[Guile-commits] 06/85: Implement floor-divide with new integer lib

[Andy Wingo]

wingo pushed a commit to branch main
in repository guile.

commit 8a6353745898a82322c813d289ed433bb7e597c4
Author: Andy Wingo <wingo@pobox.com>
AuthorDate: Sun Dec 5 22:28:59 2021 +0100

    Implement floor-divide with new integer lib
    
    * libguile/integers.c (scm_integer_floor_divide_ii)
    (scm_integer_floor_divide_iz, scm_integer_floor_divide_zi)
    (scm_integer_floor_divide_zz): New internal functions.
    * libguile/integers.h: Declare internal functions.
    * libguile/numbers.c (scm_floor_divide): Use the new functions.
---
 libguile/integers.c |  94 ++++++++++++++++++++++++++++++++++++++++++++++
 libguile/integers.h |   9 +++++
 libguile/numbers.c  | 105 ++++------------------------------------------------
 3 files changed, 111 insertions(+), 97 deletions(-)

diff --git a/libguile/integers.c b/libguile/integers.c
index e64d3f946..a791657ff 100644
--- a/libguile/integers.c
+++ b/libguile/integers.c
@@ -411,3 +411,97 @@ scm_integer_floor_remainder_zz (SCM x, SCM y)
   scm_remember_upto_here_2 (x, y);
   return SCM_PACK (normalize_bignum (take_bignum_from_mpz (r)));
 }
+
+void
+scm_integer_floor_divide_ii (scm_t_inum x, scm_t_inum y, SCM *qp, SCM *rp)
+{
+  if (y == 0)
+    scm_num_overflow ("floor-divide");
+
+  scm_t_inum q = x / y;
+  scm_t_inum r = x % y;
+  int needs_adjustment = (y > 0) ? (r < 0) : (r > 0);
+
+  if (needs_adjustment)
+    {
+      r += y;
+      q--;
+    }
+
+  *qp = long_to_scm (q);
+  *rp = SCM_I_MAKINUM (r);
+}
+
+void
+scm_integer_floor_divide_iz (scm_t_inum x, SCM y, SCM *qp, SCM *rp)
+{
+  if (!bignum_is_negative (scm_bignum (y)))
+    {
+      if (x < 0)
+        {
+          mpz_t zy, r;
+          alias_bignum_to_mpz (scm_bignum (y), zy);
+          mpz_init (r);
+          mpz_sub_ui (r, zy, -x);
+          scm_remember_upto_here_1 (y);
+          *qp = SCM_I_MAKINUM (-1);
+          *rp = SCM_PACK (normalize_bignum (take_bignum_from_mpz (r)));
+        }
+      else
+        {
+          *qp = SCM_INUM0;
+          *rp = SCM_I_MAKINUM (x);
+        }
+    }
+  else if (x <= 0)
+    {
+      *qp = SCM_INUM0;
+      *rp = SCM_I_MAKINUM (x);
+    }
+  else
+    {
+      mpz_t zy, r;
+      alias_bignum_to_mpz (scm_bignum (y), zy);
+      mpz_init (r);
+      mpz_add_ui (r, zy, x);
+      scm_remember_upto_here_1 (y);
+      *qp = SCM_I_MAKINUM (-1);
+      *rp = SCM_PACK (normalize_bignum (take_bignum_from_mpz (r)));
+    }
+}
+
+void
+scm_integer_floor_divide_zi (SCM x, scm_t_inum y, SCM *qp, SCM *rp)
+{
+  if (y == 0)
+    scm_num_overflow ("floor-divide");
+
+  mpz_t zx, q, r;
+  alias_bignum_to_mpz (scm_bignum (x), zx);
+  mpz_init (q);
+  mpz_init (r);
+  if (y > 0)
+    mpz_fdiv_qr_ui (q, r, zx, y);
+  else
+    {
+      mpz_cdiv_qr_ui (q, r, zx, -y);
+      mpz_neg (q, q);
+    }
+  scm_remember_upto_here_1 (x);
+  *qp = SCM_PACK (normalize_bignum (take_bignum_from_mpz (q)));
+  *rp = SCM_PACK (normalize_bignum (take_bignum_from_mpz (r)));
+}
+
+void
+scm_integer_floor_divide_zz (SCM x, SCM y, SCM *qp, SCM *rp)
+{
+  mpz_t zx, zy, q, r;
+  mpz_init (q);
+  mpz_init (r);
+  alias_bignum_to_mpz (scm_bignum (x), zx);
+  alias_bignum_to_mpz (scm_bignum (y), zy);
+  mpz_fdiv_qr (q, r, zx, zy);
+  scm_remember_upto_here_2 (x, y);
+  *qp = SCM_PACK (normalize_bignum (take_bignum_from_mpz (q)));
+  *rp = SCM_PACK (normalize_bignum (take_bignum_from_mpz (r)));
+}
diff --git a/libguile/integers.h b/libguile/integers.h
index 671d32ae3..7c3c3c030 100644
--- a/libguile/integers.h
+++ b/libguile/integers.h
@@ -39,6 +39,15 @@ SCM_INTERNAL SCM scm_integer_floor_remainder_iz (scm_t_inum 
x, SCM y);
 SCM_INTERNAL SCM scm_integer_floor_remainder_zi (SCM x, scm_t_inum y);
 SCM_INTERNAL SCM scm_integer_floor_remainder_zz (SCM x, SCM y);
 
+SCM_INTERNAL void scm_integer_floor_divide_ii (scm_t_inum x, scm_t_inum y,
+                                               SCM *qp, SCM *rp);
+SCM_INTERNAL void scm_integer_floor_divide_iz (scm_t_inum x, SCM y,
+                                               SCM *qp, SCM *rp);
+SCM_INTERNAL void scm_integer_floor_divide_zi (SCM x, scm_t_inum y,
+                                               SCM *qp, SCM *rp);
+SCM_INTERNAL void scm_integer_floor_divide_zz (SCM x, SCM y,
+                                               SCM *qp, SCM *rp);
+
 
 
 #endif  /* SCM_INTEGERS_H */
diff --git a/libguile/numbers.c b/libguile/numbers.c
index 44e021160..773d0da35 100644
--- a/libguile/numbers.c
+++ b/libguile/numbers.c
@@ -1409,74 +1409,14 @@ SCM_PRIMITIVE_GENERIC (scm_i_floor_divide, "floor/", 2, 
0, 0,
 void
 scm_floor_divide (SCM x, SCM y, SCM *qp, SCM *rp)
 {
-  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_floor_divide);
-         else
-           {
-             scm_t_inum qq = xx / yy;
-             scm_t_inum rr = xx % yy;
-             int needs_adjustment;
-
-             if (SCM_LIKELY (yy > 0))
-               needs_adjustment = (rr < 0);
-             else
-               needs_adjustment = (rr > 0);
-
-             if (needs_adjustment)
-               {
-                 rr += yy;
-                 qq--;
-               }
-
-             if (SCM_LIKELY (SCM_FIXABLE (qq)))
-               *qp = SCM_I_MAKINUM (qq);
-             else
-               *qp = scm_i_inum2big (qq);
-             *rp = SCM_I_MAKINUM (rr);
-           }
-       }
+      if (SCM_I_INUMP (y))
+        scm_integer_floor_divide_ii (SCM_I_INUM (x), SCM_I_INUM (y), qp, rp);
       else if (SCM_BIGP (y))
-       {
-         int sign = mpz_sgn (SCM_I_BIG_MPZ (y));
-         scm_remember_upto_here_1 (y);
-         if (sign > 0)
-           {
-             if (xx < 0)
-               {
-                 SCM r = scm_i_mkbig ();
-                 mpz_sub_ui (SCM_I_BIG_MPZ (r), SCM_I_BIG_MPZ (y), -xx);
-                 scm_remember_upto_here_1 (y);
-                 *qp = SCM_I_MAKINUM (-1);
-                 *rp = scm_i_normbig (r);
-               }
-             else
-               {
-                 *qp = SCM_INUM0;
-                 *rp = x;
-               }
-           }
-         else if (xx <= 0)
-           {
-             *qp = SCM_INUM0;
-             *rp = x;
-           }
-         else
-           {
-             SCM r = scm_i_mkbig ();
-             mpz_add_ui (SCM_I_BIG_MPZ (r), SCM_I_BIG_MPZ (y), xx);
-             scm_remember_upto_here_1 (y);
-             *qp = SCM_I_MAKINUM (-1);
-             *rp = scm_i_normbig (r);
-           }
-       }
+        scm_integer_floor_divide_iz (SCM_I_INUM (x), y, qp, rp);
       else if (SCM_REALP (y))
-       scm_i_inexact_floor_divide (xx, SCM_REAL_VALUE (y), qp, rp);
+       scm_i_inexact_floor_divide (SCM_I_INUM (x), SCM_REAL_VALUE (y), qp, rp);
       else if (SCM_FRACTIONP (y))
        scm_i_exact_rational_floor_divide (x, y, qp, rp);
       else
@@ -1485,39 +1425,10 @@ scm_floor_divide (SCM x, SCM y, SCM *qp, SCM *rp)
     }
   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_floor_divide);
-         else
-           {
-             SCM q = scm_i_mkbig ();
-             SCM r = scm_i_mkbig ();
-             if (yy > 0)
-               mpz_fdiv_qr_ui (SCM_I_BIG_MPZ (q), SCM_I_BIG_MPZ (r),
-                               SCM_I_BIG_MPZ (x), yy);
-             else
-               {
-                 mpz_cdiv_qr_ui (SCM_I_BIG_MPZ (q), SCM_I_BIG_MPZ (r),
-                                 SCM_I_BIG_MPZ (x), -yy);
-                 mpz_neg (SCM_I_BIG_MPZ (q), SCM_I_BIG_MPZ (q));
-               }
-             scm_remember_upto_here_1 (x);
-             *qp = scm_i_normbig (q);
-             *rp = scm_i_normbig (r);
-           }
-       }
+      if (SCM_I_INUMP (y))
+        scm_integer_floor_divide_zi (x, SCM_I_INUM (y), qp, rp);
       else if (SCM_BIGP (y))
-       {
-         SCM q = scm_i_mkbig ();
-         SCM r = scm_i_mkbig ();
-         mpz_fdiv_qr (SCM_I_BIG_MPZ (q), SCM_I_BIG_MPZ (r),
-                      SCM_I_BIG_MPZ (x), SCM_I_BIG_MPZ (y));
-         scm_remember_upto_here_2 (x, y);
-         *qp = scm_i_normbig (q);
-         *rp = scm_i_normbig (r);
-       }
+        scm_integer_floor_divide_zz (x, y, qp, rp);
       else if (SCM_REALP (y))
        scm_i_inexact_floor_divide (scm_i_big2dbl (x), SCM_REAL_VALUE (y),
                                     qp, rp);