From 74f87fd111904e5156727c72590d6fc4f67e8366 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Fri, 3 Mar 2017 09:17:51 -0800
Subject: logb now works correctly on large integers

* admin/merge-gnulib (GNULIB_MODULES): Add count-leading-zeros.
* etc/NEWS: Document the change.
* lib/count-leading-zeros.c, lib/count-leading-zeros.h:
* m4/count-leading-zeros.m4: New files, copied from Gnulib.
* lib/gnulib.mk, m4/gnulib-comp.m4: Regenerate.
* src/floatfns.c: Include count-leading-zeros.h.
(Flogb): Do not convert fixnum to float before taking the log,
as the rounding error can cause the answer to be off by 1.
* src/lisp.h (EMACS_UINT_WIDTH): New constant.
* test/src/floatfns-tests.el (logb-extreme-fixnum): New test.
---
 m4/count-leading-zeros.m4 | 12 ++++++++++++
 m4/gnulib-comp.m4         |  5 +++++
 2 files changed, 17 insertions(+)
 create mode 100644 m4/count-leading-zeros.m4

(limited to 'm4')

diff --git a/m4/count-leading-zeros.m4 b/m4/count-leading-zeros.m4
new file mode 100644
index 00000000000..b6e97cf13f8
--- /dev/null
+++ b/m4/count-leading-zeros.m4
@@ -0,0 +1,12 @@
+# count-leading-zeros.m4 serial 2
+dnl Copyright (C) 2012-2017 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_COUNT_LEADING_ZEROS],
+[
+  dnl We don't need (and can't compile) count_leading_zeros_ll
+  dnl unless the type 'unsigned long long int' exists.
+  AC_REQUIRE([AC_TYPE_UNSIGNED_LONG_LONG_INT])
+])
diff --git a/m4/gnulib-comp.m4 b/m4/gnulib-comp.m4
index 14af9fbd6bf..a3e30fd736e 100644
--- a/m4/gnulib-comp.m4
+++ b/m4/gnulib-comp.m4
@@ -54,6 +54,7 @@ AC_DEFUN([gl_EARLY],
   # Code from module careadlinkat:
   # Code from module clock-time:
   # Code from module close-stream:
+  # Code from module count-leading-zeros:
   # Code from module count-one-bits:
   # Code from module count-trailing-zeros:
   # Code from module crypto/md5:
@@ -190,6 +191,7 @@ AC_DEFUN([gl_INIT],
   gl_CLOCK_TIME
   gl_CLOSE_STREAM
   gl_MODULE_INDICATOR([close-stream])
+  gl_COUNT_LEADING_ZEROS
   gl_COUNT_ONE_BITS
   gl_COUNT_TRAILING_ZEROS
   gl_MD5
@@ -871,6 +873,8 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/careadlinkat.h
   lib/close-stream.c
   lib/close-stream.h
+  lib/count-leading-zeros.c
+  lib/count-leading-zeros.h
   lib/count-one-bits.c
   lib/count-one-bits.h
   lib/count-trailing-zeros.c
@@ -1000,6 +1004,7 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/c-strtod.m4
   m4/clock_time.m4
   m4/close-stream.m4
+  m4/count-leading-zeros.m4
   m4/count-one-bits.m4
   m4/count-trailing-zeros.m4
   m4/dirent_h.m4
-- 
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