view libtommath/bn_mp_cnt_lsb.c @ 1921:284c3837891c

Allow user space file locations (rootless support) Why: Running dropbear as a user (rootless) is aided if files and programs can be saved/removed without needing sudo. What: Use the same convention as DROPBEAR_DEFAULT_CLI_AUTHKEY; if not starting with '/', then is relative to hedge's /home/hedge: *_PRIV_FILENAME DROPBEAR_PIDFILE SFTPSERVER_PATH default_options.h commentary added. Changes kept to a minimum, so log entry in svr_kex.c#163 is refactored. From: Generated hostkey is <path> ... <finger-print> to: Generated hostkey path is <path> Generated hostkey fingerprint is <fp> Otherwise the unexpanded path was reported. Patch modified by Matt Johnston Signed-off-by: Begley Brothers Inc <[email protected]>
author Begley Brothers Inc <begleybrothers@gmail.com>
date Thu, 09 Jul 2020 17:47:58 +1000
parents 1051e4eea25a
children
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#include "tommath_private.h"
#ifdef BN_MP_CNT_LSB_C
/* LibTomMath, multiple-precision integer library -- Tom St Denis */
/* SPDX-License-Identifier: Unlicense */

static const int lnz[16] = {
   4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0
};

/* Counts the number of lsbs which are zero before the first zero bit */
int mp_cnt_lsb(const mp_int *a)
{
   int x;
   mp_digit q, qq;

   /* easy out */
   if (MP_IS_ZERO(a)) {
      return 0;
   }

   /* scan lower digits until non-zero */
   for (x = 0; (x < a->used) && (a->dp[x] == 0u); x++) {}
   q = a->dp[x];
   x *= MP_DIGIT_BIT;

   /* now scan this digit until a 1 is found */
   if ((q & 1u) == 0u) {
      do {
         qq  = q & 15u;
         x  += lnz[qq];
         q >>= 4;
      } while (qq == 0u);
   }
   return x;
}

#endif