From a7615a8c7c59f5c11e784c8d3b39c9030b8929a1 Mon Sep 17 00:00:00 2001
From: Jeffrey Walton <noloader@gmail.com>
Date: Sun, 28 Oct 2018 00:48:18 -0400
Subject: [PATCH] Add packed 32-bit Shuffle specializations for ChaCha on
 Power8

---
 chacha-simd.cpp | 46 +++++++++++++++++++++++-----------------------
 1 file changed, 23 insertions(+), 23 deletions(-)

diff --git a/chacha-simd.cpp b/chacha-simd.cpp
index 4315f32c..280ae490 100644
--- a/chacha-simd.cpp
+++ b/chacha-simd.cpp
@@ -262,29 +262,29 @@ inline uint32x4_p RotateRight(const uint32x4_p val)
 template <unsigned int S>
 inline uint32x4_p Shuffle(const uint32x4_p& val)
 {
-    switch (S%4)
-    {
-    case 1:
-        {
-            const uint8x16_p mask = {4,5,6,7, 8,9,10,11, 12,13,14,15, 0,1,2,3};
-            return vec_perm(val, val, mask);
-        }
-    case 2:
-        {
-            const uint8x16_p mask = {8,9,10,11, 12,13,14,15, 0,1,2,3, 4,5,6,7};
-            return vec_perm(val, val, mask);
-        }
-    case 3:
-        {
-            const uint8x16_p mask = {12,13,14,15, 0,1,2,3, 4,5,6,7, 8,9,10,11};
-            return vec_perm(val, val, mask);
-        }
-    default:
-        {
-            CRYPTOPP_ASSERT(0);
-            return val;
-        }
-    }
+    CRYPTOPP_ASSERT(0);
+    return val;
+}
+
+template <>
+inline uint32x4_p Shuffle<1>(const uint32x4_p& val)
+{
+    const uint8x16_p mask = {4,5,6,7, 8,9,10,11, 12,13,14,15, 0,1,2,3};
+    return vec_perm(val, val, mask);
+}
+
+template <>
+inline uint32x4_p Shuffle<2>(const uint32x4_p& val)
+{
+    const uint8x16_p mask = {8,9,10,11, 12,13,14,15, 0,1,2,3, 4,5,6,7};
+    return vec_perm(val, val, mask);
+}
+
+template <>
+inline uint32x4_p Shuffle<3>(const uint32x4_p& val)
+{
+    const uint8x16_p mask = {12,13,14,15, 0,1,2,3, 4,5,6,7, 8,9,10,11};
+    return vec_perm(val, val, mask);
 }
 
 // Helper to perform 64-bit addition across two elements of 32-bit vectors