//     __ _____ _____ _____
//  __|  |   __|     |   | |  JSON for Modern C++
// |  |  |__   |  |  | | | |  version 3.12.0
// |_____|_____|_____|_|___|  https://github.com/nlohmann/json
//
// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
// SPDX-FileCopyrightText: 2018-2025 The simdjson authors <https://github.com/simdjson/simdjson>
// SPDX-License-Identifier: MIT

#pragma once

#include <cstddef> // size_t
#include <cstdint> // uint8_t, uint64_t

#include <nlohmann/json.hpp>
#include <nlohmann/detail/view/macro_scope.hpp>

// Vector code for long runs of string bytes. NEON (AArch64) and SSE2 (x86-64)
// belong to the baseline instruction sets and are used by default. The vector
// UTF-8 check needs NEON, or SSSE3 if JSON_VIEW_USE_SSSE3 is defined: SSSE3 is
// not part of x86-64, so it must not depend on the flags of a translation unit
// (two translation units with different flags would have different
// definitions of the same inline functions). JSON_VIEW_NO_SIMD selects the
// portable code.
#if !defined(JSON_VIEW_NO_SIMD) && defined(__aarch64__) && (defined(__GNUC__) || defined(__clang__)) && NLOHMANN_VIEW_LITTLE_ENDIAN
    #include <arm_neon.h>
    #define NLOHMANN_VIEW_NEON 1
#else
    #define NLOHMANN_VIEW_NEON 0
#endif
#if !defined(JSON_VIEW_NO_SIMD) && !NLOHMANN_VIEW_NEON && (defined(__SSE2__) || defined(_M_X64) || (defined(_M_IX86_FP) && _M_IX86_FP >= 2))
    #include <emmintrin.h>
    #define NLOHMANN_VIEW_SSE2 1
#else
    #define NLOHMANN_VIEW_SSE2 0
#endif
#if NLOHMANN_VIEW_SSE2 && defined(JSON_VIEW_USE_SSSE3)
    #include <tmmintrin.h>
    #define NLOHMANN_VIEW_SSSE3 1
#else
    #define NLOHMANN_VIEW_SSSE3 0
#endif
#define NLOHMANN_VIEW_VECTOR (NLOHMANN_VIEW_NEON || NLOHMANN_VIEW_SSE2)
#define NLOHMANN_VIEW_VECTOR_UTF8 (NLOHMANN_VIEW_NEON || NLOHMANN_VIEW_SSSE3)

NLOHMANN_JSON_NAMESPACE_BEGIN
namespace detail
{
namespace view
{

#if NLOHMANN_VIEW_VECTOR
/*!
@brief the first byte of a string run that is a quote, a backslash, a control
character, or not ASCII, 16 bytes per step

Stops at such a byte, or where fewer than 16 bytes are left (the caller tells
the two apart). A signed compare with 0x20 finds control characters and
non-ASCII bytes at once.
*/
NLOHMANN_VIEW_ALWAYS_INLINE const unsigned char* vector_plain_run(const unsigned char* p, const unsigned char* e) noexcept
{
    while (e - p >= 16)
    {
#if NLOHMANN_VIEW_NEON
        const uint8x16_t in = vld1q_u8(p);
        const uint8x16_t special = vorrq_u8(vorrq_u8(vceqq_u8(in, vdupq_n_u8('"')), vceqq_u8(in, vdupq_n_u8('\\'))),
                                            vcltq_s8(vreinterpretq_s8_u8(in), vdupq_n_s8(0x20)));
        // one nibble per byte (the usual NEON replacement of x86's movemask, see
        // D. Kutenin, "Porting x86 vector bitmask optimizations to Arm NEON", 2022)
        const std::uint64_t bits = vget_lane_u64(vreinterpret_u64_u8(vshrn_n_u16(vreinterpretq_u16_u8(special), 4)), 0);
        if (bits != 0)
        {
            return p + (count_trailing_zeros(bits) >> 2u);
        }
#else
        const __m128i in = _mm_loadu_si128(static_cast<const __m128i*>(static_cast<const void*>(p)));
        const __m128i special = _mm_or_si128(_mm_or_si128(_mm_cmpeq_epi8(in, _mm_set1_epi8('"')), _mm_cmpeq_epi8(in, _mm_set1_epi8('\\'))),
                                             _mm_cmplt_epi8(in, _mm_set1_epi8(0x20)));
        const auto bits = static_cast<std::uint64_t>(static_cast<unsigned>(_mm_movemask_epi8(special)));
        if (bits != 0)
        {
            return p + count_trailing_zeros(bits);
        }
#endif
        p += 16;
    }
    return p;
}
#endif

#if NLOHMANN_VIEW_VECTOR_UTF8
/// Tables of the UTF-8 check of J. Keiser and D. Lemire, "Validating UTF-8 In
/// Less Than One Instruction Per Byte" (2021), as in simdjson ("lookup4"): each
/// maps a nibble (high and low nibble of the previous byte, high nibble of the
/// current byte) to the errors it allows; a byte pair is ill-formed if all
/// three have an error bit in common.
template<typename Dummy = void>
struct utf8_lookup4
{
    static constexpr std::uint8_t too_short = 1u << 0u, too_long = 1u << 1u, overlong_3 = 1u << 2u, too_large = 1u << 3u;
    static constexpr std::uint8_t surrogate = 1u << 4u, overlong_2 = 1u << 5u, too_large_1000 = 1u << 6u, overlong_4 = 1u << 6u;
    static constexpr std::uint8_t two_conts = 1u << 7u, carry = too_short | too_long | two_conts;
    static const std::uint8_t byte_1_high[16];
    static const std::uint8_t byte_1_low[16];
    static const std::uint8_t byte_2_high[16];
};

template<typename Dummy>
const std::uint8_t utf8_lookup4<Dummy>::byte_1_high[16] =
{
    too_long, too_long, too_long, too_long, too_long, too_long, too_long, too_long,
    two_conts, two_conts, two_conts, two_conts,
    too_short | overlong_2, too_short, too_short | overlong_3 | surrogate, too_short | too_large | too_large_1000 | overlong_4
};

template<typename Dummy>
const std::uint8_t utf8_lookup4<Dummy>::byte_1_low[16] =
{
    carry | overlong_3 | overlong_2 | overlong_4, carry | overlong_2, carry, carry,
    carry | too_large, carry | too_large | too_large_1000, carry | too_large | too_large_1000, carry | too_large | too_large_1000,
    carry | too_large | too_large_1000, carry | too_large | too_large_1000, carry | too_large | too_large_1000, carry | too_large | too_large_1000,
    carry | too_large | too_large_1000, carry | too_large | too_large_1000 | surrogate, carry | too_large | too_large_1000, carry | too_large | too_large_1000
};

template<typename Dummy>
const std::uint8_t utf8_lookup4<Dummy>::byte_2_high[16] =
{
    too_short, too_short, too_short, too_short, too_short, too_short, too_short, too_short,
    static_cast<std::uint8_t>(too_long | overlong_2 | two_conts | overlong_3 | too_large_1000 | overlong_4),
    static_cast<std::uint8_t>(too_long | overlong_2 | two_conts | overlong_3 | too_large),
    static_cast<std::uint8_t>(too_long | overlong_2 | two_conts | surrogate | too_large),
    static_cast<std::uint8_t>(too_long | overlong_2 | two_conts | surrogate | too_large),
    too_short, too_short, too_short, too_short
};

/// the end of scan_string_vector from block, where the vector loop stopped
/// (ill-formed UTF-8, or fewer than 16 bytes left): one byte or sequence at a
/// time, from the start of a sequence that crosses into the block
inline const unsigned char* scan_string_finish(const unsigned char* p, const unsigned char* block, const unsigned char* e, const std::uint8_t* plain) noexcept
{
    for (int i = 1; i <= 3 && block - i >= p; ++i)
    {
        const unsigned char c = block[-i];
        if (c < 0x80)
        {
            break;
        }
        if (c >= 0xC0)
        {
            const int len = c >= 0xF0 ? 4 : (c >= 0xE0 ? 3 : 2);
            if (len > i)
            {
                block -= i;
            }
            break;
        }
    }
    for (p = block; p != e;)
    {
        if (*p < 0x80)
        {
            if (plain[*p] == 0)
            {
                return p;
            }
            ++p;
            continue;
        }
        const std::size_t n = validate_one_utf8(p, static_cast<std::size_t>(e - p));
        if (n == 0)
        {
            return p;
        }
        p += n;
    }
    return p;
}

/*!
@brief the rest of a string from p (a character boundary), 16 bytes per step

The first quote, backslash, or control character is found with vector
compares, and the UTF-8 check covers the bytes up to it. Returns where the
string scan stops, like scan_string_run: before ill-formed UTF-8 and for the
last bytes of the input, the bytes are checked one sequence at a time. Out of
line, so that no constants of the check occupy registers in the parse loop.
*/
NLOHMANN_VIEW_NOINLINE inline const unsigned char* scan_string_vector(const unsigned char* p, const unsigned char* e, const std::uint8_t* plain) noexcept
{
    using lookup = utf8_lookup4<>;
    const unsigned char* block = p;
#if NLOHMANN_VIEW_NEON
    const uint8x16_t t1h = vld1q_u8(lookup::byte_1_high);
    const uint8x16_t t1l = vld1q_u8(lookup::byte_1_low);
    const uint8x16_t t2h = vld1q_u8(lookup::byte_2_high);
    uint8x16_t prev = vdupq_n_u8(0);
    while (e - block >= 16)
    {
        const uint8x16_t in = vld1q_u8(block);
        const uint8x16_t special = vorrq_u8(vorrq_u8(vceqq_u8(in, vdupq_n_u8('"')), vceqq_u8(in, vdupq_n_u8('\\'))), vcltq_u8(in, vdupq_n_u8(0x20)));
        const uint8x16_t prev1 = vextq_u8(prev, in, 15);
        const uint8x16_t sc = vandq_u8(vandq_u8(vqtbl1q_u8(t1h, vshrq_n_u8(prev1, 4)), vqtbl1q_u8(t1l, vandq_u8(prev1, vdupq_n_u8(0x0F)))), vqtbl1q_u8(t2h, vshrq_n_u8(in, 4)));
        const uint8x16_t must23 = vorrq_u8(vqsubq_u8(vextq_u8(prev, in, 14), vdupq_n_u8(0xE0 - 0x80)), vqsubq_u8(vextq_u8(prev, in, 13), vdupq_n_u8(0xF0 - 0x80)));
        const uint8x16_t err = veorq_u8(vandq_u8(must23, vdupq_n_u8(0x80)), sc);
        const std::uint64_t special_bits = vget_lane_u64(vreinterpret_u64_u8(vshrn_n_u16(vreinterpretq_u16_u8(special), 4)), 0);
        const std::uint64_t err_bits = vget_lane_u64(vreinterpret_u64_u8(vshrn_n_u16(vreinterpretq_u16_u8(vtstq_u8(err, err)), 4)), 0);
        if (special_bits != 0)
        {
            // errors up to the special byte count (an incomplete sequence
            // before a quote shows at the quote); the bytes after it do not
            const unsigned k = static_cast<unsigned>(count_trailing_zeros(special_bits)) >> 2u;
            const std::uint64_t upto = k == 15 ? ~std::uint64_t{0} :
                                       (std::uint64_t{1} << (4u * (k + 1u))) - 1u;
            if ((err_bits & upto) == 0)
            {
                return block + k;
            }
            break;
        }
        if (err_bits != 0)
        {
            break;
        }
        prev = in;
        block += 16;
    }
#else
    // the same with SSSE3 (pshufb for the table lookups; nibbles from 16-bit
    // shifts, as there are no byte shifts)
    const __m128i t1h = _mm_loadu_si128(static_cast<const __m128i*>(static_cast<const void*>(lookup::byte_1_high)));
    const __m128i t1l = _mm_loadu_si128(static_cast<const __m128i*>(static_cast<const void*>(lookup::byte_1_low)));
    const __m128i t2h = _mm_loadu_si128(static_cast<const __m128i*>(static_cast<const void*>(lookup::byte_2_high)));
    const __m128i nibble = _mm_set1_epi8(0x0F);
    const __m128i zero = _mm_setzero_si128();
    __m128i prev = zero;
    while (e - block >= 16)
    {
        const __m128i in = _mm_loadu_si128(static_cast<const __m128i*>(static_cast<const void*>(block)));
        const __m128i special = _mm_or_si128(_mm_or_si128(_mm_cmpeq_epi8(in, _mm_set1_epi8('"')), _mm_cmpeq_epi8(in, _mm_set1_epi8('\\'))),
                                             _mm_cmpeq_epi8(_mm_subs_epu8(in, _mm_set1_epi8(0x1F)), zero)); // in < 0x20
        const __m128i prev1 = _mm_alignr_epi8(in, prev, 15);
        const __m128i sc = _mm_and_si128(_mm_and_si128(_mm_shuffle_epi8(t1h, _mm_and_si128(_mm_srli_epi16(prev1, 4), nibble)),
                                         _mm_shuffle_epi8(t1l, _mm_and_si128(prev1, nibble))),
                                         _mm_shuffle_epi8(t2h, _mm_and_si128(_mm_srli_epi16(in, 4), nibble)));
        const __m128i must23 = _mm_or_si128(_mm_subs_epu8(_mm_alignr_epi8(in, prev, 14), _mm_set1_epi8(0xE0 - 0x80)),
                                            _mm_subs_epu8(_mm_alignr_epi8(in, prev, 13), _mm_set1_epi8(0xF0 - 0x80)));
        const __m128i err = _mm_xor_si128(_mm_and_si128(must23, _mm_set1_epi8(static_cast<char>(-128))), sc);
        const auto special_bits = static_cast<unsigned>(_mm_movemask_epi8(special));
        const auto err_bits = ~static_cast<unsigned>(_mm_movemask_epi8(_mm_cmpeq_epi8(err, zero))) & 0xFFFFu;
        if (special_bits != 0)
        {
            const unsigned k = static_cast<unsigned>(count_trailing_zeros(static_cast<std::uint64_t>(special_bits)));
            if ((err_bits & ((2u << k) - 1u)) == 0)
            {
                return block + k;
            }
            break;
        }
        if (err_bits != 0)
        {
            break;
        }
        prev = in;
        block += 16;
    }
#endif
    return scan_string_finish(p, block, e, plain);
}
#endif

}  // namespace view
}  // namespace detail
NLOHMANN_JSON_NAMESPACE_END