internal static uint64_t find_odd_backslash_sequences(simd_input @in, ref uint64_t prev_iter_ends_odd_backslash)
{
const uint64_t even_bits = 0x5555555555555555UL;
const uint64_t odd_bits = ~even_bits;
uint64_t bs_bits = cmp_mask_against_input(@in, (uint8_t)'\\');
uint64_t start_edges = bs_bits & ~(bs_bits << 1);
// flip lowest if we have an odd-length run at the end of the prior
// iteration
uint64_t even_start_mask = even_bits ^ prev_iter_ends_odd_backslash;
uint64_t even_starts = start_edges & even_start_mask;
uint64_t odd_starts = start_edges & ~even_start_mask;
uint64_t even_carries = bs_bits + even_starts;
uint64_t odd_carries;
// must record the carry-out of our odd-carries out of bit 63; this
// indicates whether the sense of any edge going to the next iteration
// should be flipped
bool iter_ends_odd_backslash =
add_overflow(bs_bits, odd_starts, &odd_carries);
odd_carries |=
prev_iter_ends_odd_backslash; // push in bit zero as a potential end
// if we had an odd-numbered run at the
// end of the previous iteration
prev_iter_ends_odd_backslash = iter_ends_odd_backslash ? 0x1UL : 0x0UL;
uint64_t even_carry_ends = even_carries & ~bs_bits;
uint64_t odd_carry_ends = odd_carries & ~bs_bits;
uint64_t even_start_odd_end = even_carry_ends & odd_bits;
uint64_t odd_start_even_end = odd_carry_ends & even_bits;
uint64_t odd_ends = even_start_odd_end | odd_start_even_end;
return(odd_ends);
}
internal static uint64_t unsigned_lteq_against_input(simd_input @in, uint8_t m)
{
if (Avx2.IsSupported)
{
var maxval = Vector256.Create(m);
var cmp_res_0 = Avx2.CompareEqual(Avx2.Max(maxval, @in.lo), maxval);
uint64_t res_0 = (uint32_t)(Avx2.MoveMask(cmp_res_0));
var cmp_res_1 = Avx2.CompareEqual(Avx2.Max(maxval, @in.hi), maxval);
uint64_t res_1 = (uint64_t)Avx2.MoveMask(cmp_res_1);
return(res_0 | (res_1 << 32));
}
else
{
var maxval = Vector128.Create(m);
var cmp_res_0 = Sse2.CompareEqual(Sse2.Max(maxval, @in.v0), maxval);
uint64_t res_0 = (uint64_t)Sse2.MoveMask(cmp_res_0);
var cmp_res_1 = Sse2.CompareEqual(Sse2.Max(maxval, @in.v1), maxval);
uint64_t res_1 = (uint64_t)Sse2.MoveMask(cmp_res_1);
var cmp_res_2 = Sse2.CompareEqual(Sse2.Max(maxval, @in.v2), maxval);
uint64_t res_2 = (uint64_t)Sse2.MoveMask(cmp_res_2);
var cmp_res_3 = Sse2.CompareEqual(Sse2.Max(maxval, @in.v3), maxval);
uint64_t res_3 = (uint64_t)Sse2.MoveMask(cmp_res_3);
return(res_0 | (res_1 << 16) | (res_2 << 32) | (res_3 << 48));
}
}
internal static uint64_t cmp_mask_against_input(simd_input @in, uint8_t m)
{
if (Avx2.IsSupported)
{
Vector256 <byte> mask = Vector256.Create(m);
Vector256 <byte> cmp_res_0 = Avx2.CompareEqual(@in.lo, mask);
uint64_t res_0 = (uint32_t)Avx2.MoveMask(cmp_res_0);
Vector256 <byte> cmp_res_1 = Avx2.CompareEqual(@in.hi, mask);
uint64_t res_1 = (uint64_t)Avx2.MoveMask(cmp_res_1);
return(res_0 | (res_1 << 32));
}
else
{
Vector128 <byte> mask = Vector128.Create(m);
Vector128 <byte> cmp_res_0 = Sse2.CompareEqual(@in.v0, mask);
uint64_t res_0 = (uint64_t)Sse2.MoveMask(cmp_res_0);
Vector128 <byte> cmp_res_1 = Sse2.CompareEqual(@in.v1, mask);
uint64_t res_1 = (uint64_t)Sse2.MoveMask(cmp_res_1);
Vector128 <byte> cmp_res_2 = Sse2.CompareEqual(@in.v2, mask);
uint64_t res_2 = (uint64_t)Sse2.MoveMask(cmp_res_2);
Vector128 <byte> cmp_res_3 = Sse2.CompareEqual(@in.v3, mask);
uint64_t res_3 = (uint64_t)Sse2.MoveMask(cmp_res_3);
return(res_0 | (res_1 << 16) | (res_2 << 32) | (res_3 << 48));
}
}
internal static simd_input fill_input(uint8_t *ptr)
{
if (Avx2.IsSupported)
{
simd_input @in = new simd_input();
@in.lo = Avx.LoadVector256((ptr + 0));
@in.hi = Avx.LoadVector256((ptr + 32));
return(@in);
}
else
{
simd_input @in = new simd_input();
@in.v0 = Sse2.LoadVector128((ptr + 0));
@in.v1 = Sse2.LoadVector128((ptr + 16));
@in.v2 = Sse2.LoadVector128((ptr + 32));
@in.v3 = Sse2.LoadVector128((ptr + 48));
return(@in);
}
}
internal static uint64_t find_quote_mask_and_bits(simd_input @in, uint64_t odd_ends,
ref uint64_t prev_iter_inside_quote, ref uint64_t quote_bits, ref uint64_t error_mask)
{
quote_bits = cmp_mask_against_input(@in, (uint8_t)'"');
quote_bits = quote_bits & ~odd_ends;
uint64_t quote_mask = compute_quote_mask(quote_bits);
quote_mask ^= prev_iter_inside_quote;
// All Unicode characters may be placed within the
// quotation marks, except for the characters that MUST be escaped:
// quotation mark, reverse solidus, and the control characters (U+0000
//through U+001F).
// https://tools.ietf.org/html/rfc8259
uint64_t unescaped = unsigned_lteq_against_input(@in, 0x1F);
error_mask |= quote_mask & unescaped;
// right shift of a signed value expected to be well-defined and standard
// compliant as of C++20,
// John Regher from Utah U. says this is fine code
prev_iter_inside_quote = (uint64_t)((int64_t)(quote_mask) >> 63);
return(quote_mask);
}
internal static void check_utf8(simd_input @in, utf8_checking_state state)
{
//TODO:
}
internal static JsonParseError find_structural_bits(uint8_t *buf, size_t len, ParsedJson pj)
{
if (len > pj.bytecapacity)
{
return(JsonParseError.CAPACITY);
}
uint32_t *base_ptr = pj.structural_indexes;
uint32_t @base = 0;
#if SIMDJSON_UTF8VALIDATE
utf8_checking_state state;
#endif
// we have padded the input out to 64 byte multiple with the remainder being
// zeros
// persistent state across loop
// does the last iteration end with an odd-length sequence of backslashes?
// either 0 or 1, but a 64-bit value
uint64_t prev_iter_ends_odd_backslash = 0UL;
// does the previous iteration end inside a double-quote pair?
uint64_t prev_iter_inside_quote = 0UL; // either all zeros or all ones
// does the previous iteration end on something that is a predecessor of a
// pseudo-structural character - i.e. whitespace or a structural character
// effectively the very first char is considered to follow "whitespace" for
// the
// purposes of pseudo-structural character detection so we initialize to 1
uint64_t prev_iter_ends_pseudo_pred = 1UL;
// structurals are persistent state across loop as we flatten them on the
// subsequent iteration into our array pointed to be base_ptr.
// This is harmless on the first iteration as structurals==0
// and is done for performance reasons; we can hide some of the latency of the
// expensive carryless multiply in the previous step with this work
uint64_t structurals = 0;
size_t lenminus64 = len < 64 ? 0 : len - 64;
size_t idx = 0;
uint64_t error_mask = 0; // for unescaped characters within strings (ASCII code points < 0x20)
for (; idx < lenminus64; idx += 64)
{
//__builtin_prefetch(buf + idx + 128);
simd_input @in = fill_input(buf + idx);
#if SIMDJSON_UTF8VALIDATE
check_utf8(in, state);
#endif
// detect odd sequences of backslashes
uint64_t odd_ends = find_odd_backslash_sequences(
@in, ref prev_iter_ends_odd_backslash);
// detect insides of quote pairs ("quote_mask") and also our quote_bits
// themselves
uint64_t quote_bits = 0;
uint64_t quote_mask = find_quote_mask_and_bits(
@in, odd_ends, ref prev_iter_inside_quote, ref quote_bits, ref error_mask);
// take the previous iterations structural bits, not our current iteration,
// and flatten
flatten_bits(base_ptr, ref @base, (uint32_t)idx, structurals);
uint64_t whitespace = 0;
find_whitespace_and_structurals(@in, ref whitespace, ref structurals);
// fixup structurals to reflect quotes and add pseudo-structural characters
structurals = finalize_structurals(structurals, whitespace, quote_mask,
quote_bits, ref prev_iter_ends_pseudo_pred);
}
////////////////
// we use a giant copy-paste which is ugly.
// but otherwise the string needs to be properly padded or else we
// risk invalidating the UTF-8 checks.
////////////
if (idx < len)
{
uint8_t *tmpbuf = stackalloc uint8_t[64];
memset(tmpbuf, 0x20, 64);
memcpy(tmpbuf, buf + idx, len - idx);
simd_input @in = fill_input(tmpbuf);
#if SIMDJSON_UTF8VALIDATE
check_utf8 <T>(in, state);
#endif
// detect odd sequences of backslashes
uint64_t odd_ends = find_odd_backslash_sequences(
@in, ref prev_iter_ends_odd_backslash);
// detect insides of quote pairs ("quote_mask") and also our quote_bits
// themselves
uint64_t quote_bits = 0;
uint64_t quote_mask = find_quote_mask_and_bits(
@in, odd_ends, ref prev_iter_inside_quote, ref quote_bits, ref error_mask);
// take the previous iterations structural bits, not our current iteration,
// and flatten
flatten_bits(base_ptr, ref @base, (uint)idx, structurals);
uint64_t whitespace = 0;
find_whitespace_and_structurals(@in, ref whitespace, ref structurals);
// fixup structurals to reflect quotes and add pseudo-strucural characters
structurals = finalize_structurals(structurals, whitespace, quote_mask,
quote_bits, ref prev_iter_ends_pseudo_pred);
idx += 64;
}
// is last string quote closed?
if (prev_iter_inside_quote != 0)
{
return(JsonParseError.UNCLOSED_STRING);
}
// finally, flatten out the remaining structurals from the last iteration
flatten_bits(base_ptr, ref @base, (uint)idx, structurals);
pj.n_structural_indexes = @base;
// a valid JSON file cannot have zero structural indexes - we should have
// found something
if (pj.n_structural_indexes == 0u)
{
return(JsonParseError.EMPTY);
}
if (base_ptr[pj.n_structural_indexes - 1] > len)
{
return(JsonParseError.UNEXPECTED_ERROR);
}
if (len != base_ptr[pj.n_structural_indexes - 1])
{
// the string might not be NULL terminated, but we add a virtual NULL ending
// character.
base_ptr[pj.n_structural_indexes++] = (uint)len;
}
// make it safe to dereference one beyond this array
base_ptr[pj.n_structural_indexes] = 0;
if (error_mask != 0)
{
return(JsonParseError.UNESCAPED_CHARS);
}
#if SIMDJSON_UTF8VALIDATE
return(check_utf8_errors(state));
#else
return(JsonParseError.SUCCESS);
#endif
}
internal static void find_whitespace_and_structurals(simd_input @in, ref uint64_t whitespace, ref uint64_t structurals)
{
if (Avx2.IsSupported)
{
Vector256 <byte> struct_offset = Vector256.Create((uint8_t)0xd4);
Vector256 <byte> struct_mask = Vector256.Create((uint8_t)32);
Vector256 <byte> lo_white = Avx2.CompareEqual(@in.lo,
Avx2.Shuffle(white_table_avx, @in.lo));
Vector256 <byte> hi_white = Avx2.CompareEqual(@in.hi,
Avx2.Shuffle(white_table_avx, @in.hi));
uint64_t ws_res_0 = (uint32_t)(Avx2.MoveMask(lo_white));
uint64_t ws_res_1 = (uint64_t)Avx2.MoveMask(hi_white);
whitespace = (ws_res_0 | (ws_res_1 << 32));
Vector256 <byte> lo_struct_r1 = Avx2.Add(struct_offset, @in.lo);
Vector256 <byte> hi_struct_r1 = Avx2.Add(struct_offset, @in.hi);
Vector256 <byte> lo_struct_r2 = Avx2.Or(@in.lo, struct_mask);
Vector256 <byte> hi_struct_r2 = Avx2.Or(@in.hi, struct_mask);
Vector256 <byte> lo_struct_r3 = Avx2.Shuffle(structural_table_avx, lo_struct_r1);
Vector256 <byte> hi_struct_r3 = Avx2.Shuffle(structural_table_avx, hi_struct_r1);
Vector256 <byte> lo_struct = Avx2.CompareEqual(lo_struct_r2, lo_struct_r3);
Vector256 <byte> hi_struct = Avx2.CompareEqual(hi_struct_r2, hi_struct_r3);
uint64_t structural_res_0 =
(uint32_t)(Avx2.MoveMask(lo_struct));
uint64_t structural_res_1 = (uint64_t)Avx2.MoveMask(hi_struct);
structurals = (structural_res_0 | (structural_res_1 << 32));
}
else
{
Vector128 <byte> struct_offset = Vector128.Create((byte)0xd4);
Vector128 <byte> struct_mask = Vector128.Create((byte)32);
Vector128 <byte> white0 = Sse2.CompareEqual(@in.v0,
Ssse3.Shuffle(white_table_sse, @in.v0));
Vector128 <byte> white1 = Sse2.CompareEqual(@in.v1,
Ssse3.Shuffle(white_table_sse, @in.v1));
Vector128 <byte> white2 = Sse2.CompareEqual(@in.v2,
Ssse3.Shuffle(white_table_sse, @in.v2));
Vector128 <byte> white3 = Sse2.CompareEqual(@in.v3,
Ssse3.Shuffle(white_table_sse, @in.v3));
uint64_t ws_res_0 = (uint64_t)Sse2.MoveMask(white0);
uint64_t ws_res_1 = (uint64_t)Sse2.MoveMask(white1);
uint64_t ws_res_2 = (uint64_t)Sse2.MoveMask(white2);
uint64_t ws_res_3 = (uint64_t)Sse2.MoveMask(white3);
whitespace = (ws_res_0 | (ws_res_1 << 16) | (ws_res_2 << 32) | (ws_res_3 << 48));
Vector128 <byte> struct1_r1 = Sse2.Add(struct_offset, @in.v0);
Vector128 <byte> struct2_r1 = Sse2.Add(struct_offset, @in.v1);
Vector128 <byte> struct3_r1 = Sse2.Add(struct_offset, @in.v2);
Vector128 <byte> struct4_r1 = Sse2.Add(struct_offset, @in.v3);
Vector128 <byte> struct1_r2 = Sse2.Or(@in.v0, struct_mask);
Vector128 <byte> struct2_r2 = Sse2.Or(@in.v1, struct_mask);
Vector128 <byte> struct3_r2 = Sse2.Or(@in.v2, struct_mask);
Vector128 <byte> struct4_r2 = Sse2.Or(@in.v3, struct_mask);
Vector128 <byte> struct1_r3 = Ssse3.Shuffle(structural_table_sse, struct1_r1);
Vector128 <byte> struct2_r3 = Ssse3.Shuffle(structural_table_sse, struct2_r1);
Vector128 <byte> struct3_r3 = Ssse3.Shuffle(structural_table_sse, struct3_r1);
Vector128 <byte> struct4_r3 = Ssse3.Shuffle(structural_table_sse, struct4_r1);
Vector128 <byte> struct1 = Sse2.CompareEqual(struct1_r2, struct1_r3);
Vector128 <byte> struct2 = Sse2.CompareEqual(struct2_r2, struct2_r3);
Vector128 <byte> struct3 = Sse2.CompareEqual(struct3_r2, struct3_r3);
Vector128 <byte> struct4 = Sse2.CompareEqual(struct4_r2, struct4_r3);
uint64_t structural_res_0 = (uint64_t)Sse2.MoveMask(struct1);
uint64_t structural_res_1 = (uint64_t)Sse2.MoveMask(struct2);
uint64_t structural_res_2 = (uint64_t)Sse2.MoveMask(struct3);
uint64_t structural_res_3 = (uint64_t)Sse2.MoveMask(struct4);
structurals = (structural_res_0 | (structural_res_1 << 16) | (structural_res_2 << 32) | (structural_res_3 << 48));
}
}