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