px/0x.h

/*
 * px - UNIX Pascal interpreter
 *
 * Version 1.0, July 1977
 *
 * Written by Bill Joy and Chuck Haley
 * November-December 1976
 *
 * Based on an earlier version by Ken Thompson
 *
 * Px is described in detail in the "PX 1.0 Implementation Notes"
 * The source code for px is in several major pieces:
 *
 *      int.c           C main program which reads in interpreter code
 *      00int.s         Driver including main interpreter loop
 *      dd*.s           Where dd are digits, interpreter instructions
 *                      grouped by their positions in the interpreter table.
 *      p*.c            Various C language routines supporting the system.
 *
 * In addition there are several headers defining mappings for error
 * messages names into codes, and a definition of the interpreter transfer
 * table. These are made by the script Emake in this directory and the scripts
 * in the directory '../opcodes'.
 */

int     argc;
char    **argv;

/*
 * Pascal runtime errors cause emulator traps
 * to the routine onemt which transfers to the
 * routine 'error' in the file perror.c to decode them.
 * This method saves at least one word per static error.
 */
int     onemt();

/*
 * Definitions for memory allocation
 * Memory allocation routines are in 'palloc.c'
 */
char    *bottmem, *memptr, *high, *maxstk;

/*
 * The file i/o routines maintain a notion of a "current file".
 * The printing name of this file is kept in the variable
 * "file" for use in error messages.
 */
char    *file;
\f
/*
 * THE RUNTIME DISPLAY
 *
 * The entries in the display point to the active static block marks.
 * The first entry in the display is for the global variables,
 * then the procedure or function at level one, etc.
 * Each display entry points to a stack frame as shown:
 *
 *              base of stack frame
 *                ---------------
 *                |             |
 *                | block mark  |
 *                |             |
 *                ---------------  <-- display entry points here
 *                |             |
 *                |   local     |
 *                |  variables  |
 *                |             |
 *                ---------------
 *                |             |
 *                |  expression |
 *                |  temporary  |
 *                |  storage    |
 *                |             |
 *                - - - - - - - -
 *
 * The information in the block mark is thus at positive offsets from
 * the display pointer entries while the local variables are at negative
 * offsets. The block mark actually consists of two parts. The first
 * part is created at CALL and the second at entry, i.e. BEGIN. Thus:
 *
 *              -------------------------
 *              |                       |
 *              |  Saved lino           |
 *              |  Saved lc             |
 *              |  Saved dp             |
 *              |                       |
 *              -------------------------
 *              |                       |
 *              |  Saved (dp)           |
 *              |                       |
 *              |  Current section name |
 *              |   and entry line ptr  |
 *              |                       |
 *              |  Saved file name and  |
 *              |   file buffer ptr     |
 *              |                       |
 *              |  Empty tos value      |
 *              |                       |
 *              -------------------------
 */
int     display[20], *dp;
\f
int     lino;
int     nodump;

/*
 * Random number generator constants
 */
long    seed;
double  randa;
double  randc;
double  randm;
double  randim;

/*
 * Structures to access things on the stack
 */
struct {
        char    pchar;
};
struct {
        int     pint;
        int     p2int;
};
struct {
        long    plong;
};
struct {
        double  pdouble;
};

char    discard;