From 0ce1c780126d75ce89b1e23ac9e632c9973391b2 Mon Sep 17 00:00:00 2001
From: Rui Ueyama <ruiu@cs.stanford.edu>
Date: Sat, 11 May 2024 16:50:42 +0900
Subject: [PATCH] Refactor

---
 common/siphash.cc | 47 ++++++++++++++++++++++++-----------------------
 1 file changed, 24 insertions(+), 23 deletions(-)

diff --git a/common/siphash.cc b/common/siphash.cc
index 84c28b73ae..a7b636c845 100644
--- a/common/siphash.cc
+++ b/common/siphash.cc
@@ -10,32 +10,33 @@
 // than SHA256 or Blake3.
 //
 // Our implementation always outputs a 128 bit hash value.
+//
+// Here is the reference implementation:
+//   https://github.com/veorq/SipHash/blob/master/siphash.c
 
 #include "common.h"
 
 namespace mold {
 
 #define ROUND                                   \
-  do {                                          \
-    v0 += v1;                                   \
-    v1 = std::rotl(v1, 13);                     \
-    v1 ^= v0;                                   \
-    v0 = std::rotl(v0, 32);                     \
-    v2 += v3;                                   \
-    v3 = std::rotl(v3, 16);                     \
-    v3 ^= v2;                                   \
-    v0 += v3;                                   \
-    v3 = std::rotl(v3, 21);                     \
-    v3 ^= v0;                                   \
-    v2 += v1;                                   \
-    v1 = std::rotl(v1, 17);                     \
-    v1 ^= v2;                                   \
-    v2 = std::rotl(v2, 32);                     \
-  } while (0)
+  v0 += v1;                                     \
+  v1 = std::rotl(v1, 13);                       \
+  v1 ^= v0;                                     \
+  v0 = std::rotl(v0, 32);                       \
+  v2 += v3;                                     \
+  v3 = std::rotl(v3, 16);                       \
+  v3 ^= v2;                                     \
+  v0 += v3;                                     \
+  v3 = std::rotl(v3, 21);                       \
+  v3 ^= v0;                                     \
+  v2 += v1;                                     \
+  v1 = std::rotl(v1, 17);                       \
+  v1 ^= v2;                                     \
+  v2 = std::rotl(v2, 32)
 
 // SipHash-1-3
-#define C_ROUND ROUND
-#define D_ROUND for (i64 i = 0; i < 3; i++) ROUND
+#define C_ROUNDS ROUND
+#define D_ROUNDS ROUND; ROUND; ROUND
 
 SipHash::SipHash(u8 *key) {
   u64 k0 = *(ul64 *)key;
@@ -61,7 +62,7 @@ void SipHash::update(u8 *msg, i64 msglen) {
 
     u64 m = *(ul64 *)buf;
     v3 ^= m;
-    C_ROUND;
+    C_ROUNDS;
     v0 ^= m;
 
     msg += j;
@@ -72,7 +73,7 @@ void SipHash::update(u8 *msg, i64 msglen) {
   while (msglen >= 8) {
     u64 m = *(ul64 *)msg;
     v3 ^= m;
-    C_ROUND;
+    C_ROUNDS;
     v0 ^= m;
 
     msg += 8;
@@ -88,15 +89,15 @@ void SipHash::finish(u8 *out) {
   u64 b = (total_bytes << 56) | *(ul64 *)buf;
 
   v3 ^= b;
-  C_ROUND;
+  C_ROUNDS;
   v0 ^= b;
 
   v2 ^= 0xee;
-  D_ROUND;
+  D_ROUNDS;
   *(ul64 *)out = v0 ^ v1 ^ v2 ^ v3;
 
   v1 ^= 0xdd;
-  D_ROUND;
+  D_ROUNDS;
   *(ul64 *)(out + 8) = v0 ^ v1 ^ v2 ^ v3;
 }