harvey/sys/src/cmd/gs/src/opdef.h

/* Copyright (C) 1991, 1995, 1998, 1999 artofcode LLC.  All rights reserved.
  
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  she says so in writing.  Refer to the Aladdin Free Public License (the
  "License") for full details.
  
  Every copy of AFPL Ghostscript must include a copy of the License, normally
  in a plain ASCII text file named PUBLIC.  The License grants you the right
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  requires that the copyright notice and this notice be preserved on all
  copies.
*/

/*$Id: opdef.h,v 1.3 2001/08/28 03:28:08 giles Exp $ */
/* Operator definition interface for Ghostscript */

#ifndef opdef_INCLUDED
#  define opdef_INCLUDED

/*
 * Define the structure for initializing the operator table.  Each operator
 * file zxxx.c declares an array of these as follows:

   const op_def * const zxxx_op_defs[] = {
      {"1name", zname},
      ...
      op_def_end(iproc)
   };

 * where iproc is an initialization procedure for the file or 0, and, for
 * each operator defined, the initial digit of the name string indicates
 * the number of arguments and zname is the address of the associated C
 * function to invoke.
 *
 * The array definition always appears at the END of the file, to avoid
 * the need for forward declarations for all the operator procedures.
 *
 * Operators may be stored in dictionaries other than systemdict.
 * We support this with op_def entries of a special form:

   op_def_begin_dict("dictname"),

 */
typedef struct {
    const char *oname;
    op_proc_t proc;
} op_def;

#define op_def_begin_dict(dname) {dname, 0}
#define op_def_begin_filter() op_def_begin_dict("filterdict")
#define op_def_begin_level2() op_def_begin_dict("level2dict")
#define op_def_begin_ll3() op_def_begin_dict("ll3dict")
#define op_def_is_begin_dict(def) ((def)->proc == 0)
#define op_def_end(iproc) {0, iproc}

/*
 * NOTE: for implementation reasons, a single table of operator definitions
 * is limited to 16 entries, including op_def_begin_xxx entries.  If a file
 * defines more operators than this, it must split them into multiple
 * tables and have multiple -oper entries in the makefile.  Currently,
 * only 4 out of 85 operator files require this.
 */
#define OP_DEFS_LOG2_MAX_SIZE 4
#define OP_DEFS_MAX_SIZE (1 << OP_DEFS_LOG2_MAX_SIZE)

/*
 * Define the table of pointers to all operator definition tables.
 */
extern const op_def *const op_defs_all[];

/*
 * Internal operators whose names begin with %, such as continuation
 * operators, do not appear in systemdict.  Ghostscript assumes
 * that these operators cannot appear anywhere (in executable form)
 * except on the e-stack; to maintain this invariant, the execstack
 * operator converts them to literal form, and cvx refuses to convert
 * them back.  As a result of this invariant, they do not need to
 * push themselves back on the e-stack when executed, since the only
 * place they could have come from was the e-stack.
 */
#define op_def_is_internal(def) ((def)->oname[1] == '%')

/*
 * All operators are catalogued in a table; this is necessary because
 * they must have a short packed representation for the sake of 'bind'.
 * The `size' of an operator is normally its index in this table;
 * however, internal operators have a `size' of 0, and their true index
 * must be found by searching the table for their procedure address.
 */
ushort op_find_index(P1(const ref *));

#define op_index(opref)\
  (r_size(opref) == 0 ? op_find_index(opref) : r_size(opref))

/*
 * There are actually two kinds of operators: the real ones (t_operator),
 * and ones defined by procedures (t_oparray).  The catalog for t_operators
 * is (indirectly) op_defs_all, and their index is in the range
 * [1..op_def_count-1].
 */
#define op_index_is_operator(index) ((index) < op_def_count)
extern const uint op_def_count;

#define op_index_def(index)\
  (&op_defs_all[(index) >> OP_DEFS_LOG2_MAX_SIZE]\
    [(index) & (OP_DEFS_MAX_SIZE - 1)])
#define op_num_args(opref) (op_index_def(op_index(opref))->oname[0] - '0')
#define op_index_proc(index) (op_index_def(index)->proc)

/*
 * There are two catalogs for t_oparrays, one global and one local.
 * Operator indices for the global table are in the range
 *      [op_def_count..op_def_count+op_array_global.count-1]
 * Operator indices for the local table are in the range
 *      [op_def_count+r_size(&op_array_global.table)..
 *        op_def_count+r_size(&op_array_global.table)+op_array_local.count-1]
 */
typedef struct op_array_table_s {
    ref table;			/* t_array */
    ushort *nx_table;		/* name indices */
    uint count;			/* # of occupied entries */
    uint base_index;		/* operator index of first entry */
    uint attrs;			/* ref attrs of ops in this table */
    ref *root_p;		/* self-pointer for GC root */
} op_array_table;
extern op_array_table
       op_array_table_global, op_array_table_local;

#define op_index_op_array_table(index)\
  ((index) < op_array_table_local.base_index ?\
   &op_array_table_global : &op_array_table_local)

/*
 * Convert an operator index to an operator or oparray ref.
 * This is only used for debugging and for 'get' from packed arrays,
 * so it doesn't have to be very fast.
 */
void op_index_ref(P2(uint, ref *));

#endif /* opdef_INCLUDED */