102 lines
2.2 KiB
C
102 lines
2.2 KiB
C
/*
|
|
* File: - dis.c
|
|
*
|
|
* dispose() built in standard procedure in Pascal (6.6.5.3)
|
|
*
|
|
* Re-implementation of storage allocator for Ack Pascal compiler
|
|
* under Linux, and other UNIX-like systems.
|
|
*
|
|
* Written by Erik Backerud, 2010-10-01
|
|
*
|
|
* Original copyright and author info below:
|
|
*/
|
|
/* $Id$ */
|
|
/*
|
|
* (c) copyright 1983 by the Vrije Universiteit, Amsterdam, The Netherlands.
|
|
*
|
|
* This product is part of the Amsterdam Compiler Kit.
|
|
*
|
|
* Permission to use, sell, duplicate or disclose this software must be
|
|
* obtained in writing. Requests for such permissions may be sent to
|
|
*
|
|
* Dr. Andrew S. Tanenbaum
|
|
* Wiskundig Seminarium
|
|
* Vrije Universiteit
|
|
* Postbox 7161
|
|
* 1007 MC Amsterdam
|
|
* The Netherlands
|
|
*
|
|
*/
|
|
|
|
/* Author: J.W. Stevenson */
|
|
|
|
#include <pc_err.h>
|
|
|
|
#define assert() /* nothing */
|
|
|
|
/*
|
|
* use a singly linked list of free blocks.
|
|
*/
|
|
struct adm {
|
|
struct adm *next;
|
|
int size;
|
|
};
|
|
|
|
struct adm *freep = 0; /* first element on free list */
|
|
|
|
extern void _trp(int);
|
|
|
|
/*
|
|
* Dispose
|
|
* Called with two arguments:
|
|
* n the size of the block to be freed, in bytes,
|
|
* pp address of pointer to data.
|
|
*/
|
|
void
|
|
_dis(int n, struct adm **pp)
|
|
{
|
|
struct adm *block; /* the block of data being freed (inc. header) */
|
|
struct adm *p, *q;
|
|
|
|
if (*pp == 0) {
|
|
_trp(EFREE);
|
|
}
|
|
block = *pp - 1;
|
|
if (freep == 0) {
|
|
freep = block;
|
|
block->next = 0;
|
|
} else {
|
|
q = 0; /* trail one behind */
|
|
for (p = freep; p < block; p = p->next) {
|
|
if (p == 0) { /* We reached the end of the free list. */
|
|
break;
|
|
}
|
|
q = p;
|
|
/* check if block is contained in the free block p */
|
|
if (p+p->size > block) {
|
|
_trp(EFREE);
|
|
}
|
|
}
|
|
if (p == block) { /* this block already freed */
|
|
_trp(EFREE);
|
|
}
|
|
if (q == 0) { /* block is first */
|
|
freep = block;
|
|
block->next = p;
|
|
} else {
|
|
q->next = block;
|
|
}
|
|
block->next = p;
|
|
/* merge with successor on free list? */
|
|
if (block + block->size == p) {
|
|
block->size = block->size + p->size;
|
|
block->next = p->next;
|
|
}
|
|
/* merge with preceding block on free list? */
|
|
if (q != 0 && q+q->size == block) {
|
|
q->size = q->size + block->size;
|
|
q->next = block->next;
|
|
}
|
|
}
|
|
} /* _dis */
|