Update finalization

ogxd · Oct 1, 2023 · 3e62880 · 3e62880
1 parent 8d043d7
commit 3e62880
Showing 1 changed file with 31 additions and 33 deletions.
diff --git a/src/gxhash.rs b/src/gxhash.rs
@@ -47,23 +47,16 @@ mod platform_defs {
     }
 
     #[inline]
-    pub unsafe fn mix(hash: state) -> state {
+    pub unsafe fn finalize(hash: state) -> u32 {
         let salt = vcombine_s64(vcreate_s64(4860325414534694371), vcreate_s64(8120763769363581797));
         let keys = vmulq_s32(
             ReinterpretUnion { int64: salt }.int32,
             ReinterpretUnion { int8: hash }.int32);
         let a = vaeseq_u8(ReinterpretUnion { int8: hash }.uint8, vdupq_n_u8(0));
         let b = vaesmcq_u8(a);
         let c = veorq_u8(b, ReinterpretUnion{ int32: keys }.uint8);
-        ReinterpretUnion{ uint8: c }.int8
-    }
-
-    #[inline]
-    pub unsafe fn fold(hash: state) -> u32 {
-        // Bit-cast the int8x16_t to uint32x4_t
-        let vec_u32: uint32x4_t = ReinterpretUnion { int8: hash }.uint32;
-        // Get the first u32 value from the vector
-        vgetq_lane_u32(vec_u32, 3)
+        let p = &ReinterpretUnion{ uint8: c }.int8 as *const state as *const u32;
+        *p
     }
 }
 
@@ -93,8 +86,10 @@ mod platform_defs {
     #[inline]
     pub unsafe fn get_partial(p: *const state, len: isize) -> state {
         const MASK: [u8; size_of::<state>() * 2] = [
-            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
-            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 ];
+            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 ];
 
         // Safety check
         if check_same_page(p) { // false {//
@@ -131,22 +126,26 @@ mod platform_defs {
     }
 
     #[inline]
-    pub unsafe fn mix(hash: state) -> state {
-        let salt = _mm256_set_epi64x(-4860325414534694371, 8120763769363581797, -4860325414534694371, 8120763769363581797);
-        //let keys = _mm256_mul_epu32(salt, hash);
-        _mm256_aesenc_epi128(hash, salt)
-    }
-
-    #[inline]
-    pub unsafe fn fold(hash: state) -> u32 {
-        let p = &hash as *const state as *const u32;
-        *p  ^ *p.offset(1)
-            ^ *p.offset(2)
-            ^ *p.offset(3)
-            ^ *p.offset(4)
-            ^ *p.offset(5)
-            ^ *p.offset(6)
-            ^ *p.offset(7)
+    #[allow(overflowing_literals)]
+    pub unsafe fn finalize(hash: state) -> u32 {
+        // Xor 256 state into 128 bit state for AES
+        let lower = _mm256_castsi256_si128(hash);
+        let upper = _mm256_extracti128_si256(hash, 1);
+        let mut hash = _mm_xor_si128(lower, upper);
+
+        // Hardcoded AES keys
+        let salt1 = _mm_set_epi32(0x713B01D0, 0x8F2F35DB, 0xAF163956, 0x85459F85);
+        let salt2 = _mm_set_epi32(0x1DE09647, 0x92CFA39C, 0x3DD99ACA, 0xB89C054F);
+        let salt3 = _mm_set_epi32(0xC78B122B, 0x5544B1B7, 0x689D2B7D, 0xD0012E32);
+
+        // 3 rounds of AES
+        hash = _mm_aesenc_si128(hash, salt1);
+        hash = _mm_aesenc_si128(hash, salt2);
+        hash = _mm_aesenclast_si128(hash, salt3);
+
+        // Truncate to output hash size
+        let p = &hash as *const __m128i as *const u32;
+        *p
     }
 }
 
@@ -157,8 +156,7 @@ pub use platform_defs::*;
 #[cfg(test)]
 pub static mut COUNTERS : Vec<usize> = vec![];
 
-#[inline]
-//#[inline(never)]
+#[inline] // To be disabled when profiling
 pub fn gxhash(input: &[u8]) -> u32 {
     unsafe {
         const VECTOR_SIZE: isize = std::mem::size_of::<state>() as isize;
@@ -241,7 +239,7 @@ pub fn gxhash(input: &[u8]) -> u32 {
             hash_vector = compress(hash_vector, partial_vector);
         }
 
-        fold(mix(hash_vector))
+        finalize(hash_vector)
     }
 }
 
@@ -271,10 +269,10 @@ mod tests {
     }
 
     #[test]
-    fn hash_of_zero_is_zero() {
+    fn hash_of_zero_is_not_zero() {
         let zero_bytes = [0u8; 1200];
 
         let hash = gxhash(&zero_bytes);
-        assert_eq!(0, hash);
+        assert_ne!(0, hash);
     }
 }