jdk

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/*
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 * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 *
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 * This code is free software; you can redistribute it and/or modify it
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 * under the terms of the GNU General Public License version 2 only, as
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 * published by the Free Software Foundation.
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 *
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 * This code is distributed in the hope that it will be useful, but WITHOUT
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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 * version 2 for more details (a copy is included in the LICENSE file that
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 * accompanied this code).
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 *
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 * You should have received a copy of the GNU General Public License version
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 * 2 along with this work; if not, write to the Free Software Foundation,
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 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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 *
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 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 * or visit www.oracle.com if you need additional information or have any
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 * questions.
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 *
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 */
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#include "precompiled.hpp"
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#include "utilities/byteswap.hpp"
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#include "utilities/globalDefinitions.hpp"
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#include "unittest.hpp"
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template<typename T>
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static inline void test_byteswap() {
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  const int  NBIT = sizeof(T) * 8;
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  const bool IS_U = (T)-1 > 0;
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  const int XOR_REV_BITS = (NBIT - 1);
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  const int XOR_REV_BITS_IN_BYTES = 7;  // only flip position in byte
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  const int XOR_REV_BYTES = XOR_REV_BITS ^ XOR_REV_BITS_IN_BYTES;
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  ASSERT_EQ(byteswap<T>((T)0), (T)0);
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  ASSERT_EQ(byteswap<T>((T)-1), (T)-1);
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  for (int i1 = 0; i1 < NBIT; i1++) {
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    T mask1 = (T)1 << i1;
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    T rbym1 = (T)1 << (i1 ^ XOR_REV_BYTES);
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    for (int i2 = 0; i2 <= i1; i2++) {
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      T mask2 = (T)1 << i2;
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      T rbym2 = (T)1 << (i2 ^ XOR_REV_BYTES);
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      T mask = mask1|mask2;
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#define STUFF (IS_U?"u":"s") << NBIT << "@" << i1 << "," << i2
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      ASSERT_EQ(byteswap<T>(mask), rbym1|rbym2) << STUFF;
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      ASSERT_EQ((T)~byteswap<T>((T)~mask), rbym1|rbym2) << STUFF;
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    }
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  }
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}
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TEST_VM(utilities, byteswap) {
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  test_byteswap<int64_t>();
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  test_byteswap<uint64_t>();
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  test_byteswap<int32_t>();
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  test_byteswap<uint32_t>();
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  test_byteswap<int16_t>();
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  test_byteswap<uint16_t>();
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  test_byteswap<int8_t>();
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  test_byteswap<uint8_t>();
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}
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// Here is some object code to look at if we want to do a manual
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// study.  One could find the build file named test_byteswap.o.cmdline
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// and hand-edit the command line to produce assembly code in
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// test_byteswap.s.
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//
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// Or, given the two empty "fence functions", one could do a
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// quick scan like this:
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//
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// $ objdump -D $(find build/*release -name test_byteswap.o) \
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//   | sed -n '/start_code_quality/,$p;/end_code_quality/q' \
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//   | egrep -B10 bswap  # or grep -B20 cfi_endproc
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void start_code_quality_byteswap() { }
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int32_t code_quality_reverse_bytes_32(int32_t x) {
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  return byteswap(x);
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}
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int64_t code_quality_reverse_bytes_64(int64_t x) {
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  return byteswap(x);
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}
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