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|
use crate::iter::Bytes;
pub unsafe fn parse_uri_batch_16(bytes: &mut Bytes) {
while bytes.as_ref().len() >= 16 {
let advance = match_url_char_16_sse(bytes.as_ref());
bytes.advance(advance);
if advance != 16 {
break;
}
}
}
#[target_feature(enable = "sse4.2")]
#[allow(non_snake_case, overflowing_literals)]
unsafe fn match_url_char_16_sse(buf: &[u8]) -> usize {
debug_assert!(buf.len() >= 16);
#[cfg(target_arch = "x86")]
use core::arch::x86::*;
#[cfg(target_arch = "x86_64")]
use core::arch::x86_64::*;
let ptr = buf.as_ptr();
let LSH: __m128i = _mm_set1_epi8(0x0f);
// The first 0xf8 corresponds to the 8 first rows of the first column
// of URI_MAP in the crate's root, with the first row corresponding to bit 0
// and the 8th row corresponding to bit 7.
// The 8 first rows give 0 0 0 1 1 1 1 1, which is 0xf8 (with least
// significant digit on the left).
//
// Another example just to drive the point home: in column 15, '>' is
// rejected, so the values are 0 0 1 0 1 1 1 1, which gives us 0xf4.
//
// Thanks to Vlad Krasnov for explaining this stuff to us mere mortals in
// a GitHub comment!
//
// https://github.com/seanmonstar/httparse/pull/89#issuecomment-807039219
let URI: __m128i = _mm_setr_epi8(
0xf8, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc,
0xfc, 0xfc, 0xfc, 0xfc, 0xf4, 0xfc, 0xf4, 0x7c,
);
let ARF: __m128i = _mm_setr_epi8(
0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
);
let data = _mm_lddqu_si128(ptr as *const _);
let rbms = _mm_shuffle_epi8(URI, data);
let cols = _mm_and_si128(LSH, _mm_srli_epi16(data, 4));
let bits = _mm_and_si128(_mm_shuffle_epi8(ARF, cols), rbms);
let v = _mm_cmpeq_epi8(bits, _mm_setzero_si128());
let r = 0xffff_0000 | _mm_movemask_epi8(v) as u32;
_tzcnt_u32(r) as usize
}
pub unsafe fn match_header_value_batch_16(bytes: &mut Bytes) {
while bytes.as_ref().len() >= 16 {
let advance = match_header_value_char_16_sse(bytes.as_ref());
bytes.advance(advance);
if advance != 16 {
break;
}
}
}
#[target_feature(enable = "sse4.2")]
#[allow(non_snake_case)]
unsafe fn match_header_value_char_16_sse(buf: &[u8]) -> usize {
debug_assert!(buf.len() >= 16);
#[cfg(target_arch = "x86")]
use core::arch::x86::*;
#[cfg(target_arch = "x86_64")]
use core::arch::x86_64::*;
let ptr = buf.as_ptr();
// %x09 %x20-%x7e %x80-%xff
let TAB: __m128i = _mm_set1_epi8(0x09);
let DEL: __m128i = _mm_set1_epi8(0x7f);
let LOW: __m128i = _mm_set1_epi8(0x20);
let dat = _mm_lddqu_si128(ptr as *const _);
// unsigned comparison dat >= LOW
let low = _mm_cmpeq_epi8(_mm_max_epu8(dat, LOW), dat);
let tab = _mm_cmpeq_epi8(dat, TAB);
let del = _mm_cmpeq_epi8(dat, DEL);
let bit = _mm_andnot_si128(del, _mm_or_si128(low, tab));
let rev = _mm_cmpeq_epi8(bit, _mm_setzero_si128());
let res = 0xffff_0000 | _mm_movemask_epi8(rev) as u32;
_tzcnt_u32(res) as usize
}
#[test]
fn sse_code_matches_uri_chars_table() {
match super::detect() {
super::SSE_42 | super::AVX_2_AND_SSE_42 => {},
_ => return,
}
unsafe {
assert!(byte_is_allowed(b'_', parse_uri_batch_16));
for (b, allowed) in crate::URI_MAP.iter().cloned().enumerate() {
assert_eq!(
byte_is_allowed(b as u8, parse_uri_batch_16), allowed,
"byte_is_allowed({:?}) should be {:?}", b, allowed,
);
}
}
}
#[test]
fn sse_code_matches_header_value_chars_table() {
match super::detect() {
super::SSE_42 | super::AVX_2_AND_SSE_42 => {},
_ => return,
}
unsafe {
assert!(byte_is_allowed(b'_', match_header_value_batch_16));
for (b, allowed) in crate::HEADER_VALUE_MAP.iter().cloned().enumerate() {
assert_eq!(
byte_is_allowed(b as u8, match_header_value_batch_16), allowed,
"byte_is_allowed({:?}) should be {:?}", b, allowed,
);
}
}
}
#[cfg(test)]
unsafe fn byte_is_allowed(byte: u8, f: unsafe fn(bytes: &mut Bytes<'_>)) -> bool {
let slice = [
b'_', b'_', b'_', b'_',
b'_', b'_', b'_', b'_',
b'_', b'_', byte, b'_',
b'_', b'_', b'_', b'_',
];
let mut bytes = Bytes::new(&slice);
f(&mut bytes);
match bytes.pos() {
16 => true,
10 => false,
_ => unreachable!(),
}
}
|
