simdjson-simdjson/src/arm64.cpp

#ifndef SIMDJSON_SRC_ARM64_CPP
#define SIMDJSON_SRC_ARM64_CPP

#ifndef SIMDJSON_CONDITIONAL_INCLUDE
#include <base.h>
#endif // SIMDJSON_CONDITIONAL_INCLUDE

#include <simdjson/arm64.h>
#include <simdjson/arm64/implementation.h>

#include <simdjson/arm64/begin.h>
#include <generic/amalgamated.h>
#include <generic/stage1/amalgamated.h>
#include <generic/stage2/amalgamated.h>

//
// Stage 1
//
namespace simdjson {
namespace arm64 {

simdjson_warn_unused error_code implementation::create_dom_parser_implementation(
  size_t capacity,
  size_t max_depth,
  std::unique_ptr<internal::dom_parser_implementation>& dst
) const noexcept {
  dst.reset( new (std::nothrow) dom_parser_implementation() );
  if (!dst) { return MEMALLOC; }
  if (auto err = dst->set_capacity(capacity))
    return err;
  if (auto err = dst->set_max_depth(max_depth))
    return err;
  return SUCCESS;
}

namespace {

using namespace simd;

simdjson_inline json_character_block json_character_block::classify(const simd::simd8x64<uint8_t>& in) {
  // Functional programming causes trouble with Visual Studio.
  // Keeping this version in comments since it is much nicer:
  // auto v = in.map<uint8_t>([&](simd8<uint8_t> chunk) {
  //  auto nib_lo = chunk & 0xf;
  //  auto nib_hi = chunk.shr<4>();
  //  auto shuf_lo = nib_lo.lookup_16<uint8_t>(16, 0, 0, 0, 0, 0, 0, 0, 0, 8, 12, 1, 2, 9, 0, 0);
  //  auto shuf_hi = nib_hi.lookup_16<uint8_t>(8, 0, 18, 4, 0, 1, 0, 1, 0, 0, 0, 3, 2, 1, 0, 0);
  //  return shuf_lo & shuf_hi;
  // });
  const simd8<uint8_t> table1(16, 0, 0, 0, 0, 0, 0, 0, 0, 8, 12, 1, 2, 9, 0, 0);
  const simd8<uint8_t> table2(8, 0, 18, 4, 0, 1, 0, 1, 0, 0, 0, 3, 2, 1, 0, 0);

  simd8x64<uint8_t> v(
     (in.chunks[0] & 0xf).lookup_16(table1) & (in.chunks[0].shr<4>()).lookup_16(table2),
     (in.chunks[1] & 0xf).lookup_16(table1) & (in.chunks[1].shr<4>()).lookup_16(table2),
     (in.chunks[2] & 0xf).lookup_16(table1) & (in.chunks[2].shr<4>()).lookup_16(table2),
     (in.chunks[3] & 0xf).lookup_16(table1) & (in.chunks[3].shr<4>()).lookup_16(table2)
  );


  // We compute whitespace and op separately. If the code later only use one or the
  // other, given the fact that all functions are aggressively inlined, we can
  // hope that useless computations will be omitted. This is namely case when
  // minifying (we only need whitespace). *However* if we only need spaces,
  // it is likely that we will still compute 'v' above with two lookup_16: one
  // could do it a bit cheaper. This is in contrast with the x64 implementations
  // where we can, efficiently, do the white space and structural matching
  // separately. One reason for this difference is that on ARM NEON, the table
  // lookups either zero or leave unchanged the characters exceeding 0xF whereas
  // on x64, the equivalent instruction (pshufb) automatically applies a mask,
  // ignoring the 4 most significant bits. Thus the x64 implementation is
  // optimized differently. This being said, if you use this code strictly
  // just for minification (or just to identify the structural characters),
  // there is a small untaken optimization opportunity here. We deliberately
  // do not pick it up.

  uint64_t op = simd8x64<bool>(
        v.chunks[0].any_bits_set(0x7),
        v.chunks[1].any_bits_set(0x7),
        v.chunks[2].any_bits_set(0x7),
        v.chunks[3].any_bits_set(0x7)
  ).to_bitmask();

  uint64_t whitespace = simd8x64<bool>(
        v.chunks[0].any_bits_set(0x18),
        v.chunks[1].any_bits_set(0x18),
        v.chunks[2].any_bits_set(0x18),
        v.chunks[3].any_bits_set(0x18)
  ).to_bitmask();

  return { whitespace, op };
}

simdjson_inline bool is_ascii(const simd8x64<uint8_t>& input) {
    simd8<uint8_t> bits = input.reduce_or();
    return bits.max_val() < 0x80u;
}

simdjson_unused simdjson_inline simd8<bool> must_be_continuation(const simd8<uint8_t> prev1, const simd8<uint8_t> prev2, const simd8<uint8_t> prev3) {
    simd8<bool> is_second_byte = prev1 >= uint8_t(0xc0u);
    simd8<bool> is_third_byte  = prev2 >= uint8_t(0xe0u);
    simd8<bool> is_fourth_byte = prev3 >= uint8_t(0xf0u);
    // Use ^ instead of | for is_*_byte, because ^ is commutative, and the caller is using ^ as well.
    // This will work fine because we only have to report errors for cases with 0-1 lead bytes.
    // Multiple lead bytes implies 2 overlapping multibyte characters, and if that happens, there is
    // guaranteed to be at least *one* lead byte that is part of only 1 other multibyte character.
    // The error will be detected there.
    return is_second_byte ^ is_third_byte ^ is_fourth_byte;
}

simdjson_inline simd8<uint8_t> must_be_2_3_continuation(const simd8<uint8_t> prev2, const simd8<uint8_t> prev3) {
    simd8<uint8_t> is_third_byte  = prev2.saturating_sub(0xe0u-0x80); // Only 111_____ will be >= 0x80
    simd8<uint8_t> is_fourth_byte = prev3.saturating_sub(0xf0u-0x80); // Only 1111____ will be >= 0x80
    return is_third_byte | is_fourth_byte;
}

} // unnamed namespace
} // namespace arm64
} // namespace simdjson

//
// Stage 2
//

//
// Implementation-specific overrides
//
namespace simdjson {
namespace arm64 {

simdjson_warn_unused error_code implementation::minify(const uint8_t *buf, size_t len, uint8_t *dst, size_t &dst_len) const noexcept {
  return arm64::stage1::json_minifier::minify<64>(buf, len, dst, dst_len);
}

simdjson_warn_unused error_code dom_parser_implementation::stage1(const uint8_t *_buf, size_t _len, stage1_mode streaming) noexcept {
  this->buf = _buf;
  this->len = _len;
  return arm64::stage1::json_structural_indexer::index<64>(buf, len, *this, streaming);
}

simdjson_warn_unused bool implementation::validate_utf8(const char *buf, size_t len) const noexcept {
  return arm64::stage1::generic_validate_utf8(buf,len);
}

simdjson_warn_unused error_code dom_parser_implementation::stage2(dom::document &_doc) noexcept {
  return stage2::tape_builder::parse_document<false>(*this, _doc);
}

simdjson_warn_unused error_code dom_parser_implementation::stage2_next(dom::document &_doc) noexcept {
  return stage2::tape_builder::parse_document<true>(*this, _doc);
}

simdjson_warn_unused uint8_t *dom_parser_implementation::parse_string(const uint8_t *src, uint8_t *dst, bool allow_replacement) const noexcept {
  return arm64::stringparsing::parse_string(src, dst, allow_replacement);
}

simdjson_warn_unused uint8_t *dom_parser_implementation::parse_wobbly_string(const uint8_t *src, uint8_t *dst) const noexcept {
  return arm64::stringparsing::parse_wobbly_string(src, dst);
}

simdjson_warn_unused error_code dom_parser_implementation::parse(const uint8_t *_buf, size_t _len, dom::document &_doc) noexcept {
  auto error = stage1(_buf, _len, stage1_mode::regular);
  if (error) { return error; }
  return stage2(_doc);
}

} // namespace arm64
} // namespace simdjson

#include <simdjson/arm64/end.h>

#endif // SIMDJSON_SRC_ARM64_CPP