Registerize data in reduce and columnize the addition

1 files changed, 33 insertions, 19 deletions

diff --git a/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP256R1Field.java b/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP256R1Field.java
index 5647e8f5..46e2cf10 100644
--- a/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP256R1Field.java
+++ b/core/src/main/java/org/bouncycastle/math/ec/custom/sec/SecP256R1Field.java
@@ -4,6 +4,8 @@ import java.math.BigInteger;
 
 public class SecP256R1Field
 {
+    private static final long M = 0xFFFFFFFFL;
+
     // 2^256 - 2^224 + 2^192 + 2^96 - 1
     private static final int[] P = new int[] { 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0x00000000, 0x00000000, 0x00000000,
         0x00000001, 0xFFFFFFFF };
@@ -59,25 +61,37 @@ public class SecP256R1Field
 
     private static void reduce(int[] tt, int[] z)
     {
-        int c = 0;
-
-        System.arraycopy(tt, 0, z, 0, 8); //s1
-
-        int[] s2 = new int[] { 0, 0, 0, tt[11], tt[12], tt[13], tt[14], tt[15] };
-        c += Nat256.addBothTo(s2, s2, z);
-        int[] s3 = new int[] { 0, 0, 0, tt[12], tt[13], tt[14], tt[15], 0 };
-        c += Nat256.addBothTo(s3, s3, z);
-        int[] s4 = new int[] { tt[8], tt[9], tt[10], 0, 0, 0, tt[14], tt[15] };
-        int[] s5 = new int[] { tt[9], tt[10], tt[11], tt[13], tt[14], tt[15], tt[13], tt[8] };
-        c += Nat256.addBothTo(s4, s5, z);
-
-        int[] s6 = new int[] { tt[11], tt[12], tt[13], 0, 0, 0, tt[8], tt[10] };
-        int[] s7 = new int[] { tt[12], tt[13], tt[14], tt[15], 0, 0, tt[9], tt[11] };
-        c += Nat256.subBothFrom(s6, s7, z);
-        int[] s8 = new int[] { tt[13], tt[14], tt[15], tt[8], tt[9], tt[10], 0, tt[12] };
-        int[] s9 = new int[] { tt[14], tt[15], 0, tt[9], tt[10], tt[11], 0, tt[13] };
-        c += Nat256.subBothFrom(s8, s9, z);
-
+        long t08 = tt[ 8] & M, t09 = tt[ 9] & M, t10 = tt[10] & M, t11 = tt[11] & M;
+        long t12 = tt[12] & M, t13 = tt[13] & M, t14 = tt[14] & M, t15 = tt[15] & M;
+
+        long cc = 0;
+        cc += (tt[ 0] & M) + t08 + t09 - t11 - t12 - t13 - t14;
+        z[0] = (int)cc;
+        cc >>= 32;
+        cc += (tt[ 1] & M) + t09 + t10 - t12 - t13 - t14 - t15;
+        z[1] = (int)cc;
+        cc >>= 32;
+        cc += (tt[ 2] & M) + t10 + t11 - t13 - t14 - t15;
+        z[2] = (int)cc;
+        cc >>= 32;
+        cc += (tt[ 3] & M) + ((t11 + t12) << 1) + t13 - t15 - t08 - t09;
+        z[3] = (int)cc;
+        cc >>= 32;
+        cc += (tt[ 4] & M) + ((t12 + t13) << 1) + t14 - t09 - t10;
+        z[4] = (int)cc;
+        cc >>= 32;
+        cc += (tt[ 5] & M) + ((t13 + t14) << 1) + t15 - t10 - t11;
+        z[5] = (int)cc;
+        cc >>= 32;
+        cc += (tt[ 6] & M) + ((t14 + t15) << 1) + t14 + t13 - t08 - t09;
+        z[6] = (int)cc;
+        cc >>= 32;
+        cc += (tt[ 7] & M) + (t15 << 1) + t15 + t08 - t10 - t11 - t12 - t13;
+        z[7] = (int)cc;
+        cc >>= 32;
+
+        int c = (int)cc;
+        
         if (c > 0)
         {
             do