83 lines
2.8 KiB
C++
83 lines
2.8 KiB
C++
/*
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* Copyright (c) 2022, 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/globalDefinitions.hpp"
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#include "utilities/reverse_bits.hpp"
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#include "unittest.hpp"
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template<typename T>
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static inline void test_reverse_bits() {
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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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ASSERT_EQ(reverse_bits((T)0), (T)0);
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ASSERT_EQ(reverse_bits((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 revm1 = (T)1 << (i1 ^ XOR_REV_BITS);
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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 revm2 = (T)1 << (i2 ^ XOR_REV_BITS);
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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(reverse_bits(mask), revm1|revm2) << STUFF;
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ASSERT_EQ((T)~reverse_bits((T)~mask), revm1|revm2) << STUFF;
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}
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}
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}
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TEST_VM(utilities, reverse_bits) {
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test_reverse_bits<int64_t>();
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test_reverse_bits<uint64_t>();
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test_reverse_bits<int32_t>();
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test_reverse_bits<uint32_t>();
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test_reverse_bits<int16_t>();
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test_reverse_bits<uint16_t>();
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test_reverse_bits<int8_t>();
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test_reverse_bits<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_reverse_bits.o.cmdline
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// and hand-edit the command line to produce assembly code in
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// test_reverse_bits.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 $(find build/*release -name test_reverse_bits.o) \
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// | sed -n '/start_code_quality/,$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_reverse_bits() { }
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int32_t code_quality_reverse_bits_32(int32_t x) {
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return reverse_bits(x);
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}
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int64_t code_quality_reverse_bits_64(int64_t x) {
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return reverse_bits(x);
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}
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