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strftime: support %q to output the quarter of year

Message ID c16c3a8b-857a-5109-6500-4cfebd86606d@draigBrady.com
State New
Headers show

Commit Message

Pádraig Brady Nov. 4, 2016, 1:46 a.m. UTC 
Updated patch attached.

Tested using:

 sudo alternatives --set ld /usr/bin/ld.bfd
 mkdir build.tmp
 cd build.tmp
 ../configure --quiet --disable-sanity-checks
 make PARALLELMFLAGS=-j$(nproc)
 make -r PARALLELMFLAGS=-j$(nproc) -C $PWD/../time objdir=$(pwd) check
 ./testrun.sh time/tst-strftime && echo ok

Note even though the code is trivial here,
%q is useful as from the shell you need to:
$(( ($(date +%-m)-1)/3+1 ))

thanks,
Pádraig.

Comments

Paul Eggert Nov. 4, 2016, 4:12 a.m. UTC | #1 
Pádraig Brady wrote:

> +          DO_NUMBER (1, tp->tm_mon / 3 + 1);


I couldn't resist puzzling this one out. We can assume 0 <= tp->tm_mon < 12, so 
this should be a tad more efficient:

    DO_NUMBER (1, ((tp->tm_mon * 11) >> 5) + 1);

With gcc 6.2.0 -O2 x86-64, the former uses imull with 6 insns, the latter just 
leal with 4 insns. Perhaps GCC should be smart enough to figure this out on its 
own, but what would be the fun of that?
diff mbox

Patch

From 137cc31d7870e3ecda6c67cda47e29ace2c5acf6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?P=C3=A1draig=20Brady?= <P@draigBrady.com>
Date: Thu, 3 Nov 2016 19:36:59 +0000
Subject: [PATCH] strftime: support %q to output the quarter of year

This is already supported by gnulib.

* manual/time.texi: Document %q outputs quarter 1..4.
* time/strftime_l.c: Implement %q.
* time/tst-strftime.c: Add a test case.
* NEWS: Mention the new feature.
---
 NEWS                |  2 ++
 manual/time.texi    |  6 ++++++
 time/strftime_l.c   |  4 ++++
 time/tst-strftime.c | 27 +++++++++++++++++++++++++++
 4 files changed, 39 insertions(+)

diff --git a/NEWS b/NEWS
index 65184b1..9b9fa33 100644
--- a/NEWS
+++ b/NEWS
@@ -119,6 +119,8 @@  Version 2.25
   variable for a particular architecture in the GCC source file
   'gcc/config.gcc'.
 
+* strftime now supports the %q directive to output the quarter of the year.
+
 Security related changes:
 
   On ARM EABI (32-bit), generating a backtrace for execution contexts which
diff --git a/manual/time.texi b/manual/time.texi
index 6a899b7..b6466d1 100644
--- a/manual/time.texi
+++ b/manual/time.texi
@@ -1510,6 +1510,12 @@  most locales @samp{AM}/@samp{PM} format is not supported, in such cases
 
 This format is a GNU extension.
 
+@item %q
+Quarter of the year (@samp{1}@dots{}@samp{4}),
+with January starting the first quarter.
+
+This format is a GNU extension.
+
 @item %r
 The complete calendar time using the AM/PM format of the current locale.
 
diff --git a/time/strftime_l.c b/time/strftime_l.c
index 1205035..25746a0 100644
--- a/time/strftime_l.c
+++ b/time/strftime_l.c
@@ -1085,6 +1085,10 @@  __strftime_internal (CHAR_T *s, size_t maxsize, const CHAR_T *format,
 	  goto underlying_strftime;
 #endif
 
+        case L_('q'):           /* GNU extension.  */
+          DO_NUMBER (1, tp->tm_mon / 3 + 1);
+          break;
+
 	case L_('R'):
 	  subfmt = L_("%H:%M");
 	  goto subformat;
diff --git a/time/tst-strftime.c b/time/tst-strftime.c
index af3ff72..d087266 100644
--- a/time/tst-strftime.c
+++ b/time/tst-strftime.c
@@ -154,6 +154,33 @@  do_test (void)
 	}
     }
 
+  /* Check %q.  */
+  for (size_t mon = 1; mon <= 12; mon++)
+    {
+      char out[2];
+      char exp[2] = {0,};
+      struct tm qtm = { .tm_mon = mon - 1 };
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wformat"
+      size_t r = strftime (out, sizeof (out), "%q", &qtm);
+#pragma GCC diagnostic pop
+      if (r == 0)
+        {
+          puts ("strftime(\"%q\") failed");
+          result = 1;
+          break;
+        }
+
+      exp[0] = mon < 4 ? '1' : mon < 7 ? '2' : mon < 10 ? '3' : '4';
+      if (strcmp (out, exp) != 0)
+        {
+          printf ("strftime %%q: expected \"%s\", got \"%s\"\n", exp, out);
+          result = 1;
+          break;
+        }
+    }
+
   return result + do_bz18985 ();
 }
 
-- 
2.5.5