kernel/timeconst.pl

   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 $has_bigint = eval 'use Math::BigInt qw(bgcd); 1;';
 160
 161 sub bint($)
 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 #
 171 sub fmul($$$)
 172 {
 173         my ($b,$n,$d) = @_;
 174
 175         $n = bint($n);
 176         $d = bint($d);
 177
 178         return scalar (($n << $b)+$d-bint(1))/$d;
 179 }
 180
 181 sub fadj($$$)
 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
 192 sub fmuls($$$) {
 193         my($b,$n,$d) = @_;
 194         my($s,$m);
 195         my($thres) = bint(1) << ($b-1);
 196
 197         $n = bint($n);
 198         $d = bint($d);
 199
 200         for ($s = 0; 1; $s++) {
 201                 $m = fmul($s,$n,$d);
 202                 return $s if ($m >= $thres);
 203         }
 204         return 0;
 205 }
 206
 207 # Generate a hex value if the result fits in 64 bits;
 208 # otherwise skip.
 209 sub bignum_hex($) {
 210         my($x) = @_;
 211         my $s = $x->as_hex();
 212
 213         return (length($s) > 18) ? undef : $s;
 214 }
 215
 216 # Provides mul, adj, and shr factors for a specific
 217 # (bit, time, hz) combination
 218 sub muladj($$$) {
 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
 227 sub numden($$) {
 228         my($n, $d) = @_;
 229         my $g = bgcd($n, $d);
 230         return ($n/$g, $d/$g);
 231 }
 232
 233 # All values for a specific (time, hz) combo
 234 sub conversions($$) {
 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, $t));
 245
 246         return @val;
 247 }
 248
 249 sub compute_values($) {
 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
 268 sub 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
 281 sub 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
 319 sub 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
 338 if ($hz eq '--can') {
 339         shift(@ARGV);
 340         @hzlist = sort {$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{$hz}};
 373         if (!defined(@val)) {
 374                 @val = compute_values($hz);
 375         }
 376         output($hz, @val);
 377 }
 378 exit 0;