Move the core MPI functions to src/math/mp, leaving src/math/bigint just

for the implementation of the BigInt class

1 files changed, 102 insertions, 0 deletions

diff --git a/src/math/mp/mp_misc.cpp b/src/math/mp/mp_misc.cpp
new file mode 100644
index 000000000..77b8e6f51
--- /dev/null
+++ b/src/math/mp/mp_misc.cpp
@@ -0,0 +1,102 @@
+/*
+* MP Misc Functions
+* (C) 1999-2008 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/internal/mp_core.h>
+#include <botan/internal/mp_asm.h>
+
+namespace Botan {
+
+extern "C" {
+
+/*
+* Core Division Operation
+*/
+u32bit bigint_divcore(word q, word y2, word y1,
+                      word x3, word x2, word x1)
+   {
+   // Compute (y2,y1) * q
+
+   word y3 = 0;
+   y1 = word_madd2(q, y1, &y3);
+   y2 = word_madd2(q, y2, &y3);
+
+   // Return (y3,y2,y1) >? (x3,x2,x1)
+
+   if(y3 > x3) return 1;
+   if(y3 < x3) return 0;
+   if(y2 > x2) return 1;
+   if(y2 < x2) return 0;
+   if(y1 > x1) return 1;
+   if(y1 < x1) return 0;
+   return 0;
+   }
+
+/*
+* Compare two MP integers
+*/
+s32bit bigint_cmp(const word x[], u32bit x_size,
+                  const word y[], u32bit y_size)
+   {
+   if(x_size < y_size) { return (-bigint_cmp(y, y_size, x, x_size)); }
+
+   while(x_size > y_size)
+      {
+      if(x[x_size-1])
+         return 1;
+      x_size--;
+      }
+
+   for(u32bit j = x_size; j > 0; --j)
+      {
+      if(x[j-1] > y[j-1])
+         return 1;
+      if(x[j-1] < y[j-1])
+         return -1;
+      }
+
+   return 0;
+   }
+
+/*
+* Do a 2-word/1-word Division
+*/
+word bigint_divop(word n1, word n0, word d)
+   {
+   word high = n1 % d, quotient = 0;
+
+   for(u32bit j = 0; j != MP_WORD_BITS; ++j)
+      {
+      word high_top_bit = (high & MP_WORD_TOP_BIT);
+
+      high <<= 1;
+      high |= (n0 >> (MP_WORD_BITS-1-j)) & 1;
+      quotient <<= 1;
+
+      if(high_top_bit || high >= d)
+         {
+         high -= d;
+         quotient |= 1;
+         }
+      }
+
+   return quotient;
+   }
+
+/*
+* Do a 2-word/1-word Modulo
+*/
+word bigint_modop(word n1, word n0, word d)
+   {
+   word z = bigint_divop(n1, n0, d);
+   word dummy = 0;
+   z = word_madd2(z, d, &dummy);
+   return (n0-z);
+   }
+
+}
+
+}