ack/lang/fortran/comp/malloc.c

/****************************************************************
Copyright 1990 by AT&T Bell Laboratories and Bellcore.

Permission to use, copy, modify, and distribute this software
and its documentation for any purpose and without fee is hereby
granted, provided that the above copyright notice appear in all
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AT&T and Bellcore disclaim all warranties with regard to this
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any special, indirect or consequential damages or any damages
whatsoever resulting from loss of use, data or profits, whether
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****************************************************************/

#ifndef CRAY
#define STACKMIN 512
#define MINBLK (2*sizeof(struct mem) + 16)
#define MSTUFF _malloc_stuff_
#define F MSTUFF.free
#define B MSTUFF.busy
#define SBGULP 8192
char *memcpy();

struct mem {
	struct mem *next;
	unsigned len;
	};

struct {
	struct mem *free;
	char *busy;
	} MSTUFF;

char *
malloc(size)
register unsigned size;
{
	register struct mem *p, *q, *r, *s;
	unsigned register k, m;
	extern char *sbrk();
	char *top, *top1;

	size = (size+7) & ~7;
	r = (struct mem *) &F;
	for (p = F, q = 0; p; r = p, p = p->next) {
		if ((k = p->len) >= size && (!q || m > k)) { m = k; q = p; s = r; }
		}
	if (q) {
		if (q->len - size >= MINBLK) { /* split block */
			p = (struct mem *) (((char *) (q+1)) + size);
			p->next = q->next;
			p->len = q->len - size - sizeof(struct mem);
			s->next = p;
			q->len = size;
			}
		else s->next = q->next;
		}
	else {
		top = B ? B : (char *)(((long)sbrk(0) + 7) & ~7);
		if (F && (char *)(F+1) + F->len == B)
			{ q = F; F = F->next; }
		else q = (struct mem *) top;
		top1 = (char *)(q+1) + size;
		if (top1 > top) {
			if (sbrk((int)(top1-top+SBGULP)) == (char *) -1)
				return 0;
			r = (struct mem *)top1;
			r->len = SBGULP - sizeof(struct mem);
			r->next = F;
			F = r;
			top1 += SBGULP;
			}
		q->len = size;
		B = top1;
		}
	return (char *) (q+1);
	}

free(f)
char *f;
{
	struct mem *p, *q, *r;
	char *pn, *qn;

	if (!f) return;
	q = (struct mem *) (f - sizeof(struct mem));
	qn = f + q->len;
	for (p = F, r = (struct mem *) &F; ; r = p, p = p->next) {
		if (qn == (char *) p) {
			q->len += p->len + sizeof(struct mem);
			p = p->next;
			}
		pn = p ? ((char *) (p+1)) + p->len : 0;
		if (pn == (char *) q) {
			p->len += sizeof(struct mem) + q->len;
			q->len = 0;
			q->next = p;
			r->next = p;
			break;
			}
		if (pn < (char *) q) {
			r->next = q;
			q->next = p;
			break;
			}
		}
	}

char *
realloc(f, size)
char *f;
unsigned size;
{
	struct mem *p;
	char *q, *f1;
	unsigned s1;

	if (!f) return malloc(size);
	p = (struct mem *) (f - sizeof(struct mem));
	s1 = p->len;
	free(f);
	if (s1 > size) s1 = size + 7 & ~7;
	if (!p->len) {
		f1 = (char *)(p->next + 1);
		memcpy(f1, f, s1);
		f = f1;
		}
	q = malloc(size);
	if (q && q != f)
		memcpy(q, f, s1);
	return q;
	}
#endif