Diff: BigInt.cpp

Revision:

24:a3453a18388c

Parent:

23:002f471a973e

Child:

25:3d5c1f299da2

diff -r 002f471a973e -r a3453a18388c BigInt.cpp
--- a/BigInt.cpp	Mon Mar 10 21:59:19 2014 +0000
+++ b/BigInt.cpp	Sun Apr 06 08:12:52 2014 +0000
@@ -15,7 +15,12 @@
     0x01000000, 0x02000000, 0x04000000, 0x08000000, 0x10000000, 0x20000000, 0x40000000, 0x80000000
 };
 
-static uint32_t num(const uint32_t a)
+static uint32_t BITS2[] =
+{
+    0x00FFFFFF, 0x0000FFFF, 0x00FFFFFF
+};
+
+static inline uint32_t num(const uint32_t a)
 {
     return a/4 + (a%4 ? 1:0); 
 }
@@ -539,14 +544,14 @@
     while(r > 0)
     {
         if(a.bits[j/32] & BITS[j%32])
-            result += b;
+            result.add(b);
         
         if(result.bits[0] & BITS[0])
-            result += m;
+            result.add(m);
      
         ++j; 
         --r;
-        result >>= 1;
+        result.shr();
     }
     
     if(result >= m)
@@ -579,6 +584,7 @@
     uint32_t j = 0; 
     while(j <= n)
     {
+        
         if(expn.bits[j/32] & BITS[j%32])
         {
             if(tmp.isValid())
@@ -589,6 +595,7 @@
         ++j;
         if(j <= n)  
             montA = montgomeryStep(montA, montA, modulus, r);
+        
     }
     
     // convert tmp to normal world
@@ -613,6 +620,50 @@
     printf("\n");
 }
 
+void BigInt::add(const BigInt &b)
+{
+    uint32_t al = num(size);
+    uint32_t bl = num(b.size);
+    uint32_t rsize = std::max(size, b.size) + 1;
+    size_t l = num(rsize);
+    
+    if(l > al)
+    {
+        bits = (uint32_t*)realloc(bits, sizeof(uint32_t)*l);
+        memset(&bits[al], 0, (l-al)*sizeof(uint32_t));
+        size = rsize;
+    }
+
+    uint32_t carry = 0;
+    for(int i = 0; i < l; ++i)
+    {
+        uint32_t tmpA = 0, tmpB = 0;
+        if(i < al)
+            tmpA = bits[i];
+        if(i < bl)
+            tmpB = b.bits[i];
+        bits[i] = tmpA + tmpB + carry;
+        carry = bits[i] < std::max(tmpA, tmpB);
+    }
+
+    trim();
+}
+
+void BigInt::shr()
+{
+    uint32_t lastBit = 0;
+    uint32_t tmp;
+    for(int i = num(size)-1; i >= 0; --i)
+    {
+        tmp = bits[i] & BITS[0];
+        bits[i] >>= 1;
+        bits[i] |= (lastBit ? BITS[31] : 0);
+        lastBit = tmp;
+    }
+
+    trim();
+}
+
 void BigInt::trim()
 {
     assert(isValid());
@@ -623,15 +674,12 @@
         newSize--;
     if(newSize == 0)
         newSize = 1;
-    if(num(newSize) < num(size))
+    uint32_t n = num(newSize);
+    if(n < num(size))
     {
-        uint32_t *tmp = new uint32_t[num(size)];
-        memcpy(tmp, bits, num(size)*sizeof(uint32_t));
-        delete[] bits;
-        bits = new uint32_t[num(newSize)];
-        memset(bits, 0, sizeof(uint32_t)*num(newSize));
-        memcpy(bits, tmp, newSize);
-        delete[] tmp;
+        bits = (uint32_t*)realloc(bits, n*sizeof(uint32_t));
+        if(newSize % 4 != 0)
+            bits[n-1] &= BITS2[newSize%4];
     }
     size = newSize; 
 }
@@ -651,4 +699,4 @@
     n += tmp2;
 
     return n;
-}
+}
\ No newline at end of file