Initial revision

lang/cem/libcc.ansi/stdlib/malloc.c

@@ -0,0 +1,127 @@
+/*
+ * (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
+ * See the copyright notice in the ACK home directory, in the file "Copyright".
+ */
+/* $Header$ */
+
+#include	<stdlib.h>
+
+#define	CLICK_SIZE	4096
+
+#if	EM_WSIZE == EM_PSIZE
+typedef unsigned int vir_bytes;
+#else
+typedef long vir_bytes;
+#endif
+
+
+#define ALIGN(x, a)	(((x) + (a - 1)) & ~(a - 1))
+#define BUSY		1
+#define NEXT(p)		(* (void **) (p))
+
+#ifdef pdp
+#define BUGFIX	64	/* cannot set break in top 64 bytes */
+#else
+#define BUGFIX	0
+#endif
+
+extern void bcopy(void *, void *, size_t);
+extern void *sbrk(unsigned int);
+extern void *brk(unsigned int);
+static void *bottom, *top;
+
+static int
+grow(size_t len)
+{
+	register void *p;
+	register int click = CLICK_SIZE;
+
+	p = sbrk(0);
+	len += (void *) ALIGN((vir_bytes) p, sizeof(void *)) - p;
+	while (click >= 4) {
+		size_t len1 = ALIGN((vir_bytes)p+len+sizeof(char *),click)-(vir_bytes)p;
+		void *p1 = p;
+
+		if (p + len1 + BUGFIX < p || (p1 = sbrk(len1)) == (void *) -1) {
+			click >>= 1;
+			continue;
+		}
+		p = p1;
+		if (top + sizeof(void *) != p) {
+			/* someone else has done an sbrk */
+			NEXT(top) = (void *) ((vir_bytes) p | BUSY);
+		} else {
+			for (p = bottom; NEXT(p) != NULL; p = (void *) (* (vir_bytes *) p & ~BUSY))
+				;
+		}
+		top = p + len1 - sizeof(void *);
+		NEXT(p) = top;
+		NEXT(top) = NULL;
+		return 1;
+	}
+	return 0;
+}
+
+void *
+malloc(size_t size)
+{
+	register void *p, *next, *new;
+	register size_t len = ALIGN(size, sizeof(void *)) + sizeof(void *);
+
+	if ((p = bottom) == NULL) {
+		p = sbrk(sizeof(void *));
+		sbrk((void *) ALIGN((vir_bytes) p, sizeof(void *)) - p);
+		p = (void *) ALIGN((vir_bytes) p, sizeof(void *));
+		top = bottom = p;
+		NEXT(p) = NULL;
+	}
+	while ((next = NEXT(p)) != NULL)
+		if ((vir_bytes) next & BUSY)		/* already in use */
+			p = (void *) ((vir_bytes) next & ~BUSY);
+		else {
+			while ((new = NEXT(next)) != NULL
+				&& !((vir_bytes) new & BUSY))
+			    next = new;
+			if (next - p >= len) {			/* fits */
+				if ((new = p + len) < next)	/* too big */
+					NEXT(new) = next;
+				NEXT(p) = (void *) ((vir_bytes) new | BUSY);
+				return(p + sizeof(void *));
+			}
+			p = next;
+		}
+	return grow(len) ? malloc(size) : (void *)NULL;
+}
+
+void *
+realloc(void *old, size_t size)
+{
+	register void *p = old - sizeof(void *), *next, *new;
+	register size_t len = ALIGN(size, sizeof(void *)) + sizeof(void *), n;
+
+	next = (void *) (* (vir_bytes *) p & ~BUSY);
+	n = next - old;					/* old size */
+	while ((new = NEXT(next)) != NULL && !((vir_bytes) new & BUSY))
+		next = new;
+	if (next - p >= len) {				/* does it still fit */
+		if ((new = p + len) < next) {		/* even too big */
+			NEXT(new) = next;
+			NEXT(p) = (void *) ((vir_bytes) new | BUSY);
+		}
+		else
+			NEXT(p) = (void *) ((vir_bytes) next | BUSY);
+		return(old);
+	}
+	if ((new = malloc(size)) == NULL)		/* it didn't fit */
+		return((void *)NULL);
+	bcopy(old, new, n);				/* n < size */
+	* (vir_bytes *) p &= ~BUSY;
+	return(new);
+}
+
+void
+free(void *p)
+{
+	if (p != (void *)NULL)
+		*(vir_bytes *) (p - sizeof(void *)) &= ~BUSY;
+}