src/png/scripts/options.awk

   1 #!/bin/awk -f
   2 # scripts/options.awk - library build configuration control
   3 #
   4 # last changed in libpng version 1.5.7 - December 15, 2011
   5 #
   6 # Copyright (c) 1998-2011 Glenn Randers-Pehrson
   7 #
   8 # This code is released under the libpng license.
   9 # For conditions of distribution and use, see the disclaimer
  10 # and license in png.h
  11
  12 # The output of this script is written to the file given by
  13 # the variable 'out'.  The script is run twice, once with
  14 # an intermediate output file, 'options.tmp' then again on
  15 # that file to produce the final output:
  16 #
  17 #  awk -f scripts/options.awk out=options.tmp scripts/options.dfa 1>&2
  18 #  awk -f scripts/options.awk out=options.dfn options.tmp 1>&2
  19 #
  20 # Some options may be specified on the command line:
  21 #
  22 #  deb=1            Causes debugging to be output
  23 #  logunsupported=1 Causes all options to be recorded in the output
  24 #  everything=off   Causes all options to be disabled by default
  25 #  everything=on    Causes all options to be enabled by default
  26 #
  27 # If awk fails on your platform, try nawk instead.
  28 #
  29 # These options may also be specified in the original input file (and
  30 # are copied to the preprocessed file).
  31
  32 BEGIN{
  33    out="/dev/null"              # intermediate, preprocessed, file
  34    pre=-1                       # preprocess (first line)
  35    version="libpng version unknown" # version information
  36    version_file=""              # where to find the version
  37    err=0                        # in-line exit sets this
  38    start="PNG_DEFN_MAGIC-"      # Arbitrary start
  39    end="-PNG_DEFN_END"          # Arbitrary end
  40    ct="PNG_JOIN"                # Join two tokens
  41    cx= "/" ct "*"               # Open C comment for output file
  42    comment=start cx             # Comment start
  43    cend="*/" end                # Comment end
  44    def=start "#define PNG_" ct  # Arbitrary define
  45    sup=ct "_SUPPORTED" end      # end supported option
  46    und=comment "#undef PNG_" ct # Unsupported option
  47    une=ct "_SUPPORTED" cend     # end unsupported option
  48    error=start "ERROR:"         # error message
  49
  50    # Variables
  51    deb=0                        # debug - set on command line
  52    everything=""                # do not override defaults
  53    logunsupported=0             # write unsupported options too
  54
  55    # Precreate arrays
  56    option[""] = ""    # list of all options: default enabled/disabled
  57    done[""] = 1       # marks option as having been output
  58    requires[""] = ""  # requires by option
  59    iffs[""] = ""      # if by option
  60    enabledby[""] = "" # options that enable it by option
  61    setting[""] = ""   # requires by setting
  62    defaults[""] = ""  # used for a defaulted value
  63    doneset[""] = 1    # marks setting as having been output
  64    r[""] = ""         # Temporary array
  65
  66    # For decorating the output file
  67    protect = ""
  68 }
  69
  70 # The output file must be specified before any input:
  71 out == "/dev/null" {
  72    print "out=output.file must be given on the command line"
  73    err = 1
  74    exit 1
  75 }
  76
  77 # The very first line indicates whether we are reading pre-processed
  78 # input or not, this must come *first* because 'PREPROCESSED' needs
  79 # to be the very first line in the temporary file.
  80 pre == -1{
  81    if ($0 == "PREPROCESSED") {
  82       pre = 0
  83       next
  84    } else {
  85       pre = 1
  86       print "PREPROCESSED" >out
  87       # And fall through to continue processing
  88    }
  89 }
  90
  91 # While pre-processing if version is set to "search" look for a version string
  92 # in the following file.
  93 pre && version == "search" && version_file == ""{
  94    version_file = FILENAME
  95 }
  96
  97 pre && version == "search" && version_file != FILENAME{
  98    print "version string not found in", version_file
  99    err = 1
 100    exit 1
 101 }
 102
 103 pre && version == "search" && $0 ~ /^ \* libpng version/{
 104    version = substr($0, 4)
 105    print "version =", version >out
 106    next
 107 }
 108
 109 pre && FILENAME == version_file{
 110    next
 111 }
 112
 113 # variable=value
 114 #   Sets the given variable to the given value (the syntax is fairly
 115 #   free form, except for deb (you are expected to understand how to
 116 #   set the debug variable...)
 117 #
 118 #   This happens before the check on 'pre' below skips most of the
 119 #   rest of the actions, so the variable settings happen during
 120 #   preprocessing but are recorded in the END action too.  This
 121 #   allows them to be set on the command line too.
 122 $0 ~ /^[        ]*version[      ]*=/{
 123    sub(/^[  ]*version[  ]*=[  ]*/, "")
 124    version = $0
 125    next
 126 }
 127 $0 ~ /^[        ]*everything[   =]*off[         ]*$/{
 128    everything = "off"
 129    next
 130 }
 131 $0 ~ /^[        ]*everything[   =]*on[  ]*$/{
 132    everything = "on"
 133    next
 134 }
 135 $0 ~ /^[        ]*logunsupported[       =]*0[   ]*$/{
 136    logunsupported = 0
 137    next
 138 }
 139 $0 ~ /^[        ]*logunsupported[       =]*1[   ]*$/{
 140    logunsupported = 1
 141    next
 142 }
 143 $1 == "deb" && $2 == "=" && NF == 3{
 144    deb = $3
 145    next
 146 }
 147
 148 # Preprocessing - this just copies the input file with lines
 149 # that need preprocessing (just chunk at present) expanded
 150 # The bare "pre" instead of "pre != 0" crashes under Sunos awk
 151 pre && $1 != "chunk"{
 152    print >out
 153    next
 154 }
 155
 156 # The first characters of the line determine how it is processed,
 157 # leading spaces are ignored.  In general tokens that are not
 158 # keywords are the names of options.  An option 'name' is
 159 # controlled by the definition of the corresponding macros:
 160 #
 161 #   PNG_name_SUPPORTED    The option is turned on
 162 #   PNG_NO_name
 163 #   PNG_NO_name_SUPPORTED If the first macro is not defined
 164 #                         either of these will turn the option off
 165 #
 166 # If none of these macros are defined the option is turned on, unless
 167 # the keyword 'off' is given in a line relating to the option.  The
 168 # keyword 'on' can also be given, but it will be ignored (since it is
 169 # the default.)
 170 #
 171 # In the syntax below a 'name' is indicated by "NAME", other macro
 172 # values are indicated by "MACRO", as with "NAME" the leading "PNG_"
 173 # is omitted, but in this case the "NO_" prefix and the "_SUPPORTED"
 174 # suffix are never used.
 175 #
 176 # Each line is introduced by a keyword - the first non-space characters
 177 # on the line.  A line starting with a '#' is a comment - it is totally
 178 # ignored.  Keywords are as follows, a NAME, is simply a macro name
 179 # without the leading PNG_, PNG_NO_ or the trailing _SUPPORTED.
 180
 181 $1 ~ /^#/ || $0 ~ /^[   ]*$/{
 182    next
 183 }
 184
 185 # com <comment>
 186 #   The whole line is placed in the output file as a comment with
 187 #   the preceding 'com' removed
 188 $1 == "com"{
 189    if (NF > 1) {
 190       # sub(/^[         ]*com[  ]*/, "")
 191       $1 = ""
 192       print comment, $0, cend >out
 193    } else
 194       print start end >out
 195    next
 196 }
 197
 198 # version
 199 #   Inserts a version comment
 200 $1 == "version" && NF == 1{
 201    if (version == "") {
 202       print "ERROR: no version string set"
 203       err = 1 # prevent END{} running
 204       exit 1
 205    }
 206
 207    print comment, version, cend >out
 208    next
 209 }
 210
 211 # file output input protect
 212 #   Informational: the official name of the input file (without
 213 #   make generated local directories), the official name of the
 214 #   output file and, if required, a name to use in a protection
 215 #   macro for the contents.
 216 $1 == "file" && NF >= 2{
 217    print comment, $2, cend >out
 218    print comment, "Machine generated file: DO NOT EDIT", cend >out
 219    if (NF >= 3)
 220       print comment, "Derived from:", $3, cend >out
 221    protect = $4
 222    if (protect != "") {
 223       print start "#ifndef", protect end >out
 224       print start "#define", protect end >out
 225    }
 226    next
 227 }
 228
 229 # option NAME ( (requires|enables|if) NAME* | on | off | disabled )*
 230 #   Declares an option 'NAME' and describes its default setting (disabled)
 231 #   and its relationship to other options.  The option is disabled
 232 #   unless *all* the options listed after 'requires' are set and at
 233 #   least one of the options listed after 'if' is set.  If the
 234 #   option is set then it turns on all the options listed after 'enables'.
 235 #
 236 #   Note that "enables" takes priority over the required/if/disabled/off
 237 #   setting of the target option.
 238 #
 239 #   The definition file may list an option as 'disabled': off by default,
 240 #   otherwise the option is enabled: on by default.  A later (and it must
 241 #   be later) entry may turn an option on or off explicitly.
 242
 243 $1 == "option" && NF >= 2{
 244    onoff = option[$2]  # records current (and the default is "", enabled)
 245    key = ""
 246    for (i=3; i<=NF; ++i) {
 247       if ($(i) == "on" || $(i) == "off" || $(i) == "disabled") {
 248          key = ""
 249          if (onoff != $(i)) {
 250             # on or off can zap disabled or enabled:
 251             if (onoff == "" || (onoff == "disabled" || onoff == "enabled") && ($(i) == "on" || $(i) == "off")) {
 252                # It's easy to mis-spell the option when turning it
 253                # on or off, so warn about it here:
 254                if (onoff == "" && ($(i) == "on" || $(i) == "off")) {
 255                   print $2 ": ERROR: turning unrecognized option", $(i)
 256                   # For the moment error out - it is safer
 257                   err = 1 # prevent END{} running
 258                   exit 1
 259                }
 260                onoff = $(i)
 261             } else {
 262                # Print a message, otherwise the error
 263                # below is incomprehensible
 264                print $2 ": currently", onoff ": attempt to turn", $(i)
 265                break
 266             }
 267          }
 268       } else if ($(i) == "requires" || $(i) == "if" || $(i) == "enables") {
 269          key = $(i)
 270       } else if (key == "requires") {
 271          requires[$2] = requires[$2] " " $(i)
 272       } else if (key == "if") {
 273          iffs[$2] = iffs[$2] " " $(i)
 274       } else if (key == "enables") {
 275          enabledby[$(i)] = enabledby[$(i)] " " $2
 276       } else
 277          break # bad line format
 278    }
 279
 280    if (i > NF) {
 281       # Set the option, defaulting to 'enabled'
 282       if (onoff == "") onoff = "enabled"
 283       option[$2] = onoff
 284       next
 285    }
 286    # Else fall through to the error handler
 287 }
 288
 289 # chunk NAME [requires OPT] [on|off|disabled]
 290 #   Expands to the 'option' settings appropriate to the reading and
 291 #   writing of an ancilliary PNG chunk 'NAME':
 292 #
 293 #   option READ_NAME requires READ_ANCILLARY_CHUNKS [READ_OPT]
 294 #   option READ_NAME enables NAME
 295 #   [option READ_NAME off]
 296 #   option WRITE_NAME requires WRITE_ANCILLARY_CHUNKS [WRITE_OPT]
 297 #   option WRITE_NAME enables NAME
 298 #   [option WRITE_NAME off]
 299
 300 pre != 0 && $1 == "chunk" && NF >= 2{
 301    # 'chunk' is handled on the first pass by writing appropriate
 302    # 'option' lines into the intermediate file.
 303    onoff = ""
 304    reqread = ""
 305    reqwrite = ""
 306    i = 3 # indicates format error
 307    if (NF > 2) {
 308       # read the keywords/additional OPTS
 309       req = 0
 310       for (i=3; i<=NF; ++i) {
 311          if ($(i) == "on" || $(i) == "off" || $(i) == "disabled") {
 312             if (onoff != $(i)) {
 313                if (onoff == "")
 314                   onoff = $(i)
 315                else
 316                   break # on/off conflict
 317             }
 318          } else if ($(i) == "requires")
 319             req = 1
 320          else if (req != 1)
 321             break # bad line: handled below
 322          else {
 323             reqread = reqread " READ_" $(i)
 324             reqwrite = reqwrite " WRITE_" $(i)
 325          }
 326       }
 327    }
 328
 329    if (i > NF) {
 330       # Output new 'option' lines to the intermediate file (out)
 331       print "option READ_" $2, "requires READ_ANCILLARY_CHUNKS" reqread, "enables", $2, onoff >out
 332       print "option WRITE_" $2, "requires WRITE_ANCILLARY_CHUNKS" reqwrite, "enables", $2, onoff >out
 333       next
 334    }
 335    # Else hit the error handler below - bad line format!
 336 }
 337
 338 # setting MACRO ( requires MACRO* )* [ default VALUE ]
 339 #   Behaves in a similar way to 'option' without looking for NO_ or
 340 #   _SUPPORTED; the macro is enabled if it is defined so long as all
 341 #   the 'requires' macros are also defined.  The definitions may be
 342 #   empty, an error will be issued if the 'requires' macros are
 343 #   *not* defined.  If given the 'default' value is used if the
 344 #   macro is not defined.  The default value will be re-tokenised.
 345 #   (BTW: this is somewhat restrictive, it mainly exists for the
 346 #   support of non-standard configurations and numeric parameters,
 347 #   see the uses in scripts/options.dat
 348
 349 $1 == "setting" && (NF == 2 || NF >= 3 && ($3 == "requires" || $3 == "default")){
 350    reqs = ""
 351    deflt = ""
 352    isdef = 0
 353    key = ""
 354    for (i=3; i<=NF; ++i)
 355       if ($(i) == "requires" || $(i) == "default") {
 356          key = $(i)
 357          if (key == "default") isdef = 1
 358       } else if (key == "requires")
 359          reqs = reqs " " $(i)
 360       else if (key == "default")
 361          deflt = deflt " " $(i)
 362       else
 363          break # Format error, handled below
 364
 365    setting[$2] = reqs
 366    # NOTE: this overwrites a previous value silently
 367    if (isdef && deflt == "")
 368       deflt = " " # as a flag to force output
 369    defaults[$2] = deflt
 370    next
 371 }
 372
 373 # The order of the dependency lines (option, chunk, setting) is irrelevant
 374 # - the 'enables', 'requires' and 'if' settings will be used to determine
 375 # the correct order in the output and the final values in pnglibconf.h are
 376 # not order dependent.  'requires' and 'if' entries take precedence over
 377 # 'enables' from other options; if an option requires another option it
 378 # won't be set regardless of any options that enable it unless the other
 379 # option is also enabled.
 380 #
 381 # Similarly 'enables' trumps a NO_ definition in CFLAGS or pngusr.h
 382 #
 383 # For simplicity cycles in the definitions are regarded as errors,
 384 # even if they are not ambiguous.
 385 # A given NAME can be specified in as many 'option' lines as required, the
 386 # definitions are additive.
 387
 388 # For backwards compatibility equivalent macros may be listed thus:
 389 #
 390 # = [NO_]NAME MACRO
 391 #   Makes -DMACRO equivalent to -DPNG_NO_NAME or -DPNG_NAME_SUPPORTED
 392 #   as appropriate.
 393 #
 394 # The definition is injected into the C compiler input when encountered
 395 # in the second pass (so all these definitions appear *after* the @
 396 # lines!)
 397 #
 398 # 'NAME' is as above, but 'MACRO' is the full text of the equivalent
 399 # old, deprecated, macro.
 400
 401 $1 == "=" && NF == 3{
 402    print "#ifdef PNG_" $3 >out
 403    if ($2 ~ /^NO_/)
 404       print "#   define PNG_" $2 >out
 405    else
 406       print "#   define PNG_" $2 "_SUPPORTED" >out
 407    print "#endif" >out
 408    next
 409 }
 410
 411 # Lines may be injected into the C compiler input by preceding them
 412 # with an "@" character.  The line is copied with just the leading
 413 # @ removed.
 414
 415 $1 ~ /^@/{
 416    # sub(/^[    ]*@/, "")
 417    $1 = substr($1, 2)
 418    print >out
 419    next
 420 }
 421
 422 # Check for unreognized lines, because of the preprocessing chunk
 423 # format errors will be detected on the first pass independent of
 424 # any other format errors.
 425 {
 426    print "options.awk: bad line (" NR "):", $0
 427    err = 1 # prevent END{} running
 428    exit 1
 429 }
 430
 431 # For checking purposes names that start with "ok_" or "fail_" are
 432 # not output to pnglibconf.h and must be either enabled or disabled
 433 # respectively for the build to succeed.  This allows interdependencies
 434 # between options of the form "at least one of" or "at most one of"
 435 # to be checked.  For example:
 436 #
 437 # option FLOATING_POINT enables ok_math
 438 # option FIXED_POINT enables ok_math
 439 #   This ensures that at least one of FLOATING_POINT and FIXED_POINT
 440 #   must be set for the build to succeed.
 441 #
 442 # option fail_math requires FLOATING_POINT FIXED_POINT
 443 #   This means the build will fail if *both* FLOATING_POINT and
 444 #   FIXED_POINT are set (this is an example; in fact both are allowed.)
 445 #
 446 # If all these options were given the build would require exactly one
 447 # of the names to be enabled.
 448
 449 END{
 450    # END{} gets run on an exit (a traditional awk feature)
 451    if (err) exit 1
 452
 453    if (pre) {
 454       # Record the final value of the variables
 455       print "deb =", deb >out
 456       if (everything != "") {
 457          print "everything =", everything >out
 458       }
 459       print "logunsupported =", logunsupported >out
 460       exit 0
 461    }
 462
 463    # Do the 'setting' values first, the algorithm the standard
 464    # tree walk (O(1)) done in an O(2) while/for loop; interations
 465    # settings x depth, outputing the deepest required macros
 466    # first.
 467    print "" >out
 468    print "/* SETTINGS */" >out
 469    print comment, "settings", cend >out
 470    finished = 0
 471    while (!finished) {
 472       finished = 1
 473       movement = 0 # done nothing
 474       for (i in setting) if (!doneset[i]) {
 475          nreqs = split(setting[i], r)
 476          if (nreqs > 0) {
 477             for (j=1; j<=nreqs; ++j) if (!doneset[r[j]]) {
 478                break
 479             }
 480             if (j<=nreqs) {
 481                finished = 0
 482                continue # try a different setting
 483             }
 484          }
 485
 486          # All the requirements have been processed, output
 487          # this setting.
 488          if (deb) print "setting", i
 489          print "" >out
 490          print "/* setting: ", i >out
 491          print " *   requires:" setting[i] >out
 492          print " *   default: ", defaults[i], "*/" >out
 493          if (defaults[i] == "") { # no default, only check if defined
 494             print "#ifdef PNG_" i >out
 495          }
 496          for (j=1; j<=nreqs; ++j) {
 497             print "# ifndef PNG_" r[j] >out
 498             print error, i, "requires", r[j] end >out
 499             print "# endif" >out
 500          }
 501          if (defaults[i] != "") { # default handling
 502             print "#ifdef PNG_" i >out
 503          }
 504          print def i, "PNG_" i end >out
 505          if (defaults[i] != "") {
 506             print "#else /*default*/" >out
 507             # And add the default definition for the benefit
 508             # of later settings an options test:
 509             print "# define PNG_" i defaults[i] >out
 510             print def i defaults[i] end >out
 511          }
 512          print "#endif" >out
 513
 514          doneset[i] = 1
 515          ++movement
 516       }
 517
 518       if (!finished && !movement) {
 519          print "setting: loop or missing setting in 'requires', cannot process:"
 520          for (i in setting) if (!doneset[i]) {
 521             print "  setting", i, "requires" setting[i]
 522          }
 523          exit 1
 524       }
 525    }
 526    print comment, "end of settings", cend >out
 527
 528    # Now do the options - somewhat more complex.  The dependency
 529    # tree is thus:
 530    #
 531    #   name     >     name
 532    #   name requires  name
 533    #   name if        name
 534    #   name enabledby name
 535    #
 536    # First build a list 'tree' by option of all the things on which
 537    # it depends.
 538    print "" >out
 539    print "/* OPTIONS */" >out
 540    print comment, "options", cend >out
 541    for (opt in enabledby) tree[opt] = 1  # may not be explicit options
 542    for (opt in option) if (opt != "") {
 543       o = option[opt]
 544       # option should always be one of the following values
 545       if (o != "on" && o != "off" && o != "disabled" && o != "enabled") {
 546          print "internal option error (" o ")"
 547          exit 1
 548       }
 549       tree[opt] = ""   # so unlisted options marked
 550    }
 551    for (opt in tree) if (opt != "") {
 552       if (tree[opt] == 1) {
 553          tree[opt] = ""
 554          if (option[opt] != "") {
 555             print "internal error (1)"
 556             exit 1
 557          }
 558          # Macros only listed in 'enables' remain off unless
 559          # one of the enabling macros is on.
 560          option[opt] = "disabled"
 561       }
 562
 563       split("", list) # clear 'list'
 564       # Now add every requires, iffs or enabledby entry to 'list'
 565       # so that we can add a unique list of requirements to tree[i]
 566       split(requires[opt] iffs[opt] enabledby[opt], r)
 567       for (i in r) list[r[i]] = 1
 568       for (i in list) tree[opt] = tree[opt] " " i
 569    }
 570
 571    # print the tree for extreme debugging
 572    if (deb > 2) for (i in tree) if (i != "") print i, "depends-on" tree[i]
 573
 574    # Ok, now check all options marked explicitly 'on' or 'off':
 575    #
 576    # If an option[opt] is 'on' then turn on all requires[opt]
 577    # If an option[opt] is 'off' then turn off all enabledby[opt]
 578    #
 579    # Error out if we have to turn 'on' an 'off' option or vice versa.
 580    npending = 0
 581    for (opt in option) if (opt != "") {
 582       if (option[opt] == "on" || option[opt] == "off") {
 583          pending[++npending] = opt
 584       }
 585    }
 586
 587    err = 0 # set on error
 588    while (npending > 0) {
 589       opt = pending[npending--]
 590       if (option[opt] == "on") {
 591          nreqs = split(requires[opt], r)
 592          for (j=1; j<=nreqs; ++j) {
 593             if (option[r[j]] == "off") {
 594                print "option", opt, "turned on, but requirement", r[j], "is turned off"
 595                err = 1
 596             } else if (option[r[j]] != "on") {
 597                option[r[j]] = "on"
 598                pending[++npending] = r[j]
 599             }
 600          }
 601       } else {
 602          if (option[opt] != "off") {
 603             print "internal error (2)"
 604             exit 1
 605          }
 606          nreqs = split(enabledby[opt], r)
 607          for (j=1; j<=nreqs; ++j) {
 608             if (option[r[j]] == "on") {
 609                print "option", opt, "turned off, but enabled by", r[j], "which is turned on"
 610                err = 1
 611             } else if (option[r[j]] != "off") {
 612                option[r[j]] = "off"
 613                pending[++npending] = r[j]
 614             }
 615          }
 616       }
 617    }
 618    if (err) exit 1
 619
 620    # option[i] is now the complete list of all the tokens we may
 621    # need to output, go through it as above, depth first.
 622    finished = 0
 623    while (!finished) {
 624       finished = 1
 625       movement = 0 # done nothing
 626       for (i in option) if (!done[i]) {
 627          nreqs = split(tree[i], r)
 628          if (nreqs > 0) {
 629             for (j=1; j<=nreqs; ++j) if (!done[r[j]]) {
 630                break
 631             }
 632             if (j<=nreqs) {
 633                finished = 0
 634                continue  # next option
 635             }
 636          }
 637
 638          # All the requirements have been processed, output
 639          # this option.  An option is _SUPPORTED if:
 640          #
 641          # all 'requires' are _SUPPORTED AND
 642          # at least one of the 'if' options are _SUPPORTED AND
 643          # EITHER:
 644          #   The name is _SUPPORTED (on the command line)
 645          # OR:
 646          #   an 'enabledby' is _SUPPORTED
 647          # OR:
 648          #   NO_name is not defined AND
 649          #   the option is not disabled; an option is disabled if:
 650          #    option == off
 651          #    option == disabled && everything != on
 652          #    option == "" && everything == off
 653          if (deb) print "option", i
 654          print "" >out
 655          print "/* option:", i, option[i] >out
 656          print " *   requires:  " requires[i] >out
 657          print " *   if:      " iffs[i] >out
 658          print " *   enabled-by:" enabledby[i], "*/" >out
 659          print "#undef PNG_on" >out
 660          print "#define PNG_on 1" >out
 661
 662          # requires
 663          nreqs = split(requires[i], r)
 664          for (j=1; j<=nreqs; ++j) {
 665             print "#ifndef PNG_" r[j] "_SUPPORTED" >out
 666             print "#   undef PNG_on /*!" r[j] "*/" >out
 667             # this error appears in the final output if something
 668             # was switched 'on' but the processing above to force
 669             # the requires did not work
 670             if (option[i] == "on") {
 671                print error, i, "requires", r[j] end >out
 672             }
 673             print "#endif" >out
 674          }
 675
 676          # if
 677          nreqs = split(iffs[i], r)
 678          print "#undef PNG_no_if" >out
 679          if (nreqs > 0) {
 680             print "/* if" iffs[i], "*/" >out
 681             print "#define PNG_no_if 1" >out
 682             for (j=1; j<=nreqs; ++j) {
 683                print "#ifdef PNG_" r[j] "_SUPPORTED" >out
 684                print "#   undef PNG_no_if /*" r[j] "*/" >out
 685                print "#endif" >out
 686             }
 687             print "#ifdef PNG_no_if /*missing if*/" >out
 688             print "#   undef PNG_on" >out
 689             # There is no checking above for this, because we
 690             # don't know which 'if' to choose, so whine about
 691             # it here:
 692             if (option[i] == "on") {
 693                print error, i, "needs one of:", iffs[i] end >out
 694             }
 695             print "#endif" >out
 696          }
 697
 698          print "#ifdef PNG_on /*requires, if*/" >out
 699          # enables
 700          print "#   undef PNG_not_enabled" >out
 701          print "#   define PNG_not_enabled 1" >out
 702          print "   /* enabled by" enabledby[i], "*/" >out
 703          nreqs = split(enabledby[i], r)
 704          for (j=1; j<=nreqs; ++j) {
 705             print "#ifdef PNG_" r[j] "_SUPPORTED" >out
 706             print "#   undef PNG_not_enabled /*" r[j] "*/" >out
 707             # Oops, probably not intended (should be factored
 708             # out by the checks above).
 709             if (option[i] == "off") {
 710                print error, i, "enabled by:", r[j] end >out
 711             }
 712             print "#endif" >out
 713          }
 714
 715          print "#   ifndef PNG_" i "_SUPPORTED /*!command line*/" >out
 716          print "#    ifdef PNG_not_enabled /*!enabled*/" >out
 717          if (option[i] == "off" || option[i] == "disabled" && everything != "on" || option[i] == "enabled" && everything == "off") {
 718             print "#      undef PNG_on /*default off*/" >out
 719          } else {
 720             print "#      ifdef PNG_NO_" i >out
 721             print "#       undef PNG_on /*turned off*/" >out
 722             print "#      endif" >out
 723             print "#      ifdef PNG_NO_" i "_SUPPORTED" >out
 724             print "#       undef PNG_on /*turned off*/" >out
 725             print "#      endif" >out
 726          }
 727          print "#    endif /*!enabled*/" >out
 728          print "#    ifdef PNG_on" >out
 729          # The _SUPPORTED macro must be defined so that dependent
 730          # options output later work.
 731          print "#      define PNG_" i "_SUPPORTED" >out
 732          print "#    endif" >out
 733          print "#   endif /*!command line*/" >out
 734          # If PNG_on is still set the option should be defined in
 735          # pnglibconf.h
 736          print "#   ifdef PNG_on" >out
 737          if (i ~ /^fail_/) {
 738             print error, i, "is on: enabled by:" iffs[i] enabledby[i] ", requires" requires[i] end >out
 739          } else if (i !~ /^ok_/) {
 740             print def i sup >out
 741          }
 742          print "#   endif /* definition */" >out
 743          print "#endif /*requires, if*/" >out
 744          if (logunsupported || i ~ /^ok_/) {
 745             print "#ifndef  PNG_on" >out
 746             if (logunsupported) {
 747                print und i une >out
 748             }
 749             if (i ~ /^ok_/) {
 750                print error, i, "not enabled: requires:" requires[i] ", enabled by:" iffs[i] enabledby[i] end >out
 751             }
 752             print "#endif" >out
 753          }
 754
 755          done[i] = 1
 756          ++movement
 757       }
 758
 759       if (!finished && !movement) {
 760          print "option: loop or missing option in dependency tree, cannot process:"
 761          for (i in option) if (!done[i]) {
 762             print "  option", i, "depends on" tree[i], "needs:"
 763             nreqs = split(tree[i], r)
 764             if (nreqs > 0) for (j=1; j<=nreqs; ++j) if (!done[r[j]]) {
 765                print "   " r[j]
 766             }
 767          }
 768          exit 1
 769       }
 770    }
 771    print comment, "end of options", cend >out
 772
 773    # Regular end - everything looks ok
 774    if (protect != "") {
 775       print start "#endif", cx, protect, "*/" end >out
 776    }
 777 }