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Support (ash INTEGER BIGNUM)

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* src/data.c (emacs_mpz_mul_2exp): 2nd arg is now a
nonnegative EMACS_INT not mp_bitcnt_t, to simplify checking.
(Fash): Support COUNT values that are bignums or that
exceed mp_bitcnt_t range.
* test/src/data-tests.el (data-tests-ash-lsh): Test this.
This commit is contained in:
Paul Eggert 2018-12-18 12:21:27 -08:00
parent 5a04e82614
commit cdaaaf2e1b
2 changed files with 25 additions and 8 deletions
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29
src/data.c
View file

@ -2414,14 +2414,14 @@ emacs_mpz_mul (mpz_t rop, mpz_t const op1, mpz_t const op2)
}
static void
emacs_mpz_mul_2exp (mpz_t rop, mpz_t const op1, mp_bitcnt_t op2)
emacs_mpz_mul_2exp (mpz_t rop, mpz_t const op1, EMACS_INT op2)
{
/* Fudge factor derived from GMP 6.1.2, to avoid an abort in
mpz_mul_2exp (look for the '+ 1' in its source code). */
enum { mul_2exp_extra_limbs = 1 };
enum { lim = min (NLIMBS_LIMIT, GMP_NLIMBS_MAX - mul_2exp_extra_limbs) };
mp_bitcnt_t op2limbs = op2 / GMP_NUMB_BITS;
EMACS_INT op2limbs = op2 / GMP_NUMB_BITS;
if (lim - emacs_mpz_size (op1) < op2limbs)
overflow_error ();
mpz_mul_2exp (rop, op1, op2);
@ -3251,12 +3251,21 @@ If COUNT is negative, shifting is actually to the right.
In this case, the sign bit is duplicated. */)
(Lisp_Object value, Lisp_Object count)
{
/* The negative of the minimum value of COUNT that fits into a fixnum,
such that mpz_fdiv_q_exp supports -COUNT. */
EMACS_INT minus_count_min = min (-MOST_NEGATIVE_FIXNUM,
TYPE_MAXIMUM (mp_bitcnt_t));
CHECK_INTEGER (value);
CHECK_RANGED_INTEGER (count, - minus_count_min, TYPE_MAXIMUM (mp_bitcnt_t));
CHECK_INTEGER (count);
if (! FIXNUMP (count))
{
if (EQ (value, make_fixnum (0)))
return value;
if (mpz_sgn (XBIGNUM (count)->value) < 0)
{
EMACS_INT v = (FIXNUMP (value) ? XFIXNUM (value)
: mpz_sgn (XBIGNUM (value)->value));
return make_fixnum (v < 0 ? -1 : 0);
}
overflow_error ();
}
if (XFIXNUM (count) <= 0)
{
@ -3275,7 +3284,11 @@ In this case, the sign bit is duplicated. */)
mpz_t *zval = bignum_integer (&mpz[0], value);
if (XFIXNUM (count) < 0)
mpz_fdiv_q_2exp (mpz[0], *zval, - XFIXNUM (count));
{
if (TYPE_MAXIMUM (mp_bitcnt_t) < - XFIXNUM (count))
return make_fixnum (mpz_sgn (*zval) < 0 ? -1 : 0);
mpz_fdiv_q_2exp (mpz[0], *zval, - XFIXNUM (count));
}
else
emacs_mpz_mul_2exp (mpz[0], *zval, XFIXNUM (count));
return make_integer_mpz ();

4
test/src/data-tests.el
View file

@ -656,6 +656,10 @@ comparing the subr with a much slower lisp implementation."
(ert-deftest data-tests-ash-lsh ()
(should (= (ash most-negative-fixnum 1)
(* most-negative-fixnum 2)))
(should (= (ash 0 (* 2 most-positive-fixnum)) 0))
(should (= (ash 1000 (* 2 most-negative-fixnum)) 0))
(should (= (ash -1000 (* 2 most-negative-fixnum)) -1))
(should (= (ash (* 2 most-negative-fixnum) (* 2 most-negative-fixnum)) -1))
(should (= (lsh most-negative-fixnum 1)
(* most-negative-fixnum 2)))
(should (= (ash (* 2 most-negative-fixnum) -1)