Commit 1f224bf0 authored by Bodo Möller's avatar Bodo Möller
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Adjust BN_mod_inverse algorithm selection according to experiments on 

Ultra-Sparcs (both 32-bit and 64-bit compilations)
parent 4d231b43

CHANGES

+6 −3
Original line number Diff line number Diff line
@@ -6,9 +6,12 @@ 


  *) Implement binary inversion algorithm for BN_mod_inverse in addition

     to the algorithm using long divison.  The binary algorithm can be

     used only if the modulus is odd.  It is faster only for relatively

     small moduli (roughly 20% for 128-bit moduli, roughly 5% for 256-bit

     moduli), so we use it only for moduli up to 400 bits.

     used only if the modulus is odd.  On 32-bit systems, it is faster

     only for relatively small moduli (roughly 20-30% for 128-bit moduli,

     roughly 5-15% for 256-bit moduli), so we use it only for moduli

     up to 450 bits.  In 64-bit environments, the binary algorithm

     appears to be advantageous for much longer moduli; here we use it

     for moduli up to 2048 bits.

     [Bodo Moeller]



  *) Change bctest again: '-x' expressions are not available in all

crypto/bn/bn_gcd.c

+3 −2
Original line number Diff line number Diff line
@@ -244,11 +244,12 @@ BIGNUM *BN_mod_inverse(BIGNUM *in, 
	 *      sign*Y*a  ==  A   (mod |n|).

	 */



	if (BN_is_odd(n) && (BN_num_bits(n) <= 400))

	if (BN_is_odd(n) && (BN_num_bits(n) <= (BN_BITS <= 32 ? 450 : 2048)))

		{

		/* Binary inversion algorithm; requires odd modulus.

		 * This is faster than the general algorithm if the modulus

		 * is sufficiently small. */

		 * is sufficiently small (about 400 .. 500 bits on 32-bit

		 * sytems, but much more on 64-bit systems) */

		int shift;

		

		while (!BN_is_zero(B))