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construct/ircd/utf.cc

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C++

// The Construct
//
// Copyright (C) The Construct Developers, Authors & Contributors
// Copyright (C) 2016-2020 Jason Volk <jason@zemos.net>
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice is present in all copies. The
// full license for this software is available in the LICENSE file.
//
// utf16
//
/// Decodes one or two escaped surrogates (surrogate pair) aligned to the
/// front of the input block. If the surrogates are a pair which decode into
/// a single codepoint, only the first element of the return vector is used;
/// otherwise each surrogate decodes into each element. Three surrogates
/// cannot be decoded at once, so the last two elements are never used.
ircd::u32x4
ircd::utf16::decode_surrogate_aligned_next(const u8x16 input)
noexcept
{
const u8x16 is_hex[3]
{
input >= '0' && input <= '9',
input >= 'A' && input <= 'F',
input >= 'a' && input <= 'f',
};
const u8x16 hex_nibble
{
((input - 0x30) & is_hex[0])
| ((input - 0x41 + 0x0a) & is_hex[1])
| ((input - 0x61 + 0x0a) & is_hex[2])
};
const u128x1 is_hex_nibble
{
is_hex[0] | is_hex[1] | is_hex[2]
};
// Masks the starting byte (the '\' char) of each valid surrogate.
const u32x4 is_surrogate
{
u128x1(input == '\\') &
shr<8>(u128x1(input == 'u')) &
shr<16>(is_hex_nibble) &
shr<24>(is_hex_nibble) &
shr<32>(is_hex_nibble) &
shr<40>(is_hex_nibble)
};
// is_surrogate may leave byte[0] and byte[6] (and possibly byte[12] which
// we don't care about here) as 0xff. Our result will be 4 byte codepoints
// matching those 6 byte inputs, so we shift the byte[6] over to byte[4]
// and stiffen the mask about to be generated.
const u32x4 surrogate_mask
{
((is_surrogate & 0xff) | (is_surrogate >> 16)) == 0xffU
};
// Decide if one or two surrogates were actually input and assert that
// between both lanes if so.
const u32x4 surrogate_deuce
{
(surrogate_mask & shr<32>(u128x1(surrogate_mask))) |
(surrogate_mask & shl<32>(u128x1(surrogate_mask)))
};
// ASCII to integral converion of the upper nibbles
const u8x16 hex_upper
{
shr<16>(u128x1(hex_nibble))
};
// ASCII to integral converion of the lower nibbles
const u8x16 hex_lower
{
shr<24>(u128x1(hex_nibble))
};
// pack upper and lower nibbles into bytes, though these have a space
// between them when 4 nibbles becomes 2 bytes
const u8x16 hex_byte
{
(hex_upper << 4) | hex_lower
};
// Result for one or two unpaired surrogates
const u32x4 codepoint_unpaired
{
u8x16
{
hex_byte[2], hex_byte[0], 0, 0,
hex_byte[8], hex_byte[6], 0, 0,
0, 0, 0, 0,
0, 0, 0, 0,
}
};
// Determine if the unpaired codepoints can make a surrogate pair
const u32x4 surrogate_pair_range
{
codepoint_unpaired >= 0xd800U && codepoint_unpaired <= 0xdfffU
};
// Mask lane[0] if the codepoints are actually a surrogate pair
const u32x4 surrogate_paired
{
surrogate_pair_range & shr<32>(u128x1(surrogate_pair_range))
};
// Pre-processing shuffle for surrogate pair decode
const u32x4 codepoint_pre_paired
{
shr<16>(u128x1(codepoint_unpaired)) | codepoint_unpaired
};
// Decode surrogate pair
const u32x4 codepoint_paired
{
0x10000U +
((codepoint_pre_paired & 0x000003ffU) << 10) +
((codepoint_pre_paired & 0x03ff0000U) >> 16)
};
// Decide if the codepoint is in the supplementary plane (3+ bytes)
const u32x4 codepoint_high
{
(codepoint_paired > 0xffffU) & surrogate_paired
};
// Decide if the codepoint is in the BMP (2- bytes)
const u32x4 codepoint_low
{
(codepoint_paired <= 0xffffU) & ~(shl<32>(u128x1(codepoint_high)))
};
// When two surrogates in a pair are input, lane[0] only
const u32x4 ret_codepoint_paired
{
codepoint_paired & (surrogate_paired & surrogate_deuce)
};
// When two unrelated surrogates are input, lane[0] and lane[1]
const u32x4 ret_codepoint_unpaired
{
codepoint_unpaired & ~surrogate_pair_range & surrogate_deuce
};
// When one surrogate is input, only lane[0]
const u32x4 ret_codepoint_single
{
codepoint_unpaired & ~surrogate_pair_range & ~surrogate_deuce
};
return 0
| ret_codepoint_paired
| ret_codepoint_unpaired
| ret_codepoint_single
;
}
namespace ircd::utf16
{
static const u128x1 full_mask {~u128x1{0}};
extern const u128x1 truncation_table[6];
}
decltype(ircd::utf16::truncation_table)
ircd::utf16::truncation_table
{
~shl<0x30>(~full_mask),
~shl<0x28>(~full_mask),
~shl<0x20>(~full_mask),
~shl<0x18>(~full_mask),
~shl<0x10>(~full_mask),
~shl<0x08>(~full_mask),
};
/// scan for utf-16 surrogates including incomplete sequences truncated
/// by the end of the input; also matches a single trailing slash.
ircd::u8x16
ircd::utf16::find_surrogate_partial(const u8x16 input)
noexcept
{
const u128x1 is_esc
{
input == '\\'
};
const u128x1 is_u
{
input == 'u'
};
const u128x1 is_hex_nibble
{
(input >= '0' && input <= '9') ||
(input >= 'A' && input <= 'F') ||
(input >= 'a' && input <= 'f')
};
const u128x1 surrogate_sans[6]
{
// complete
is_esc
& shr<8>(is_u)
& shr<16>(is_hex_nibble) & shr<24>(is_hex_nibble)
& shr<32>(is_hex_nibble) & shr<40>(is_hex_nibble),
// sans 1
is_esc
& shr<8>(is_u)
& shr<16>(is_hex_nibble) & shr<24>(is_hex_nibble)
& shr<32>(is_hex_nibble),
// sans 2
is_esc
& shr<8>(is_u)
& shr<16>(is_hex_nibble) & shr<24>(is_hex_nibble),
// sans 3
is_esc
& shr<8>(is_u)
& shr<16>(is_hex_nibble),
// sans 4
is_esc
& shr<8>(is_u),
// sans 5
is_esc,
};
const u128x1 ret
{
(surrogate_sans[0] & truncation_table[0]) |
(surrogate_sans[1] & truncation_table[1]) |
(surrogate_sans[2] & truncation_table[2]) |
(surrogate_sans[3] & truncation_table[3]) |
(surrogate_sans[4] & truncation_table[4]) |
(surrogate_sans[5] & truncation_table[5])
};
return ret;
}
ircd::u8x16
ircd::utf16::find_surrogate(const u8x16 input)
noexcept
{
const u128x1 is_hex_nibble
{
(input >= '0' && input <= '9') ||
(input >= 'A' && input <= 'F') ||
(input >= 'a' && input <= 'f')
};
const auto is_surrogate
{
u128x1(input == '\\') &
shr<8>(u128x1(input == 'u')) &
shr<16>(is_hex_nibble) &
shr<24>(is_hex_nibble) &
shr<32>(is_hex_nibble) &
shr<40>(is_hex_nibble)
};
return is_surrogate;
}
/// Convert utf-16 two-byte surrogates (in big-endian) to char32_t codepoints
/// in parallel. The result vector is twice the size as the input; no template
/// is offered yet, just the dimensions someone needed for somewhere.
ircd::u32x8
ircd::utf16::convert_u32x8(const u8x16 string)
noexcept
{
return u32x8
{
string[0x01] | (u32(string[0x00]) << 8),
string[0x03] | (u32(string[0x02]) << 8),
string[0x05] | (u32(string[0x04]) << 8),
string[0x07] | (u32(string[0x06]) << 8),
string[0x09] | (u32(string[0x08]) << 8),
string[0x0b] | (u32(string[0x0a]) << 8),
string[0x0d] | (u32(string[0x0c]) << 8),
string[0x0f] | (u32(string[0x0e]) << 8),
};
}
//
// utf8
//
ircd::u32x16
ircd::utf8::decode(const u8x16 string)
noexcept
{
const u32x16 in
{
simd::lane_cast<u32x16>(string)
};
const u32x16 is_single
{
(in & 0x80) == 0
};
const u32x16 is_lead
{
(in - 0xc2) <= 0x32
};
const u32x16 is_trail
{
in >= 0x80 && in < 0xbf
};
const u32x16 expect_trail
{
(((in >= 0xe0) & 1) + ((in >= 0xf0) & 1) + 1) & is_lead
};
const u32x16 expect_length
{
expect_trail + 1
};
const u32x16 shift[4]
{
in << 0,
in << 8,
in << 16,
in << 24,
};
const u32x16 multibyte_packs
{
in[0x00] | shift[0x01][0x01] | shift[0x02][0x02] | shift[0x03][0x03],
in[0x01] | shift[0x01][0x02] | shift[0x02][0x03] | shift[0x03][0x04],
in[0x02] | shift[0x01][0x03] | shift[0x02][0x04] | shift[0x03][0x05],
in[0x03] | shift[0x01][0x04] | shift[0x02][0x05] | shift[0x03][0x06],
in[0x04] | shift[0x01][0x05] | shift[0x02][0x06] | shift[0x03][0x07],
in[0x05] | shift[0x01][0x06] | shift[0x02][0x07] | shift[0x03][0x08],
in[0x06] | shift[0x01][0x07] | shift[0x02][0x08] | shift[0x03][0x09],
in[0x07] | shift[0x01][0x08] | shift[0x02][0x09] | shift[0x03][0x0a],
in[0x08] | shift[0x01][0x09] | shift[0x02][0x0a] | shift[0x03][0x0b],
in[0x09] | shift[0x01][0x0a] | shift[0x02][0x0b] | shift[0x03][0x0c],
in[0x0a] | shift[0x01][0x0b] | shift[0x02][0x0c] | shift[0x03][0x0d],
in[0x0b] | shift[0x01][0x0c] | shift[0x02][0x0d] | shift[0x03][0x0e],
in[0x0c] | shift[0x01][0x0d] | shift[0x02][0x0e] | shift[0x03][0x0f],
in[0x0d] | shift[0x01][0x0e] | shift[0x02][0x0f] | shift[0x03][0x0f],
in[0x0e] | shift[0x01][0x0f] | shift[0x02][0x0f] | shift[0x03][0x0f],
in[0x0f] | shift[0x01][0x0f] | shift[0x02][0x0f] | shift[0x03][0x0f],
};
const u32x16 multibyte
{
0
| (multibyte_packs & (expect_length == 1) & 0x000000ffU)
| (multibyte_packs & (expect_length == 2) & 0x0000ffffU)
| (multibyte_packs & (expect_length == 3) & 0x00ffffffU)
| (multibyte_packs & (expect_length == 4) & 0xffffffffU)
};
const u32x16 integers
{
(in & is_single) | (multibyte & is_lead)
};
return integers;
}
namespace ircd::utf8
{
template<class u32xN> static u32xN _encode(const u32xN codepoint) noexcept;
}
ircd::u32x4
ircd::utf8::encode(const u32x4 codepoint)
noexcept
{
return _encode(codepoint);
}
ircd::u32x8
ircd::utf8::encode(const u32x8 codepoint)
noexcept
{
return _encode(codepoint);
}
ircd::u32x16
ircd::utf8::encode(const u32x16 codepoint)
noexcept
{
return _encode(codepoint);
}
/// Transform multiple char32_t codepoints to their utf-8 encodings in
/// parallel, returning a sparse result in each char32_t (this does not
/// compress the result down).
template<class u32xN>
u32xN
ircd::utf8::_encode(const u32xN codepoint)
noexcept
{
const u32xN len
{
length(codepoint)
};
const u32xN enc_2
{
(((codepoint >> 6) | 0xc0) & 0xff) // byte[0]
| ((((codepoint & 0x3f) | 0x80) &0xff) << 8) // byte[1]
};
const u32xN enc_3
{
(((codepoint >> 12) | 0xe0) & 0xff) | // byte[0]
(((((codepoint >> 6) & 0x3f) | 0x80) & 0xff) << 8) | // byte[1]
((((codepoint & 0x3f) | 0x80) & 0xff) << 16) // byte[3]
};
const u32xN enc_4
{
(((codepoint >> 18) | 0xf0) & 0xff) | // byte[0]
(((((codepoint >> 12) & 0x3f) | 0x80) & 0xff) << 8) | // byte[1]
(((((codepoint >> 6) & 0x3f) | 0x80) & 0xff) << 16) | // byte[2]
((((codepoint & 0x3f) | 0x80) & 0xff) << 24) // byte[3]
};
return 0
| ((len == 0) & 0xFFFD)
| ((len == 1) & codepoint)
| ((len == 2) & enc_2)
| ((len == 3) & enc_3)
| ((len == 4) & enc_4)
;
}
namespace ircd::utf8
{
template<class u32xN> static u32xN _length(const u32xN codepoint) noexcept;
}
ircd::u32x4
ircd::utf8::length(const u32x4 codepoint)
noexcept
{
return _length(codepoint);
}
ircd::u32x8
ircd::utf8::length(const u32x8 codepoint)
noexcept
{
return _length(codepoint);
}
ircd::u32x16
ircd::utf8::length(const u32x16 codepoint)
noexcept
{
return _length(codepoint);
}
/// Determine the utf-8 encoding length of multiple codepoints in parallel.
/// The input vector char32_t codepoints and the output yields an integer
/// of 0-4 for each lane.
template<class u32xN>
u32xN
ircd::utf8::_length(const u32xN codepoint)
noexcept
{
const u32xN
length_1 { codepoint <= 0x7f },
length_2 { codepoint <= 0x7ff && codepoint > 0x7f },
length_3_lo { codepoint <= 0xd7ff && codepoint > 0x7ff },
length_3_hi { codepoint <= 0xffff && codepoint > 0xdfff },
length_4 { codepoint <= 0x10ffff && codepoint > 0xffff };
[[gnu::unused]] const u32xN // Preserved here for future reference
length_3_err { codepoint <= 0xdfff && codepoint > 0xd7ff },
length_err { (codepoint > 0x10ffff) | length_3_err };
return 0
| (length_1 & 1)
| (length_2 & 2)
| (length_3_lo & 3)
| (length_3_hi & 3)
| (length_4 & 4)
;
}