368 lines
8.2 KiB
C
368 lines
8.2 KiB
C
/*
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* implement stack functions for dc
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*
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* Copyright (C) 1994 Free Software Foundation, Inc.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, you can either send email to this
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* program's author (see below) or write to: The Free Software Foundation,
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* Inc.; 675 Mass Ave. Cambridge, MA 02139, USA.
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*/
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/* This module is the only one that knows what stacks (both the
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* regular evaluation stack and the named register stacks)
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* look like.
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*/
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#include "config.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include "dc.h"
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#include "dc-proto.h"
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#include "dc-regdef.h"
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/* an oft-used error message: */
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#define Empty_Stack fprintf(stderr, "%s: stack empty\n", progname)
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/* simple linked-list implementaion suffices: */
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struct dc_list {
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dc_data value;
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struct dc_list *link;
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};
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typedef struct dc_list dc_list;
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/* the anonymous evaluation stack */
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static dc_list *dc_stack=NULL;
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/* the named register stacks */
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static dc_list *dc_register[DC_REGCOUNT];
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/* allocate a new dc_list item */
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static dc_list *
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dc_alloc DC_DECLVOID()
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{
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dc_list *result;
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result = dc_malloc(sizeof *result);
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result->value.dc_type = DC_UNINITIALIZED;
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result->link = NULL;
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return result;
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}
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/* check that there are two numbers on top of the stack,
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* then call op with the popped numbers. Construct a dc_data
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* value from the dc_num returned by op and push it
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* on the stack.
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* If the op call doesn't return DC_SUCCESS, then leave the stack
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* unmodified.
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*/
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void
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dc_binop DC_DECLARG((op, kscale))
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int (*op)DC_PROTO((dc_num, dc_num, int, dc_num *)) DC_DECLSEP
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int kscale DC_DECLEND
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{
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dc_data a;
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dc_data b;
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dc_data r;
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if (!dc_stack || !dc_stack->link){
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Empty_Stack;
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return;
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}
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if (dc_stack->value.dc_type!=DC_NUMBER
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|| dc_stack->link->value.dc_type!=DC_NUMBER){
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fprintf(stderr, "%s: non-numeric value\n", progname);
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return;
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}
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(void)dc_pop(&b);
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(void)dc_pop(&a);
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if ((*op)(a.v.number, b.v.number, kscale, &r.v.number) == DC_SUCCESS){
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r.dc_type = DC_NUMBER;
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dc_push(r);
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dc_free_num(&a.v.number);
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dc_free_num(&b.v.number);
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}else{
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/* op failed; restore the stack */
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dc_push(a);
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dc_push(b);
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}
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}
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/* check that there are two numbers on top of the stack,
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* then call dc_compare with the popped numbers.
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* Return negative, zero, or positive based on the ordering
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* of the two numbers.
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*/
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int
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dc_cmpop DC_DECLVOID()
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{
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int result;
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dc_data a;
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dc_data b;
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if (!dc_stack || !dc_stack->link){
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Empty_Stack;
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return 0;
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}
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if (dc_stack->value.dc_type!=DC_NUMBER
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|| dc_stack->link->value.dc_type!=DC_NUMBER){
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fprintf(stderr, "%s: non-numeric value\n", progname);
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return 0;
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}
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(void)dc_pop(&b);
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(void)dc_pop(&a);
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result = dc_compare(b.v.number, a.v.number);
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dc_free_num(&a.v.number);
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dc_free_num(&b.v.number);
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return result;
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}
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/* initialize the register stacks to their initial values */
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void
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dc_register_init DC_DECLVOID()
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{
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int i;
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for (i=0; i<DC_REGCOUNT; ++i)
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dc_register[i] = NULL;
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}
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/* clear the evaluation stack */
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void
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dc_clear_stack DC_DECLVOID()
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{
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dc_list *n;
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dc_list *t;
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for (n=dc_stack; n; n=t){
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t = n->link;
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if (n->value.dc_type == DC_NUMBER)
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dc_free_num(&n->value.v.number);
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else if (n->value.dc_type == DC_STRING)
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dc_free_str(&n->value.v.string);
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else
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dc_garbage("in stack", -1);
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free(n);
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}
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dc_stack = NULL;
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}
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/* push a value onto the evaluation stack */
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void
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dc_push DC_DECLARG((value))
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dc_data value DC_DECLEND
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{
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dc_list *n = dc_alloc();
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if (value.dc_type!=DC_NUMBER && value.dc_type!=DC_STRING)
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dc_garbage("in data being pushed", -1);
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n->value = value;
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n->link = dc_stack;
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dc_stack = n;
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}
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/* push a value onto the named register stack */
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void
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dc_register_push DC_DECLARG((stackid, value))
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int stackid DC_DECLSEP
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dc_data value DC_DECLEND
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{
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dc_list *n = dc_alloc();
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stackid = regmap(stackid);
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n->value = value;
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n->link = dc_register[stackid];
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dc_register[stackid] = n;
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}
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/* set *result to the value on the top of the evaluation stack */
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/* The caller is responsible for duplicating the value if it
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* is to be maintained as anything more than a transient identity.
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*
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* DC_FAIL is returned if the stack is empty (and *result unchanged),
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* DC_SUCCESS is returned otherwise
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*/
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int
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dc_top_of_stack DC_DECLARG((result))
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dc_data *result DC_DECLEND
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{
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if (!dc_stack){
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Empty_Stack;
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return DC_FAIL;
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}
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if (dc_stack->value.dc_type!=DC_NUMBER
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&& dc_stack->value.dc_type!=DC_STRING)
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dc_garbage("at top of stack", -1);
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*result = dc_stack->value;
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return DC_SUCCESS;
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}
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/* set *result to a dup of the value on the top of the named register stack */
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/*
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* DC_FAIL is returned if the named stack is empty (and *result unchanged),
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* DC_SUCCESS is returned otherwise
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*/
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int
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dc_register_get DC_DECLARG((regid, result))
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int regid DC_DECLSEP
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dc_data *result DC_DECLEND
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{
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dc_list *r;
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regid = regmap(regid);
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r = dc_register[regid];
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if ( ! r ){
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fprintf(stderr, "%s: register ", progname);
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dc_show_id(stderr, regid, " is empty\n");
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return DC_FAIL;
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}
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*result = dc_dup(r->value);
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return DC_SUCCESS;
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}
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/* set the top of the named register stack to the indicated value */
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/* If the named stack is empty, craft a stack entry to enter the
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* value into.
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*/
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void
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dc_register_set DC_DECLARG((regid, value))
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int regid DC_DECLSEP
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dc_data value DC_DECLEND
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{
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dc_list *r;
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regid = regmap(regid);
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r = dc_register[regid];
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if ( ! r )
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dc_register[regid] = dc_alloc();
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else if (r->value.dc_type == DC_NUMBER)
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dc_free_num(&r->value.v.number);
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else if (r->value.dc_type == DC_STRING)
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dc_free_str(&r->value.v.string);
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else
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dc_garbage("", regid);
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dc_register[regid]->value = value;
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}
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/* pop from the evaluation stack
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*
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* DC_FAIL is returned if the stack is empty (and *result unchanged),
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* DC_SUCCESS is returned otherwise
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*/
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int
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dc_pop DC_DECLARG((result))
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dc_data *result DC_DECLEND
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{
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dc_list *r;
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r = dc_stack;
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if (!r){
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Empty_Stack;
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return DC_FAIL;
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}
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if (r->value.dc_type!=DC_NUMBER && r->value.dc_type!=DC_STRING)
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dc_garbage("at top of stack", -1);
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*result = r->value;
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dc_stack = r->link;
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free(r);
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return DC_SUCCESS;
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}
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/* pop from the named register stack
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*
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* DC_FAIL is returned if the named stack is empty (and *result unchanged),
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* DC_SUCCESS is returned otherwise
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*/
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int
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dc_register_pop DC_DECLARG((stackid, result))
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int stackid DC_DECLSEP
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dc_data *result DC_DECLEND
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{
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dc_list *r;
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stackid = regmap(stackid);
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r = dc_register[stackid];
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if (!r){
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fprintf(stderr, "%s: stack register ", progname);
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dc_show_id(stderr, stackid, " is empty\n");
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return DC_FAIL;
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}
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if (r->value.dc_type!=DC_NUMBER && r->value.dc_type!=DC_STRING)
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dc_garbage(" stack", stackid);
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*result = r->value;
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dc_register[stackid] = r->link;
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free(r);
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return DC_SUCCESS;
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}
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/* tell how many entries are currently on the evaluation stack */
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int
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dc_tell_stackdepth DC_DECLVOID()
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{
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dc_list *n;
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int depth=0;
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for (n=dc_stack; n; n=n->link)
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++depth;
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return depth;
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}
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/* return the length of the indicated data value;
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* if discard_flag is true, the deallocate the value when done
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*
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* The definition of a datum's length is deligated to the
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* appropriate module.
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*/
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int
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dc_tell_length DC_DECLARG((value, discard_flag))
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dc_data value DC_DECLSEP
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dc_boolean discard_flag DC_DECLEND
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{
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int length;
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if (value.dc_type == DC_NUMBER){
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length = dc_numlen(value.v.number);
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if (discard_flag == DC_TRUE)
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dc_free_num(&value.v.number);
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} else if (value.dc_type == DC_STRING) {
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length = dc_strlen(value.v.string);
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if (discard_flag == DC_TRUE)
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dc_free_str(&value.v.string);
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} else {
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dc_garbage("in tell_length", -1);
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/*NOTREACHED*/
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length = 0; /*just to suppress spurious compiler warnings*/
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}
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return length;
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}
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/* print out all of the values on the evaluation stack */
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void
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dc_printall DC_DECLARG((obase))
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int obase DC_DECLEND
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{
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dc_list *n;
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for (n=dc_stack; n; n=n->link)
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dc_print(n->value, obase);
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}
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