[Guile-commits] 10/85: Implement truncate-quotient with new integer lib

[Andy Wingo]

wingo pushed a commit to branch main
in repository guile.

commit ff636774b4f7ecf4f1f43721d9afde9d32fb53c1
Author: Andy Wingo <wingo@pobox.com>
AuthorDate: Mon Dec 13 09:43:28 2021 +0100

    Implement truncate-quotient with new integer lib
    
    * libguile/integers.c (scm_integer_truncate_quotient_ii)
    (scm_integer_truncate_quotient_iz, scm_integer_truncate_quotient_zi)
    (scm_integer_truncate_quotient_zz): New internal functions.
    * libguile/integers.h: Declare internal functions.
    * libguile/numbers.c (scm_truncate_quotient): Use the new functions.
---
 libguile/integers.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++++
 libguile/integers.h |  5 ++++
 libguile/numbers.c  | 68 ++++++++---------------------------------------------
 3 files changed, 77 insertions(+), 58 deletions(-)

diff --git a/libguile/integers.c b/libguile/integers.c
index 1d2254745..5653fa8d2 100644
--- a/libguile/integers.c
+++ b/libguile/integers.c
@@ -812,3 +812,65 @@ scm_integer_ceiling_divide_zz (SCM x, SCM y, SCM *qp, SCM 
*rp)
   *qp = take_mpz (q);
   *rp = take_mpz (r);
 }
+
+SCM
+scm_integer_truncate_quotient_ii (scm_t_inum x, scm_t_inum y)
+{
+  if (y == 0)
+    scm_num_overflow ("truncate-quotient");
+  else
+    {
+      scm_t_inum q = x / y;
+      return long_to_scm (q);
+    }
+}
+
+SCM
+scm_integer_truncate_quotient_iz (scm_t_inum x, SCM y)
+{
+  if (x == SCM_MOST_NEGATIVE_FIXNUM &&
+      bignum_cmp_long (scm_bignum (y), -SCM_MOST_NEGATIVE_FIXNUM) == 0)
+    {
+      /* Special case: x == fixnum-min && y == abs (fixnum-min) */
+      scm_remember_upto_here_1 (y);
+      return SCM_I_MAKINUM (-1);
+    }
+  else
+    return SCM_INUM0;
+}
+
+SCM
+scm_integer_truncate_quotient_zi (SCM x, scm_t_inum y)
+{
+  if (y == 0)
+    scm_num_overflow ("truncate-quotient");
+  else if (y == 1)
+    return x;
+  else
+    {
+      mpz_t q, zx;
+      mpz_init (q);
+      alias_bignum_to_mpz (scm_bignum (x), zx);
+      if (y > 0)
+        mpz_tdiv_q_ui (q, zx, y);
+      else
+        {
+          mpz_tdiv_q_ui (q, zx, -y);
+          mpz_neg (q, q);
+        }
+      scm_remember_upto_here_1 (x);
+      return take_mpz (q);
+    }
+}
+
+SCM
+scm_integer_truncate_quotient_zz (SCM x, SCM y)
+{
+  mpz_t q, zx, zy;
+  mpz_init (q);
+  alias_bignum_to_mpz (scm_bignum (x), zx);
+  alias_bignum_to_mpz (scm_bignum (y), zy);
+  mpz_tdiv_q (q, zx, zy);
+  scm_remember_upto_here_2 (x, y);
+  return take_mpz (q);
+}
diff --git a/libguile/integers.h b/libguile/integers.h
index 331f4aec6..9707444f7 100644
--- a/libguile/integers.h
+++ b/libguile/integers.h
@@ -67,6 +67,11 @@ SCM_INTERNAL void scm_integer_ceiling_divide_zi (SCM x, 
scm_t_inum y,
 SCM_INTERNAL void scm_integer_ceiling_divide_zz (SCM x, SCM y,
                                                  SCM *qp, SCM *rp);
 
+SCM_INTERNAL SCM scm_integer_truncate_quotient_ii (scm_t_inum x, scm_t_inum y);
+SCM_INTERNAL SCM scm_integer_truncate_quotient_iz (scm_t_inum x, SCM y);
+SCM_INTERNAL SCM scm_integer_truncate_quotient_zi (SCM x, scm_t_inum y);
+SCM_INTERNAL SCM scm_integer_truncate_quotient_zz (SCM x, SCM y);
+
 
 
 #endif  /* SCM_INTEGERS_H */
diff --git a/libguile/numbers.c b/libguile/numbers.c
index 2e73bac1d..7abc727d7 100644
--- a/libguile/numbers.c
+++ b/libguile/numbers.c
@@ -1815,38 +1815,16 @@ SCM_PRIMITIVE_GENERIC (scm_truncate_quotient, 
"truncate-quotient", 2, 0, 0,
                       "@end lisp")
 #define FUNC_NAME s_scm_truncate_quotient
 {
-  if (SCM_LIKELY (SCM_I_INUMP (x)))
+  if (SCM_I_INUMP (x))
     {
-      scm_t_inum xx = SCM_I_INUM (x);
-      if (SCM_LIKELY (SCM_I_INUMP (y)))
-       {
-         scm_t_inum yy = SCM_I_INUM (y);
-         if (SCM_UNLIKELY (yy == 0))
-           scm_num_overflow (s_scm_truncate_quotient);
-         else
-           {
-             scm_t_inum qq = xx / yy;
-             if (SCM_LIKELY (SCM_FIXABLE (qq)))
-               return SCM_I_MAKINUM (qq);
-             else
-               return scm_i_inum2big (qq);
-           }
-       }
+      if (SCM_I_INUMP (y))
+        return scm_integer_truncate_quotient_ii (SCM_I_INUM (x),
+                                                 SCM_I_INUM (y));
       else if (SCM_BIGP (y))
-       {
-         if (SCM_UNLIKELY (xx == SCM_MOST_NEGATIVE_FIXNUM)
-             && SCM_UNLIKELY (mpz_cmp_ui (SCM_I_BIG_MPZ (y),
-                                          - SCM_MOST_NEGATIVE_FIXNUM) == 0))
-           {
-             /* Special case: x == fixnum-min && y == abs (fixnum-min) */
-             scm_remember_upto_here_1 (y);
-             return SCM_I_MAKINUM (-1);
-           }
-         else
-           return SCM_INUM0;
-       }
+        return scm_integer_truncate_quotient_iz (SCM_I_INUM (x), y);
       else if (SCM_REALP (y))
-       return scm_i_inexact_truncate_quotient (xx, SCM_REAL_VALUE (y));
+       return scm_i_inexact_truncate_quotient (SCM_I_INUM (x),
+                                                SCM_REAL_VALUE (y));
       else if (SCM_FRACTIONP (y))
        return scm_i_exact_rational_truncate_quotient (x, y);
       else
@@ -1855,36 +1833,10 @@ SCM_PRIMITIVE_GENERIC (scm_truncate_quotient, 
"truncate-quotient", 2, 0, 0,
     }
   else if (SCM_BIGP (x))
     {
-      if (SCM_LIKELY (SCM_I_INUMP (y)))
-       {
-         scm_t_inum yy = SCM_I_INUM (y);
-         if (SCM_UNLIKELY (yy == 0))
-           scm_num_overflow (s_scm_truncate_quotient);
-         else if (SCM_UNLIKELY (yy == 1))
-           return x;
-         else
-           {
-             SCM q = scm_i_mkbig ();
-             if (yy > 0)
-               mpz_tdiv_q_ui (SCM_I_BIG_MPZ (q), SCM_I_BIG_MPZ (x), yy);
-             else
-               {
-                 mpz_tdiv_q_ui (SCM_I_BIG_MPZ (q), SCM_I_BIG_MPZ (x), -yy);
-                 mpz_neg (SCM_I_BIG_MPZ (q), SCM_I_BIG_MPZ (q));
-               }
-             scm_remember_upto_here_1 (x);
-             return scm_i_normbig (q);
-           }
-       }
+      if (SCM_I_INUMP (y))
+        return scm_integer_truncate_quotient_zi (x, SCM_I_INUM (y));
       else if (SCM_BIGP (y))
-       {
-         SCM q = scm_i_mkbig ();
-         mpz_tdiv_q (SCM_I_BIG_MPZ (q),
-                     SCM_I_BIG_MPZ (x),
-                     SCM_I_BIG_MPZ (y));
-         scm_remember_upto_here_2 (x, y);
-         return scm_i_normbig (q);
-       }
+        return scm_integer_truncate_quotient_zz (x, y);
       else if (SCM_REALP (y))
        return scm_i_inexact_truncate_quotient
          (scm_i_big2dbl (x), SCM_REAL_VALUE (y));