[PATCH 2/3] convert timeconst.pl to mktimeconst.c
From: Rob Landley
Date: Wed Feb 27 2013 - 00:59:42 EST
From: Rob Landley <rob@xxxxxxxxxxx>
Replace perl header file generator with smaller/faster/simpler C version.
Hasn't changed in several years, see:
Message-ID: <4D35FEF3.4070001@xxxxxxxxxxxxx>
Subject: Re: [PATCH] Use sed instead of perl to generate x86/kernel/cpu/capflags.c.
Note, the version I submitted 2 years ago included a test program to show
it was producing the same output for HZ 1 through 5000:
https://lkml.org/lkml/2011/1/18/257
Signed-off-by: Rob Landley <rob@xxxxxxxxxxx>
---
kernel/Makefile | 10 -
kernel/mktimeconst.c | 110 +++++++++++
kernel/timeconst.pl | 376 -----------------------------------------
3 files changed, 116 insertions(+), 380 deletions(-)
diff --git a/kernel/Makefile b/kernel/Makefile
index eceac38..f00be6d 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -127,11 +127,13 @@ $(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
+++ linux/kernel/mktimeconst.c
@@ -0,0 +1,110 @@
+/* Copyright 2010 Parallels Inc, licensed under GPLv2 */
+/* Copyright 2010-2013 Rob Landley <rob@xxxxxxxxxxx> */
+
+#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);
+}
--- linux/kernel/timeconst.pl
+++ /dev/null
@@ -1,376 +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";
- }
-
- $cv = $canned_values{$hz};
- @val = defined($cv) ? @$cv : compute_values($hz);
- output($hz, @val);
-}
-exit 0;
--
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