# avx2.rs - source
Source of the Rust file `/home/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/httparse-1.3.6/src/simd/avx2.rs`.
Keywords: rust, rustlang, rust-lang

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    use ::iter::Bytes;

    pub enum Scan {
        /// Returned when an implementation finds a noteworthy token.
        Found,
        /// Returned when an implementation couldn't keep running because the input was too short.
        TooShort,
    }

    pub unsafe fn parse_uri_batch_32<'a>(bytes: &mut Bytes<'a>) -> Scan {
        while bytes.as_ref().len() >= 32 {
            let advance = match_url_char_32_avx(bytes.as_ref());
            bytes.advance(advance);

            if advance != 32 {
                return Scan::Found;
            }
        }
        Scan::TooShort
    }

    #[cfg(target_arch = "x86_64")]
    #[target_feature(enable = "avx2")]
    #[inline]
    #[allow(non_snake_case, overflowing_literals)]
    unsafe fn match_url_char_32_avx(buf: &[u8]) -> usize {
        debug_assert!(buf.len() >= 32);

        /*
        #[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: __m256i = _mm256_set1_epi8(0x0f);

        // See comment in sse42::match_url_char_16_sse.

        let URI: __m256i = _mm256_setr_epi8(
            0xf8, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc,
            0xfc, 0xfc, 0xfc, 0xfc, 0xf4, 0xfc, 0xf4, 0x7c,
            0xf8, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc, 0xfc,
            0xfc, 0xfc, 0xfc, 0xfc, 0xf4, 0xfc, 0xf4, 0x7c,
        );
        let ARF: __m256i = _mm256_setr_epi8(
            0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80,
            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80,
            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        );

        let data = _mm256_lddqu_si256(ptr as *const _);
        let rbms = _mm256_shuffle_epi8(URI, data);
        let cols = _mm256_and_si256(LSH, _mm256_srli_epi16(data, 4));
        let bits = _mm256_and_si256(_mm256_shuffle_epi8(ARF, cols), rbms);

        let v = _mm256_cmpeq_epi8(bits, _mm256_setzero_si256());
        let r = 0xffffffff_00000000 | _mm256_movemask_epi8(v) as u64;

        _tzcnt_u64(r) as usize
    }

    #[cfg(target_arch = "x86")]
    unsafe fn match_url_char_32_avx(_: &[u8]) -> usize {
        unreachable!("AVX2 detection should be disabled for x86");
    }

    pub unsafe fn match_header_value_batch_32(bytes: &mut Bytes) -> Scan {
        while bytes.as_ref().len() >= 32 {
            let advance = match_header_value_char_32_avx(bytes.as_ref());
            bytes.advance(advance);

            if advance != 32 {
                return Scan::Found;
            }
        }
        Scan::TooShort
    }

    #[cfg(target_arch = "x86_64")]
    #[target_feature(enable = "avx2")]
    #[inline]
    #[allow(non_snake_case)]
    unsafe fn match_header_value_char_32_avx(buf: &[u8]) -> usize {
        debug_assert!(buf.len() >= 32);

        /*
        #[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: __m256i = _mm256_set1_epi8(0x09);
        let DEL: __m256i = _mm256_set1_epi8(0x7f);
        let LOW: __m256i = _mm256_set1_epi8(0x1f);

        let dat = _mm256_lddqu_si256(ptr as *const _);
        let low = _mm256_cmpgt_epi8(dat, LOW);
        let tab = _mm256_cmpeq_epi8(dat, TAB);
        let del = _mm256_cmpeq_epi8(dat, DEL);
        let bit = _mm256_andnot_si256(del, _mm256_or_si256(low, tab));
        let rev = _mm256_cmpeq_epi8(bit, _mm256_setzero_si256());
        let res = 0xffffffff_00000000 | _mm256_movemask_epi8(rev) as u64;

        _tzcnt_u64(res) as usize
    }

    #[cfg(target_arch = "x86")]
    unsafe fn match_header_value_char_32_avx(_: &[u8]) -> usize {
        unreachable!("AVX2 detection should be disabled for x86");
    }

    #[test]
    fn avx2_code_matches_uri_chars_table() {
        match super::detect() {
            super::AVX_2 | super::AVX_2_AND_SSE_42 => {},
            _ => return,
        }

        unsafe {
            assert!(byte_is_allowed(b'_'));

            for (b, allowed) in ::URI_MAP.iter().cloned().enumerate() {
                assert_eq!(
                    byte_is_allowed(b as u8), allowed,
                    "byte_is_allowed({:?}) should be {:?}", b, allowed,
                );
            }
        }
    }

    #[cfg(test)]
    unsafe fn byte_is_allowed(byte: u8) -> bool {
        let slice = [
            b'_', b'_', b'_', b'_',
            b'_', b'_', b'_', b'_',
            b'_', b'_', b'_', b'_',
            b'_', b'_', b'_', b'_',
            b'_', b'_', b'_', b'_',
            b'_', b'_', b'_', b'_',
            b'_', b'_', byte, b'_',
            b'_', b'_', b'_', b'_',
        ];
        let mut bytes = Bytes::new(&slice);

        parse_uri_batch_32(&mut bytes);

        match bytes.pos() {
            32 => true,
            26 => false,
            _ => unreachable!(),
        }
    }