Add NEON encode and check

src/decode.rs

@@ -1,5 +1,7 @@
 // avx2 decode modified from https://github.com/zbjornson/fast-hex/blob/master/src/hex.cc
 
+#[cfg(target_arch = "aarch64")]
+use core::arch::aarch64::*;
 #[cfg(target_arch = "x86")]
 use core::arch::x86::*;
 #[cfg(target_arch = "x86_64")]
@@ -113,7 +115,15 @@ pub fn hex_check_with_case(src: &[u8], check_case: CheckCase) -> bool {
         }
     }
 
-    #[cfg(not(any(target_arch = "x86", target_arch = "x86_64")))]
+    #[cfg(target_arch = "aarch64")]
+    {
+        match crate::vectorization_support() {
+            crate::Vectorization::Neon => unsafe { hex_check_neon_with_case(src, check_case) },
+            crate::Vectorization::None => hex_check_fallback_with_case(src, check_case),
+        }
+    }
+
+    #[cfg(not(any(target_arch = "x86", target_arch = "x86_64", target_arch = "aarch64")))]
     hex_check_fallback_with_case(src, check_case)
 }
 
@@ -210,6 +220,72 @@ pub unsafe fn hex_check_sse_with_case(mut src: &[u8], check_case: CheckCase) ->
     hex_check_fallback_with_case(src, check_case)
 }
 
+#[target_feature(enable = "neon")]
+#[cfg(target_arch = "aarch64")]
+pub unsafe fn hex_check_neon(src: &[u8]) -> bool {
+    hex_check_neon_with_case(src, CheckCase::None)
+}
+
+#[target_feature(enable = "neon")]
+#[cfg(target_arch = "aarch64")]
+pub unsafe fn hex_check_neon_with_case(mut src: &[u8], check_case: CheckCase) -> bool {
+    let ascii_zero = vdupq_n_u8(b'0' - 1);
+    let ascii_nine = vdupq_n_u8(b'9' + 1);
+    let ascii_ua = vdupq_n_u8(b'A' - 1);
+    let ascii_uf = vdupq_n_u8(b'F' + 1);
+    let ascii_la = vdupq_n_u8(b'a' - 1);
+    let ascii_lf = vdupq_n_u8(b'f' + 1);
+
+    while src.len() >= 16 {
+        let unchecked = vld1q_u8(src.as_ptr() as *const _);
+
+        let gt0 = vcgtq_u8(unchecked, ascii_zero);
+        let lt9 = vcltq_u8(unchecked, ascii_nine);
+        let valid_digit = vandq_u8(gt0, lt9);
+
+        let (valid_la_lf, valid_ua_uf) = match check_case {
+            CheckCase::None => {
+                let gtua = vcgtq_u8(unchecked, ascii_ua);
+                let ltuf = vcltq_u8(unchecked, ascii_uf);
+
+                let gtla = vcgtq_u8(unchecked, ascii_la);
+                let ltlf = vcltq_u8(unchecked, ascii_lf);
+
+                (Some(vandq_u8(gtla, ltlf)), Some(vandq_u8(gtua, ltuf)))
+            }
+            CheckCase::Lower => {
+                let gtla = vcgtq_u8(unchecked, ascii_la);
+                let ltlf = vcltq_u8(unchecked, ascii_lf);
+
+                (Some(vandq_u8(gtla, ltlf)), None)
+            }
+            CheckCase::Upper => {
+                let gtua = vcgtq_u8(unchecked, ascii_ua);
+                let ltuf = vcltq_u8(unchecked, ascii_uf);
+
+                (None, Some(vandq_u8(gtua, ltuf)))
+            }
+        };
+
+        let valid_letter = match (valid_la_lf, valid_ua_uf) {
+            (Some(valid_lower), Some(valid_upper)) => vorrq_u8(valid_lower, valid_upper),
+            (Some(valid_lower), None) => valid_lower,
+            (None, Some(valid_upper)) => valid_upper,
+            _ => unreachable!(),
+        };
+
+        let ret = vminvq_u8(vorrq_u8(valid_digit, valid_letter));
+
+        if ret == 0 {
+            return false;
+        }
+
+        src = &src[16..];
+    }
+
+    hex_check_fallback_with_case(src, check_case)
+}
+
 /// Hex decode src into dst.
 /// The length of src must be even, and it's allowed to decode a zero length src.
 /// The length of dst must be at least src.len() / 2.
@@ -454,15 +530,25 @@ mod tests {
     }
 }
 
-#[cfg(all(test, any(target_arch = "x86", target_arch = "x86_64")))]
-mod test_sse {
+#[cfg(all(
+    test,
+    any(target_arch = "x86", target_arch = "x86_64", target_arch = "aarch64")
+))]
+mod test_simd {
     use crate::decode::{
-        hex_check, hex_check_fallback, hex_check_fallback_with_case, hex_check_sse,
-        hex_check_sse_with_case, hex_check_with_case, hex_decode, hex_decode_unchecked,
-        hex_decode_with_case, CheckCase,
+        hex_check, hex_check_fallback, hex_check_fallback_with_case, hex_check_with_case,
+        hex_decode, hex_decode_unchecked, hex_decode_with_case, CheckCase,
     };
+    #[cfg(target_arch = "aarch64")]
+    use crate::decode::{hex_check_neon, hex_check_neon_with_case};
+    #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
+    use crate::decode::{hex_check_sse, hex_check_sse_with_case};
+    #[cfg(target_arch = "aarch64")]
+    use std::arch::is_aarch64_feature_detected;
+
     use proptest::proptest;
 
+    #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
     fn _test_check_sse_with_case(s: &String, check_case: CheckCase, expect_result: bool) {
         if is_x86_feature_detected!("sse4.1") {
             assert_eq!(
@@ -472,12 +558,14 @@ mod test_sse {
         }
     }
 
+    #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
     fn _test_check_sse_true(s: &String) {
         if is_x86_feature_detected!("sse4.1") {
             assert!(unsafe { hex_check_sse(s.as_bytes()) });
         }
     }
 
+    #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
     proptest! {
     #[test]
     fn test_check_sse_true(ref s in "([0-9a-fA-F][0-9a-fA-F])+") {
@@ -504,12 +592,13 @@ mod test_sse {
         }
     }
 
+    #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
     fn _test_check_sse_false(s: &String) {
         if is_x86_feature_detected!("sse4.1") {
             assert!(!unsafe { hex_check_sse(s.as_bytes()) });
         }
     }
-
+    #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
     proptest! {
         #[test]
         fn test_check_sse_false(ref s in ".{16}[^0-9a-fA-F]+") {
@@ -520,6 +609,67 @@ mod test_sse {
         }
     }
 
+    #[cfg(target_arch = "aarch64")]
+    fn _test_check_neon_with_case(s: &String, check_case: CheckCase, expect_result: bool) {
+        if is_aarch64_feature_detected!("neon") {
+            assert_eq!(
+                unsafe { hex_check_neon_with_case(s.as_bytes(), check_case) },
+                expect_result
+            )
+        }
+    }
+
+    #[cfg(target_arch = "aarch64")]
+    fn _test_check_neon_true(s: &String) {
+        if is_aarch64_feature_detected!("neon") {
+            assert!(unsafe { hex_check_neon(s.as_bytes()) });
+        }
+    }
+
+    #[cfg(target_arch = "aarch64")]
+    proptest! {
+    #[test]
+    fn test_check_neon_true(ref s in "([0-9a-fA-F][0-9a-fA-F])+") {
+            _test_check_neon_true(s);
+            _test_check_neon_with_case(s, CheckCase::None, true);
+            match (s.contains(char::is_lowercase), s.contains(char::is_uppercase)){
+                (true, true) => {
+                    _test_check_neon_with_case(s, CheckCase::Lower, false);
+                    _test_check_neon_with_case(s, CheckCase::Upper, false);
+                },
+                (true, false) => {
+                    _test_check_neon_with_case(s, CheckCase::Lower, true);
+                    _test_check_neon_with_case(s, CheckCase::Upper, false);
+                },
+                (false, true) => {
+                    _test_check_neon_with_case(s, CheckCase::Lower, false);
+                    _test_check_neon_with_case(s, CheckCase::Upper, true);
+                },
+                (false, false) => {
+                    _test_check_neon_with_case(s, CheckCase::Lower, true);
+                    _test_check_neon_with_case(s, CheckCase::Upper, true);
+                }
+            }
+        }
+    }
+
+    #[cfg(target_arch = "aarch64")]
+    fn _test_check_neon_false(s: &String) {
+        if is_aarch64_feature_detected!("neon") {
+            assert!(!unsafe { hex_check_neon(s.as_bytes()) });
+        }
+    }
+    #[cfg(target_arch = "aarch64")]
+    proptest! {
+        #[test]
+        fn test_check_neon_false(ref s in ".{16}[^0-9a-fA-F]+") {
+            _test_check_neon_false(s);
+            _test_check_neon_with_case(s, CheckCase::None, false);
+            _test_check_neon_with_case(s, CheckCase::Lower, false);
+            _test_check_neon_with_case(s, CheckCase::Upper, false);
+        }
+    }
+
     #[test]
     fn test_decode_zero_length_src_should_not_be_ok() {
         let src = b"";
@@ -535,11 +685,18 @@ mod test_sse {
         assert!(hex_check_fallback(src));
         assert!(hex_check_fallback_with_case(src, CheckCase::None));
 
+        #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
         if is_x86_feature_detected!("sse4.1") {
             assert!(unsafe { hex_check_sse_with_case(src, CheckCase::None) });
             assert!(unsafe { hex_check_sse(src) });
         }
 
+        #[cfg(target_arch = "aarch64")]
+        if is_aarch64_feature_detected!("neon") {
+            assert!(unsafe { hex_check_neon_with_case(src, CheckCase::None) });
+            assert!(unsafe { hex_check_neon(src) });
+        }
+
         // this function have no return value, so we just execute it and expect no panic
         hex_decode_unchecked(src, &mut dst);
     }

src/encode.rs

@@ -3,6 +3,9 @@ use core::arch::x86::*;
 #[cfg(target_arch = "x86_64")]
 use core::arch::x86_64::*;
 
+#[cfg(target_arch = "aarch64")]
+use core::arch::aarch64::*;
+
 #[cfg(feature = "alloc")]
 use alloc::{string::String, vec};
 
@@ -102,7 +105,16 @@ pub fn hex_encode_custom<'a>(
         // Safety: We just wrote valid utf8 hex string into the dst
         return Ok(unsafe { mut_str(dst) });
     }
-    #[cfg(not(any(target_arch = "x86", target_arch = "x86_64")))]
+    #[cfg(target_arch = "aarch64")]
+    {
+        match crate::vectorization_support() {
+            crate::Vectorization::Neon => unsafe { hex_encode_neon(src, dst, upper_case) },
+            crate::Vectorization::None => hex_encode_custom_case_fallback(src, dst, upper_case),
+        }
+        // Safety: We just wrote valid utf8 hex string into the dst
+        return Ok(unsafe { mut_str(dst) });
+    }
+    #[cfg(not(any(target_arch = "x86", target_arch = "x86_64", target_arch = "aarch64")))]
     {
         hex_encode_custom_case_fallback(src, dst, upper_case);
         // Saftey: We just wrote valid utf8 hex string into the dst
@@ -215,6 +227,49 @@ unsafe fn hex_encode_sse41(mut src: &[u8], dst: &mut [u8], upper_case: bool) {
     hex_encode_custom_case_fallback(src, &mut dst[i * 2..], upper_case);
 }
 
+#[target_feature(enable = "neon")]
+#[cfg(target_arch = "aarch64")]
+unsafe fn hex_encode_neon(mut src: &[u8], dst: &mut [u8], upper_case: bool) {
+    let ascii_zero = vdupq_n_u8(b'0');
+    let nines = vdupq_n_u8(9);
+    let ascii_a = if upper_case {
+        vdupq_n_u8(b'A' - 9 - 1)
+    } else {
+        vdupq_n_u8(b'a' - 9 - 1)
+    };
+    let and4bits = vdupq_n_u8(0xf);
+
+    let mut i = 0_isize;
+
+    while src.len() >= 16 {
+        let invec = vld1q_u8(src.as_ptr() as *const _);
+
+        let masked1 = vandq_u8(invec, and4bits);
+        let masked2 = vandq_u8(vshrq_n_u8::<4>(invec), and4bits);
+
+        // return 0xff corresponding to the elements > 9, or 0x00 otherwise
+        let cmpmask1 = vcgtq_u8(masked1, nines);
+        let cmpmask2 = vcgtq_u8(masked2, nines);
+
+        // add '0' or the offset depending on the masks
+        let masked1 = vaddq_u8(masked1, vbslq_u8(cmpmask1, ascii_a, ascii_zero));
+        let masked2 = vaddq_u8(masked2, vbslq_u8(cmpmask2, ascii_a, ascii_zero));
+
+        // interleave masked1 and masked2 bytes
+        let res1 = vzip1q_u8(masked2, masked1);
+        let res2 = vzip2q_u8(masked2, masked1);
+
+        vst1q_u8(dst.as_mut_ptr().offset(i * 2) as *mut _, res1);
+        vst1q_u8(dst.as_mut_ptr().offset(i * 2 + 16) as *mut _, res2);
+
+        src = &src[16..];
+        i += 16;
+    }
+
+    let i = i as usize;
+    hex_encode_custom_case_fallback(src, &mut dst[i * 2..], upper_case);
+}
+
 #[inline]
 fn hex_lower(byte: u8) -> u8 {
     TABLE_LOWER[byte as usize]