| /* Copyright (C) 1989 Aladdin Enterprises. All rights reserved. |
| Distributed by Free Software Foundation, Inc. |
| |
| This file is part of Ghostscript. |
| |
| Ghostscript is distributed in the hope that it will be useful, but |
| WITHOUT ANY WARRANTY. No author or distributor accepts responsibility |
| to anyone for the consequences of using it or for whether it serves any |
| particular purpose or works at all, unless he says so in writing. Refer |
| to the Ghostscript General Public License for full details. |
| |
| Everyone is granted permission to copy, modify and redistribute |
| Ghostscript, but only under the conditions described in the Ghostscript |
| General Public License. A copy of this license is supposed to have been |
| given to you along with Ghostscript so you can know your rights and |
| responsibilities. It should be in a file named COPYING. Among other |
| things, the copyright notice and this notice must be preserved on all |
| copies. */ |
| |
| /* estack.h */ |
| /* Definitions for execution stack operators for GhostScript */ |
| |
| /* Import the execution stack */ |
| extern ref estack[]; |
| extern ref *esp; /* points to current top element of stack */ |
| extern ref *estop; /* points to end of stack */ |
| |
| /* The execution stack is used for three purposes: */ |
| /* - Procedures being executed are held here. They always have */ |
| /* type = t_array or type = t_packedarray, with a_executable set. */ |
| /* - if, ifelse, etc. push arguments to be executed here. */ |
| /* They may be any kind of object whatever. */ |
| /* - for, repeat, loop, forall, pathforall, run, and stopped */ |
| /* mark the stack by pushing an object with type = t_null, */ |
| /* attrs = a_executable, and value.index = 0 for loops, 1 for run/stopped. */ |
| /* (Null objects can't ever appear on the stack otherwise: */ |
| /* if a control operator pushes one, it gets popped immediately.) */ |
| /* The loop operators also push whatever state they need, */ |
| /* followed by an operator object that handles continuing the loop. */ |
| |
| /* Macro for marking the execution stack */ |
| #define mark_estack(idx)\ |
| (++esp, make_tav(esp, t_null, a_executable, index, idx)) |
| |
| /* Macro for pushing an operator on the execution stack */ |
| /* to represent a continuation procedure */ |
| #define push_op_estack(proc)\ |
| (++esp, make_tasv(esp, t_operator, a_executable, 0, opproc, proc)) |
| |
| /* Macro to ensure enough room on the execution stack */ |
| #define check_estack(n)\ |
| if ( esp + (n) > estop ) return e_execstackoverflow |
| |
| /* Define the various kinds of execution stack marks. */ |
| #define es_other 0 /* internal use */ |
| #define es_show 1 /* show operators */ |
| #define es_for 2 /* iteration operators */ |
| #define es_stopped 3 /* stopped operator */ |
