kc3-lang/libtommath/bn_mp_tc_xor.c

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• Hash : 4534056c
  Author :
  Date : 2019-05-13T00:22:18
  

  use enums mp_err, mp_ord, mp_bool, mp_sign * MP_USE_ENUMS enables enums * Wc++-compat catches some implicit conversions if MP_USE_ENUMS is defined * 100% backwards compatible API/ABI if MP_USE_ENUMS is not defined

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• bn_mp_tc_xor.c

• #include "tommath_private.h"
  #ifdef BN_MP_TC_XOR_C
  /* LibTomMath, multiple-precision integer library -- Tom St Denis */
  /* SPDX-License-Identifier: Unlicense */
  
  /* two complement xor */
  mp_err mp_tc_xor(const mp_int *a, const mp_int *b, mp_int *c)
  {
     mp_err res = MP_OKAY;
     int bits, abits, bbits;
     mp_sign sa = a->sign, sb = b->sign;
     mp_int *mx = NULL, _mx, acpy, bcpy;
  
     if ((sa == MP_NEG) || (sb == MP_NEG)) {
        abits = mp_count_bits(a);
        bbits = mp_count_bits(b);
        bits = MP_MAX(abits, bbits);
        res = mp_init_set_int(&_mx, 1uL);
        if (res != MP_OKAY) {
           goto end;
        }
  
        mx = &_mx;
        res = mp_mul_2d(mx, bits + 1, mx);
        if (res != MP_OKAY) {
           goto end;
        }
  
        if (sa == MP_NEG) {
           res = mp_init(&acpy);
           if (res != MP_OKAY) {
              goto end;
           }
  
           res = mp_add(mx, a, &acpy);
           if (res != MP_OKAY) {
              mp_clear(&acpy);
              goto end;
           }
           a = &acpy;
        }
        if (sb == MP_NEG) {
           res = mp_init(&bcpy);
           if (res != MP_OKAY) {
              goto end;
           }
  
           res = mp_add(mx, b, &bcpy);
           if (res != MP_OKAY) {
              mp_clear(&bcpy);
              goto end;
           }
           b = &bcpy;
        }
     }
  
     res = mp_xor(a, b, c);
  
     if ((((sa == MP_NEG) && (sb != MP_NEG)) || ((sa != MP_NEG) && (sb == MP_NEG))) && (res == MP_OKAY)) {
        res = mp_sub(c, mx, c);
     }
  
  end:
     if (a == &acpy) {
        mp_clear(&acpy);
     }
  
     if (b == &bcpy) {
        mp_clear(&bcpy);
     }
  
     if (mx == &_mx) {
        mp_clear(mx);
     }
  
     return res;
  }
  #endif
  

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