+
     public static long floorDiv(long a, int b) {
         return floorDiv(a, (long) b);
     }
@@ -152,16 +159,67 @@ public final class TMath extends TObject {
         return (a ^ b) < 0 && div * b != a ? div - 1 : div;
     }
 
+    public static long floorDivExact(long a, long b) {
+        if (a == Long.MIN_VALUE && b == -1) {
+            throw new ArithmeticException();
+        }
+        return floorDiv(a, b);
+    }
+
+    public static int ceilDiv(int a, int b) {
+        int div = a / b;
+        return (a ^ b) >= 0 && div * b != a ? div + 1 : div;
+    }
+
+    public static int ceilDivExact(int a, int b) {
+        if (a == Integer.MIN_VALUE && b == -1) {
+            throw new ArithmeticException();
+        }
+        return ceilDiv(a, b);
+    }
+
+    public static long ceilDiv(long a, int b) {
+        return ceilDiv(a, (long) b);
+    }
+
+    public static long ceilDiv(long a, long b) {
+        long div = a / b;
+        return (a ^ b) >= 0 && div * b != a ? div + 1 : div;
+    }
+
+    public static long ceilDivExact(long a, long b) {
+        if (a == Long.MIN_VALUE && b == -1) {
+            throw new ArithmeticException();
+        }
+        return ceilDiv(a, b);
+    }
+
     public static int floorMod(int a, int b) {
-        return a - floorDiv(a, b) * b;
+        int mod = a % b;
+        return (a ^ b) < 0 && mod != 0 ? mod + b : mod;
     }
 
     public static int floorMod(long a, int b) {
-        return (int) (a - floorDiv(a, b) * b);
+        return (int) floorMod(a, (long) b);
     }
 
     public static long floorMod(long a, long b) {
-        return a - floorDiv(a, b) * b;
+        long mod = a % b;
+        return (a ^ b) < 0 && mod != 0 ? mod + b : mod;
+    }
+
+    public static int ceilMod(int a, int b) {
+        int mod = a % b;
+        return (a ^ b) >= 0 && mod != 0 ? mod - b : mod;
+    }
+
+    public static int ceilMod(long a, int b) {
+        return (int) ceilMod(a, (long) b);
+    }
+
+    public static long ceilMod(long a, long b) {
+        long mod = a % b;
+        return (a ^ b) >= 0 && mod != 0 ? mod - b : mod;
     }
 
     public static int incrementExact(int a) {
@@ -419,10 +477,26 @@ public final class TMath extends TObject {
         return n >= 0 ? n : -n;
     }
 
+    public static int absExact(int n) {
+        if (n == Integer.MIN_VALUE) {
+            throw new ArithmeticException();
+        } else {
+            return abs(n);
+        }
+    }
+
     public static long abs(long n) {
         return n >= 0 ? n : -n;
     }
 
+    public static long absExact(long n) {
+        if (n == Long.MIN_VALUE) {
+            throw new ArithmeticException();
+        } else {
+            return abs(n);
+        }
+    }
+
     @GeneratedBy(MathNativeGenerator.class)
     @NoSideEffects
     private static native float absImpl(float d);
diff --git a/tests/src/test/java/org/teavm/classlib/java/lang/MathTest.java b/tests/src/test/java/org/teavm/classlib/java/lang/MathTest.java
index 6a882a9f9..2cc2974b9 100644
--- a/tests/src/test/java/org/teavm/classlib/java/lang/MathTest.java
+++ b/tests/src/test/java/org/teavm/classlib/java/lang/MathTest.java
@@ -291,4 +291,24 @@ public class MathTest {
             });
         });
     }
+
+    @Test
+    public void ceilFloorModDiv() {
+        assertEquals(-2, Math.ceilMod(+4, +3));
+        assertEquals(+2, Math.ceilMod(-4, -3));
+        assertEquals(+1, Math.ceilMod(+4, -3));
+        assertEquals(-1, Math.ceilMod(-4, +3));
+        assertEquals(+1, Math.floorMod(+4, +3));
+        assertEquals(-1, Math.floorMod(-4, -3));
+        assertEquals(-2, Math.floorMod(+4, -3));
+        assertEquals(+2, Math.floorMod(-4, +3));
+        assertEquals(+2, Math.ceilDiv(5, 3));
+        assertEquals(+2, Math.ceilDiv(6, 3));
+        assertEquals(-1, Math.ceilDiv(-5, 3));
+        assertEquals(-2, Math.ceilDiv(-6, 3));
+        assertEquals(+1, Math.floorDiv(5, 3));
+        assertEquals(+2, Math.floorDiv(6, 3));
+        assertEquals(-2, Math.floorDiv(-5, 3));
+        assertEquals(-2, Math.floorDiv(-6, 3));
+    }
 }