2 %%Creator: dvips(k) 5.86 Copyright 1999 Radical Eye Software
6 %%BoundingBox: 0 0 612 792
7 %%DocumentFonts: Times-Bold Times-Roman Times-Italic Helvetica-Bold
8 %%+ Courier Times-BoldItalic Courier-Bold Courier-BoldOblique Helvetica
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74 % author = "S. Rahtz, P. MacKay, Alan Jeffrey, B. Horn, K. Berry",
76 % date = "1 July 1998",
77 % filename = "8r.enc",
78 % email = "tex-fonts@@tug.org",
79 % docstring = "Encoding for TrueType or Type 1 fonts
80 % to be used with TeX."
83 % Idea is to have all the characters normally included in Type 1 fonts
84 % available for typesetting. This is effectively the characters in Adobe
85 % Standard Encoding + ISO Latin 1 + extra characters from Lucida.
87 % Character code assignments were made as follows:
89 % (1) the Windows ANSI characters are almost all in their Windows ANSI
90 % positions, because some Windows users cannot easily reencode the
91 % fonts, and it makes no difference on other systems. The only Windows
92 % ANSI characters not available are those that make no sense for
93 % typesetting -- rubout (127 decimal), nobreakspace (160), softhyphen
94 % (173). quotesingle and grave are moved just because it's such an
95 % irritation not having them in TeX positions.
97 % (2) Remaining characters are assigned arbitrarily to the lower part
98 % of the range, avoiding 0, 10 and 13 in case we meet dumb software.
100 % (3) Y&Y Lucida Bright includes some extra text characters; in the
101 % hopes that other PostScript fonts, perhaps created for public
102 % consumption, will include them, they are included starting at 0x12.
104 % (4) Remaining positions left undefined are for use in (hopefully)
105 % upward-compatible revisions, if someday more characters are generally
108 % (5) hyphen appears twice for compatibility with both
112 % 0x00 (encoded characters from Adobe Standard not in Windows 3.1)
113 /.notdef /dotaccent /fi /fl
114 /fraction /hungarumlaut /Lslash /lslash
115 /ogonek /ring /.notdef
116 /breve /minus /.notdef
117 % These are the only two remaining unencoded characters, so may as
122 % (unusual TeX characters available in, e.g., Lucida Bright)
123 /dotlessj /ff /ffi /ffl
124 /.notdef /.notdef /.notdef /.notdef
125 /.notdef /.notdef /.notdef /.notdef
126 % very contentious; it's so painful not having quoteleft and quoteright
127 % at 96 and 145 that we move the things normally found there to here.
129 % 0x20 (ASCII begins)
130 /space /exclam /quotedbl /numbersign
131 /dollar /percent /ampersand /quoteright
132 /parenleft /parenright /asterisk /plus /comma /hyphen /period /slash
134 /zero /one /two /three /four /five /six /seven
135 /eight /nine /colon /semicolon /less /equal /greater /question
137 /at /A /B /C /D /E /F /G /H /I /J /K /L /M /N /O
139 /P /Q /R /S /T /U /V /W
140 /X /Y /Z /bracketleft /backslash /bracketright /asciicircum /underscore
142 /quoteleft /a /b /c /d /e /f /g /h /i /j /k /l /m /n /o
144 /p /q /r /s /t /u /v /w
145 /x /y /z /braceleft /bar /braceright /asciitilde
146 /.notdef % rubout; ASCII ends
148 /.notdef /.notdef /quotesinglbase /florin
149 /quotedblbase /ellipsis /dagger /daggerdbl
150 /circumflex /perthousand /Scaron /guilsinglleft
151 /OE /.notdef /.notdef /.notdef
153 /.notdef /.notdef /.notdef /quotedblleft
154 /quotedblright /bullet /endash /emdash
155 /tilde /trademark /scaron /guilsinglright
156 /oe /.notdef /.notdef /Ydieresis
158 /.notdef % nobreakspace
159 /exclamdown /cent /sterling
160 /currency /yen /brokenbar /section
161 /dieresis /copyright /ordfeminine /guillemotleft
163 /hyphen % Y&Y (also at 45); Windows' softhyphen
167 /degree /plusminus /twosuperior /threesuperior
168 /acute /mu /paragraph /periodcentered
169 /cedilla /onesuperior /ordmasculine /guillemotright
170 /onequarter /onehalf /threequarters /questiondown
172 /Agrave /Aacute /Acircumflex /Atilde /Adieresis /Aring /AE /Ccedilla
173 /Egrave /Eacute /Ecircumflex /Edieresis
174 /Igrave /Iacute /Icircumflex /Idieresis
176 /Eth /Ntilde /Ograve /Oacute
177 /Ocircumflex /Otilde /Odieresis /multiply
178 /Oslash /Ugrave /Uacute /Ucircumflex
179 /Udieresis /Yacute /Thorn /germandbls
181 /agrave /aacute /acircumflex /atilde
182 /adieresis /aring /ae /ccedilla
183 /egrave /eacute /ecircumflex /edieresis
184 /igrave /iacute /icircumflex /idieresis
186 /eth /ntilde /ograve /oacute
187 /ocircumflex /otilde /odieresis /divide
188 /oslash /ugrave /uacute /ucircumflex
189 /udieresis /yacute /thorn /ydieresis
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269 TeXDict begin/setcmykcolor where{pop}{/setcmykcolor{dup 10 eq{pop
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1107 g(us)g(as)h(an)f(opaque)f(data)h(struc-)0 899 y(ture)26
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1388 /$F2psBegin {$F2psDict begin /$F2psEnteredState save def} def
1389 /$F2psEnd {$F2psEnteredState restore end} def
1397 n 780 705 m 750 705 750 855 30 arcto 4 {pop} repeat
1398 750 885 900 885 30 arcto 4 {pop} repeat
1399 930 885 930 735 30 arcto 4 {pop} repeat
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1401 cp gs 0.00 setgray ef gr gs col0 s gr
1403 n 1035 1185 m 1005 1185 1005 1335 30 arcto 4 {pop} repeat
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1406 1185 1185 1035 1185 30 arcto 4 {pop} repeat
1407 cp gs 0.00 setgray ef gr gs col0 s gr
1409 n 3075 2760 m 3045 2760 3045 2910 30 arcto 4 {pop} repeat
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1412 3225 2760 3075 2760 30 arcto 4 {pop} repeat
1413 cp gs 0.00 setgray ef gr gs col0 s gr
1415 n 3105 885 m 3075 885 3075 1035 30 arcto 4 {pop} repeat
1416 3075 1065 3225 1065 30 arcto 4 {pop} repeat
1417 3255 1065 3255 915 30 arcto 4 {pop} repeat
1418 3255 885 3105 885 30 arcto 4 {pop} repeat
1419 cp gs 0.00 setgray ef gr gs col0 s gr
1421 n 2040 1500 m 2010 1500 2010 1650 30 arcto 4 {pop} repeat
1422 2010 1680 2160 1680 30 arcto 4 {pop} repeat
1423 2190 1680 2190 1530 30 arcto 4 {pop} repeat
1424 2190 1500 2040 1500 30 arcto 4 {pop} repeat
1425 cp gs 0.00 setgray ef gr gs col0 s gr
1427 n 2040 2100 m 2010 2100 2010 2250 30 arcto 4 {pop} repeat
1428 2010 2280 2160 2280 30 arcto 4 {pop} repeat
1429 2190 2280 2190 2130 30 arcto 4 {pop} repeat
1430 2190 2100 2040 2100 30 arcto 4 {pop} repeat
1431 cp gs 0.00 setgray ef gr gs col0 s gr
1433 n 1035 705 m 1005 705 1005 855 30 arcto 4 {pop} repeat
1434 1005 885 1155 885 30 arcto 4 {pop} repeat
1435 1185 885 1185 735 30 arcto 4 {pop} repeat
1436 1185 705 1035 705 30 arcto 4 {pop} repeat
1437 cp gs 0.00 setgray ef gr gs col0 s gr
1439 n 2040 2640 m 2010 2640 2010 2790 30 arcto 4 {pop} repeat
1440 2010 2820 2160 2820 30 arcto 4 {pop} repeat
1441 2190 2820 2190 2670 30 arcto 4 {pop} repeat
1442 2190 2640 2040 2640 30 arcto 4 {pop} repeat
1443 cp gs 0.00 setgray ef gr gs col0 s gr
1445 n 2040 525 m 2010 525 2010 675 30 arcto 4 {pop} repeat
1446 2010 705 2160 705 30 arcto 4 {pop} repeat
1447 2190 705 2190 555 30 arcto 4 {pop} repeat
1448 2190 525 2040 525 30 arcto 4 {pop} repeat
1449 cp gs 0.00 setgray ef gr gs col0 s gr
1451 n 3075 2505 m 3045 2505 3045 2655 30 arcto 4 {pop} repeat
1452 3045 2685 3195 2685 30 arcto 4 {pop} repeat
1453 3225 2685 3225 2535 30 arcto 4 {pop} repeat
1454 3225 2505 3075 2505 30 arcto 4 {pop} repeat
1455 cp gs 0.00 setgray ef gr gs col0 s gr
1457 n 1305 1500 m 1275 1500 1275 1650 30 arcto 4 {pop} repeat
1458 1275 1680 1425 1680 30 arcto 4 {pop} repeat
1459 1455 1680 1455 1530 30 arcto 4 {pop} repeat
1460 1455 1500 1305 1500 30 arcto 4 {pop} repeat
1461 cp gs 0.00 setgray ef gr gs col0 s gr
1463 n 1545 3225 m 1515 3225 1515 3375 30 arcto 4 {pop} repeat
1464 1515 3405 1665 3405 30 arcto 4 {pop} repeat
1465 1695 3405 1695 3255 30 arcto 4 {pop} repeat
1466 1695 3225 1545 3225 30 arcto 4 {pop} repeat
1467 cp gs 0.00 setgray ef gr gs col0 s gr
1469 n 1350 570 m 1320 570 1320 720 30 arcto 4 {pop} repeat
1470 1320 750 1470 750 30 arcto 4 {pop} repeat
1471 1500 750 1500 600 30 arcto 4 {pop} repeat
1472 1500 570 1350 570 30 arcto 4 {pop} repeat
1473 cp gs 0.00 setgray ef gr gs col0 s gr
1475 n 3345 2505 m 3315 2505 3315 2655 30 arcto 4 {pop} repeat
1476 3315 2685 3465 2685 30 arcto 4 {pop} repeat
1477 3495 2685 3495 2535 30 arcto 4 {pop} repeat
1478 3495 2505 3345 2505 30 arcto 4 {pop} repeat
1479 cp gs 0.00 setgray ef gr gs col0 s gr
1480 /Times-Bold ff 150.00 scf sf
1482 gs 1 -1 sc (12) col7 sh gr
1485 n 630 270 m 1890 270 l 1890 3600 l 630 3600 l
1488 n 2340 270 m 3600 270 l 3600 1800 l 2340 1800 l
1491 n 2340 2070 m 3600 2070 l 3600 3600 l 2340 3600 l
1495 n 1980 810 m 2025 720 l 2070 900 l 2115 720 l 2160 900 l
1496 2205 810 l gs col0 s gr [] 0 sd
1499 n 1980 1170 m 2014 1081 l 2059 1261 l 2104 1081 l 2149 1261 l
1500 2205 1170 l gs col0 s gr [] 0 sd
1504 1275 660 m 1275 600 l 1124 600 l 1244 630 l 1124 660 l cp
1506 n 1260 4586 m 1980 4593 l 1980 3690 l 450 3690 l 450 630 l 990 630 l
1508 1260 630 l gs col0 s gr gr
1512 n 1124 660 m 1244 630 l 1124 600 l 1124 660 l cp gs 0.00 setgray ef gr col0 s
1516 1995 840 m 1995 780 l 1844 780 l 1964 810 l 1844 840 l cp
1518 n 1260 630 m 1260 810 l
1519 1980 810 l gs col0 s gr gr
1523 n 1844 840 m 1964 810 l 1844 780 l 1844 840 l cp gs 0.00 setgray ef gr col0 s
1527 2985 840 m 2985 780 l 2834 780 l 2954 810 l 2834 840 l cp
1530 2970 810 l gs col0 s gr gr
1534 n 2834 840 m 2954 810 l 2834 780 l 2834 840 l cp gs 0.00 setgray ef gr col0 s
1538 2940 1185 m 3000 1185 l 3000 1034 l 2970 1154 l 2940 1034 l cp
1541 2970 1170 l gs col0 s gr gr
1545 n 2940 1034 m 2970 1154 l 3000 1034 l 2940 1034 l cp gs 0.00 setgray ef gr col0 s
1549 2190 1140 m 2190 1200 l 2341 1200 l 2221 1170 l 2341 1140 l cp
1552 2970 1170 l gs col0 s gr gr
1556 n 2341 1140 m 2221 1170 l 2341 1200 l 2341 1140 l cp gs 0.00 setgray ef gr col0 s
1560 1245 1140 m 1245 1200 l 1396 1200 l 1276 1170 l 1396 1140 l cp
1563 1980 1170 l gs col0 s gr gr
1567 n 1396 1140 m 1276 1170 l 1396 1200 l 1396 1140 l cp gs 0.00 setgray ef gr col0 s
1571 2985 1470 m 2985 1410 l 2834 1410 l 2954 1440 l 2834 1470 l cp
1574 2970 1440 l gs col0 s gr gr
1578 n 2834 1470 m 2954 1440 l 2834 1410 l 2834 1470 l cp gs 0.00 setgray ef gr col0 s
1582 1260 1440 l gs col0 s gr
1585 2985 2550 m 2985 2490 l 2834 2490 l 2954 2520 l 2834 2550 l cp
1587 n 2970 1440 m 2970 1890 l 2250 1890 l 2250 2520 l
1588 2970 2520 l gs col0 s gr gr
1592 n 2834 2550 m 2954 2520 l 2834 2490 l 2834 2550 l cp gs 0.00 setgray ef gr col0 s
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1599 1230 2852 m 1229 2912 l 1380 2913 l 1261 2883 l 1381 2853 l cp
1602 1245 2883 l gs col0 s gr gr
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1610 1229 4751 m 1230 4811 l 1381 4809 l 1261 4781 l 1380 4749 l cp
1612 n 1260 2880 m 1260 3150 l 2070 3150 l 2062 4773 l
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1617 n 1380 4749 m 1261 4781 l 1381 4809 l 1380 4749 l cp gs 0.00 setgray ef gr col0 s
1621 1230 4601 m 1290 4601 l 1290 4450 l 1260 4570 l 1230 4450 l cp
1623 n 450 4050 m 1260 4050 l
1624 1260 4586 l gs col0 s gr gr
1628 n 1230 4450 m 1260 4570 l 1290 4450 l 1230 4450 l cp gs 0.00 setgray ef gr col0 s
1632 1230 5235 m 1290 5234 l 1287 5083 l 1260 5204 l 1227 5084 l cp
1635 1260 5220 l gs col0 s gr gr
1639 n 1227 5084 m 1260 5204 l 1287 5083 l 1227 5084 l cp gs 0.00 setgray ef gr col0 s
1645 2985 4260 m 2985 4200 l 2834 4200 l 2954 4230 l 2834 4260 l cp
1647 n 2970 3150 m 2970 3690 l 2250 3690 l 2250 4230 l
1648 2970 4230 l gs col0 s gr gr
1653 n 2834 4260 m 2954 4230 l 2834 4200 l 2834 4260 l cp gs 0.00 setgray ef gr col0 s
1655 n 630 6300 m 1890 6300 l
1656 1890 7290 l gs col0 s gr
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1663 3690 7560 l gs col0 s gr gr
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1668 n 3660 7424 m 3690 7544 l 3720 7424 l 3660 7424 l cp gs 0.00 setgray ef gr col0 s
1670 n 2340 6300 m 3600 6300 l 3600 7560 l 2340 7560 l
1673 n 630 3780 m 1890 3780 l 1890 6120 l 630 6120 l
1676 n 2340 3780 m 3600 3780 l 3600 6120 l 2340 6120 l
1683 2985 3180 m 2985 3120 l 2834 3120 l 2954 3150 l 2834 3180 l cp
1685 n 1260 5220 m 2160 5220 l 2160 3150 l
1686 2970 3150 l gs col0 s gr gr
1691 n 2834 3180 m 2954 3150 l 2834 3120 l 2834 3180 l cp gs 0.00 setgray ef gr col0 s
1694 630 7380 l gs col0 s gr
1698 900 6300 l gs col0 s gr
1701 1170 6300 l gs col0 s gr
1704 1440 6300 l gs col0 s gr
1707 1710 6300 l gs col0 s gr
1710 1890 6435 l gs col0 s gr
1713 1890 6750 l gs col0 s gr
1716 1890 7020 l gs col0 s gr
1719 2610 6300 l gs col0 s gr
1722 2925 6300 l gs col0 s gr
1725 3240 6300 l gs col0 s gr
1728 3510 6300 l gs col0 s gr
1731 3600 6570 l gs col0 s gr
1734 3600 6930 l gs col0 s gr
1737 3600 7245 l gs col0 s gr
1742 2940 5325 m 3000 5325 l 3000 5174 l 2970 5294 l 2940 5174 l cp
1745 2970 5310 l gs col0 s gr gr
1750 n 2940 5174 m 2970 5294 l 3000 5174 l 2940 5174 l cp gs 0.00 setgray ef gr col0 s
1756 1245 5280 m 1245 5340 l 1396 5340 l 1276 5310 l 1396 5280 l cp
1759 1260 5310 l gs col0 s gr gr
1764 n 1396 5280 m 1276 5310 l 1396 5340 l 1396 5280 l cp gs 0.00 setgray ef gr col0 s
1770 1245 5640 m 1245 5700 l 1396 5700 l 1276 5670 l 1396 5640 l cp
1772 n 2970 5580 m 2970 5670 l
1773 1260 5670 l gs col0 s gr gr
1778 n 1396 5640 m 1276 5670 l 1396 5700 l 1396 5640 l cp gs 0.00 setgray ef gr col0 s
1784 345 5910 m 345 5970 l 496 5970 l 376 5940 l 496 5910 l cp
1786 n 1260 5670 m 1260 5940 l
1787 360 5940 l gs col0 s gr gr
1792 n 496 5910 m 376 5940 l 496 5970 l 496 5910 l cp gs 0.00 setgray ef gr col0 s
1798 2985 5610 m 2985 5550 l 2834 5550 l 2954 5580 l 2834 5610 l cp
1800 n 1260 5355 m 1260 5580 l
1801 2970 5580 l gs col0 s gr gr
1806 n 2834 5610 m 2954 5580 l 2834 5550 l 2834 5610 l cp gs 0.00 setgray ef gr col0 s
1808 n 630 7380 m 631 7381 l 634 7383 l 639 7388 l 647 7394 l 657 7402 l
1809 670 7412 l 686 7423 l 703 7435 l 723 7448 l 744 7460 l
1810 766 7472 l 791 7483 l 817 7493 l 845 7502 l 877 7509 l
1811 911 7514 l 949 7517 l 991 7518 l 1035 7515 l 1076 7510 l
1812 1115 7502 l 1150 7493 l 1181 7483 l 1207 7473 l 1228 7463 l
1813 1245 7453 l 1259 7443 l 1269 7433 l 1278 7423 l 1286 7414 l
1814 1294 7404 l 1303 7394 l 1314 7384 l 1327 7373 l 1344 7362 l
1815 1364 7350 l 1390 7338 l 1419 7326 l 1454 7313 l 1491 7301 l
1816 1530 7290 l 1576 7279 l 1619 7271 l 1657 7265 l 1690 7262 l
1817 1720 7261 l 1747 7261 l 1771 7263 l 1793 7266 l 1813 7269 l
1818 1831 7273 l 1847 7277 l 1861 7280 l 1872 7284 l 1880 7286 l
1819 1885 7288 l 1889 7289 l
1820 1890 7290 l gs col0 s gr
1821 /Times-Bold ff 150.00 scf sf
1823 gs 1 -1 sc (sk_addr) col0 sh gr
1824 /Times-Bold ff 150.00 scf sf
1826 gs 1 -1 sc (main stack) col0 sh gr
1827 /Times-Bold ff 150.00 scf sf
1829 gs 1 -1 sc (main) col0 sh gr
1830 /Times-Bold ff 150.00 scf sf
1832 gs 1 -1 sc (sf_addr\(sf_arg\)) col0 sh gr
1833 /Times-Bold ff 150.00 scf sf
1835 gs 1 -1 sc (mctx_create) col0 sh gr
1836 /Times-Bold ff 150.00 scf sf
1838 gs 1 -1 sc (mctx_create) col0 sh gr
1839 /Times-Bold ff 150.00 scf sf
1841 gs 1 -1 sc (mctx_create) col0 sh gr
1842 /Times-Bold ff 150.00 scf sf
1844 gs 1 -1 sc (_boot) col0 sh gr
1845 /Times-Bold ff 150.00 scf sf
1847 gs 1 -1 sc (_trampoline) col0 sh gr
1848 /Times-Bold ff 150.00 scf sf
1850 gs 1 -1 sc 90.0 rot (sk_size) col0 sh gr
1851 /Times-Bold ff 150.00 scf sf
1853 gs 1 -1 sc (mctx_switch) col0 sh gr
1854 /Times-Bold ff 150.00 scf sf
1856 gs 1 -1 sc (mctx_switch) col0 sh gr
1857 /Times-Bold ff 150.00 scf sf
1859 gs 1 -1 sc (mctx_switch) col0 sh gr
1860 /Times-Bold ff 150.00 scf sf
1862 gs 1 -1 sc (mctx_switch) col0 sh gr
1863 /Times-Bold ff 150.00 scf sf
1865 gs 1 -1 sc (mctx_create) col0 sh gr
1866 /Times-Bold ff 150.00 scf sf
1868 gs 1 -1 sc (1) col7 sh gr
1869 /Times-Bold ff 150.00 scf sf
1871 gs 1 -1 sc (2) col7 sh gr
1872 /Times-Bold ff 150.00 scf sf
1874 gs 1 -1 sc (6) col7 sh gr
1875 /Times-Bold ff 150.00 scf sf
1877 gs 1 -1 sc (7) col7 sh gr
1878 /Times-Bold ff 150.00 scf sf
1880 gs 1 -1 sc (8) col7 sh gr
1881 /Times-Bold ff 150.00 scf sf
1883 gs 1 -1 sc (4) col7 sh gr
1884 /Times-Bold ff 150.00 scf sf
1886 gs 1 -1 sc (3) col7 sh gr
1887 /Times-Bold ff 150.00 scf sf
1889 gs 1 -1 sc (5) col7 sh gr
1890 /Times-Bold ff 150.00 scf sf
1892 gs 1 -1 sc (9) col7 sh gr
1893 /Times-Bold ff 150.00 scf sf
1895 gs 1 -1 sc (13) col7 sh gr
1896 /Times-Bold ff 150.00 scf sf
1898 gs 1 -1 sc (10) col7 sh gr
1899 /Times-Bold ff 150.00 scf sf
1901 gs 1 -1 sc (14) col7 sh gr
1902 /Times-Bold ff 150.00 scf sf
1904 gs 1 -1 sc (11) col7 sh gr
1911 2025 4944 a Fn(Figur)o(e)d(1:)66 b Fm(Illustration)18
1912 b(of)c(the)h(machine)h(conte)o(xt)g(creation)h(procedure.)22
1913 b(The)2350 5012 y(thick)h(solid)f(lines)h(and)e(numeric)i(marks)e
1914 (correspond)i(to)f(the)g(al-)2350 5080 y(gorithm)c(steps)g(as)f
1915 (described)i(in)f(section)h(3.2.)h(The)d(thick)i(dotted)2350
1916 5148 y(lines)h(sho)n(w)f(a)g(possible)h(further)g(processing)h(where)f
1917 (a)f(fe)n(w)g(con-)2350 5216 y(te)o(xt)i(switches)h(are)e(performed)i
1918 (to)e(dispatch)i(between)f(the)g(main)2350 5284 y(thread)e(and)e(the)h
1919 (ne)n(w)g(created)h(thread.)p Black 1929 5700 a Fx(6)p
1922 7 6 bop Black Black 0 83 a FA(3.3)99 b(Sour)n(ce)27 b(Code)0
1923 239 y Fx(The)43 b(corresponding)d(ANSI-C)k(code,)49 b(which)43
1924 b(implements)0 338 y Fp(mctx)p 205 338 25 4 v 29 w(create)p
1925 Fx(,)37 b(is)d(a)h(little)f(bit)h(more)e(complicated.)64
1926 b(But)0 438 y(with)23 b(the)g(presented)e(algorithm)g(in)i(mind,)f(it)i
1927 (is)f(no)n(w)f(straight-)0 538 y(forw)o(ard.)p Black
1928 Black 0 693 a Fi(static)44 b Fk(mctx_t)313 b(mctx_caller;)0
1929 767 y Fi(static)44 b Fk(sig_atomic_t)f(mctx_called;)0
1930 917 y Fi(static)h Fk(mctx_t)268 b(*mctx_creat;)0 992
1931 y Fi(static)44 b(void)313 b Fk(\(*mctx_creat_func\)\()p
1932 Fi(void)41 b Fk(*\);)0 1066 y Fi(static)j(void)358 b
1933 Fk(*mctx_creat_arg;)0 1141 y Fi(static)44 b Fk(sigset_t)223
1934 b(mctx_creat_sigs;)0 1290 y Fi(void)44 b Fk(mctx_create\()179
1935 1365 y(mctx_t)g(*mctx,)179 1440 y Fi(void)g Fk(\(*sf_addr\)\()p
1936 Fi(void)f Fk(*\),)h Fi(void)g Fk(*sf_arg,)179 1515 y
1937 Fi(void)g Fk(*sk_addr,)g Fi(size_t)g Fk(sk_size\))0 1589
1938 y Fo(f)179 1664 y Fi(struct)g Fk(sigaction)f(sa;)179
1939 1739 y Fi(struct)h Fk(sigaction)f(osa;)179 1813 y Fi(struct)h
1940 Fk(sigaltstack)f(ss;)179 1888 y Fi(struct)h Fk(sigaltstack)f(oss;)179
1941 1963 y(sigset_t)h(osigs;)179 2038 y(sigset_t)g(sigs;)179
1942 2187 y(/*)64 b Fj(Step)18 b(1:)45 b Fk(*/)179 2262 y
1943 (sigemptyset\(&sigs\);)179 2336 y(sigaddset\(&sigs,)d(SIGUSR1\);)179
1944 2411 y(sigprocmask\(SIG_BLOCK,)f(&sigs,)j(&osigs\);)179
1945 2561 y(/*)64 b Fj(Step)18 b(2:)45 b Fk(*/)179 2635 y(memset\(\()p
1946 Fi(void)e Fk(*\)&sa,)h(0,)493 2710 y Fi(sizeof)p Fk(\()p
1947 Fi(struct)f Fk(sigaction\)\);)179 2785 y(sa.sa_handler)g(=)i
1948 (mctx_create_trampoline;)179 2860 y(sa.sa_flags)e(=)i(SA_ONSTACK;)179
1949 2934 y(sigemptyset\(&sa.sa_mask\);)179 3009 y(sigaction\(SIGUSR1,)d
1950 (&sa,)i(&osa\);)179 3158 y(/*)64 b Fj(Step)18 b(3:)45
1951 b Fk(*/)179 3233 y(ss.ss_sp)178 b(=)45 b(sk_addr;)179
1952 3308 y(ss.ss_size)88 b(=)45 b(sk_size;)179 3383 y(ss.ss_flags)e(=)i(0;)
1953 179 3457 y(sigaltstack\(&ss,)d(&oss\);)179 3607 y(/*)64
1954 b Fj(Step)18 b(4:)45 b Fk(*/)179 3681 y(mctx_creat)268
1955 b(=)44 b(mctx;)179 3756 y(mctx_creat_func)f(=)h(sf_addr;)179
1956 3831 y(mctx_creat_arg)88 b(=)44 b(sf_arg;)179 3906 y(mctx_creat_sigs)f
1957 (=)h(osigs;)179 3980 y(mctx_called)223 b(=)44 b(FALSE;)179
1958 4055 y(kill\(getpid\(\),)f(SIGUSR1\);)179 4130 y(sigfillset\(&sigs\);)
1959 179 4204 y(sigdelset\(&sigs,)f(SIGUSR1\);)179 4279 y
1960 Fi(while)i Fk(\(!mctx_called\))359 4354 y(sigsuspend\(&sigs\);)179
1961 4503 y(/*)64 b Fj(Step)18 b(6:)45 b Fk(*/)179 4578 y
1962 (sigaltstack\(NULL,)d(&ss\);)179 4653 y(ss.ss_flags)h(=)i(SS_DISABLE;)
1963 179 4728 y(sigaltstack\(&ss,)d(NULL\);)179 4802 y(if)j
1964 (\(!\(oss.ss_flags)d(&)j(SS_DISABLE\)\))359 4877 y(sigaltstack\(&oss,)d
1965 (NULL\);)179 4952 y(sigaction\(SIGUSR1,)g(&osa,)i(NULL\);)179
1966 5026 y(sigprocmask\(SIG_SETMASK,)717 5101 y(&osigs,)g(NULL\);)179
1967 5251 y(/*)64 b Fj(Step)18 b(7)h(&)g(Step)f(8:)45 b Fk(*/)179
1968 5325 y(mctx_switch\(&mctx_caller,)c(mctx\);)2204 83 y(/*)64
1969 b Fj(Step)18 b(14:)45 b Fk(*/)2204 158 y Fi(return)p
1970 Fk(;)2025 232 y Fo(g)2025 382 y Fi(void)f Fk(mctx_create_trampoline\()p
1971 Fi(int)d Fk(sig\))2025 457 y Fo(f)2204 531 y Fk(/*)64
1972 b Fj(Step)18 b(5:)45 b Fk(*/)2204 606 y Fi(if)g Fk
1973 (\(mctx_save\(mctx_creat\))c(==)j(0\))h Fo(f)2384 681
1974 y Fk(mctx_called)e(=)h(TRUE;)2384 756 y Fi(return)p Fk(;)2204
1975 830 y Fo(g)2204 980 y Fk(/*)64 b Fj(Step)18 b(9:)45 b
1976 Fk(*/)2204 1054 y(mctx_create_boot\(\);)2025 1129 y Fo(g)2025
1977 1279 y Fi(void)f Fk(mctx_create_boot\()p Fi(void)p Fk(\))2025
1978 1353 y Fo(f)2204 1428 y Fi(void)g Fk(\(*mctx_start_func\)\()p
1979 Fi(void)d Fk(*\);)2204 1503 y Fi(void)j Fk(*mctx_start_arg;)2204
1980 1652 y(/*)64 b Fj(Step)18 b(10:)45 b Fk(*/)2204 1727
1981 y(sigprocmask\(SIG_SETMASK,)2742 1802 y(&mctx_creat_sigs,)d(NULL\);)
1982 2204 1951 y(/*)64 b Fj(Step)18 b(11:)45 b Fk(*/)2204
1983 2026 y(mctx_start_func)e(=)h(mctx_creat_func;)2204 2100
1984 y(mctx_start_arg)88 b(=)44 b(mctx_creat_arg;)2204 2250
1985 y(/*)64 b Fj(Step)18 b(12)h(&)g(Step)g(13:)45 b Fk(*/)2204
1986 2325 y(mctx_switch\(mctx_creat,)c(&mctx_caller\);)2204
1987 2474 y(/*)64 b Fj(The)18 b(thread)h(``magically'')g(starts...)62
1988 b Fk(*/)2204 2549 y(mctx_start_func\(mctx_start_arg\);)2204
1989 2698 y(/*)45 b(NOTREACHED)e(*/)2204 2773 y(abort\(\);)2025
1990 2848 y Fo(g)2025 3124 y FA(3.4)99 b(Run-time)26 b(P)n(enalty)2025
1991 3294 y Fx(After)31 b(this)h(discussion)f(of)g(the)g(implementation)e
1992 (details,)35 b(an)2025 3393 y(ob)o(viously)29 b(occuring)h(question)g
1993 (no)n(w)h(is)h(what)g(the)f(e)o(xpected)2025 3493 y(run-time)g(penalty)
1994 h(is.)63 b(That)32 b(is,)k(what)d(does)f(our)g(presented)2025
1995 3592 y(machine)43 b(conte)o(xt)f(implementation)g(cost)i(compared)e(to)
1996 i(a)2025 3692 y Fp(ucontext)p Fx(\(3\))33 b(based)j(solution.)70
1997 b(From)35 b(the)g(already)f(dis-)2025 3792 y(cussed)21
1998 b(details)h(we)g(can)f(easily)h(guess)f(that)h(our)e(comple)o(x)g(ma-)
1999 2025 3891 y(chine)27 b(conte)o(xt)f(creation)h(procedure)d(\()p
2000 Fp(mctx)p 3392 3891 V 29 w(create)p Fx(\))j(will)2025
2001 3991 y(be)20 b(certainly)f(noticeably)f(slo)n(wer)i(than)g(a)g
2002 (solution)f(based)h(on)f(a)2025 4091 y Fp(ucontext)p
2003 Fx(\(3\))f(f)o(acility)-5 b(.)2150 4197 y(But)48 b(a)g(wild)g(guess)f
2004 (is)i(not)e(suf)n(\002cing)g(for)g(a)h(reason-)2025 4297
2005 y(able)d(statement.)101 b(So)45 b(we)h(ha)n(v)o(e)f(written)g(a)h
2006 Fr(Simple)f(Ma-)2025 4397 y(c)o(hine)21 b(Conte)n(xt)g(Benc)o(hmark)g
2007 Fx(\(SMCB)i([32)n(]\))f(which)f(w)o(as)h(used)2025 4496
2008 y(to)36 b(compare)e(run-time)g(costs)j(of)e(the)h Fp(mctx)p
2009 3421 4496 V 29 w(create)f Fx(and)2025 4596 y Fp(mctx)p
2010 2230 4596 V 29 w(switch)27 b Fx(functions)f(if)h(once)f(implemented)g
2011 (through)2025 4696 y(the)17 b Fr(POSIX)i Fp(makecontext)p
2012 Fx(\(3\)/)p Fp(swapcontext)p Fx(\(3\))11 b(func-)2025
2013 4795 y(tions)55 b(\(as)h(sho)n(wn)f(in)g(section)h(2.3\),)63
2014 b(and)55 b(once)f(imple-)2025 4895 y(mented)44 b(with)g(our)g(based)g
2015 (f)o(allback)g(implementation)f(\(for)2025 4994 y(con)m(v)o(enience)c
2016 (reasons)j(we)h(directly)e(used)h Fp(sigjmp)p 3706 4994
2017 V 29 w(buf)p Fx(,)2025 5094 y Fp(sigsetjmp)p Fx(\(3\))g(and)h
2018 Fp(siglongjmp)p Fx(\(3\))f(in)i(the)g(bench-)2025 5194
2019 y(mark,)31 b(because)d(all)i(tested)g(platforms)e(pro)o(vided)e
2020 (this\).)53 b(The)2025 5293 y(results)21 b(are)f(sho)n(wn)f(T)-7
2021 b(able)20 b(3)h(belo)n(w)-5 b(.)2150 5400 y(As)32 b(one)e(can)h(deri)n
2022 (v)o(e)f(from)g(these)i(e)n(v)n(aluations,)g(our)e(sig-)p
2023 Black 1929 5700 a(7)p Black eop
2025 8 7 bop Black Black 0 83 a Fx(nal)25 b(stack)f(trick)h(to)f(implement)f
2026 Fp(mctx)p 1174 83 25 4 v 30 w(create)h Fx(in)g(practice)0
2027 183 y(is)31 b(approximately)c(15)j(times)h(slo)n(wer)f(than)f(the)h
2028 Fp(makecon-)0 282 y(text)p Fx(\(3\))36 b(based)i(v)n(ariant.)77
2029 b(This)38 b(cost)g(should)f(not)g(be)h(ne-)0 382 y(glected.)f(On)25
2030 b(the)f(other)g(hand,)g(the)h Fp(sigsetjmp)p Fx(\(3\)/)d
2031 Fp(sig-)0 482 y(longjmp)p Fx(\(3\))29 b(based)i Fp(mctx)p
2032 903 482 V 29 w(switch)g Fx(performs)f(about)g(as)0 581
2033 y(good)17 b(as)h(the)g Fp(swapcontext)p Fx(\(3\))e(based)i(v)n(ariant)f
2034 (\(the)g(reason)0 681 y(why)29 b(on)g(most)g(of)h(the)f(tested)h
2035 (platforms)e(it)j(is)f(e)n(v)o(en)f(slightly)0 780 y(f)o(aster)37
2036 b(is)h(not)f(kno)n(wn)e(\226)i(b)n(ut)g(we)g(guess)g(it)h(is)g(related)
2037 e(to)h(a)0 880 y(greater)26 b(management)f(o)o(v)o(erhead)f(in)k(the)f
2038 Fp(ucontext)p Fx(\(3\))e(f)o(a-)0 980 y(cility)-5 b(,)16
2039 b(which)f(is)i(a)f(superset)f(of)g(the)h(functionality)e(we)h
2040 (require\).)0 1079 y(Or)h(in)g(short:)22 b(our)15 b(presented)g(f)o
2041 (allback)g(approach)e(costs)j(notice-)0 1179 y(able)24
2042 b(e)o(xtra)g(CPU)h(c)o(ycles)f(on)g(thread)f(creation)g(time,)i(b)n(ut)
2043 g(is)g(as)0 1279 y(f)o(ast)17 b(as)g(the)g(standardized)d(solution)i
2044 (under)f(thread)g(dispatching)0 1378 y(time.)p 0 1492
2045 1899 4 v 0 2931 4 1440 v 78 1562 a Fn(10000)j Ff(\002)e
2046 Fn(mctx)p 475 1562 20 4 v 25 w(cr)o(eate)j(\(in)e(seconds\):)78
2047 1710 y(Platf)n(orm)p 827 1734 4 79 v 561 w(mcsc)p 1080
2048 1734 V 165 w(sjlj)p 1332 1734 V 103 w(o)o(v)o(erhead)78
2049 1789 y Fm(Sun)g(Solaris)h(2.6)f(\(SP)-6 b(ARC\))p 827
2050 1813 V 133 w(0.076)p 1080 1813 V 104 w(1.268)p 1332 1813
2051 V 247 w(16.7)78 1868 y(DEC)16 b(T)n(ru64)h(5.0)g(\(Alpha\))p
2052 827 1892 V 171 w(0.019)p 1080 1892 V 104 w(0.235)p 1332
2053 1892 V 247 w(12.4)78 1947 y(SGI)g(IRIX)g(6.5)f(\(MIPS\))p
2054 827 1971 V 227 w(0.105)p 1080 1971 V 104 w(1.523)p 1332
2055 1971 V 247 w(14.5)78 2026 y(SCO)h(UnixW)-5 b(are)18 b(7.0)e(\(Intel\))p
2056 827 2050 V 105 w(0.204)p 1080 2050 V 104 w(3.827)p 1332
2057 2050 V 247 w(18.8)78 2105 y(HP)h(HP/UX)f(11.0)h(\(HPP)-6
2058 b(A\))p 827 2128 V 144 w(0.057)p 1080 2128 V 104 w(0.667)p
2059 1332 2128 V 247 w(11.8)1192 2184 y Fn(A)f(v)o(erage:)89
2060 b(14.8)78 2311 y(10000)18 b Ff(\002)e Fn(mctx)p 475 2311
2061 20 4 v 25 w(switch)i(\(in)f(seconds\):)78 2410 y(Platf)n(orm)p
2062 827 2433 4 79 v 561 w(mcsc)p 1080 2433 V 165 w(sjlj)p
2063 1332 2433 V 103 w(o)o(v)o(erhead)78 2488 y Fm(Sun)g(Solaris)h(2.6)f
2064 (\(SP)-6 b(ARC\))p 827 2512 V 133 w(0.137)p 1080 2512
2065 V 104 w(0.210)p 1332 2512 V 281 w(1.5)78 2567 y(DEC)16
2066 b(T)n(ru64)h(5.0)g(\(Alpha\))p 827 2591 V 171 w(0.034)p
2067 1080 2591 V 104 w(0.022)p 1332 2591 V 281 w(0.6)78 2646
2068 y(SGI)g(IRIX)g(6.5)f(\(MIPS\))p 827 2670 V 227 w(0.235)p
2069 1080 2670 V 104 w(0.190)p 1332 2670 V 281 w(0.8)78 2725
2070 y(SCO)h(UnixW)-5 b(are)18 b(7.0)e(\(Intel\))p 827 2749
2071 V 105 w(0.440)p 1080 2749 V 104 w(0.398)p 1332 2749 V
2072 281 w(0.9)78 2804 y(HP)h(HP/UX)f(11.0)h(\(HPP)-6 b(A\))p
2073 827 2828 V 144 w(0.106)p 1080 2828 V 104 w(0.065)p 1332
2074 2828 V 281 w(0.6)1225 2883 y Fn(A)f(v)o(erage:)90 b(0.9)p
2075 1896 2931 4 1440 v 0 2934 1899 4 v 0 3022 a(T)-6 b(able)18
2076 b(3:)67 b Fm(Summary)20 b(of)h Fl(Simple)i(Mac)o(hine)g(Conte)o(xt)g
2077 (Benc)o(hmark)g Fm(\(SMCB,)295 3090 y([32]\).)d(The)d(speed)g(of)g
2078 (machine)h(conte)o(xt)h(creation)g(and)e(switching)295
2079 3158 y(found)25 b(on)g(each)h(tested)g(operating)i(system.)44
2080 b Fn(mcsc)p Fm(:)38 b(functional)295 3226 y Fh(makecontext)p
2081 Fm(\(3\))11 b(/)i Fh(switchcontext)p Fm(\(3\),)f Fn(sjlj)p
2082 Fm(:)20 b(functional)295 3293 y Fh(sigsetjmp)p Fm(\(3\)/)p
2083 Fh(siglongjmp)p Fm(\(3\).)58 b Fn(o)o(v)o(erhead)p Fm(:)49
2084 b(the)31 b(o)o(v)o(er)o(-)295 3359 y(head)18 b(of)f(using)g
2085 Fn(sjlj)g Fm(instead)i(of)e Fn(mcsc)p Fm(.)0 3573 y FA(3.5)99
2086 b(Remaining)25 b(Issues)0 3730 y Fx(The)20 b(presented)e(algorithm)h
2087 (and)g(source)g(code)h(can)f(be)h(directly)0 3829 y(used)29
2088 b(in)h(practice)f(for)f(implementing)g(a)i(minimal)e(threading)0
2089 3929 y(system)e(or)g(the)g(concept)e(of)i(co-routines.)40
2090 b(Its)27 b(big)f(adv)n(antage)0 4029 y(is)20 b(that)f(if)g(the)g
2091 (operating)e(system)i(pro)o(vides)e(the)i(required)e(stan-)0
2092 4128 y(dardized)j(primiti)n(v)o(es,)g(we)h(do)g(not)g(need)f(to)i(kno)n
2093 (w)e(an)o(ything)f(at)0 4228 y(all)28 b(about)e(the)h(machine)g(we)g
2094 (are)g(running)f(on)g(\227)i(e)n(v)o(erything)0 4327
2095 y(just)d(w)o(orks.)38 b(Ne)n(v)o(ertheless,)25 b(there)f(remain)g(a)h
2096 (fe)n(w)f(special)h(is-)0 4427 y(sues)c(we)f(still)i(ha)n(v)o(e)d(to)i
2097 (discuss.)0 4577 y FA(The)26 b(W)-6 b(aggly)23 b(longjmp\(3\))i(after)h
2098 (Retur)o(n)0 4702 y Fx(On)e(some)f(platforms,)h Fp(longjmp)p
2099 Fx(\(3\))e(may)h(not)g(be)h(called)g(af-)0 4802 y(ter)30
2100 b(the)g(function)e(which)i(called)f(the)h Fp(setjmp)p
2101 Fx(\(3\))f(returned.)0 4902 y(When)22 b(this)i(is)f(done,)f(the)h
2102 (stack)g(frame)e(situation)i(is)g(not)f(guar)n(-)0 5001
2103 y(anteed)k(to)h(be)g(in)f(a)i(clean)e(and)g(consistent)h(state.)45
2104 b(But)27 b(this)h(is)0 5101 y(e)o(xactly)c(the)h(mechanism)f(we)h(use)g
2105 (in)g(order)f(to)h(get)g(rid)g(of)g(the)0 5200 y(signal)20
2106 b(handler)f(scope)h(in)g(step)g(5.)125 5300 y(The)c(only)g(alternati)n
2107 (v)o(e)g(w)o(ould)g(be)h(to)g(lea)n(v)o(e)g(the)g(signal)f(han-)0
2108 5400 y(dler)27 b(via)g Fp(longjmp)p Fx(\(3\),)g(b)n(ut)g(then)g(we)h(w)
2109 o(ould)e(ha)n(v)o(e)h(another)2025 83 y(problem,)f(as)h(e)o(xperience)d
2110 (sho)n(wed.)41 b(F)o(or)26 b(instance,)j(R)q Fm(O)t(B)t(E)t(RT)2027
2111 183 y Fx(S)t(.)k(T)t Fm(H)t(AU)r Fx(')-5 b(s)29 b Fr(Really)e(Simple)g
2112 (Thr)m(eads)h Fx(\()p Fr(r)o(sthr)m(eads)p Fx(\))f([27)o(])h(w)o(as)
2113 2025 282 y(ported)17 b(to)h(se)n(v)o(eral)f(platforms)g(and)g(w)o(as)i
2114 (used)f(to)g(run)f(an)h(e)o(xper)n(-)2025 382 y(imental)23
2115 b(multithreaded)d(v)o(ersion)i(of)h(the)g(Apache)f(webserv)o(er)-5
2116 b(.)2027 482 y(T)t Fm(H)t(AU)r Fx(')g(s)18 b(approach)d(w)o(as)i
2117 (similar)g(to)g(ours,)g(b)n(ut)f(dif)n(fered)f(signif-)2025
2118 581 y(icantly)k(in)h(the)f(w)o(ay)g(the)h(signal)f(handler)f(is)i
2119 (left.)25 b(In)19 b(particular)m(,)2025 681 y(in)27 b(an)f(attempt)g
2120 (to)h(a)n(v)n(oid)f(the)g(unsafe)g(stack)h(frame,)g(it)g(used)f(a)2025
2121 780 y Fp(longjmp)p Fx(\(3\))19 b(call)i(to)g(lea)n(v)o(e)f(the)h
2122 (signal)f(handler)m(,)f(rather)h(than)2025 880 y(returning)27
2123 b(from)h(it.)51 b(But)30 b(this)f(approach)e(does)h(not)h(w)o(ork)f(on)
2124 2025 980 y(some)20 b Fr(SysV)6 b Fx(-deri)n(v)o(ed)18
2125 b(k)o(ernels,)h(as)i(we)g(already)e(mentioned.)2150 1079
2126 y(The)31 b(problem)e(is)k(that)e(these)h(k)o(ernels)f(do)g(not)g
2127 (\223belie)n(v)o(e\224)2025 1179 y(that)e(the)g(code)g(is)h(out)e(of)h
2128 (the)g(signal-handling)e(conte)o(xt,)i(un-)2025 1279
2129 y(til)k(the)f(signal)f(handler)g(has)h(returned)e(\227)i(and)g
2130 (accordingly)-5 b(,)2025 1378 y(refuse)28 b(to)g(allo)n(w)g
2131 (readjustment)f(of)g(the)i(signal)f(stack)g(until)g(it)2025
2132 1478 y(has.)61 b(But)32 b(with)g(the)h Fr(r)o(sthr)m(eads)f
2133 Fx(approach,)g(the)h(signal)e(han-)2025 1577 y(dler)23
2134 b(that)f(created)h(the)f(\002rst)i(thread)e(ne)n(v)o(er)f(returns,)i
2135 (and)f(when)2025 1677 y Fr(r)o(sthr)m(eads)17 b Fx(w)o(ants)g(to)g
2136 (create)g(the)g(second)f(thread,)g(these)h(k)o(ernels)2025
2137 1777 y(refuse)23 b(to)g(readjust)g(the)h(signal)f(stack,)h(and)f(we)h
2138 (are)f(stuck.)34 b(So)2025 1876 y(with)17 b(portability)e(in)i(mind,)f
2139 (we)h(decided)e(that)i(it)g(is)h(better)e(to)h(get)2025
2140 1976 y(rid)23 b(of)f(the)h(signal)g(handler)f(scope)g(with)h(the)g
2141 (straight-forw)o(ard)2025 2076 y(\223)p Fp(return)p Fx(\224)38
2142 b(and)h(instead)g(\002ght)g(the)g(mentioned)f(\(simpler\))2025
2143 2175 y(problem)18 b(of)i(an)h(unsafe)e(stack)h(frame.)2150
2144 2275 y(F)o(ortunately)-5 b(,)24 b(in)i(practice)e(this)i(is)h(not)e(as)
2145 h(problematic)e(as)2025 2374 y(it)j(seems,)h(because)e(e)n(v)n
2146 (aluations)f(\(for)h Fr(GNU)h(Pth)p Fx(\))f(on)g(a)h(wide)2025
2147 2474 y(range)35 b(of)g(current)g(Unix)g(platforms)g(sho)n(wed)g(that)h
2148 (one)f(can)2025 2574 y(reach)21 b(a)g(safe)h(stack)f(frame)f(again)h
2149 (by)f(just)i(calling)f(a)h(function.)2025 2673 y(That)k(is)i(the)e
2150 (reason)g(why)f(our)h(algorithm)f(enters)h(the)g(second)2025
2151 2773 y(trampoline)18 b(function)h(in)h(step)h(9.)2025
2152 2918 y FA(The)26 b(Uncooperati)o(v)o(e)g(longjmp\(3\))2025
2153 3040 y Fx(Ev)o(en)e(on)i(operating)d(systems)j(which)f(ha)n(v)o(e)g(w)o
2154 (orking)f Fr(POSIX)2025 3140 y Fx(functions,)c(our)g(approach)f(may)h
2155 (theoretically)g(still)i(not)e(w)o(ork,)2025 3240 y(because)48
2156 b Fp(longjmp)p Fx(\(3\))f(does)i(not)f(cooperate.)109
2157 b(F)o(or)49 b(in-)2025 3339 y(stance,)17 b(on)e(some)h(platforms)f(the)
2158 h(standard)f Fr(libc)i Fp(longjmp)p Fx(\(3\))2025 3439
2159 y(branches)d(to)h(error)n(-handling)d(code)j(if)g(it)h(detects)g(that)f
2160 (the)h(caller)2025 3539 y(tries)j(to)h(jump)e Fr(up)g
2161 Fx(the)h(stack,)g Fr(i.e)o(.)p Fx(,)g(into)g(a)g(stack)g(frame)f(that)h
2162 (has)2025 3638 y(already)g(returned.)2150 3738 y(This)28
2163 b(is)h(usually)f(implemented)f(by)h(comparing)e(the)i(cur)n(-)2025
2164 3837 y(rent)f(stack)g(pointer)f(to)h(the)g(one)f(in)h(the)g
2165 Fp(jmp)p 3387 3837 25 4 v 30 w(buf)g Fx(structure.)2025
2166 3937 y(That)j(is)h(why)e(it)i(is)g(important)e(for)g(our)h(algorithm)e
2167 (to)j(return)2025 4037 y(from)19 b(the)g(signal)h(handler)e(and)h(this)
2168 h(w)o(ay)f(enter)g(the)h(\(dif)n(ferent\))2025 4136 y(stack)31
2169 b(of)g(the)h(parent)e(thread.)57 b(In)31 b(practice,)i(the)e(implemen-)
2170 2025 4236 y(tation)26 b(in)g Fr(GNU)h(Pth)f Fx(sho)n(wed)g(that)g(then)
2171 g(one)f(no)h(longer)f(suf-)2025 4336 y(fers)16 b(from)f(those)g
2172 (uncooperati)n(v)o(e)d Fp(longjmp)p Fx(\(3\))i(implementa-)2025
2173 4435 y(tions,)k(b)n(ut)f(one)f(should)h(k)o(eep)f(this)i(point)e(in)i
2174 (mind)e(when)h(reach-)2025 4535 y(ing)29 b(e)n(v)o(en)f(more)h
2175 (uncooperati)n(v)o(e)d(v)n(ariants)j(on)g(esoteric)g(Unix)2025
2176 4634 y(platforms.)22 b(If)16 b(it)h(still)g(occurs,)f(one)g(can)g(only)
2177 f(try)h(to)g(resume)g(the)2025 4734 y(operation)24 b(by)h(using)f(a)i
2178 (possibly)f(e)o(xisting)g(platform-speci\002c)2025 4834
2179 y(error)19 b(handling)f(hook.)2025 4979 y FA(Garbage)25
2180 b(at)g(Bottom)g(of)g(Stacks)2025 5101 y Fx(There)17 b(is)i(a)f(subtle)f
2181 (side-ef)n(fect)g(of)g(our)g(implementation:)22 b(there)2025
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2183 (thread)f(stack.)2025 5300 y(The)33 b(reason)g(is)i(that)e(if)h(a)g
2184 (signal)g(is)g(deli)n(v)o(ered,)h(the)f(operat-)2025
2185 5400 y(ing)d(system)g(pushes)f(some)h(state)h(onto)e(the)h(stack,)i
2186 (which)e(is)p Black 1929 5700 a(8)p Black eop
2188 9 8 bop Black Black 0 83 a Fx(restored)27 b(later)m(,)j(when)e(the)h
2189 (signal)f(handler)f(returns.)48 b(But)29 b(al-)0 183
2190 y(though)h(we)h(return)f(from)h(the)g(signal)g(handler)m(,)h(we)g(jump)
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2198 886 y(of)h(memory)e(at)i(the)h(bottom)d(of)i(the)g(established)g
2199 (thread)f(stack.)0 986 y(F)o(or)d(some)h(systems)g(this)g(can)g(be)g(e)
2200 n(v)o(en)e(up)i(to)g(1)g(KB)g(of)g(garbage)0 1085 y([27)o(].)25
2201 b(But)19 b(e)o(xcept)g(for)f(the)i(additional)d(memory)h(consumption)0
2202 1185 y(it)j(does)f(not)g(hurt.)125 1291 y(W)-7 b(e)32
2203 b(just)g(ha)n(v)o(e)f(to)h(k)o(eep)f(in)h(mind)f(this)h(additional)e
2204 (stack)0 1391 y(consumption)25 b(when)j(deciding)e(the)i(stack)g(size)h
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projects / platform / upstream / pth.git / blob