Discussion related to cado-nfs

[Reza <gk.inst@gmail.com>]

Hi dear,

I'm tracing the sieving algorithm in CADO-NFS for improving some functions.

Unfortunately, I could not understand the goal of following part of the  code; and why this part have been added to code?.

Note that, the main problem is the Bold line.

PATH: cado-nfs-1.1/sieve/las.c

Line1702:

#ifndef SSE_NORM_INIT

        uint64_t y;

        unsigned char n;

        for (i = 0; i < (int) si->I; i++) {

          /* the double precision number 1.0 has high bit 0 (sign),

             then 11-bit biased exponent 1023, and 52-bit mantissa 0 */

          /* the magic constant here is simply 1023*2^52, where

             1023 is the exponent bias in binary64 */

          y = (zx->x - (uint64_t) 0x3FF0000000000000) >> (52 - l);

          n = rat->S[y & mask];

          ASSERT (n > 0);

          *S++ = n;

          zx->z += gi;

        }

#else

Best regrads,

Ghasem