INT86X(DOS)              XENIX System V               INT86X(DOS)



     Name
          int86x - Executes an interrupt.

     Syntax
          #include <dos.h>

          int int86x (intno, inregs, outregs, segregs);
          int intno;
          union REGS *inregs;
          union REGS *outregs;
          struct SREGS *segregs;

     Description
          The int86x function executes the 8086 software interrupt
          specified by the interrupt number intno.  Unlike the int86
          function, int86x accepts segment register values in segregs,
          letting programs that use long model data segments or far
          pointers specify which segment or pointer should be used
          during the system call.

          Before executing the specified interrupt, int86x copies the
          contents of inregs and segregs to the corresponding
          registers.  Only the DS and ES register values in segregs
          are used.  After the interrupt returns, the function copies
          the current register values to outregs and restores DS.  It
          also copies the status of the system carry flag to the cflag
          field in outregs.  The inregs and outregs arguments are
          unions of type REGS.  The segregs argument is a structure of
          type SREGS.  These types are defined in the include file
          dos.h.

          int86x is intended to be used to directly invoke DOS
          interrupts that take an argument in the ES register, or take
          a DS register value that is different than the default data
          segment.

     Return Value
          The return value is the value in the AX register after the
          interrupt returns.  If the flag field in outregs is nonzero,
          an error has occurred and the doserrno variable is also set
          to the corresponding error code.

     See Also
          bdos(DOS), intdos(DOS), intdosx(DOS), int86(DOS), seg-
          read(DOS), FP_SEG(DOS)










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     INT86X(DOS)              XENIX System V               INT86X(DOS)



     Example
          #include <signal.h> #include <dos.h> #include <stdio.h>
          #include <process.h>

          /*
           * Use int86x routine to generate an interrupt 0x21 (system
           * call), which invokes the DOS 'Change Attributes' system
           * call.  The int86x routine is used because the filename to
           * be referenced may be in a segment other than the default
           * data segment (it is referenced by a far pointer), so the
           * DS register must be explicitly set via the SREGS struct.
           */
          #define SYSCALL     0x21        /* INT 21H invokes system
                                             calls */ #define
          CHANGE_ATTR 0x43        /* system call 43H - change
                                             attributes */

          char far *filename;             /* filename in 'far' data
                                             segment */

          union REGS inregs, outregs; struct SREGS segregs; int
          result;      .       .       .  inregs.h.ah = CHANGE_ATTR;
          /* AH is system call
                                             number */ inregs.h.al =
          0;                /* AL is function (get
                                             attributes) */
          inregs.x.dx = FP_OFF(filename); /* DS:DX points to file
                                             name */ segregs.ds =
          FP_SEG(filename); result = int86x (SYSCALL, &inregs,
          &outregs, &segregs); if (outregs.x.cflag) {
              printf ("can't get attributes of file; error number
          %d\n",          result);
              exit (1);
              } else {
              printf ("Attribs = %#x\n", outregs.x.cx);
              }

     Notes
          Segment values for the segregs argument can be obtained by
          using either the segread function or the FP_SEG macro.

          This call must be compiled with the -dos flag.













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