Re: [ 03/53] timeconst.pl: Eliminate Perl warning

[Rob Landley <rob@landley.net>]

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On 02/26/2013 05:57:32 PM, Greg Kroah-Hartman wrote:
> 3.0-stable review patch.  If anyone has any objections, please let me  
> know.
> 
> ------------------
> 
> From: "H. Peter Anvin" <hpa@linux.intel.com>
> 
> commit 63a3f603413ffe82ad775f2d62a5afff87fd94a0 upstream.
> 
> defined(@array) is deprecated in Perl and gives off a warning.
> Restructure the code to remove that warning.
> 
> [ hpa: it would be interesting to revert to the timeconst.bc script.

Or, you know, the mktimeconst.c I've posted to this list several times  
over the past few years as part of the perl removal series I maintain?  
Most recently  
http://lkml.indiana.edu/hypermail/linux/kernel/1212.2/00729.html but  
before that rather a lot of times (list at  
http://lkml.indiana.edu/hypermail/linux/kernel/1212.2/00734.html) and  
the newest version of which is always at:

http://landley.net/hg/aboriginal/file/tip/sources/patches

I just updated them for 3.8. The mktimeconst one is attached to this  
message.

(I'm told the balsa email program manages to break whitespace in  
attachments. I'm aware how sad that is. I'm writing a darn python  
script to send mail inline without doing that. I'll repost the series  
with that. My first attempt at that script is why the posts I linked to  
above have my name mangled. Working on it...)

Rob

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From: Rob Landley <rlandley@parallels.com>

Replace perl header file generator with smaller/faster/simpler C version.

Hasn't changed since last submission, which was:

Message-ID: <4D35FEF3.4070001@parallels.com>
Subject: Re: [PATCH] Use sed instead of perl to generate x86/kernel/cpu/capflags.c.

Signed-off-by: Rob Landley <rlandley@parallels.com>
---

I ran the attached test script to compare the output of the C program
with the output of the perl version for every HZ from 1 to 5000 to make
sure it was producing the same constants.

 kernel/Makefile      |   10 -
 kernel/mktimeconst.c |  109 +++++++++++
 kernel/timeconst.pl  |  378 -----------------------------------------
 3 files changed, 115 insertions(+), 382 deletions(-)

diff --git a/kernel/Makefile b/kernel/Makefile
index 5669f71..ba9ce6d 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -133,11 +133,13 @@ $(obj)/config_data.h: $(obj)/config_data.gz FORCE
 
 $(obj)/time.o: $(obj)/timeconst.h
 
-quiet_cmd_timeconst  = TIMEC   $@
-      cmd_timeconst  = $(PERL) $< $(CONFIG_HZ) > $@
+hostprogs-y	+= mktimeconst
+quiet_cmd_mktimeconst = TIMEC   $@
+	cmd_mktimeconst = $(obj)/mktimeconst $(CONFIG_HZ) $@ || ( rm -f $@ && exit 1 )
+
 targets += timeconst.h
-$(obj)/timeconst.h: $(src)/timeconst.pl FORCE
-	$(call if_changed,timeconst)
+$(obj)/timeconst.h: $(obj)/mktimeconst FORCE
+	$(call if_changed,mktimeconst)
 
 ifeq ($(CONFIG_MODULE_SIG),y)
 #
--- /dev/null	2011-01-13 17:00:36.470564274 -0600
+++ b/kernel/mktimeconst.c	2011-01-16 12:44:04.091168778 -0600
@@ -0,0 +1,109 @@
+/* Copyright 2010 Parallels Inc, licensed under GPLv2 */
+
+#include <inttypes.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+int main(int argc, char *argv[])
+{
+	uint64_t hz, periods[] = {1000, 1000000};
+	char *names[] = {"MSEC", "USEC"};
+	FILE *file;
+	int i, j;
+
+	if (argc != 3 || (hz = atol(argv[1])) < 1
+	    || !(file = fopen(argv[2], "w")))
+	{
+		fprintf(stderr, "Usage: mktimeconst HZ FILENAME\n\n");
+		fprintf(stderr, "Generate a header file with constants to convert between\n");
+		fprintf(stderr, "decimal HZ timer ticks and milisecond or microsecond delays,\n");
+		fprintf(stderr, "using reciprocal multiplication to avoid 64 bit division.\n");
+		exit(1);
+	}
+
+	fprintf(file,
+		"/* Automatically generated by kernel/mktimeconst */\n"
+		"/* Conversion constants for HZ == %"PRIu64" */\n\n"
+		"#ifndef __KERNEL_TIMECONST_H\n"
+		"#define __KERNEL_TIMECONST_H\n\n"
+		"#include <linux/param.h>\n"
+		"#include <linux/types.h>\n\n"
+		"#if HZ != %"PRIu64"\n"
+		"#error \"kernel/timeconst.h has the wrong HZ value!\"\n"
+		"#endif\n\n", hz, hz);
+
+	/* Repeat for MSEC and USEC */
+
+	for (i = 0; i < 2; i++) {
+		uint64_t gcd, period;
+
+		/* Find greatest common denominator using Euclid's algorithm. */
+
+		gcd = hz;
+		period = periods[i];
+		while (period) {
+			uint64_t temp = gcd % period;
+			gcd = period;
+			period = temp;
+		}
+
+		/* Output both directions (HZ_TO_PERIOD and PERIOD_TO_HZ) */
+
+		for (j = 0; j < 2; j++) {
+			char name[16];
+			uint64_t from = j ? periods[i] : hz;
+			uint64_t to = j ? hz : periods[i];
+			uint64_t mul32 = 0, adj32 = 0, shift = 0;
+
+			sprintf(name, j ? "%s_TO_HZ" : "HZ_TO_%s", names[i]);
+
+			/* Figure out what shift value gives 32 significant
+			   bits of MUL32 data.  (Worst case to=1 from=1000000
+			   uses 52 bits, to<<shift won't overflow 64 bit math.)
+			*/
+
+			for (;;) {
+				mul32 = ((to << shift) + from - 1) / from;
+				if (mul32 >= (1UL<<31))
+					break;
+				shift++;
+			}
+
+			/* ADJ32 is is just (((FROM/GCD)-1)<<SHIFT)/(FROM/GCD)
+			   but this can overflow 64 bit math (examples, HZ=24
+			   or HZ=122).  Worst case scenario uses 32+20+20=72
+			   bits.  Workaround: split off bottom 32 bits and
+			   reassemble after calculation (32+64=96 bits). */
+
+			adj32 = from / gcd;
+
+			if (shift > 32) {
+				uint64_t upper, lower;
+
+				upper = (adj32 - 1) << (shift - 32);
+				lower = (upper % adj32) << 32;
+				adj32 = ((upper/adj32) << 32) + (lower/adj32);
+			} else
+				adj32 = ((adj32 - 1) << shift) / adj32;
+
+			/* Emit the constants into the header file. */
+
+			fprintf(file, "#define %s_MUL32\tU64_C(0x%"PRIx64")\n",
+				name, mul32);
+			fprintf(file, "#define %s_ADJ32\tU64_C(0x%"PRIx64")\n",
+				name, adj32);
+			fprintf(file, "#define %s_SHR32\t%"PRIu64"\n",
+				name, shift);
+			fprintf(file, "#define %s_NUM\t\tU64_C(%"PRIu64")\n",
+				name, to/gcd);
+			fprintf(file, "#define %s_DEN\t\tU64_C(%"PRIu64")\n\n",
+				name, from/gcd);
+		}
+	}
+	fprintf(file, "#endif /* __KERNEL_TIMECONST_H */\n");
+
+	/* Notice if the disk fills up. */
+
+	fflush(stdout);
+	return ferror(stdout);
+}
--- a/kernel/timeconst.pl	2010-12-19 11:33:53.969732934 -0600
+++ /dev/null	2011-01-13 17:00:36.470564274 -0600
@@ -1,378 +0,0 @@
-#!/usr/bin/perl
-# -----------------------------------------------------------------------
-#
-#   Copyright 2007-2008 rPath, Inc. - All Rights Reserved
-#
-#   This file is part of the Linux kernel, and is made available under
-#   the terms of the GNU General Public License version 2 or (at your
-#   option) any later version; incorporated herein by reference.
-#
-# -----------------------------------------------------------------------
-#
-
-#
-# Usage: timeconst.pl HZ > timeconst.h
-#
-
-# Precomputed values for systems without Math::BigInt
-# Generated by:
-# timeconst.pl --can 24 32 48 64 100 122 128 200 250 256 300 512 1000 1024 1200
-%canned_values = (
-	24 => [
-		'0xa6aaaaab','0x2aaaaaa',26,
-		125,3,
-		'0xc49ba5e4','0x1fbe76c8b4',37,
-		3,125,
-		'0xa2c2aaab','0xaaaa',16,
-		125000,3,
-		'0xc9539b89','0x7fffbce4217d',47,
-		3,125000,
-	], 32 => [
-		'0xfa000000','0x6000000',27,
-		125,4,
-		'0x83126e98','0xfdf3b645a',36,
-		4,125,
-		'0xf4240000','0x0',17,
-		31250,1,
-		'0x8637bd06','0x3fff79c842fa',46,
-		1,31250,
-	], 48 => [
-		'0xa6aaaaab','0x6aaaaaa',27,
-		125,6,
-		'0xc49ba5e4','0xfdf3b645a',36,
-		6,125,
-		'0xa2c2aaab','0x15555',17,
-		62500,3,
-		'0xc9539b89','0x3fffbce4217d',46,
-		3,62500,
-	], 64 => [
-		'0xfa000000','0xe000000',28,
-		125,8,
-		'0x83126e98','0x7ef9db22d',35,
-		8,125,
-		'0xf4240000','0x0',18,
-		15625,1,
-		'0x8637bd06','0x1fff79c842fa',45,
-		1,15625,
-	], 100 => [
-		'0xa0000000','0x0',28,
-		10,1,
-		'0xcccccccd','0x733333333',35,
-		1,10,
-		'0x9c400000','0x0',18,
-		10000,1,
-		'0xd1b71759','0x1fff2e48e8a7',45,
-		1,10000,
-	], 122 => [
-		'0x8325c53f','0xfbcda3a',28,
-		500,61,
-		'0xf9db22d1','0x7fbe76c8b',35,
-		61,500,
-		'0x8012e2a0','0x3ef36',18,
-		500000,61,
-		'0xffda4053','0x1ffffbce4217',45,
-		61,500000,
-	], 128 => [
-		'0xfa000000','0x1e000000',29,
-		125,16,
-		'0x83126e98','0x3f7ced916',34,
-		16,125,
-		'0xf4240000','0x40000',19,
-		15625,2,
-		'0x8637bd06','0xfffbce4217d',44,
-		2,15625,
-	], 200 => [
-		'0xa0000000','0x0',29,
-		5,1,
-		'0xcccccccd','0x333333333',34,
-		1,5,
-		'0x9c400000','0x0',19,
-		5000,1,
-		'0xd1b71759','0xfff2e48e8a7',44,
-		1,5000,
-	], 250 => [
-		'0x80000000','0x0',29,
-		4,1,
-		'0x80000000','0x180000000',33,
-		1,4,
-		'0xfa000000','0x0',20,
-		4000,1,
-		'0x83126e98','0x7ff7ced9168',43,
-		1,4000,
-	], 256 => [
-		'0xfa000000','0x3e000000',30,
-		125,32,
-		'0x83126e98','0x1fbe76c8b',33,
-		32,125,
-		'0xf4240000','0xc0000',20,
-		15625,4,
-		'0x8637bd06','0x7ffde7210be',43,
-		4,15625,
-	], 300 => [
-		'0xd5555556','0x2aaaaaaa',30,
-		10,3,
-		'0x9999999a','0x1cccccccc',33,
-		3,10,
-		'0xd0555556','0xaaaaa',20,
-		10000,3,
-		'0x9d495183','0x7ffcb923a29',43,
-		3,10000,
-	], 512 => [
-		'0xfa000000','0x7e000000',31,
-		125,64,
-		'0x83126e98','0xfdf3b645',32,
-		64,125,
-		'0xf4240000','0x1c0000',21,
-		15625,8,
-		'0x8637bd06','0x3ffef39085f',42,
-		8,15625,
-	], 1000 => [
-		'0x80000000','0x0',31,
-		1,1,
-		'0x80000000','0x0',31,
-		1,1,
-		'0xfa000000','0x0',22,
-		1000,1,
-		'0x83126e98','0x1ff7ced9168',41,
-		1,1000,
-	], 1024 => [
-		'0xfa000000','0xfe000000',32,
-		125,128,
-		'0x83126e98','0x7ef9db22',31,
-		128,125,
-		'0xf4240000','0x3c0000',22,
-		15625,16,
-		'0x8637bd06','0x1fff79c842f',41,
-		16,15625,
-	], 1200 => [
-		'0xd5555556','0xd5555555',32,
-		5,6,
-		'0x9999999a','0x66666666',31,
-		6,5,
-		'0xd0555556','0x2aaaaa',22,
-		2500,3,
-		'0x9d495183','0x1ffcb923a29',41,
-		3,2500,
-	]
-);
-
-$has_bigint = eval 'use Math::BigInt qw(bgcd); 1;';
-
-sub bint($)
-{
-	my($x) = @_;
-	return Math::BigInt->new($x);
-}
-
-#
-# Constants for division by reciprocal multiplication.
-# (bits, numerator, denominator)
-#
-sub fmul($$$)
-{
-	my ($b,$n,$d) = @_;
-
-	$n = bint($n);
-	$d = bint($d);
-
-	return scalar (($n << $b)+$d-bint(1))/$d;
-}
-
-sub fadj($$$)
-{
-	my($b,$n,$d) = @_;
-
-	$n = bint($n);
-	$d = bint($d);
-
-	$d = $d/bgcd($n, $d);
-	return scalar (($d-bint(1)) << $b)/$d;
-}
-
-sub fmuls($$$) {
-	my($b,$n,$d) = @_;
-	my($s,$m);
-	my($thres) = bint(1) << ($b-1);
-
-	$n = bint($n);
-	$d = bint($d);
-
-	for ($s = 0; 1; $s++) {
-		$m = fmul($s,$n,$d);
-		return $s if ($m >= $thres);
-	}
-	return 0;
-}
-
-# Generate a hex value if the result fits in 64 bits;
-# otherwise skip.
-sub bignum_hex($) {
-	my($x) = @_;
-	my $s = $x->as_hex();
-
-	return (length($s) > 18) ? undef : $s;
-}
-
-# Provides mul, adj, and shr factors for a specific
-# (bit, time, hz) combination
-sub muladj($$$) {
-	my($b, $t, $hz) = @_;
-	my $s = fmuls($b, $t, $hz);
-	my $m = fmul($s, $t, $hz);
-	my $a = fadj($s, $t, $hz);
-	return (bignum_hex($m), bignum_hex($a), $s);
-}
-
-# Provides numerator, denominator values
-sub numden($$) {
-	my($n, $d) = @_;
-	my $g = bgcd($n, $d);
-	return ($n/$g, $d/$g);
-}
-
-# All values for a specific (time, hz) combo
-sub conversions($$) {
-	my ($t, $hz) = @_;
-	my @val = ();
-
-	# HZ_TO_xx
-	push(@val, muladj(32, $t, $hz));
-	push(@val, numden($t, $hz));
-
-	# xx_TO_HZ
-	push(@val, muladj(32, $hz, $t));
-	push(@val, numden($hz, $t));
-
-	return @val;
-}
-
-sub compute_values($) {
-	my($hz) = @_;
-	my @val = ();
-	my $s, $m, $a, $g;
-
-	if (!$has_bigint) {
-		die "$0: HZ == $hz not canned and ".
-		    "Math::BigInt not available\n";
-	}
-
-	# MSEC conversions
-	push(@val, conversions(1000, $hz));
-
-	# USEC conversions
-	push(@val, conversions(1000000, $hz));
-
-	return @val;
-}
-
-sub outputval($$)
-{
-	my($name, $val) = @_;
-	my $csuf;
-
-	if (defined($val)) {
-	    if ($name !~ /SHR/) {
-		$val = "U64_C($val)";
-	    }
-	    printf "#define %-23s %s\n", $name.$csuf, $val.$csuf;
-	}
-}
-
-sub output($@)
-{
-	my($hz, @val) = @_;
-	my $pfx, $bit, $suf, $s, $m, $a;
-
-	print "/* Automatically generated by kernel/timeconst.pl */\n";
-	print "/* Conversion constants for HZ == $hz */\n";
-	print "\n";
-	print "#ifndef KERNEL_TIMECONST_H\n";
-	print "#define KERNEL_TIMECONST_H\n";
-	print "\n";
-
-	print "#include <linux/param.h>\n";
-	print "#include <linux/types.h>\n";
-
-	print "\n";
-	print "#if HZ != $hz\n";
-	print "#error \"kernel/timeconst.h has the wrong HZ value!\"\n";
-	print "#endif\n";
-	print "\n";
-
-	foreach $pfx ('HZ_TO_MSEC','MSEC_TO_HZ',
-		      'HZ_TO_USEC','USEC_TO_HZ') {
-		foreach $bit (32) {
-			foreach $suf ('MUL', 'ADJ', 'SHR') {
-				outputval("${pfx}_$suf$bit", shift(@val));
-			}
-		}
-		foreach $suf ('NUM', 'DEN') {
-			outputval("${pfx}_$suf", shift(@val));
-		}
-	}
-
-	print "\n";
-	print "#endif /* KERNEL_TIMECONST_H */\n";
-}
-
-# Pretty-print Perl values
-sub perlvals(@) {
-	my $v;
-	my @l = ();
-
-	foreach $v (@_) {
-		if (!defined($v)) {
-			push(@l, 'undef');
-		} elsif ($v =~ /^0x/) {
-			push(@l, "\'".$v."\'");
-		} else {
-			push(@l, $v.'');
-		}
-	}
-	return join(',', @l);
-}
-
-($hz) = @ARGV;
-
-# Use this to generate the %canned_values structure
-if ($hz eq '--can') {
-	shift(@ARGV);
-	@hzlist = sort {$a <=> $b} (@ARGV);
-
-	print "# Precomputed values for systems without Math::BigInt\n";
-	print "# Generated by:\n";
-	print "# timeconst.pl --can ", join(' ', @hzlist), "\n";
-	print "\%canned_values = (\n";
-	my $pf = "\t";
-	foreach $hz (@hzlist) {
-		my @values = compute_values($hz);
-		print "$pf$hz => [\n";
-		while (scalar(@values)) {
-			my $bit;
-			foreach $bit (32) {
-				my $m = shift(@values);
-				my $a = shift(@values);
-				my $s = shift(@values);
-				print "\t\t", perlvals($m,$a,$s), ",\n";
-			}
-			my $n = shift(@values);
-			my $d = shift(@values);
-			print "\t\t", perlvals($n,$d), ",\n";
-		}
-		print "\t]";
-		$pf = ', ';
-	}
-	print "\n);\n";
-} else {
-	$hz += 0;			# Force to number
-	if ($hz < 1) {
-		die "Usage: $0 HZ\n";
-	}
-
-	@val = @{$canned_values{$hz}};
-	if (!defined(@val)) {
-		@val = compute_values($hz);
-	}
-	output($hz, @val);
-}
-exit 0;

--------------070402000802050303040701
Content-Type: application/x-sh; name="loopy.sh"
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment; filename="loopy.sh"

#!/bin/bash

gcc mktimeconst.c || exit 1

X=1
while [ $X -lt 5000 ]
do
  echo $X

  perl ~/linux/linux/kernel/timeconst.pl $X | sed 's/KERNEL_TIMECONST/__KERNEL_TIMECONST/;/Automatically generated/d;/^$/d'> temp.txt
  ./a.out $X temp2.txt
  sed -i '/Automatically generated/d;/^$/d' temp2.txt

  diff -uw temp.txt temp2.txt || exit 1

  X=$(($X+1))
done

--------------070402000802050303040701--