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

for the implementation of the BigInt class

1 files changed, 340 insertions, 0 deletions

diff --git a/src/math/mp/mp_karat.cpp b/src/math/mp/mp_karat.cpp
new file mode 100644
index 000000000..8ae346f1e
--- /dev/null
+++ b/src/math/mp/mp_karat.cpp
@@ -0,0 +1,340 @@
+/*
+* Karatsuba Multiplication/Squaring
+* (C) 1999-2008 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/internal/mp_core.h>
+#include <botan/mem_ops.h>
+#include <botan/internal/mp_asmi.h>
+
+namespace Botan {
+
+namespace {
+
+/*
+* Karatsuba Multiplication Operation
+*/
+void karatsuba_mul(word z[], const word x[], const word y[], u32bit N,
+                   word workspace[])
+   {
+   if(N == 6)
+      bigint_comba_mul6(z, x, y);
+   else if(N == 8)
+      bigint_comba_mul8(z, x, y);
+   else if(N == 16)
+      bigint_comba_mul16(z, x, y);
+   else if(N < BOTAN_KARAT_MUL_THRESHOLD || N % 2)
+      bigint_simple_mul(z, x, N, y, N);
+   else
+      {
+      const u32bit N2 = N / 2;
+
+      const word* x0 = x;
+      const word* x1 = x + N2;
+      const word* y0 = y;
+      const word* y1 = y + N2;
+      word* z0 = z;
+      word* z1 = z + N;
+
+      const s32bit cmp0 = bigint_cmp(x0, N2, x1, N2);
+      const s32bit cmp1 = bigint_cmp(y1, N2, y0, N2);
+
+      clear_mem(workspace, 2*N);
+
+      if(cmp0 && cmp1)
+         {
+         if(cmp0 > 0)
+            bigint_sub3(z0, x0, N2, x1, N2);
+         else
+            bigint_sub3(z0, x1, N2, x0, N2);
+
+         if(cmp1 > 0)
+            bigint_sub3(z1, y1, N2, y0, N2);
+         else
+            bigint_sub3(z1, y0, N2, y1, N2);
+
+         karatsuba_mul(workspace, z0, z1, N2, workspace+N);
+         }
+
+      karatsuba_mul(z0, x0, y0, N2, workspace+N);
+      karatsuba_mul(z1, x1, y1, N2, workspace+N);
+
+      const u32bit blocks_of_8 = N - (N % 8);
+
+      word carry = 0;
+
+      for(u32bit j = 0; j != blocks_of_8; j += 8)
+         carry = word8_add3(workspace + N + j, z0 + j, z1 + j, carry);
+
+      for(u32bit j = blocks_of_8; j != N; ++j)
+         workspace[N + j] = word_add(z0[j], z1[j], &carry);
+
+      word carry2 = 0;
+
+      for(u32bit j = 0; j != blocks_of_8; j += 8)
+         carry2 = word8_add2(z + N2 + j, workspace + N + j, carry2);
+
+      for(u32bit j = blocks_of_8; j != N; ++j)
+         z[N2 + j] = word_add(z[N2 + j], workspace[N + j], &carry2);
+
+      z[N + N2] = word_add(z[N + N2], carry2, &carry);
+
+      if(carry)
+         for(u32bit j = 1; j != N2; ++j)
+            if(++z[N + N2 + j])
+               break;
+
+      if((cmp0 == cmp1) || (cmp0 == 0) || (cmp1 == 0))
+         bigint_add2(z + N2, 2*N-N2, workspace, N);
+      else
+         bigint_sub2(z + N2, 2*N-N2, workspace, N);
+      }
+   }
+
+/*
+* Karatsuba Squaring Operation
+*/
+void karatsuba_sqr(word z[], const word x[], u32bit N, word workspace[])
+   {
+   if(N == 6)
+      bigint_comba_sqr6(z, x);
+   else if(N == 8)
+      bigint_comba_sqr8(z, x);
+   else if(N == 16)
+      bigint_comba_sqr16(z, x);
+   else if(N < BOTAN_KARAT_SQR_THRESHOLD || N % 2)
+      bigint_simple_sqr(z, x, N);
+   else
+      {
+      const u32bit N2 = N / 2;
+
+      const word* x0 = x;
+      const word* x1 = x + N2;
+      word* z0 = z;
+      word* z1 = z + N;
+
+      const s32bit cmp = bigint_cmp(x0, N2, x1, N2);
+
+      clear_mem(workspace, 2*N);
+
+      if(cmp)
+         {
+         if(cmp > 0)
+            bigint_sub3(z0, x0, N2, x1, N2);
+         else
+            bigint_sub3(z0, x1, N2, x0, N2);
+
+         karatsuba_sqr(workspace, z0, N2, workspace+N);
+         }
+
+      karatsuba_sqr(z0, x0, N2, workspace+N);
+      karatsuba_sqr(z1, x1, N2, workspace+N);
+
+      const u32bit blocks_of_8 = N - (N % 8);
+
+      word carry = 0;
+
+      for(u32bit j = 0; j != blocks_of_8; j += 8)
+         carry = word8_add3(workspace + N + j, z0 + j, z1 + j, carry);
+
+      for(u32bit j = blocks_of_8; j != N; ++j)
+         workspace[N + j] = word_add(z0[j], z1[j], &carry);
+
+      word carry2 = 0;
+
+      for(u32bit j = 0; j != blocks_of_8; j += 8)
+         carry2 = word8_add2(z + N2 + j, workspace + N + j, carry2);
+
+      for(u32bit j = blocks_of_8; j != N; ++j)
+         z[N2 + j] = word_add(z[N2 + j], workspace[N + j], &carry2);
+
+      z[N + N2] = word_add(z[N + N2], carry2, &carry);
+
+      if(carry)
+         for(u32bit j = 1; j != N2; ++j)
+            if(++z[N + N2 + j])
+               break;
+
+      if(cmp == 0)
+         bigint_add2(z + N2, 2*N-N2, workspace, N);
+      else
+         bigint_sub2(z + N2, 2*N-N2, workspace, N);
+      }
+   }
+
+/*
+* Pick a good size for the Karatsuba multiply
+*/
+u32bit karatsuba_size(u32bit z_size,
+                      u32bit x_size, u32bit x_sw,
+                      u32bit y_size, u32bit y_sw)
+   {
+   if(x_sw > x_size || x_sw > y_size || y_sw > x_size || y_sw > y_size)
+      return 0;
+
+   if(((x_size == x_sw) && (x_size % 2)) ||
+      ((y_size == y_sw) && (y_size % 2)))
+      return 0;
+
+   const u32bit start = (x_sw > y_sw) ? x_sw : y_sw;
+   const u32bit end = (x_size < y_size) ? x_size : y_size;
+
+   if(start == end)
+      {
+      if(start % 2)
+         return 0;
+      return start;
+      }
+
+   for(u32bit j = start; j <= end; ++j)
+      {
+      if(j % 2)
+         continue;
+
+      if(2*j > z_size)
+         return 0;
+
+      if(x_sw <= j && j <= x_size && y_sw <= j && j <= y_size)
+         {
+         if(j % 4 == 2 &&
+            (j+2) <= x_size && (j+2) <= y_size && 2*(j+2) <= z_size)
+            return j+2;
+         return j;
+         }
+      }
+
+   return 0;
+   }
+
+/*
+* Pick a good size for the Karatsuba squaring
+*/
+u32bit karatsuba_size(u32bit z_size, u32bit x_size, u32bit x_sw)
+   {
+   if(x_sw == x_size)
+      {
+      if(x_sw % 2)
+         return 0;
+      return x_sw;
+      }
+
+   for(u32bit j = x_sw; j <= x_size; ++j)
+      {
+      if(j % 2)
+         continue;
+
+      if(2*j > z_size)
+         return 0;
+
+      if(j % 4 == 2 && (j+2) <= x_size && 2*(j+2) <= z_size)
+         return j+2;
+      return j;
+      }
+
+   return 0;
+   }
+
+}
+
+/*
+* Multiplication Algorithm Dispatcher
+*/
+void bigint_mul(word z[], u32bit z_size, word workspace[],
+                const word x[], u32bit x_size, u32bit x_sw,
+                const word y[], u32bit y_size, u32bit y_sw)
+   {
+   if(x_sw == 1)
+      {
+      bigint_linmul3(z, y, y_sw, x[0]);
+      }
+   else if(y_sw == 1)
+      {
+      bigint_linmul3(z, x, x_sw, y[0]);
+      }
+   else if(x_sw <= 4 && x_size >= 4 &&
+           y_sw <= 4 && y_size >= 4 && z_size >= 8)
+      {
+      bigint_comba_mul4(z, x, y);
+      }
+   else if(x_sw <= 6 && x_size >= 6 &&
+           y_sw <= 6 && y_size >= 6 && z_size >= 12)
+      {
+      bigint_comba_mul6(z, x, y);
+      }
+   else if(x_sw <= 8 && x_size >= 8 &&
+           y_sw <= 8 && y_size >= 8 && z_size >= 16)
+      {
+      bigint_comba_mul8(z, x, y);
+      }
+   else if(x_sw <= 16 && x_size >= 16 &&
+           y_sw <= 16 && y_size >= 16 && z_size >= 32)
+      {
+      bigint_comba_mul16(z, x, y);
+      }
+   else if(x_sw < BOTAN_KARAT_MUL_THRESHOLD ||
+           y_sw < BOTAN_KARAT_MUL_THRESHOLD ||
+           !workspace)
+      {
+      bigint_simple_mul(z, x, x_sw, y, y_sw);
+      }
+   else
+      {
+      const u32bit N = karatsuba_size(z_size, x_size, x_sw, y_size, y_sw);
+
+      if(N)
+         {
+         clear_mem(workspace, 2*N);
+         karatsuba_mul(z, x, y, N, workspace);
+         }
+      else
+         bigint_simple_mul(z, x, x_sw, y, y_sw);
+      }
+   }
+
+/*
+* Squaring Algorithm Dispatcher
+*/
+void bigint_sqr(word z[], u32bit z_size, word workspace[],
+                const word x[], u32bit x_size, u32bit x_sw)
+   {
+   if(x_sw == 1)
+      {
+      bigint_linmul3(z, x, x_sw, x[0]);
+      }
+   else if(x_sw <= 4 && x_size >= 4 && z_size >= 8)
+      {
+      bigint_comba_sqr4(z, x);
+      }
+   else if(x_sw <= 6 && x_size >= 6 && z_size >= 12)
+      {
+      bigint_comba_sqr6(z, x);
+      }
+   else if(x_sw <= 8 && x_size >= 8 && z_size >= 16)
+      {
+      bigint_comba_sqr8(z, x);
+      }
+   else if(x_sw <= 16 && x_size >= 16 && z_size >= 32)
+      {
+      bigint_comba_sqr16(z, x);
+      }
+   else if(x_size < BOTAN_KARAT_SQR_THRESHOLD || !workspace)
+      {
+      bigint_simple_sqr(z, x, x_sw);
+      }
+   else
+      {
+      const u32bit N = karatsuba_size(z_size, x_size, x_sw);
+
+      if(N)
+         {
+         clear_mem(workspace, 2*N);
+         karatsuba_sqr(z, x, N, workspace);
+         }
+      else
+         bigint_simple_sqr(z, x, x_sw);
+      }
+   }
+
+}