1#!/usr/bin/perl
2# -----------------------------------------------------------------------
3#
4#   Copyright 2007-2008 rPath, Inc. - All Rights Reserved
5#
6#   This file is part of the Linux kernel, and is made available under
7#   the terms of the GNU General Public License version 2 or (at your
8#   option) any later version; incorporated herein by reference.
9#
10# -----------------------------------------------------------------------
11#
12
13#
14# Usage: timeconst.pl HZ > timeconst.h
15#
16
17# Precomputed values for systems without Math::BigInt
18# Generated by:
19# timeconst.pl --can 24 32 48 64 100 122 128 200 250 256 300 512 1000 1024 1200
20%canned_values = (
21	24 => [
22		'0xa6aaaaab','0x2aaaaaa',26,
23		125,3,
24		'0xc49ba5e4','0x1fbe76c8b4',37,
25		3,125,
26		'0xa2c2aaab','0xaaaa',16,
27		125000,3,
28		'0xc9539b89','0x7fffbce4217d',47,
29		3,125000,
30	], 32 => [
31		'0xfa000000','0x6000000',27,
32		125,4,
33		'0x83126e98','0xfdf3b645a',36,
34		4,125,
35		'0xf4240000','0x0',17,
36		31250,1,
37		'0x8637bd06','0x3fff79c842fa',46,
38		1,31250,
39	], 48 => [
40		'0xa6aaaaab','0x6aaaaaa',27,
41		125,6,
42		'0xc49ba5e4','0xfdf3b645a',36,
43		6,125,
44		'0xa2c2aaab','0x15555',17,
45		62500,3,
46		'0xc9539b89','0x3fffbce4217d',46,
47		3,62500,
48	], 64 => [
49		'0xfa000000','0xe000000',28,
50		125,8,
51		'0x83126e98','0x7ef9db22d',35,
52		8,125,
53		'0xf4240000','0x0',18,
54		15625,1,
55		'0x8637bd06','0x1fff79c842fa',45,
56		1,15625,
57	], 100 => [
58		'0xa0000000','0x0',28,
59		10,1,
60		'0xcccccccd','0x733333333',35,
61		1,10,
62		'0x9c400000','0x0',18,
63		10000,1,
64		'0xd1b71759','0x1fff2e48e8a7',45,
65		1,10000,
66	], 122 => [
67		'0x8325c53f','0xfbcda3a',28,
68		500,61,
69		'0xf9db22d1','0x7fbe76c8b',35,
70		61,500,
71		'0x8012e2a0','0x3ef36',18,
72		500000,61,
73		'0xffda4053','0x1ffffbce4217',45,
74		61,500000,
75	], 128 => [
76		'0xfa000000','0x1e000000',29,
77		125,16,
78		'0x83126e98','0x3f7ced916',34,
79		16,125,
80		'0xf4240000','0x40000',19,
81		15625,2,
82		'0x8637bd06','0xfffbce4217d',44,
83		2,15625,
84	], 200 => [
85		'0xa0000000','0x0',29,
86		5,1,
87		'0xcccccccd','0x333333333',34,
88		1,5,
89		'0x9c400000','0x0',19,
90		5000,1,
91		'0xd1b71759','0xfff2e48e8a7',44,
92		1,5000,
93	], 250 => [
94		'0x80000000','0x0',29,
95		4,1,
96		'0x80000000','0x180000000',33,
97		1,4,
98		'0xfa000000','0x0',20,
99		4000,1,
100		'0x83126e98','0x7ff7ced9168',43,
101		1,4000,
102	], 256 => [
103		'0xfa000000','0x3e000000',30,
104		125,32,
105		'0x83126e98','0x1fbe76c8b',33,
106		32,125,
107		'0xf4240000','0xc0000',20,
108		15625,4,
109		'0x8637bd06','0x7ffde7210be',43,
110		4,15625,
111	], 300 => [
112		'0xd5555556','0x2aaaaaaa',30,
113		10,3,
114		'0x9999999a','0x1cccccccc',33,
115		3,10,
116		'0xd0555556','0xaaaaa',20,
117		10000,3,
118		'0x9d495183','0x7ffcb923a29',43,
119		3,10000,
120	], 512 => [
121		'0xfa000000','0x7e000000',31,
122		125,64,
123		'0x83126e98','0xfdf3b645',32,
124		64,125,
125		'0xf4240000','0x1c0000',21,
126		15625,8,
127		'0x8637bd06','0x3ffef39085f',42,
128		8,15625,
129	], 1000 => [
130		'0x80000000','0x0',31,
131		1,1,
132		'0x80000000','0x0',31,
133		1,1,
134		'0xfa000000','0x0',22,
135		1000,1,
136		'0x83126e98','0x1ff7ced9168',41,
137		1,1000,
138	], 1024 => [
139		'0xfa000000','0xfe000000',32,
140		125,128,
141		'0x83126e98','0x7ef9db22',31,
142		128,125,
143		'0xf4240000','0x3c0000',22,
144		15625,16,
145		'0x8637bd06','0x1fff79c842f',41,
146		16,15625,
147	], 1200 => [
148		'0xd5555556','0xd5555555',32,
149		5,6,
150		'0x9999999a','0x66666666',31,
151		6,5,
152		'0xd0555556','0x2aaaaa',22,
153		2500,3,
154		'0x9d495183','0x1ffcb923a29',41,
155		3,2500,
156	]
157);
158
159$has_bigint = eval 'use Math::BigInt qw(bgcd); 1;';
160
161sub bint($)
162{
163	my($x) = @_;
164	return Math::BigInt->new($x);
165}
166
167#
168# Constants for division by reciprocal multiplication.
169# (bits, numerator, denominator)
170#
171sub fmul($$$)
172{
173	my ($b,$n,$d) = @_;
174
175	$n = bint($n);
176	$d = bint($d);
177
178	return scalar (($n << $b)+$d-bint(1))/$d;
179}
180
181sub fadj($$$)
182{
183	my($b,$n,$d) = @_;
184
185	$n = bint($n);
186	$d = bint($d);
187
188	$d = $d/bgcd($n, $d);
189	return scalar (($d-bint(1)) << $b)/$d;
190}
191
192sub fmuls($$$) {
193	my($b,$n,$d) = @_;
194	my($s,$m);
195	my($thres) = bint(1) << ($b-1);
196
197	$n = bint($n);
198	$d = bint($d);
199
200	for ($s = 0; 1; $s++) {
201		$m = fmul($s,$n,$d);
202		return $s if ($m >= $thres);
203	}
204	return 0;
205}
206
207# Generate a hex value if the result fits in 64 bits;
208# otherwise skip.
209sub bignum_hex($) {
210	my($x) = @_;
211	my $s = $x->as_hex();
212
213	return (length($s) > 18) ? undef : $s;
214}
215
216# Provides mul, adj, and shr factors for a specific
217# (bit, time, hz) combination
218sub muladj($$$) {
219	my($b, $t, $hz) = @_;
220	my $s = fmuls($b, $t, $hz);
221	my $m = fmul($s, $t, $hz);
222	my $a = fadj($s, $t, $hz);
223	return (bignum_hex($m), bignum_hex($a), $s);
224}
225
226# Provides numerator, denominator values
227sub numden($$) {
228	my($n, $d) = @_;
229	my $g = bgcd($n, $d);
230	return ($n/$g, $d/$g);
231}
232
233# All values for a specific (time, hz) combo
234sub conversions($$) {
235	my ($t, $hz) = @_;
236	my @val = ();
237
238	# HZ_TO_xx
239	push(@val, muladj(32, $t, $hz));
240	push(@val, numden($t, $hz));
241
242	# xx_TO_HZ
243	push(@val, muladj(32, $hz, $t));
244	push(@val, numden($hz, $t));
245
246	return @val;
247}
248
249sub compute_values($) {
250	my($hz) = @_;
251	my @val = ();
252	my $s, $m, $a, $g;
253
254	if (!$has_bigint) {
255		die "$0: HZ == $hz not canned and ".
256		    "Math::BigInt not available\n";
257	}
258
259	# MSEC conversions
260	push(@val, conversions(1000, $hz));
261
262	# USEC conversions
263	push(@val, conversions(1000000, $hz));
264
265	return @val;
266}
267
268sub outputval($$)
269{
270	my($name, $val) = @_;
271	my $csuf;
272
273	if (defined($val)) {
274	    if ($name !~ /SHR/) {
275		$val = "U64_C($val)";
276	    }
277	    printf "#define %-23s %s\n", $name.$csuf, $val.$csuf;
278	}
279}
280
281sub output($@)
282{
283	my($hz, @val) = @_;
284	my $pfx, $bit, $suf, $s, $m, $a;
285
286	print "/* Automatically generated by kernel/timeconst.pl */\n";
287	print "/* Conversion constants for HZ == $hz */\n";
288	print "\n";
289	print "#ifndef KERNEL_TIMECONST_H\n";
290	print "#define KERNEL_TIMECONST_H\n";
291	print "\n";
292
293	print "#include <linux/param.h>\n";
294	print "#include <linux/types.h>\n";
295
296	print "\n";
297	print "#if HZ != $hz\n";
298	print "#error \"kernel/timeconst.h has the wrong HZ value!\"\n";
299	print "#endif\n";
300	print "\n";
301
302	foreach $pfx ('HZ_TO_MSEC','MSEC_TO_HZ',
303		      'HZ_TO_USEC','USEC_TO_HZ') {
304		foreach $bit (32) {
305			foreach $suf ('MUL', 'ADJ', 'SHR') {
306				outputval("${pfx}_$suf$bit", shift(@val));
307			}
308		}
309		foreach $suf ('NUM', 'DEN') {
310			outputval("${pfx}_$suf", shift(@val));
311		}
312	}
313
314	print "\n";
315	print "#endif /* KERNEL_TIMECONST_H */\n";
316}
317
318# Pretty-print Perl values
319sub perlvals(@) {
320	my $v;
321	my @l = ();
322
323	foreach $v (@_) {
324		if (!defined($v)) {
325			push(@l, 'undef');
326		} elsif ($v =~ /^0x/) {
327			push(@l, "\'".$v."\'");
328		} else {
329			push(@l, $v.'');
330		}
331	}
332	return join(',', @l);
333}
334
335($hz) = @ARGV;
336
337# Use this to generate the %canned_values structure
338if ($hz eq '--can') {
339	shift(@ARGV);
340	@hzlist = sort {$a <=> $b} (@ARGV);
341
342	print "# Precomputed values for systems without Math::BigInt\n";
343	print "# Generated by:\n";
344	print "# timeconst.pl --can ", join(' ', @hzlist), "\n";
345	print "\%canned_values = (\n";
346	my $pf = "\t";
347	foreach $hz (@hzlist) {
348		my @values = compute_values($hz);
349		print "$pf$hz => [\n";
350		while (scalar(@values)) {
351			my $bit;
352			foreach $bit (32) {
353				my $m = shift(@values);
354				my $a = shift(@values);
355				my $s = shift(@values);
356				print "\t\t", perlvals($m,$a,$s), ",\n";
357			}
358			my $n = shift(@values);
359			my $d = shift(@values);
360			print "\t\t", perlvals($n,$d), ",\n";
361		}
362		print "\t]";
363		$pf = ', ';
364	}
365	print "\n);\n";
366} else {
367	$hz += 0;			# Force to number
368	if ($hz < 1) {
369		die "Usage: $0 HZ\n";
370	}
371
372	@val = @{$canned_values{$hz}};
373	if (!@val) {
374		@val = compute_values($hz);
375	}
376	output($hz, @val);
377}
378exit 0;
379