view lwlib/lw_stack.c @ 416:b4d0eafc5bfe

Fix code generation error in gcc6809 It turned out that under some circumstances, the gcc optimizer would select an instruction sequence that had the sense of a branch inverted. It seems this was due to a particular instruction pattern included in the machine description not being quite right with respect to how the condition codes were tracked. Removing that instruction pattern seems to fix things (subtraction with the arguments reversed). gcc seems to be smart enough to figure out how to reorganize code to work without this reversed sense subtraction and then do the right thing.
author William Astle <lost@l-w.ca>
date Thu, 24 Mar 2016 20:07:20 -0600
parents 00ddfdc1e1e3
children
line wrap: on
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/*
lw_stack.c

Copyright © 2010 William Astle

This file is part of LWTOOLS.

LWTOOLS is free software: you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
Foundation, either version 3 of the License, or (at your option) any later
version.

This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
more details.

You should have received a copy of the GNU General Public License along with
this program. If not, see <http://www.gnu.org/licenses/>.
*/

#define ___lw_stack_c_seen___
#include "lw_stack.h"
#include "lw_alloc.h"

/* this is technically valid but dubious */
#define NULL 0

lw_stack_t lw_stack_create(void (*freefn)(void *d))
{
	lw_stack_t S;
	
	S = lw_alloc(sizeof(struct lw_stack_priv));
	S -> head = NULL;
	S -> freefn = freefn;
	return S;
}

void *lw_stack_pop(lw_stack_t S)
{
	if (S -> head)
	{
		void *ret, *r2;
		
		ret = S -> head -> data;
		r2 = S -> head;
		S -> head = S -> head -> next;
		lw_free(r2);
		return ret;
	}
	return NULL;
}

void lw_stack_destroy(lw_stack_t S)
{
	void *d;
	
	while ((d = lw_stack_pop(S)))
		(S->freefn)(d);
	lw_free(S);
}

void *lw_stack_top(lw_stack_t S)
{
	if (S -> head)
		return S -> head -> data;
	return NULL;
}

void lw_stack_push(lw_stack_t S, void *item)
{
	struct lw_stack_node_priv *t;
	
	t = lw_alloc(sizeof(struct lw_stack_node_priv));
	t -> next = S -> head;
	S -> head = t;
	t -> data = item;
}