From 649eae8f1b689e90695bbf24b636ca941dfb9689 Mon Sep 17 00:00:00 2001 From: Werner Koch Date: Thu, 27 Nov 1997 11:44:13 +0000 Subject: Improved prime number test --- mpi/mpi-div.c | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) (limited to 'mpi/mpi-div.c') diff --git a/mpi/mpi-div.c b/mpi/mpi-div.c index 2b39cb4cf..527375748 100644 --- a/mpi/mpi-div.c +++ b/mpi/mpi-div.c @@ -278,6 +278,37 @@ mpi_tdiv_qr( MPI quot, MPI rem, MPI num, MPI den) mpi_free_limb_space(marker[--markidx]); } +void +mpi_tdiv_q_2exp( MPI w, MPI u, unsigned count ) +{ + mpi_size_t usize, wsize; + mpi_size_t limb_cnt; + + usize = u->nlimbs; + limb_cnt = count / BITS_PER_MPI_LIMB; + wsize = usize - limb_cnt; + if( limb_cnt >= usize ) + w->nlimbs = 0; + else { + mpi_ptr_t wp; + mpi_ptr_t up; + + RESIZE_IF_NEEDED( w, wsize ); + wp = w->d; + up = u->d; + + count %= BITS_PER_MPI_LIMB; + if( count ) { + mpihelp_rshift( wp, up + limb_cnt, wsize, count ); + wsize -= !wp[wsize - 1]; + } + else { + MPN_COPY_INCR( wp, up + limb_cnt, wsize); + } + + w->nlimbs = wsize; + } +} /**************** * Check wether dividend is divisible by divisor -- cgit v1.2.3