From fc49094d96556d39a10e60d7c0da5377446d2200 Mon Sep 17 00:00:00 2001
From: Ivan Hetman <Ihromant@users.noreply.github.com>
Date: Fri, 27 Oct 2023 17:52:33 +0300
Subject: [PATCH] classlib: fix support of positive/negative zeros in
 Float/Double.toHexString (#830)

---
 .../src/main/java/org/teavm/classlib/java/lang/TDouble.java | 6 +++++-
 .../src/main/java/org/teavm/classlib/java/lang/TFloat.java  | 6 +++++-
 .../test/java/org/teavm/classlib/java/lang/DoubleTest.java  | 2 ++
 .../test/java/org/teavm/classlib/java/lang/FloatTest.java   | 2 ++
 4 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/classlib/src/main/java/org/teavm/classlib/java/lang/TDouble.java b/classlib/src/main/java/org/teavm/classlib/java/lang/TDouble.java
index 4c4f3d362..526fcefaf 100644
--- a/classlib/src/main/java/org/teavm/classlib/java/lang/TDouble.java
+++ b/classlib/src/main/java/org/teavm/classlib/java/lang/TDouble.java
@@ -293,9 +293,13 @@ public class TDouble extends TNumber implements TComparable<TDouble> {
         int sz = 0;
         long bits = doubleToLongBits(d);
         boolean subNormal = false;
+        boolean negative = (bits & (1L << 63)) != 0;
         int exp = (int) ((bits >>> 52) & 0x7FF) - 1023;
         long mantissa = bits & 0xFFFFFFFFFFFFFL;
         if (exp == -1023) {
+            if (mantissa == 0) {
+                return negative ? "-0x0.0p0" : "0x0.0p0";
+            }
             ++exp;
             subNormal = true;
         }
@@ -314,7 +318,7 @@ public class TDouble extends TNumber implements TComparable<TDouble> {
         buffer[sz++] = subNormal ? '0' : '1';
         buffer[sz++] = 'x';
         buffer[sz++] = '0';
-        if ((bits & (1L << 63)) != 0) {
+        if (negative) {
             buffer[sz++] = '-';
         }
         int half = sz / 2;
diff --git a/classlib/src/main/java/org/teavm/classlib/java/lang/TFloat.java b/classlib/src/main/java/org/teavm/classlib/java/lang/TFloat.java
index 14c31ebba..6553cc9f2 100644
--- a/classlib/src/main/java/org/teavm/classlib/java/lang/TFloat.java
+++ b/classlib/src/main/java/org/teavm/classlib/java/lang/TFloat.java
@@ -289,9 +289,13 @@ public class TFloat extends TNumber implements TComparable<TFloat> {
         int sz = 0;
         int bits = floatToIntBits(f);
         boolean subNormal = false;
+        boolean negative = (bits & (1 << 31)) != 0;
         int exp = ((bits >>> 23) & 0xFF) - 127;
         int mantissa = (bits & 0x7FFFFF) << 1;
         if (exp == -127) {
+            if (mantissa == 0) {
+                return negative ? "-0x0.0p0" : "0x0.0p0";
+            }
             ++exp;
             subNormal = true;
         }
@@ -310,7 +314,7 @@ public class TFloat extends TNumber implements TComparable<TFloat> {
         buffer[sz++] = subNormal ? '0' : '1';
         buffer[sz++] = 'x';
         buffer[sz++] = '0';
-        if ((bits & (1L << 31)) != 0) {
+        if (negative) {
             buffer[sz++] = '-';
         }
         int half = sz / 2;
diff --git a/tests/src/test/java/org/teavm/classlib/java/lang/DoubleTest.java b/tests/src/test/java/org/teavm/classlib/java/lang/DoubleTest.java
index 4f3a67429..178e7bec2 100644
--- a/tests/src/test/java/org/teavm/classlib/java/lang/DoubleTest.java
+++ b/tests/src/test/java/org/teavm/classlib/java/lang/DoubleTest.java
@@ -131,6 +131,8 @@ public class DoubleTest {
         assertEquals("0x1.0p-1022", Double.toHexString(0x1.0p-1022));
         assertEquals("0x0.8p-1022", Double.toHexString(0x0.8p-1022));
         assertEquals("0x0.001p-1022", Double.toHexString(0x0.001p-1022));
+        assertEquals("0x0.0p0", Double.toHexString(0.0D));
+        assertEquals("-0x0.0p0", Double.toHexString(-0.0D));
     }
 
     @Test
diff --git a/tests/src/test/java/org/teavm/classlib/java/lang/FloatTest.java b/tests/src/test/java/org/teavm/classlib/java/lang/FloatTest.java
index 80bac2282..57190126c 100644
--- a/tests/src/test/java/org/teavm/classlib/java/lang/FloatTest.java
+++ b/tests/src/test/java/org/teavm/classlib/java/lang/FloatTest.java
@@ -112,6 +112,8 @@ public class FloatTest {
         assertEquals("0x1.0p-2", Float.toHexString(0.25f));
         assertEquals("0x1.0p-126", Float.toHexString((float) Math.pow(2, -126)));
         assertEquals("0x0.001p-126", Float.toHexString(0x0.001p-126f));
+        assertEquals("0x0.0p0", Float.toHexString(0.0F));
+        assertEquals("-0x0.0p0", Float.toHexString(-0.0F));
     }
 
     @Test