Porting Content to Mandrake Linux 7.0 with Red Hat Motif 2.1
------------------------------------------------------------
These notes describe the changes I made in the vibrant and content source
trees to port Content 1.5 to Mandrake Linux 7.0 with Red Hat Motif 2.1.
In performing the port, I followed the directions in the file mandrake7.0_inst.
My hardware and software configurations are also described in that document.
You might want to read that file first before reading this one.

1. Once I altered $CONTENT/vibrant/make/viball.lnx to include -lXp and
   the path to the Motif header files /usr/X11R6/include/Xm, the vibrant
   library compiled without incident.

2. I altered the make file $CONTENT/content/makefile_v as I described in my
   Mandrake 7.0 installation document.  When I attempted to make Content,
   I encountered the following errors.

      ./libcontent.a(curve.o): In function `StartCR':
      curve.o(.text+0x7437): undefined reference to `__setfpucw'
      ./libcontent.a(curve.o): In function `EndCR':
      curve.o(.text+0x74e4): undefined reference to `__setfpucw'
      collect2: ld returned 1 exit status
      make[2]: *** [content] Error 1
      make[2]: Leaving directory `/usr/local/src/content-1.5/content/victor'

   The function __setfpucw is used to set the floating point unit command
   word under glibc1.  There is a new facility for accomplishing this task
   under glibc2.  The FPU command word may be changed using the macro
   _FPU_SETCW under glibc2.  This macro resides in /usr/include/fpu_control.h.
   It take a single argument of type fpu_control_t.

   The macro is defined as

      #define _FPU_SETCW(cw) __asm__ ("fldcw %0" : : "m" (*&cw))

   The command __asm__ ("fldcw %0" : : "m" (*&cw)) accepts a single input
   that is a memory address and produces no output.  It executes the
   assembler command "fldcw" with the given input.  See "Extended Asm",
   also called "Assembler Instructions with C Expression Operands", under
   the "Extensions to the C Language Family" section of the GCC Manual 

      http://gcc.gnu.org/onlinedocs/gcc_4.html#SEC96

   and "Constraints", also called "Operand Constraints", under
   the "Machine Descriptions" section of the GCC manual

      http://gcc.gnu.org/onlinedocs/gcc_16.html#SEC179

   for further details.  The URLs

      http://www.netlib.no/netlib/ampl/solvers/fpinit.c
      http://gcc.gnu.org/ml/gcc-bugs/1999-11/msg00846.html
      http://gcc.gnu.org/ml/gcc-bugs/1999-11/msg00871.html

   show examples of how to use the macro.

   The function __setfpucw is only used in $CONTENT/victor/curve.c,
   once in each of the functions StartCR and EndCR.  To correct the error
   for glibc2, I defined a variable of type fpu_control_t at the top of
   each of these functions when the compilation was occuring for a system
   of type _UNIX_LNX

      #ifdef _UNIX_LNX
              fpu_control_t cw;
      #endif        /* _UNIX_LNX */

  Where __setfpucw was used in the previous code, I set cw to the appropriate
  value and invoked _FPU_SETCW on cw for each function

      // StartCR
      cw = _FPU_IEEE^(_FPU_MASK_IM|_FPU_MASK_OM|_FPU_MASK_ZM);
      _FPU_SETCW(cw);

      // EndCR
      cw = _FPU_IEEE;
      _FPU_SETCW(cw);

   Rather than replacing the __setfpucw code, it would be easy to create
   a conditional to execute either __setfpucw or _FPU_SETCW depending on
   which one was available.  One of the examples listed above shows one way
   to do this.

3. Once I made the above changes to $CONTENT/content/victor/curve.c, Content
   compiled without difficulty aside from the segmentation fault problem
   described in my installation document.  However, when I tried to execute
   the setup program from the root shell, it failed because the C++ compiler
   stopped on errors in $CONTENT/content/autodif.c.  The errors were

      In file included from autodif.cc:61:
      autodif.c: In function `char * Mult(char *, char *, char)':
      autodif.c:509: assignment to `char *' from `const char *' discards
      qualifiers
      autodif.c: In function `char * Sub(char *, char *, char)':
      autodif.c:659: assignment to `char *' from `const char *' discards
      qualifiers
      autodif.c:668: assignment to `char *' from `const char *' discards
      qualifiers
      autodif.c: In function `char * Div(char *, char *, char)':
      autodif.c:753: assignment to `char *' from `const char *' discards
      qualifiers
      autodif.c: In function `char * rel(char *, char *, char *, int)':
      autodif.c:1609: assignment to `char *' from `const char *' discards
      qualifiers
      autodif.c: In function `char * GetExpr_(const Gradient &)':
      autodif.c:1872: return to `char *' from `const char *' discards
      qualifiers
      autodif.c: In function `char * GetDer1_(const Gradient &, int)':
      autodif.c:1888: return to `char *' from `const char *' discards
      qualifiers
      autodif.c: In function `char * GetDer2_(const Gradient &, int, int)':
      autodif.c:1904: return to `char *' from `const char *' discards
      qualifiers
      autodif.c: In function `char * GetDer3_(const Gradient &, int, int, int)':
      autodif.c:1921: return to `char *' from `const char *' discards
      qualifiers

   To solve this problem, I added casts to the lines containing errors to
   make the values on the right hand sides or the return values of type
   "char *" rather than "const char *".  For example, I changed

      508,509c508,509
      <       f=lneed ? (rneed ? "(%s)*(%s)" : "(%s)*%s") :
      <                 (rneed ? "%s*(%s)" : "%s*%s");

   to

      >       f=lneed ? (char *)(rneed ? "(%s)*(%s)" : "(%s)*%s") :
      >                 (char *)(rneed ? "%s*(%s)" : "%s*%s");

   and

      1872c1872
      <   return p ? p : "0";

   to

      >   return p ? p : (char *)"0";

4. Resolving these problems allowed me to successfully compile and install
   Content.  I tested my work by setting up Content as a user and invoking
   it for an example problem.  Everything seemed to work fine.