Modularize bignums better

* src/bignum.c, src/bignum.h: New files.  Only modules that
need to know how bignums are implemented should include
bignum.h.  Currently these are alloc.c, bignum.c (of course),
data.c, emacs.c, emacs-module.c, floatfns.c, fns.c, print.c.
* src/Makefile.in (base_obj): Add bignum.o.
* src/alloc.c (make_bignum_str): Move to bignum.c.
(make_number): Remove; replaced by bignum.c’s make_integer.
All callers changed.
* src/conf_post.h (ARG_NONNULL): New macro.
* src/json.c (json_to_lisp): Use it.
* src/data.c (Fnatnump):
Move NATNUMP’s implementation here from lisp.h.
* src/data.c (Fnumber_to_string):
* src/editfns.c (styled_format):
Move conversion of string to bignum to bignum_to_string, and
call it here.
* src/emacs-module.c (module_make_integer):
* src/floatfns.c (Fabs):
Simplify by using make_int.
* src/emacs.c: Include bignum.h, to expand its inline fns.
* src/floatfns.c (Ffloat): Simplify by using XFLOATINT.
(rounding_driver): Simplify by using double_to_bignum.
(rounddiv_q): Clarify use of temporaries.
* src/lisp.h: Move decls that need to know bignum internals to
bignum.h.  Do not include gmp.h or mini-gmp.h; that is now
bignum.h’s job.
(GMP_NUM_BITS, struct Lisp_Bignum, XBIGNUM, mpz_set_intmax):
Move to bignum.h.
(make_int): New function.
(NATNUMP): Remove; all callers changed to use Fnatnump.
(XFLOATINT): If arg is a bignum, use bignum_to_double, so that
bignum internals are not exposed here.
* src/print.c (print_vectorlike): Use SAFE_ALLOCA to avoid the
need for a record_unwind_protect_ptr.

1 files changed, 70 insertions, 0 deletions

diff --git a/src/bignum.h b/src/bignum.h
new file mode 100644
index 00000000000..a368333d77e
--- /dev/null
+++ b/src/bignum.h
@@ -0,0 +1,70 @@
+/* Big numbers for Emacs.
+
+Copyright 2018 Free Software Foundation, Inc.
+
+This file is part of GNU Emacs.
+
+GNU Emacs is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or (at
+your option) any later version.
+
+GNU Emacs is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
+
+/* Include this header only if access to bignum internals is needed.  */
+
+#ifndef BIGNUM_H
+#define BIGNUM_H
+
+#ifdef HAVE_GMP
+# include <gmp.h>
+#else
+# include "mini-gmp.h"
+#endif
+
+#include "lisp.h"
+
+/* Number of data bits in a limb.  */
+#ifndef GMP_NUMB_BITS
+enum { GMP_NUMB_BITS = TYPE_WIDTH (mp_limb_t) };
+#endif
+
+struct Lisp_Bignum
+{
+  union vectorlike_header header;
+  mpz_t value;
+};
+
+extern Lisp_Object make_integer (mpz_t const) ARG_NONNULL ((1));
+extern void mpz_set_intmax_slow (mpz_t, intmax_t) ARG_NONNULL ((1));
+
+INLINE_HEADER_BEGIN
+
+INLINE struct Lisp_Bignum *
+XBIGNUM (Lisp_Object a)
+{
+  eassert (BIGNUMP (a));
+  return XUNTAG (a, Lisp_Vectorlike, struct Lisp_Bignum);
+}
+
+INLINE void ARG_NONNULL ((1))
+mpz_set_intmax (mpz_t result, intmax_t v)
+{
+  /* mpz_set_si works in terms of long, but Emacs may use a wider
+     integer type, and so sometimes will have to construct the mpz_t
+     by hand.  */
+  if (LONG_MIN <= v && v <= LONG_MAX)
+    mpz_set_si (result, v);
+  else
+    mpz_set_intmax_slow (result, v);
+}
+
+INLINE_HEADER_END
+
+#endif /* BIGNUM_H */