Delete bundled copy of NSS and replace with README.

nss/lib/freebl/mpi/mplogic.c

-/*
- *  mplogic.c
- *
- *  Bitwise logical operations on MPI values
- *
- * This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-#include "mpi-priv.h"
-#include "mplogic.h"
-
-/* {{{ Lookup table for population count */
-
-static unsigned char bitc[] = {
-   0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4, 
-   1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, 
-   1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, 
-   2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 
-   1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, 
-   2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 
-   2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 
-   3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, 
-   1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, 
-   2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 
-   2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 
-   3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, 
-   2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 
-   3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, 
-   3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, 
-   4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8
-};
-
-/* }}} */
-
-/*------------------------------------------------------------------------*/
-/*
-  mpl_not(a, b)    - compute b = ~a
-  mpl_and(a, b, c) - compute c = a & b
-  mpl_or(a, b, c)  - compute c = a | b
-  mpl_xor(a, b, c) - compute c = a ^ b
- */
-
-/* {{{ mpl_not(a, b) */
-
-mp_err mpl_not(mp_int *a, mp_int *b)
-{
-  mp_err   res;
-  unsigned int      ix;
-
-  ARGCHK(a != NULL && b != NULL, MP_BADARG);
-
-  if((res = mp_copy(a, b)) != MP_OKAY)
-    return res;
-
-  /* This relies on the fact that the digit type is unsigned */
-  for(ix = 0; ix < USED(b); ix++) 
-    DIGIT(b, ix) = ~DIGIT(b, ix);
-
-  s_mp_clamp(b);
-
-  return MP_OKAY;
-
-} /* end mpl_not() */
-
-/* }}} */
-
-/* {{{ mpl_and(a, b, c) */
-
-mp_err mpl_and(mp_int *a, mp_int *b, mp_int *c)
-{
-  mp_int  *which, *other;
-  mp_err   res;
-  unsigned int      ix;
-
-  ARGCHK(a != NULL && b != NULL && c != NULL, MP_BADARG);
-
-  if(USED(a) <= USED(b)) {
-    which = a;
-    other = b;
-  } else {
-    which = b;
-    other = a;
-  }
-
-  if((res = mp_copy(which, c)) != MP_OKAY)
-    return res;
-
-  for(ix = 0; ix < USED(which); ix++)
-    DIGIT(c, ix) &= DIGIT(other, ix);
-
-  s_mp_clamp(c);
-
-  return MP_OKAY;
-
-} /* end mpl_and() */
-
-/* }}} */
-
-/* {{{ mpl_or(a, b, c) */
-
-mp_err mpl_or(mp_int *a, mp_int *b, mp_int *c)
-{
-  mp_int  *which, *other;
-  mp_err   res;
-  unsigned int      ix;
-
-  ARGCHK(a != NULL && b != NULL && c != NULL, MP_BADARG);
-
-  if(USED(a) >= USED(b)) {
-    which = a;
-    other = b;
-  } else {
-    which = b;
-    other = a;
-  }
-
-  if((res = mp_copy(which, c)) != MP_OKAY)
-    return res;
-
-  for(ix = 0; ix < USED(which); ix++)
-    DIGIT(c, ix) |= DIGIT(other, ix);
-
-  return MP_OKAY;
-
-} /* end mpl_or() */
-
-/* }}} */
-
-/* {{{ mpl_xor(a, b, c) */
-
-mp_err mpl_xor(mp_int *a, mp_int *b, mp_int *c)
-{
-  mp_int  *which, *other;
-  mp_err   res;
-  unsigned int      ix;
-
-  ARGCHK(a != NULL && b != NULL && c != NULL, MP_BADARG);
-
-  if(USED(a) >= USED(b)) {
-    which = a;
-    other = b;
-  } else {
-    which = b;
-    other = a;
-  }
-
-  if((res = mp_copy(which, c)) != MP_OKAY)
-    return res;
-
-  for(ix = 0; ix < USED(which); ix++)
-    DIGIT(c, ix) ^= DIGIT(other, ix);
-
-  s_mp_clamp(c);
-
-  return MP_OKAY;
-
-} /* end mpl_xor() */
-
-/* }}} */
-
-/*------------------------------------------------------------------------*/
-/*
-  mpl_rsh(a, b, d)     - b = a >> d
-  mpl_lsh(a, b, d)     - b = a << d
- */
-
-/* {{{ mpl_rsh(a, b, d) */
-
-mp_err mpl_rsh(const mp_int *a, mp_int *b, mp_digit d)
-{
-  mp_err   res;
-
-  ARGCHK(a != NULL && b != NULL, MP_BADARG);
-
-  if((res = mp_copy(a, b)) != MP_OKAY)
-    return res;
-
-  s_mp_div_2d(b, d);
-
-  return MP_OKAY;
-
-} /* end mpl_rsh() */
-
-/* }}} */
-
-/* {{{ mpl_lsh(a, b, d) */
-
-mp_err mpl_lsh(const mp_int *a, mp_int *b, mp_digit d)
-{
-  mp_err   res;
-
-  ARGCHK(a != NULL && b != NULL, MP_BADARG);
-
-  if((res = mp_copy(a, b)) != MP_OKAY)
-    return res;
-
-  return s_mp_mul_2d(b, d);
-
-} /* end mpl_lsh() */
-
-/* }}} */
-
-/*------------------------------------------------------------------------*/
-/*
-  mpl_num_set(a, num)
-
-  Count the number of set bits in the binary representation of a.
-  Returns MP_OKAY and sets 'num' to be the number of such bits, if
-  possible.  If num is NULL, the result is thrown away, but it is
-  not considered an error.
-
-  mpl_num_clear() does basically the same thing for clear bits.
- */
-
-/* {{{ mpl_num_set(a, num) */
-
-mp_err mpl_num_set(mp_int *a, int *num)
-{
-  unsigned int   ix;
-  int            db, nset = 0;
-  mp_digit       cur;
-  unsigned char  reg;
-
-  ARGCHK(a != NULL, MP_BADARG);
-
-  for(ix = 0; ix < USED(a); ix++) {
-    cur = DIGIT(a, ix);
-    
-    for(db = 0; db < sizeof(mp_digit); db++) {
-      reg = (unsigned char)(cur >> (CHAR_BIT * db));
-
-      nset += bitc[reg];
-    }
-  }
-
-  if(num)
-    *num = nset;
-
-  return MP_OKAY;
-
-} /* end mpl_num_set() */
-
-/* }}} */
-
-/* {{{ mpl_num_clear(a, num) */
-
-mp_err mpl_num_clear(mp_int *a, int *num)
-{
-  unsigned int   ix;
-  int            db, nset = 0;
-  mp_digit       cur;
-  unsigned char  reg;
-
-  ARGCHK(a != NULL, MP_BADARG);
-
-  for(ix = 0; ix < USED(a); ix++) {
-    cur = DIGIT(a, ix);
-    
-    for(db = 0; db < sizeof(mp_digit); db++) {
-      reg = (unsigned char)(cur >> (CHAR_BIT * db));
-
-      nset += bitc[UCHAR_MAX - reg];
-    }
-  }
-
-  if(num)
-    *num = nset;
-
-  return MP_OKAY;
-
-
-} /* end mpl_num_clear() */
-
-/* }}} */
-
-/*------------------------------------------------------------------------*/
-/*
-  mpl_parity(a)
-
-  Determines the bitwise parity of the value given.  Returns MP_EVEN
-  if an even number of digits are set, MP_ODD if an odd number are
-  set.
- */
-
-/* {{{ mpl_parity(a) */
-
-mp_err mpl_parity(mp_int *a)
-{
-  unsigned int ix;
-  int      par = 0;
-  mp_digit cur;
-
-  ARGCHK(a != NULL, MP_BADARG);
-
-  for(ix = 0; ix < USED(a); ix++) {
-    int   shft = (sizeof(mp_digit) * CHAR_BIT) / 2;
-
-    cur = DIGIT(a, ix);
-
-    /* Compute parity for current digit */
-    while(shft != 0) {
-      cur ^= (cur >> shft);
-      shft >>= 1;
-    }
-    cur &= 1;
-
-    /* XOR with running parity so far   */
-    par ^= cur;
-  }
-
-  if(par)
-    return MP_ODD;
-  else
-    return MP_EVEN;
-
-} /* end mpl_parity() */
-
-/* }}} */
-
-/*
-  mpl_set_bit
-
-  Returns MP_OKAY or some error code.
-  Grows a if needed to set a bit to 1.
- */
-mp_err mpl_set_bit(mp_int *a, mp_size bitNum, mp_size value)
-{
-  mp_size      ix;
-  mp_err       rv;
-  mp_digit     mask;
-
-  ARGCHK(a != NULL, MP_BADARG);
-
-  ix = bitNum / MP_DIGIT_BIT;
-  if (ix + 1 > MP_USED(a)) {
-    rv = s_mp_pad(a, ix + 1);
-    if (rv != MP_OKAY)
-      return rv;
-  }
-
-  bitNum = bitNum % MP_DIGIT_BIT;
-  mask = (mp_digit)1 << bitNum;
-  if (value)
-    MP_DIGIT(a,ix) |= mask;
-  else
-    MP_DIGIT(a,ix) &= ~mask;
-  s_mp_clamp(a);
-  return MP_OKAY;
-}
-
-/*
-  mpl_get_bit
-
-  returns 0 or 1 or some (negative) error code.
- */
-mp_err mpl_get_bit(const mp_int *a, mp_size bitNum)
-{
-  mp_size      bit, ix;
-  mp_err       rv;
-
-  ARGCHK(a != NULL, MP_BADARG);
-
-  ix = bitNum / MP_DIGIT_BIT;
-  ARGCHK(ix <= MP_USED(a) - 1, MP_RANGE);
-
-  bit   = bitNum % MP_DIGIT_BIT;
-  rv = (mp_err)(MP_DIGIT(a, ix) >> bit) & 1;
-  return rv;
-}
-
-/*
-  mpl_get_bits
-  - Extracts numBits bits from a, where the least significant extracted bit
-  is bit lsbNum.  Returns a negative value if error occurs.
-  - Because sign bit is used to indicate error, maximum number of bits to 
-  be returned is the lesser of (a) the number of bits in an mp_digit, or
-  (b) one less than the number of bits in an mp_err.
-  - lsbNum + numbits can be greater than the number of significant bits in
-  integer a, as long as bit lsbNum is in the high order digit of a.
- */
-mp_err mpl_get_bits(const mp_int *a, mp_size lsbNum, mp_size numBits) 
-{
-  mp_size    rshift = (lsbNum % MP_DIGIT_BIT);
-  mp_size    lsWndx = (lsbNum / MP_DIGIT_BIT);
-  mp_digit * digit  = MP_DIGITS(a) + lsWndx;
-  mp_digit   mask   = ((1 << numBits) - 1);
-
-  ARGCHK(numBits < CHAR_BIT * sizeof mask, MP_BADARG);
-  ARGCHK(MP_HOWMANY(lsbNum, MP_DIGIT_BIT) <= MP_USED(a), MP_RANGE);
-
-  if ((numBits + lsbNum % MP_DIGIT_BIT <= MP_DIGIT_BIT) ||
-      (lsWndx + 1 >= MP_USED(a))) {
-    mask &= (digit[0] >> rshift);
-  } else {
-    mask &= ((digit[0] >> rshift) | (digit[1] << (MP_DIGIT_BIT - rshift)));
-  }
-  return (mp_err)mask;
-}
-
-/*
-  mpl_significant_bits
-  returns number of significnant bits in abs(a).
-  returns 1 if value is zero.
- */
-mp_size mpl_significant_bits(const mp_int *a)
-{
-  mp_size bits = 0;
-  int    ix;
-
-  ARGCHK(a != NULL, MP_BADARG);
-
-  ix = MP_USED(a);
-  for (ix = MP_USED(a); ix > 0; ) {
-    mp_digit d;
-    d = MP_DIGIT(a, --ix);
-    if (d) {
-      while (d) {
-        ++bits;
-        d >>= 1;
-      }
-      break;
-    }
-  }
-  bits += ix * MP_DIGIT_BIT;
-  if (!bits)
-    bits = 1;
-  return bits;
-}
-
-/*------------------------------------------------------------------------*/
-/* HERE THERE BE DRAGONS                                                  */