c3-lang/libtommath/bn_mp_toom_sqr.c

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• Hash : 4e3f1344
  Author :
  Date : 2015-11-12T01:49:07
  

  provide tommath_private.h tommath.h contains declarations for the public part of the library. tommath_private.h contains the functions which are private to ltm and should not be exposed to the public.

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• bn_mp_toom_sqr.c

• #include <tommath_private.h>
  #ifdef BN_MP_TOOM_SQR_C
  /* LibTomMath, multiple-precision integer library -- Tom St Denis
   *
   * LibTomMath is a library that provides multiple-precision
   * integer arithmetic as well as number theoretic functionality.
   *
   * The library was designed directly after the MPI library by
   * Michael Fromberger but has been written from scratch with
   * additional optimizations in place.
   *
   * The library is free for all purposes without any express
   * guarantee it works.
   *
   * Tom St Denis, tstdenis82@gmail.com, http://libtom.org
   */
  
  /* squaring using Toom-Cook 3-way algorithm */
  int
  mp_toom_sqr(mp_int *a, mp_int *b)
  {
      mp_int w0, w1, w2, w3, w4, tmp1, a0, a1, a2;
      int res, B;
  
      /* init temps */
      if ((res = mp_init_multi(&w0, &w1, &w2, &w3, &w4, &a0, &a1, &a2, &tmp1, NULL)) != MP_OKAY) {
         return res;
      }
  
      /* B */
      B = a->used / 3;
  
      /* a = a2 * B**2 + a1 * B + a0 */
      if ((res = mp_mod_2d(a, DIGIT_BIT * B, &a0)) != MP_OKAY) {
         goto ERR;
      }
  
      if ((res = mp_copy(a, &a1)) != MP_OKAY) {
         goto ERR;
      }
      mp_rshd(&a1, B);
      if ((res = mp_mod_2d(&a1, DIGIT_BIT * B, &a1)) != MP_OKAY) {
         goto ERR;
      }
  
      if ((res = mp_copy(a, &a2)) != MP_OKAY) {
         goto ERR;
      }
      mp_rshd(&a2, B*2);
  
      /* w0 = a0*a0 */
      if ((res = mp_sqr(&a0, &w0)) != MP_OKAY) {
         goto ERR;
      }
  
      /* w4 = a2 * a2 */
      if ((res = mp_sqr(&a2, &w4)) != MP_OKAY) {
         goto ERR;
      }
  
      /* w1 = (a2 + 2(a1 + 2a0))**2 */
      if ((res = mp_mul_2(&a0, &tmp1)) != MP_OKAY) {
         goto ERR;
      }
      if ((res = mp_add(&tmp1, &a1, &tmp1)) != MP_OKAY) {
         goto ERR;
      }
      if ((res = mp_mul_2(&tmp1, &tmp1)) != MP_OKAY) {
         goto ERR;
      }
      if ((res = mp_add(&tmp1, &a2, &tmp1)) != MP_OKAY) {
         goto ERR;
      }
  
      if ((res = mp_sqr(&tmp1, &w1)) != MP_OKAY) {
         goto ERR;
      }
  
      /* w3 = (a0 + 2(a1 + 2a2))**2 */
      if ((res = mp_mul_2(&a2, &tmp1)) != MP_OKAY) {
         goto ERR;
      }
      if ((res = mp_add(&tmp1, &a1, &tmp1)) != MP_OKAY) {
         goto ERR;
      }
      if ((res = mp_mul_2(&tmp1, &tmp1)) != MP_OKAY) {
         goto ERR;
      }
      if ((res = mp_add(&tmp1, &a0, &tmp1)) != MP_OKAY) {
         goto ERR;
      }
  
      if ((res = mp_sqr(&tmp1, &w3)) != MP_OKAY) {
         goto ERR;
      }
  
  
      /* w2 = (a2 + a1 + a0)**2 */
      if ((res = mp_add(&a2, &a1, &tmp1)) != MP_OKAY) {
         goto ERR;
      }
      if ((res = mp_add(&tmp1, &a0, &tmp1)) != MP_OKAY) {
         goto ERR;
      }
      if ((res = mp_sqr(&tmp1, &w2)) != MP_OKAY) {
         goto ERR;
      }
  
      /* now solve the matrix
  
         0  0  0  0  1
         1  2  4  8  16
         1  1  1  1  1
         16 8  4  2  1
         1  0  0  0  0
  
         using 12 subtractions, 4 shifts, 2 small divisions and 1 small multiplication.
       */
  
      /* r1 - r4 */
      if ((res = mp_sub(&w1, &w4, &w1)) != MP_OKAY) {
         goto ERR;
      }
      /* r3 - r0 */
      if ((res = mp_sub(&w3, &w0, &w3)) != MP_OKAY) {
         goto ERR;
      }
      /* r1/2 */
      if ((res = mp_div_2(&w1, &w1)) != MP_OKAY) {
         goto ERR;
      }
      /* r3/2 */
      if ((res = mp_div_2(&w3, &w3)) != MP_OKAY) {
         goto ERR;
      }
      /* r2 - r0 - r4 */
      if ((res = mp_sub(&w2, &w0, &w2)) != MP_OKAY) {
         goto ERR;
      }
      if ((res = mp_sub(&w2, &w4, &w2)) != MP_OKAY) {
         goto ERR;
      }
      /* r1 - r2 */
      if ((res = mp_sub(&w1, &w2, &w1)) != MP_OKAY) {
         goto ERR;
      }
      /* r3 - r2 */
      if ((res = mp_sub(&w3, &w2, &w3)) != MP_OKAY) {
         goto ERR;
      }
      /* r1 - 8r0 */
      if ((res = mp_mul_2d(&w0, 3, &tmp1)) != MP_OKAY) {
         goto ERR;
      }
      if ((res = mp_sub(&w1, &tmp1, &w1)) != MP_OKAY) {
         goto ERR;
      }
      /* r3 - 8r4 */
      if ((res = mp_mul_2d(&w4, 3, &tmp1)) != MP_OKAY) {
         goto ERR;
      }
      if ((res = mp_sub(&w3, &tmp1, &w3)) != MP_OKAY) {
         goto ERR;
      }
      /* 3r2 - r1 - r3 */
      if ((res = mp_mul_d(&w2, 3, &w2)) != MP_OKAY) {
         goto ERR;
      }
      if ((res = mp_sub(&w2, &w1, &w2)) != MP_OKAY) {
         goto ERR;
      }
      if ((res = mp_sub(&w2, &w3, &w2)) != MP_OKAY) {
         goto ERR;
      }
      /* r1 - r2 */
      if ((res = mp_sub(&w1, &w2, &w1)) != MP_OKAY) {
         goto ERR;
      }
      /* r3 - r2 */
      if ((res = mp_sub(&w3, &w2, &w3)) != MP_OKAY) {
         goto ERR;
      }
      /* r1/3 */
      if ((res = mp_div_3(&w1, &w1, NULL)) != MP_OKAY) {
         goto ERR;
      }
      /* r3/3 */
      if ((res = mp_div_3(&w3, &w3, NULL)) != MP_OKAY) {
         goto ERR;
      }
  
      /* at this point shift W[n] by B*n */
      if ((res = mp_lshd(&w1, 1*B)) != MP_OKAY) {
         goto ERR;
      }
      if ((res = mp_lshd(&w2, 2*B)) != MP_OKAY) {
         goto ERR;
      }
      if ((res = mp_lshd(&w3, 3*B)) != MP_OKAY) {
         goto ERR;
      }
      if ((res = mp_lshd(&w4, 4*B)) != MP_OKAY) {
         goto ERR;
      }
  
      if ((res = mp_add(&w0, &w1, b)) != MP_OKAY) {
         goto ERR;
      }
      if ((res = mp_add(&w2, &w3, &tmp1)) != MP_OKAY) {
         goto ERR;
      }
      if ((res = mp_add(&w4, &tmp1, &tmp1)) != MP_OKAY) {
         goto ERR;
      }
      if ((res = mp_add(&tmp1, b, b)) != MP_OKAY) {
         goto ERR;
      }
  
  ERR:
      mp_clear_multi(&w0, &w1, &w2, &w3, &w4, &a0, &a1, &a2, &tmp1, NULL);
      return res;
  }
  
  #endif
  
  /* $Source$ */
  /* $Revision$ */
  /* $Date$ */
  

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