mirror of
https://github.com/simdjson/simdjson
synced 2026-06-08 17:27:07 +00:00
Paul Dreik
64 lines
2.0 KiB
C++
64 lines
2.0 KiB
C++
#ifndef SIMDJSON_ARM64_BITMANIPULATION_H
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#define SIMDJSON_ARM64_BITMANIPULATION_H
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namespace simdjson {
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namespace SIMDJSON_IMPLEMENTATION {
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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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NO_SANITIZE_UNDEFINED
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simdjson_really_inline int trailing_zeroes(uint64_t input_num) {
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#ifdef SIMDJSON_REGULAR_VISUAL_STUDIO
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unsigned long ret;
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// Search the mask data from least significant bit (LSB)
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// to the most significant bit (MSB) for a set bit (1).
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_BitScanForward64(&ret, input_num);
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return (int)ret;
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#else // SIMDJSON_REGULAR_VISUAL_STUDIO
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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_really_inline uint64_t clear_lowest_bit(uint64_t input_num) {
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return input_num & (input_num-1);
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}
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/* result might be undefined when input_num is zero */
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simdjson_really_inline int leading_zeroes(uint64_t input_num) {
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#ifdef SIMDJSON_REGULAR_VISUAL_STUDIO
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unsigned long leading_zero = 0;
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// Search the mask data from most significant bit (MSB)
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// to least significant bit (LSB) for a set bit (1).
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if (_BitScanReverse64(&leading_zero, input_num))
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return (int)(63 - leading_zero);
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else
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return 64;
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#else
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return __builtin_clzll(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_really_inline int count_ones(uint64_t input_num) {
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return vaddv_u8(vcnt_u8(vcreate_u8(input_num)));
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}
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simdjson_really_inline bool add_overflow(uint64_t value1, uint64_t value2, uint64_t *result) {
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#ifdef SIMDJSON_REGULAR_VISUAL_STUDIO
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*result = value1 + value2;
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return *result < value1;
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#else
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return __builtin_uaddll_overflow(value1, value2,
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(unsigned long long *)result);
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#endif
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}
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} // unnamed namespace
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} // namespace SIMDJSON_IMPLEMENTATION
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} // namespace simdjson
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#endif // SIMDJSON_ARM64_BITMANIPULATION_H
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