kc3-lang/libtommath/bn_mp_radix_size.c

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• Hash : d4f6b43f
  Author :
  Date : 2019-10-11T00:29:20
  

  use of mp_ilogb in mp_radix_size

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• bn_mp_radix_size.c

• #include "tommath_private.h"
  #ifdef BN_MP_RADIX_SIZE_C
  /* LibTomMath, multiple-precision integer library -- Tom St Denis */
  /* SPDX-License-Identifier: Unlicense */
  
  /* returns size of ASCII representation */
  mp_err mp_radix_size(const mp_int *a, int radix, int *size)
  {
     mp_err err;
     mp_int a_, b;
  
     /* make sure the radix is in range */
     if ((radix < 2) || (radix > 64)) {
        return MP_VAL;
     }
  
     if (MP_IS_ZERO(a)) {
        *size = 2;
        return MP_OKAY;
     }
  
     if ((err = mp_init(&b)) != MP_OKAY) {
        goto LBL_ERR;
     }
  
     a_ = *a;
     a_.sign = MP_ZPOS;
     if ((err = mp_ilogb(&a_, (uint32_t)radix, &b)) != MP_OKAY) {
        goto LBL_ERR;
     }
  
     *size = (int)mp_get_l(&b);
  
     /* mp_ilogb truncates to zero, hence we need one extra put on top and one for `\0`. */
     *size += 2 + (a->sign == MP_NEG);
  
  LBL_ERR:
     mp_clear(&b);
     return err;
  }
  
  
  #endif
  

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