2014-02-05 18:27:27 +01:00
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// Copyright 2013, ARM Limited
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are met:
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//
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// * Redistributions of source code must retain the above copyright notice,
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// this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above copyright notice,
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// this list of conditions and the following disclaimer in the documentation
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// and/or other materials provided with the distribution.
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// * Neither the name of ARM Limited nor the names of its contributors may be
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// used to endorse or promote products derived from this software without
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// specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS CONTRIBUTORS "AS IS" AND
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// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
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// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#include "utils.h"
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#include <stdio.h>
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namespace vixl {
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uint32_t float_to_rawbits(float value) {
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uint32_t bits = 0;
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memcpy(&bits, &value, 4);
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return bits;
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}
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uint64_t double_to_rawbits(double value) {
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uint64_t bits = 0;
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memcpy(&bits, &value, 8);
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return bits;
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}
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float rawbits_to_float(uint32_t bits) {
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float value = 0.0;
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memcpy(&value, &bits, 4);
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return value;
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}
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double rawbits_to_double(uint64_t bits) {
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double value = 0.0;
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memcpy(&value, &bits, 8);
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return value;
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}
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int CountLeadingZeros(uint64_t value, int width) {
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2014-05-13 17:09:35 +02:00
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VIXL_ASSERT((width == 32) || (width == 64));
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2014-02-05 18:27:27 +01:00
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int count = 0;
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2014-05-13 17:09:35 +02:00
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uint64_t bit_test = UINT64_C(1) << (width - 1);
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2014-02-05 18:27:27 +01:00
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while ((count < width) && ((bit_test & value) == 0)) {
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count++;
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bit_test >>= 1;
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}
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return count;
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}
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int CountLeadingSignBits(int64_t value, int width) {
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2014-05-13 17:09:35 +02:00
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VIXL_ASSERT((width == 32) || (width == 64));
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2014-02-05 18:27:27 +01:00
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if (value >= 0) {
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return CountLeadingZeros(value, width) - 1;
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} else {
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return CountLeadingZeros(~value, width) - 1;
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}
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}
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int CountTrailingZeros(uint64_t value, int width) {
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2014-05-13 17:09:35 +02:00
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VIXL_ASSERT((width == 32) || (width == 64));
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2014-02-05 18:27:27 +01:00
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int count = 0;
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while ((count < width) && (((value >> count) & 1) == 0)) {
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count++;
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}
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return count;
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}
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int CountSetBits(uint64_t value, int width) {
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// TODO: Other widths could be added here, as the implementation already
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// supports them.
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2014-05-13 17:09:35 +02:00
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VIXL_ASSERT((width == 32) || (width == 64));
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2014-02-05 18:27:27 +01:00
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// Mask out unused bits to ensure that they are not counted.
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2014-05-13 17:09:35 +02:00
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value &= (UINT64_C(0xffffffffffffffff) >> (64-width));
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2014-02-05 18:27:27 +01:00
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// Add up the set bits.
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// The algorithm works by adding pairs of bit fields together iteratively,
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// where the size of each bit field doubles each time.
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// An example for an 8-bit value:
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// Bits: h g f e d c b a
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// \ | \ | \ | \ |
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// value = h+g f+e d+c b+a
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// \ | \ |
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// value = h+g+f+e d+c+b+a
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// \ |
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// value = h+g+f+e+d+c+b+a
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2014-05-13 17:09:35 +02:00
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const uint64_t kMasks[] = {
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UINT64_C(0x5555555555555555),
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UINT64_C(0x3333333333333333),
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UINT64_C(0x0f0f0f0f0f0f0f0f),
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UINT64_C(0x00ff00ff00ff00ff),
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UINT64_C(0x0000ffff0000ffff),
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UINT64_C(0x00000000ffffffff),
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};
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for (unsigned i = 0; i < (sizeof(kMasks) / sizeof(kMasks[0])); i++) {
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int shift = 1 << i;
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value = ((value >> shift) & kMasks[i]) + (value & kMasks[i]);
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}
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2014-02-05 18:27:27 +01:00
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return value;
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}
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2014-08-29 16:00:27 +02:00
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uint64_t LowestSetBit(uint64_t value) {
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return value & -value;
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}
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bool IsPowerOf2(int64_t value) {
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return (value != 0) && ((value & (value - 1)) == 0);
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}
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2014-10-24 13:19:11 +02:00
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2014-02-05 18:27:27 +01:00
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} // namespace vixl
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