LUCENE-9047: Adapt big endian dependent code to work in little endian

Author: iverase

lucene/core/src/java/org/apache/lucene/codecs/lucene90/compressing/Lucene90CompressingStoredFieldsWriter.java

@@ -361,7 +361,9 @@ static void writeZFloat(DataOutput out, float f) throws IOException {
       out.writeByte((byte) (0x80 | (1 + intVal)));
     } else if ((floatBits >>> 31) == 0) {
       // other positive floats: 4 bytes
-      out.writeInt(floatBits);
+      out.writeByte((byte) (floatBits >> 24));
+      out.writeShort((short) (floatBits >>> 8));
+      out.writeByte((byte) floatBits);
     } else {
       // other negative float: 5 bytes
       out.writeByte((byte) 0xFF);
@@ -399,7 +401,10 @@ static void writeZDouble(DataOutput out, double d) throws IOException {
       out.writeInt(Float.floatToIntBits((float) d));
     } else if ((doubleBits >>> 63) == 0) {
       // other positive doubles: 8 bytes
-      out.writeLong(doubleBits);
+      out.writeByte((byte) (doubleBits >> 56));
+      out.writeInt((int) (doubleBits >>> 24));
+      out.writeShort((short) (doubleBits >>> 8));
+      out.writeByte((byte) (doubleBits));
     } else {
       // other negative doubles: 9 bytes
       out.writeByte((byte) 0xFF);

lucene/core/src/java/org/apache/lucene/util/bkd/DocIdsWriter.java

@@ -50,7 +50,29 @@ static void writeDocIds(int[] docIds, int start, int count, DataOutput out) thro
       }
       if (max <= 0xffffff) {
         out.writeByte((byte) 24);
-        for (int i = 0; i < count; ++i) {
+        // write them the same way we are reading them.
+        int i;
+        for (i = 0; i < count - 7; i += 8) {
+          int doc1 = docIds[start + i];
+          int doc2 = docIds[start + i + 1];
+          int doc3 = docIds[start + i + 2];
+          int doc4 = docIds[start + i + 3];
+          int doc5 = docIds[start + i + 4];
+          int doc6 = docIds[start + i + 5];
+          int doc7 = docIds[start + i + 6];
+          int doc8 = docIds[start + i + 7];
+          long l1 = (doc1 & 0xffffffL) << 40 | (doc2 & 0xffffffL) << 16 | ((doc3 >>> 8) & 0xffffL);
+          long l2 =
+              (doc3 & 0xffL) << 56
+                  | (doc4 & 0xffffffL) << 32
+                  | (doc5 & 0xffffffL) << 8
+                  | ((doc6 >> 16) & 0xffL);
+          long l3 = (doc6 & 0xffffL) << 48 | (doc7 & 0xffffffL) << 24 | (doc8 & 0xffffffL);
+          out.writeLong(l1);
+          out.writeLong(l2);
+          out.writeLong(l3);
+        }
+        for (; i < count; ++i) {
           out.writeShort((short) (docIds[start + i] >>> 8));
           out.writeByte((byte) docIds[start + i]);
         }

lucene/core/src/java/org/apache/lucene/util/bkd/OfflinePointWriter.java

@@ -62,8 +62,13 @@ public void append(byte[] packedValue, int docID) throws IOException {
             + "] but was ["
             + packedValue.length
             + "]";
+
     out.writeBytes(packedValue, 0, packedValue.length);
-    out.writeInt(docID);
+    // write bytes for comparing in lexicographically order
+    out.writeByte((byte) (docID >> 24));
+    out.writeByte((byte) (docID >> 16));
+    out.writeByte((byte) (docID >> 8));
+    out.writeByte((byte) docID);
     count++;
     assert expectedCount == 0 || count <= expectedCount
         : "expectedCount=" + expectedCount + " vs count=" + count;