wingo pushed a commit to branch wip-inline-digits
in repository guile.
commit f17bd62fde42e9f752e2da158a8f410e09d9b690
Author: Andy Wingo <[email protected]>
AuthorDate: Fri Jan 7 11:18:48 2022 +0100
Simplify scm_exact_integer_quotient
* libguile/integers.h:
* libguile/integers.c (scm_integer_exact_quotient_iz): New internal
function.
* libguile/numbers.c (scm_i_make_ratio): Simplify and enforce
invariants.
(scm_exact_integer_quotient): Use integer lib.
---
libguile/integers.c | 14 ++++++++
libguile/integers.h | 2 ++
libguile/numbers.c | 102 +++++++++++++++-------------------------------------
3 files changed, 44 insertions(+), 74 deletions(-)
diff --git a/libguile/integers.c b/libguile/integers.c
index f8a03266e..f6d33a21c 100644
--- a/libguile/integers.c
+++ b/libguile/integers.c
@@ -2939,6 +2939,20 @@ scm_integer_exact_quotient_ii (scm_t_inum n, scm_t_inum
d)
return scm_integer_truncate_quotient_ii (n, d);
}
+SCM
+scm_integer_exact_quotient_iz (scm_t_inum n, struct scm_bignum *d)
+{
+ // There are only two fixnum numerators that are evenly divided by
+ // bignum denominators: 0, which is evenly divided 0 times by
+ // anything, and SCM_MOST_NEGATIVE_FIXNUM, which is evenly divided -1
+ // time by SCM_MOST_POSITIVE_FIXNUM+1.
+ if (n == 0)
+ return SCM_INUM0;
+ ASSERT (n == SCM_MOST_NEGATIVE_FIXNUM);
+ ASSERT (bignum_cmp_long (d, SCM_MOST_POSITIVE_FIXNUM + 1) == 0);
+ return SCM_I_MAKINUM (-1);
+}
+
/* Return the exact integer q such that n = q*d, for exact integers n
and d, where d is known in advance to divide n evenly (with zero
remainder). For large integers, this can be computed more
diff --git a/libguile/integers.h b/libguile/integers.h
index 1acfc1609..470d3ea54 100644
--- a/libguile/integers.h
+++ b/libguile/integers.h
@@ -197,6 +197,8 @@ SCM_INTERNAL int scm_is_integer_divisible_zz (struct
scm_bignum *x,
struct scm_bignum *y);
SCM_INTERNAL SCM scm_integer_exact_quotient_ii (scm_t_inum n, scm_t_inum d);
+SCM_INTERNAL SCM scm_integer_exact_quotient_iz (scm_t_inum n,
+ struct scm_bignum *d);
SCM_INTERNAL SCM scm_integer_exact_quotient_zi (struct scm_bignum *n,
scm_t_inum d);
SCM_INTERNAL SCM scm_integer_exact_quotient_zz (struct scm_bignum *n,
diff --git a/libguile/numbers.c b/libguile/numbers.c
index 9bf85686c..280a91ab4 100644
--- a/libguile/numbers.c
+++ b/libguile/numbers.c
@@ -412,22 +412,19 @@ static SCM
scm_i_make_ratio (SCM numerator, SCM denominator)
#define FUNC_NAME "make-ratio"
{
- /* Make sure the arguments are proper */
- if (!SCM_LIKELY (SCM_I_INUMP (numerator) || SCM_BIGP (numerator)))
- SCM_WRONG_TYPE_ARG (1, numerator);
- else if (!SCM_LIKELY (SCM_I_INUMP (denominator) || SCM_BIGP (denominator)))
- SCM_WRONG_TYPE_ARG (2, denominator);
- else
+ if (!scm_is_exact_integer (numerator))
+ abort();
+ if (!scm_is_exact_integer (denominator))
+ abort();
+
+ SCM the_gcd = scm_gcd (numerator, denominator);
+ if (!(scm_is_eq (the_gcd, SCM_INUM1)))
{
- SCM the_gcd = scm_gcd (numerator, denominator);
- if (!(scm_is_eq (the_gcd, SCM_INUM1)))
- {
- /* Reduce to lowest terms */
- numerator = scm_exact_integer_quotient (numerator, the_gcd);
- denominator = scm_exact_integer_quotient (denominator, the_gcd);
- }
- return scm_i_make_ratio_already_reduced (numerator, denominator);
+ /* Reduce to lowest terms */
+ numerator = scm_exact_integer_quotient (numerator, the_gcd);
+ denominator = scm_exact_integer_quotient (denominator, the_gcd);
}
+ return scm_i_make_ratio_already_reduced (numerator, denominator);
}
#undef FUNC_NAME
@@ -921,73 +918,30 @@ static SCM
scm_exact_integer_quotient (SCM n, SCM d)
#define FUNC_NAME "exact-integer-quotient"
{
- if (SCM_LIKELY (SCM_I_INUMP (n)))
+ if (SCM_I_INUMP (n))
{
- scm_t_inum nn = SCM_I_INUM (n);
- if (SCM_LIKELY (SCM_I_INUMP (d)))
- {
- scm_t_inum dd = SCM_I_INUM (d);
- if (SCM_UNLIKELY (dd == 0))
- scm_num_overflow ("exact-integer-quotient");
- else
- {
- scm_t_inum qq = nn / dd;
- if (SCM_LIKELY (SCM_FIXABLE (qq)))
- return SCM_I_MAKINUM (qq);
- else
- return scm_i_inum2big (qq);
- }
- }
- else if (SCM_LIKELY (SCM_BIGP (d)))
- {
- /* n is an inum and d is a bignum. Given that d is known to
- divide n evenly, there are only two possibilities: n is 0,
- or else n is fixnum-min and d is abs(fixnum-min). */
- if (nn == 0)
- return SCM_INUM0;
- else
- return SCM_I_MAKINUM (-1);
- }
+ if (scm_is_eq (n, d))
+ return SCM_INUM1;
+ if (SCM_I_INUMP (d))
+ return scm_integer_exact_quotient_ii (SCM_I_INUM (n), SCM_I_INUM (d));
+ else if (SCM_BIGP (d))
+ return scm_integer_exact_quotient_iz (SCM_I_INUM (n), scm_bignum (d));
else
- SCM_WRONG_TYPE_ARG (2, d);
+ abort (); // Unreachable.
}
- else if (SCM_LIKELY (SCM_BIGP (n)))
+ else if (SCM_BIGP (n))
{
- if (SCM_LIKELY (SCM_I_INUMP (d)))
- {
- scm_t_inum dd = SCM_I_INUM (d);
- if (SCM_UNLIKELY (dd == 0))
- scm_num_overflow ("exact-integer-quotient");
- else if (SCM_UNLIKELY (dd == 1))
- return n;
- else
- {
- SCM q = scm_i_mkbig ();
- if (dd > 0)
- mpz_divexact_ui (SCM_I_BIG_MPZ (q), SCM_I_BIG_MPZ (n), dd);
- else
- {
- mpz_divexact_ui (SCM_I_BIG_MPZ (q), SCM_I_BIG_MPZ (n), -dd);
- mpz_neg (SCM_I_BIG_MPZ (q), SCM_I_BIG_MPZ (q));
- }
- scm_remember_upto_here_1 (n);
- return scm_i_normbig (q);
- }
- }
- else if (SCM_LIKELY (SCM_BIGP (d)))
- {
- SCM q = scm_i_mkbig ();
- mpz_divexact (SCM_I_BIG_MPZ (q),
- SCM_I_BIG_MPZ (n),
- SCM_I_BIG_MPZ (d));
- scm_remember_upto_here_2 (n, d);
- return scm_i_normbig (q);
- }
+ if (scm_is_eq (n, d))
+ return SCM_INUM1;
+ if (SCM_I_INUMP (d))
+ return scm_integer_exact_quotient_zi (scm_bignum (n), SCM_I_INUM (d));
+ else if (SCM_BIGP (d))
+ return scm_integer_exact_quotient_zz (scm_bignum (n), scm_bignum (d));
else
- SCM_WRONG_TYPE_ARG (2, d);
+ abort (); // Unreachable.
}
else
- SCM_WRONG_TYPE_ARG (1, n);
+ abort (); // Unreachable.
}
#undef FUNC_NAME
