| // 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) { |
| ASSERT((width == 32) || (width == 64)); |
| int count = 0; |
| uint64_t bit_test = 1UL << (width - 1); |
| while ((count < width) && ((bit_test & value) == 0)) { |
| count++; |
| bit_test >>= 1; |
| } |
| return count; |
| } |
| |
| |
| int CountLeadingSignBits(int64_t value, int width) { |
| 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) { |
| 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. |
| ASSERT((width == 32) || (width == 64)); |
| |
| // Mask out unused bits to ensure that they are not counted. |
| value &= (0xffffffffffffffffULL >> (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 |
| value = ((value >> 1) & 0x5555555555555555ULL) + |
| (value & 0x5555555555555555ULL); |
| value = ((value >> 2) & 0x3333333333333333ULL) + |
| (value & 0x3333333333333333ULL); |
| value = ((value >> 4) & 0x0f0f0f0f0f0f0f0fULL) + |
| (value & 0x0f0f0f0f0f0f0f0fULL); |
| value = ((value >> 8) & 0x00ff00ff00ff00ffULL) + |
| (value & 0x00ff00ff00ff00ffULL); |
| value = ((value >> 16) & 0x0000ffff0000ffffULL) + |
| (value & 0x0000ffff0000ffffULL); |
| value = ((value >> 32) & 0x00000000ffffffffULL) + |
| (value & 0x00000000ffffffffULL); |
| |
| return value; |
| } |
| } // namespace vixl |