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#[cfg(target_arch = "x86")]
use std::arch::x86 as arch;
#[cfg(target_arch = "x86_64")]
use std::arch::x86_64 as arch;
use crate::{
Deserializer, Result, SillyWrapper,
error::ErrorType,
safer_unchecked::GetSaferUnchecked,
stringparse::{ESCAPE_MAP, handle_unicode_codepoint},
};
use arch::{
__m128i, _mm_cmpeq_epi8, _mm_loadu_si128, _mm_movemask_epi8, _mm_set1_epi8, _mm_storeu_si128,
};
#[target_feature(enable = "sse4.2")]
#[allow(clippy::if_not_else, clippy::cast_possible_wrap)]
#[cfg_attr(not(feature = "no-inline"), inline)]
pub(crate) unsafe fn parse_str<'invoke, 'de>(
input: SillyWrapper<'de>,
data: &'invoke [u8],
buffer: &'invoke mut [u8],
mut idx: usize,
) -> Result<&'de str> {
unsafe {
use ErrorType::{InvalidEscape, InvalidUnicodeCodepoint};
let input = input.input;
// Add 1 to skip the initial "
idx += 1;
// we include the terminal '"' so we know where to end
// This is safe since we check sub's length in the range access above and only
// create sub sliced form sub to `sub.len()`.
let src: &[u8] = data.get_kinda_unchecked(idx..);
let mut src_i: usize = 0;
let mut len = src_i;
loop {
// _mm_loadu_si128 does not require alignment
#[allow(clippy::cast_ptr_alignment)]
let v: __m128i = _mm_loadu_si128(src.as_ptr().add(src_i).cast::<arch::__m128i>());
// store to dest unconditionally - we can overwrite the bits we don't like
// later
let bs_bits: u32 = static_cast_u32!(_mm_movemask_epi8(_mm_cmpeq_epi8(
v,
_mm_set1_epi8(b'\\' as i8)
)));
let quote_mask = _mm_cmpeq_epi8(v, _mm_set1_epi8(b'"' as i8));
let quote_bits = static_cast_u32!(_mm_movemask_epi8(quote_mask));
if (bs_bits.wrapping_sub(1) & quote_bits) != 0 {
// we encountered quotes first. Move dst to point to quotes and exit
// find out where the quote is...
let quote_dist: u32 = quote_bits.trailing_zeros();
///////////////////////
// Above, check for overflow in case someone has a crazy string (>=4GB?)
// But only add the overflow check when the document itself exceeds 4GB
// Currently unneeded because we refuse to parse docs larger or equal to 4GB.
////////////////////////
// we advance the point, accounting for the fact that we have a NULl termination
len += quote_dist as usize;
let v =
std::str::from_utf8_unchecked(std::slice::from_raw_parts(input.add(idx), len));
return Ok(v);
// we compare the pointers since we care if they are 'at the same spot'
// not if they are the same value
}
if (quote_bits.wrapping_sub(1) & bs_bits) == 0 {
// they are the same. Since they can't co-occur, it means we encountered
// neither.
src_i += 16;
len += 16;
} else {
// Move to the 'bad' character
let bs_dist: u32 = bs_bits.trailing_zeros();
len += bs_dist as usize;
src_i += bs_dist as usize;
break;
}
}
let mut dst_i: usize = 0;
// To be more conform with upstream
loop {
// _mm_loadu_si128 does not require alignment
#[allow(clippy::cast_ptr_alignment)]
let v: __m128i = _mm_loadu_si128(src.as_ptr().add(src_i).cast::<arch::__m128i>());
// _mm_storeu_si128 does not require alignment
#[allow(clippy::cast_ptr_alignment)]
_mm_storeu_si128(buffer.as_mut_ptr().add(dst_i).cast::<arch::__m128i>(), v);
// store to dest unconditionally - we can overwrite the bits we don't like
// later
let bs_bits: u32 = static_cast_u32!(_mm_movemask_epi8(_mm_cmpeq_epi8(
v,
_mm_set1_epi8(b'\\' as i8)
)));
let quote_mask = _mm_cmpeq_epi8(v, _mm_set1_epi8(b'"' as i8));
let quote_bits = static_cast_u32!(_mm_movemask_epi8(quote_mask));
if (bs_bits.wrapping_sub(1) & quote_bits) != 0 {
// we encountered quotes first. Move dst to point to quotes and exit
// find out where the quote is...
let quote_dist: u32 = quote_bits.trailing_zeros();
///////////////////////
// Above, check for overflow in case someone has a crazy string (>=4GB?)
// But only add the overflow check when the document itself exceeds 4GB
// Currently unneeded because we refuse to parse docs larger or equal to 4GB.
////////////////////////
// we advance the point, accounting for the fact that we have a NULl termination
dst_i += quote_dist as usize;
input
.add(idx + len)
.copy_from_nonoverlapping(buffer.as_ptr(), dst_i);
let v = std::str::from_utf8_unchecked(std::slice::from_raw_parts(
input.add(idx),
len + dst_i,
));
return Ok(v);
// we compare the pointers since we care if they are 'at the same spot'
// not if they are the same value
}
if (quote_bits.wrapping_sub(1) & bs_bits) != 0 {
// find out where the backspace is
let bs_dist: u32 = bs_bits.trailing_zeros();
let escape_char: u8 = *src.get_kinda_unchecked(src_i + bs_dist as usize + 1);
// we encountered backslash first. Handle backslash
if escape_char == b'u' {
// move src/dst up to the start; they will be further adjusted
// within the unicode codepoint handling code.
src_i += bs_dist as usize;
dst_i += bs_dist as usize;
let Ok((o, s)) = handle_unicode_codepoint(
src.get_kinda_unchecked(src_i..),
buffer.get_kinda_unchecked_mut(dst_i..),
) else {
return Err(Deserializer::error_c(src_i, 'u', InvalidUnicodeCodepoint));
};
if o == 0 {
return Err(Deserializer::error_c(src_i, 'u', InvalidUnicodeCodepoint));
}
// We moved o steps forward at the destination and 6 on the source
src_i += s;
dst_i += o;
} else {
// simple 1:1 conversion. Will eat bs_dist+2 characters in input and
// write bs_dist+1 characters to output
// note this may reach beyond the part of the buffer we've actually
// seen. I think this is ok
let escape_result: u8 = *ESCAPE_MAP.get_kinda_unchecked(escape_char as usize);
if escape_result == 0 {
return Err(Deserializer::error_c(
src_i,
escape_char as char,
InvalidEscape,
));
}
*buffer.get_kinda_unchecked_mut(dst_i + bs_dist as usize) = escape_result;
src_i += bs_dist as usize + 2;
dst_i += bs_dist as usize + 1;
}
} else {
// they are the same. Since they can't co-occur, it means we encountered
// neither.
src_i += 16;
dst_i += 16;
}
}
}
}