DVI Driver Family Update #12 [28-Sep-87] This issue announces Version 2.09, some minor editorial changes, and fixes to three serious bugs, one of which affects only dvijep, another only dvialw, and the third, most of the dot-matrix printer drivers. The fixes are extracted from the 00REVHST.TXT file, and I record below everything posted to it since Version 2.08 (20-Aug-87) I am pleased to announce that the Free Software Foundation GNU Project C compiler, gcc, now successfully compiles the entire DVI driver family, both with and without optimization, on the Sun workstation. gcc can be built to produce code for Motorola 68000, 68010, and 68020 CPU's, and for the DEC VAX architecture. I have installed version 1.11 here, and applied two bug fixes supplied by Richard Stallman to correct problems in gcc that showed up during the installation and testing of gcc on the DVI driver family. This testing also revealed a bug in the driver family itself; the fix is documented below. gcc currently runs with the host (Sun or VAX) C library, and consequently produces code which is calling-sequence compatible with the native Unix cc compilers. Presumably a later release of gcc will include complete run-time libraries, since the goal of the GNU project is to produce a complete free-standing operating system that runs on multiple architectures, and is freely available in source form. gcc's command-line switches are a superset of cc's. An important virtue is that specification of the debug switch (-g) does not nullify the optimization switch (-O), which is one of the great flaws with the Sun compilers. Optimization is likely to exhibit compiler bugs, and it is convenient to be able to track these down with a source-level debugger that can still find variables and line numbers, instead of an assembly-level debugger that only knows about machine addresses. gcc also is current with the October 1986 draft of the ANSI C standard, including string concatenation ("foo" "bar" becomes "foobar"), preprocessor token squashing ('#define X(n) X##n' results in X(abc) expanding to Xabc), and function prototype declarations. SRI has just released Version 4 of the TOPS-20 KCC compiler. Like gcc, this too conforms to the draft ANSI standard, and to the second edition of S. Harbison and G. Steele, ``C -- A Reference Manual'', Prentice-Hall (1987). This version also finally implements ioctl.h and signal.h, and fills in miscellaneous other routines from the 4.2BSD Unix library that were missing in earlier KCC releases The value of early availability of ANSI conformant compilers is significant, in that it permits more extensive testing of software portability, and also exposes the code to the more rigorous cross-checking available via function argument prototype declarations, a new feature introduced by the ANSI C committee. Function prototypes were actually borrowed from B. Stroustrup's C++ language, which is currently implemented as a preprocessor whose output is fed to the C compiler. C's readiness to automatically coerce values in expressions, assignments, and function calls is sometimes convenient, but more often introduces subtle machine dependencies. The approach I have rigorously adhered to in the DVI family is to use typecasts to specify explicit coercion, but such rigor requires automated tools which can check for compliance. ANSI extensions to VAX VMS C have been reported by at least one site; we do not yet have the upgrade locally. Microsoft C Version 5.0 is due out in October 1987, and should be similarly enhanced (it already had function prototypes declarations in Version 4.0). Here now are the recent change log entries: [28-Sep-87] Updated all makefiles to include a generic target dvi$(PGM) and an extra compilation flag value XCFLAGS, so test versions can be constructed by a command like "make PGM=foo XCFLAGS=-g dvifoo". [28-Sep-87] {Thanks to Ian Young (ian@latlog.uucp)} At the end of readgf.h, newfont() is called before the loop which retrieves character metrics via chargf(). This is incorrect for HPJETPLUS, where the newfont() code in dvijep.c uses some of the metrics. For the other devices, newfont() only sets values in the font character tables. Therefore, move the newfont() call to AFTER the loop, so that the code reads in readgf.H: for (the_char = FIRSTPXLCHAR; the_char <= LASTPXLCHAR; the_char++) { /* Get remaining character metrics, and ignore error returns for now. */ tcharptr = &(fontptr->ch[the_char]); if (tcharptr->fontrp >= 0L) (void)chargf(the_char,(void(*)())NULL); } #if (BBNBITGRAPH | HPJETPLUS | POSTSCRIPT | IMPRESS | CANON_A2) (void)newfont(); #endif [28-Sep-87] On Unix systems, getlogin() returns (char*)NULL if the process is not attached to a terminal, in particular, if the process is attached to a pseudo-terminal (pty), such as a window or an editor shell buffer. The way to get the real login name in these circumstances is to use cuserid((char*)NULL) in place of getlogin(), and I have according made that change in dvialw.c and lptops.c, and added appropriate function declarations in gblprocs.h. This change affects only text output in a PostScript comment. Both cuserid and getlogin are defined in 4.2BSD Unix, AT&T SYS V Unix, HPUX, KCC (version 4), and IEEE Posix (which draft ANSI C follows). PCC and V7 Unix had only getlogin. VAX VMS C has only cuserid. KCC (version 3), Microsoft C, Lattice C, and Wizard C have neither. [23-Sep-87] {Version 2.09 announcement} Testing of the Free Software Foundation gcc compiler has uncovered two bugs so far in the compiler (they are being fixed rapidly). gcc produces code for both VAX and Motorola architectures, and is being used to develop the GNU operating system. The testing also found a serious bug in my code which unfortunately impacts most of the DVI drivers, and can be the cause of core dumps or other failures. The value of XSIZE in dvi*.c is currently computed as XDPI*XPSIZE, that is, the number of dots across the page. Unfortunately, one or more local arrays are later allocated and used with the assumption that XSIZE is a multiple of the machine word size, HOST_WORD_SIZE, and in dvijet, it was assumed to be a multiple of 2*HOST_WORD_SIZE. This bug was never caught on the DEC-20, because there stacks grow upward, so beyond-bounds references to stack arrays may just be writing into unused memory. However, on the VAX, Intel iAPX, and Motorola architectures, stacks grow downward, and such references can wipe out the call history, precipitating at best an address exception or illegal instruction violation when the return instruction is executed. This would only happen if text was set against the right-hand side of the page, and since TeX documents usually produce wide margins, this may be unlikely to happen. To avoid complex dimension computations, and preserve uniformity of definition among the family, XSIZE is now increased to a multiple of 2*HOST_WORD_SIZE throughout. The fix is to change #define XSIZE (XDPI*XPSIZE) /* number of horizontal dots */ to #define XSIZE (((XDPI*XPSIZE+2*HOST_WORD_SIZE-1)/\ (2*HOST_WORD_SIZE))*(2*HOST_WORD_SIZE)) /* number of horizontal dots; */ /* MUST BE multiple of */ /* 2*HOST_WORD_SIZE */ in all the dvi*.c files. I view this bug fix to be important enough to warrant a version number change, so the family is now at version 2.09. The following Unix script can be used on Unix systems to automate the patch: #!/bin/csh foreach f (dvi*.c) echo $f mv $f $f-old sed -f bugfix.sed <$f-old >$f end Here is bugfix.sed: s|"2.08|"2.09| s|(XDPI\*XPSIZE)[ ]*/\* number of horizontal dots \*/|(((XDPI*XPSIZE+2*HOST_WORD_SIZE-1)/\\\ (2*HOST_WORD_SIZE))*(2*HOST_WORD_SIZE))\ /* number of horizontal dots; */\ /* MUST BE multiple of */\ /* 2*HOST_WORD_SIZE */| [23-Sep-87] In openfont.h, nopen is incremented when the requested font is not found in the list of currently open files, but the code forgets to decrement it if the request font never gets successfully opened, when can happen if the font file cannot be found, and no substitution font is provided. Change the code about line 185 to decrement nopen on open failure, so that it now reads: if (fontfp == (FILE*)NULL) { --nopen; /* don't count this failed open */ (void)sprintf(message,"Font file [%s [mag %d]] could not be \ [18-Sep-87] {Thanks to Mic Kaczmarczik (CC.KCACMARCZIK@A20.CC.UTEXAS.EDU)} When dvialw.ps is modified to select LANDSCAPE mode instead of NOTE (portrait), the output is positioned incorrectly, and character bitmaps look somewhat raggged. The former is due to a missing translation command, and the latter to tiny non-zero transformation matrix elements which introduce computed coordinates which are in error by one pixel. I have also taken the liberty of installing a fix for the fact that NOTE is not defined on non-Apple PostScript printers. It should no longer be necessary to edit dvialw.ps for Texas Instruments, QMS, et al PostScript printers. There is one problem with this change, and that is that the SNAP call in the CharBuilder routine must now be executed for each character set on the page, so the output may prove to be somewhat slower. To check this, I downloaded dvialw.ps to our new Apple LaserWriter Plus, then executed TeXdict begin usertime 10000 {0 0 SNAP pop pop} repeat usertime exch sub pstack which results in a time of 70844 msec for 10000 calls, or an extra overhead of 7 msec per character. Repeating the experiment using an empty procedure body gives a loop overhead time of 0.2 msec. With an average of 3000 characters set per page, this amounts to 21 sec per page, which is definitely not negligible. You may therefore wish to leave the SNAP call out of a version of dvialw.ps that is used only for portrait orientation output. Similar timing loops can be used to reveal an average execution time of 1 msec for any arithmetic operation (+-/*); PostScript interpreters badly need hardware floating-point support! There is a repeatable difference of about 10% increase in speed when operands are floating-point instead of integer values. dvialw could be changed to write floating-point values instead of integer ones, with a tradeoff of slightly increased output file size to be balanced against slightly faster arithmetic. At the same time, I increased XPSIZE to 14 in dvialw.c so that landscape mode output is not clipped. Future work should introduce a general flexible solution to the problem of paper size specification for all of the drivers. Here is a context difference which records the changes. Additions are flagged with a "+" in the first column, and changes with a "!", with the old code first, and the new second. *** dvialw.ps-old Wed Jul 29 14:35:41 1987 --- dvialw.ps Fri Sep 18 17:48:10 1987 *************** *** 1,3 **** --- 1,10 ---- + % DVIALW.PS.17, 18-Sep-87 17:48:04, Edit by BEEBE + % Add test for note paper and if unknown, use letter paper instead. + % Non-Apple PostScript implementations do not know about note paper + % but its use on the Apple LaserWriter gains 92K of virtual memory + % DVIALW.PS.16, 18-Sep-87 15:50:52, Edit by BEEBE + % Modify coordinate computations to remove round-off errors + % in landscape mode, and correct landscape page origin % DVIALW.PS.14, 22-Jun-87 09:55:05, Edit by BEEBE % Add missing "0 900 translate Mtrx currentmatrix pop" to /LEGAL % DVIALW.PS.13, 7-Jan-87 17:38:51, Edit by BEEBE *************** *** 110,116 **** /BOJ { 72 Resolution div 72 Resolution div scale ! NOTE % default page format } bdf % BOP -- beginning of page --- 117,126 ---- /BOJ { 72 Resolution div 72 Resolution div scale ! userdict /note known ! {NOTE} % default page format for ALW ! {LETTER} % default page format for others ! ifelse } bdf % BOP -- beginning of page *************** *** 146,151 **** --- 156,162 ---- ch-xoff neg ch-yoff ch-height sub ch-width ch-xoff sub ch-yoff setcachedevice + 0 0 SNAP translate ch-width ch-height true [ 1 0 0 -1 ch-xoff ch-yoff ] {ch-image} imagemask } if *************** *** 185,190 **** --- 196,202 ---- 72 Resolution div dup scale 0 3300 translate -90 rotate + 0 -750 translate Mtrx currentmatrix pop } bdf *************** *** 271,276 **** --- 283,292 ---- % SF -- set new font at scale nnn (nnn = 1 normally; 2 gives double size chars) % Usage -- nnn /fontname SF /SF {findfont exch scalefont setfont} bdf() pop + + % SNAP -- convert coordinates to integer device coordinates and back again + % Usage -- xxx yyy SNAP (leave xxx' yyy' on stack) + /SNAP {transform 2 {floor 0.5 add exch} repeat itransform} bdf % T -- move absolute horizontally and show string, updating horizontal position % to new endpt [08-Sep-87] In lptops.c, change OUTSTR(getlogin()); to if (getlogin() != (char*)NULL) OUTSTR(getlogin()); because getlogin() can sometimes return a null pointer, instead of a null string. [31-Aug-87] {Thanks to HUXTABLE@UKANVAX.BITNET} In gblprocs.h in the ANSI type declarations for dvifile and main, change "char *[0]" to "char *[]". The "[0]" is an odd production of Microsoft C which was used to prepare the type declarations at compile time. It sneaked through the editing (it is not needed for Microsoft C to compile these). VAX VMS C version 2.3-024 now supports ANSI function declaration prototypes; I don't have it up yet. 28-Sep-87 19:15:06-MDT,17660;000000000000 Date: Mon 28 Sep 87 19:15:06-MDT From: "Nelson H.F. Beebe" Subject: DVI driver family update #12 To: "DVI mailing list": ; cc: BEEBE@SCIENCE.UTAH.EDU X-US-Mail: "Center for Scientific Computation, South Physics, University of Utah, Salt Lake City, UT 84112" X-Telephone: (801) 581-5254 Message-ID: <12338345320.27.BEEBE@SCIENCE.UTAH.EDU> DVI Driver Family Update #12 [28-Sep-87] This issue announces Version 2.09, some minor editorial changes, and fixes to three serious bugs, one of which affects only dvijep, another only dvialw, and the third, most of the dot-matrix printer drivers. The fixes are extracted from the 00REVHST.TXT file, and I record below everything posted to it since Version 2.08 (20-Aug-87) I am pleased to announce that the Free Software Foundation GNU Project C compiler, gcc, now successfully compiles the entire DVI driver family, both with and without optimization, on the Sun workstation. gcc can be built to produce code for Motorola 68000, 68010, and 68020 CPU's, and for the DEC VAX architecture. I have installed version 1.11 here, and applied two bug fixes supplied by Richard Stallman to correct problems in gcc that showed up during the installation and testing of gcc on the DVI driver family. This testing also revealed a bug in the driver family itself; the fix is documented below. gcc currently runs with the host (Sun or VAX) C library, and consequently produces code which is calling-sequence compatible with the native Unix cc compilers. Presumably a later release of gcc will include complete run-time libraries, since the goal of the GNU project is to produce a complete free-standing operating system that runs on multiple architectures, and is freely available in source form. gcc's command-line switches are a superset of cc's. An important virtue is that specification of the debug switch (-g) does not nullify the optimization switch (-O), which is one of the great flaws with the Sun compilers. Optimization is likely to exhibit compiler bugs, and it is convenient to be able to track these down with a source-level debugger that can still find variables and line numbers, instead of an assembly-level debugger that only knows about machine addresses. gcc also is current with the October 1986 draft of the ANSI C standard, including string concatenation ("foo" "bar" becomes "foobar"), preprocessor token squashing ('#define X(n) X##n' results in X(abc) expanding to Xabc), and function prototype declarations. SRI has just released Version 4 of the TOPS-20 KCC compiler. Like gcc, this too conforms to the draft ANSI standard, and to the second edition of S. Harbison and G. Steele, ``C -- A Reference Manual'', Prentice-Hall (1987). This version also finally implements ioctl.h and signal.h, and fills in miscellaneous other routines from the 4.2BSD Unix library that were missing in earlier KCC releases The value of early availability of ANSI conformant compilers is significant, in that it permits more extensive testing of software portability, and also exposes the code to the more rigorous cross-checking available via function argument prototype declarations, a new feature introduced by the ANSI C committee. Function prototypes were actually borrowed from B. Stroustrup's C++ language, which is currently implemented as a preprocessor whose output is fed to the C compiler. C's readiness to automatically coerce values in expressions, assignments, and function calls is sometimes convenient, but more often introduces subtle machine dependencies. The approach I have rigorously adhered to in the DVI family is to use typecasts to specify explicit coercion, but such rigor requires automated tools which can check for compliance. ANSI extensions to VAX VMS C have been reported by at least one site; we do not yet have the upgrade locally. Microsoft C Version 5.0 is due out in October 1987, and should be similarly enhanced (it already had function prototypes declarations in Version 4.0). Here now are the recent change log entries: [28-Sep-87] Updated all makefiles to include a generic target dvi$(PGM) and an extra compilation flag value XCFLAGS, so test versions can be constructed by a command like "make PGM=foo XCFLAGS=-g dvifoo". [28-Sep-87] {Thanks to Ian Young (ian@latlog.uucp)} At the end of readgf.h, newfont() is called before the loop which retrieves character metrics via chargf(). This is incorrect for HPJETPLUS, where the newfont() code in dvijep.c uses some of the metrics. For the other devices, newfont() only sets values in the font character tables. Therefore, move the newfont() call to AFTER the loop, so that the code reads in readgf.H: for (the_char = FIRSTPXLCHAR; the_char <= LASTPXLCHAR; the_char++) { /* Get remaining character metrics, and ignore error returns for now. */ tcharptr = &(fontptr->ch[the_char]); if (tcharptr->fontrp >= 0L) (void)chargf(the_char,(void(*)())NULL); } #if (BBNBITGRAPH | HPJETPLUS | POSTSCRIPT | IMPRESS | CANON_A2) (void)newfont(); #endif [28-Sep-87] On Unix systems, getlogin() returns (char*)NULL if the process is not attached to a terminal, in particular, if the process is attached to a pseudo-terminal (pty), such as a window or an editor shell buffer. The way to get the real login name in these circumstances is to use cuserid((char*)NULL) in place of getlogin(), and I have according made that change in dvialw.c and lptops.c, and added appropriate function declarations in gblprocs.h. This change affects only text output in a PostScript comment. Both cuserid and getlogin are defined in 4.2BSD Unix, AT&T SYS V Unix, HPUX, KCC (version 4), and IEEE Posix (which draft ANSI C follows). PCC and V7 Unix had only getlogin. VAX VMS C has only cuserid. KCC (version 3), Microsoft C, Lattice C, and Wizard C have neither. [23-Sep-87] {Version 2.09 announcement} Testing of the Free Software Foundation gcc compiler has uncovered two bugs so far in the compiler (they are being fixed rapidly). gcc produces code for both VAX and Motorola architectures, and is being used to develop the GNU operating system. The testing also found a serious bug in my code which unfortunately impacts most of the DVI drivers, and can be the cause of core dumps or other failures. The value of XSIZE in dvi*.c is currently computed as XDPI*XPSIZE, that is, the number of dots across the page. Unfortunately, one or more local arrays are later allocated and used with the assumption that XSIZE is a multiple of the machine word size, HOST_WORD_SIZE, and in dvijet, it was assumed to be a multiple of 2*HOST_WORD_SIZE. This bug was never caught on the DEC-20, because there stacks grow upward, so beyond-bounds references to stack arrays may just be writing into unused memory. However, on the VAX, Intel iAPX, and Motorola architectures, stacks grow downward, and such references can wipe out the call history, precipitating at best an address exception or illegal instruction violation when the return instruction is executed. This would only happen if text was set against the right-hand side of the page, and since TeX documents usually produce wide margins, this may be unlikely to happen. To avoid complex dimension computations, and preserve uniformity of definition among the family, XSIZE is now increased to a multiple of 2*HOST_WORD_SIZE throughout. The fix is to change #define XSIZE (XDPI*XPSIZE) /* number of horizontal dots */ to #define XSIZE (((XDPI*XPSIZE+2*HOST_WORD_SIZE-1)/\ (2*HOST_WORD_SIZE))*(2*HOST_WORD_SIZE)) /* number of horizontal dots; */ /* MUST BE multiple of */ /* 2*HOST_WORD_SIZE */ in all the dvi*.c files. I view this bug fix to be important enough to warrant a version number change, so the family is now at version 2.09. The following Unix script can be used on Unix systems to automate the patch: #!/bin/csh foreach f (dvi*.c) echo $f mv $f $f-old sed -f bugfix.sed <$f-old >$f end Here is bugfix.sed: s|"2.08|"2.09| s|(XDPI\*XPSIZE)[ ]*/\* number of horizontal dots \*/|(((XDPI*XPSIZE+2*HOST_WORD_SIZE-1)/\\\ (2*HOST_WORD_SIZE))*(2*HOST_WORD_SIZE))\ /* number of horizontal dots; */\ /* MUST BE multiple of */\ /* 2*HOST_WORD_SIZE */| [23-Sep-87] In openfont.h, nopen is incremented when the requested font is not found in the list of currently open files, but the code forgets to decrement it if the request font never gets successfully opened, when can happen if the font file cannot be found, and no substitution font is provided. Change the code about line 185 to decrement nopen on open failure, so that it now reads: if (fontfp == (FILE*)NULL) { --nopen; /* don't count this failed open */ (void)sprintf(message,"Font file [%s [mag %d]] could not be \ [18-Sep-87] {Thanks to Mic Kaczmarczik (CC.KCACMARCZIK@A20.CC.UTEXAS.EDU)} When dvialw.ps is modified to select LANDSCAPE mode instead of NOTE (portrait), the output is positioned incorrectly, and character bitmaps look somewhat raggged. The former is due to a missing translation command, and the latter to tiny non-zero transformation matrix elements which introduce computed coordinates which are in error by one pixel. I have also taken the liberty of installing a fix for the fact that NOTE is not defined on non-Apple PostScript printers. It should no longer be necessary to edit dvialw.ps for Texas Instruments, QMS, et al PostScript printers. There is one problem with this change, and that is that the SNAP call in the CharBuilder routine must now be executed for each character set on the page, so the output may prove to be somewhat slower. To check this, I downloaded dvialw.ps to our new Apple LaserWriter Plus, then executed TeXdict begin usertime 10000 {0 0 SNAP pop pop} repeat usertime exch sub pstack which results in a time of 70844 msec for 10000 calls, or an extra overhead of 7 msec per character. Repeating the experiment using an empty procedure body gives a loop overhead time of 0.2 msec. With an average of 3000 characters set per page, this amounts to 21 sec per page, which is definitely not negligible. You may therefore wish to leave the SNAP call out of a version of dvialw.ps that is used only for portrait orientation output. Similar timing loops can be used to reveal an average execution time of 1 msec for any arithmetic operation (+-/*); PostScript interpreters badly need hardware floating-point support! There is a repeatable difference of about 10% increase in speed when operands are floating-point instead of integer values. dvialw could be changed to write floating-point values instead of integer ones, with a tradeoff of slightly increased output file size to be balanced against slightly faster arithmetic. At the same time, I increased XPSIZE to 14 in dvialw.c so that landscape mode output is not clipped. Future work should introduce a general flexible solution to the problem of paper size specification for all of the drivers. Here is a context difference which records the changes. Additions are flagged with a "+" in the first column, and changes with a "!", with the old code first, and the new second. *** dvialw.ps-old Wed Jul 29 14:35:41 1987 --- dvialw.ps Fri Sep 18 17:48:10 1987 *************** *** 1,3 **** --- 1,10 ---- + % DVIALW.PS.17, 18-Sep-87 17:48:04, Edit by BEEBE + % Add test for note paper and if unknown, use letter paper instead. + % Non-Apple PostScript implementations do not know about note paper + % but its use on the Apple LaserWriter gains 92K of virtual memory + % DVIALW.PS.16, 18-Sep-87 15:50:52, Edit by BEEBE + % Modify coordinate computations to remove round-off errors + % in landscape mode, and correct landscape page origin % DVIALW.PS.14, 22-Jun-87 09:55:05, Edit by BEEBE % Add missing "0 900 translate Mtrx currentmatrix pop" to /LEGAL % DVIALW.PS.13, 7-Jan-87 17:38:51, Edit by BEEBE *************** *** 110,116 **** /BOJ { 72 Resolution div 72 Resolution div scale ! NOTE % default page format } bdf % BOP -- beginning of page --- 117,126 ---- /BOJ { 72 Resolution div 72 Resolution div scale ! userdict /note known ! {NOTE} % default page format for ALW ! {LETTER} % default page format for others ! ifelse } bdf % BOP -- beginning of page *************** *** 146,151 **** --- 156,162 ---- ch-xoff neg ch-yoff ch-height sub ch-width ch-xoff sub ch-yoff setcachedevice + 0 0 SNAP translate ch-width ch-height true [ 1 0 0 -1 ch-xoff ch-yoff ] {ch-image} imagemask } if *************** *** 185,190 **** --- 196,202 ---- 72 Resolution div dup scale 0 3300 translate -90 rotate + 0 -750 translate Mtrx currentmatrix pop } bdf *************** *** 271,276 **** --- 283,292 ---- % SF -- set new font at scale nnn (nnn = 1 normally; 2 gives double size chars) % Usage -- nnn /fontname SF /SF {findfont exch scalefont setfont} bdf() pop + + % SNAP -- convert coordinates to integer device coordinates and back again + % Usage -- xxx yyy SNAP (leave xxx' yyy' on stack) + /SNAP {transform 2 {floor 0.5 add exch} repeat itransform} bdf % T -- move absolute horizontally and show string, updating horizontal position % to new endpt [08-Sep-87] In lptops.c, change OUTSTR(getlogin()); to if (getlogin() != (char*)NULL) OUTSTR(getlogin()); because getlogin() can sometimes return a null pointer, instead of a null string. [31-Aug-87] {Thanks to HUXTABLE@UKANVAX.BITNET} In gblprocs.h in the ANSI type declarations for dvifile and main, change "char *[0]" to "char *[]". The "[0]" is an odd production of Microsoft C which was used to prepare the type declarations at compile time. It sneaked through the editing (it is not needed for Microsoft C to compile these). VAX VMS C version 2.3-024 now supports ANSI function declaration prototypes; I don't have it up yet. -------