mirror of
https://github.com/simdjson/simdjson
synced 2026-06-08 17:27:07 +00:00
John Keiser
71 lines
2.2 KiB
C++
71 lines
2.2 KiB
C++
#ifndef SIMDJSON_ICELAKE_BITMANIPULATION_H
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#define SIMDJSON_ICELAKE_BITMANIPULATION_H
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#ifndef SIMDJSON_CONDITIONAL_INCLUDE
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#include "simdjson/icelake/base.h"
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#include "simdjson/icelake/intrinsics.h"
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#endif // SIMDJSON_CONDITIONAL_INCLUDE
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namespace simdjson {
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namespace icelake {
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namespace {
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// We sometimes call trailing_zero on inputs that are zero,
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// but the algorithms do not end up using the returned value.
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// Sadly, sanitizers are not smart enough to figure it out.
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SIMDJSON_NO_SANITIZE_UNDEFINED
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// This function can be used safely even if not all bytes have been
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// initialized.
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// See issue https://github.com/simdjson/simdjson/issues/1965
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SIMDJSON_NO_SANITIZE_MEMORY
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simdjson_inline int trailing_zeroes(uint64_t input_num) {
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#if SIMDJSON_REGULAR_VISUAL_STUDIO
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return (int)_tzcnt_u64(input_num);
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#else // SIMDJSON_REGULAR_VISUAL_STUDIO
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////////
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// You might expect the next line to be equivalent to
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// return (int)_tzcnt_u64(input_num);
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// but the generated code differs and might be less efficient?
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////////
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return __builtin_ctzll(input_num);
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#endif // SIMDJSON_REGULAR_VISUAL_STUDIO
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}
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/* result might be undefined when input_num is zero */
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simdjson_inline uint64_t clear_lowest_bit(uint64_t input_num) {
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return _blsr_u64(input_num);
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}
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/* result might be undefined when input_num is zero */
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simdjson_inline int leading_zeroes(uint64_t input_num) {
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return int(_lzcnt_u64(input_num));
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}
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#if SIMDJSON_REGULAR_VISUAL_STUDIO
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simdjson_inline unsigned __int64 count_ones(uint64_t input_num) {
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// note: we do not support legacy 32-bit Windows
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return __popcnt64(input_num);// Visual Studio wants two underscores
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}
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#else
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simdjson_inline long long int count_ones(uint64_t input_num) {
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return _popcnt64(input_num);
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}
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#endif
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simdjson_inline bool add_overflow(uint64_t value1, uint64_t value2,
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uint64_t *result) {
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#if SIMDJSON_REGULAR_VISUAL_STUDIO
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return _addcarry_u64(0, value1, value2,
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reinterpret_cast<unsigned __int64 *>(result));
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#else
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return __builtin_uaddll_overflow(value1, value2,
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reinterpret_cast<unsigned long long *>(result));
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#endif
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}
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} // unnamed namespace
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} // namespace icelake
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} // namespace simdjson
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#endif // SIMDJSON_ICELAKE_BITMANIPULATION_H
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