vmalloc.c

SMDK2440 boot code, base on vivi

/*
 * vivi/lib/vmalloc.c: simple dynamic memory allocation routine
 *
 */

#include <config.h>
#include <memory.h>
#include <vstring.h>
#include <types.h>

typedef long Align;	/* for alignment to long boundary */

union header {		/* block header: */
	struct {
		union header *ptr;	/* next block if on free list */
		unsigned long size;	/* size of this block */
	} s;
	Align x;	/* force alignment of blocks */
};

typedef union header Header;

static Header *freep = NULL;	/* start of free list */

/* vmalloc: general-purpose storage allocator for vivi */
void *vmalloc(unsigned long nbytes)
{
	Header *p, *prevp;
	unsigned long nunits;

	nunits = (nbytes+sizeof(Header)-1)/sizeof(Header) + 1;
	
	if ((prevp = freep) == NULL) {
		printk("%s(): not initialized heap\n", __FUNCTION__);
		return NULL;
	}

	for (p = prevp->s.ptr; ; prevp = p, p = p->s.ptr) {
		if (p->s.size >= nunits) {	/* big enough */
			if (p->s.size == nunits) {	/* exactly */
				prevp->s.ptr = p->s.ptr;
			} else {
				p->s.size -= nunits;
				p += p->s.size;
				p->s.size = nunits;
			}
			freep = prevp;
			//printk("%s(): allocated at 0x%x, size = %d\n", __FUNCTION__, (void *)(p+1), p->s.size);
			return (void *)(p+1);
		}
		if (p == freep) {	/* wrapped around free list */
			printk("%s(): no space\n", __FUNCTION__);
			return NULL;	/* none left */
		}
	}
}

/* vfree: put block ap in free list */
void free(void *ap)
{
	Header *bp, *p;

	bp = (Header *)ap - 1;	/* point to block header */
	for (p = freep; !(bp > p && bp < p->s.ptr); p = p->s.ptr)
		if (p >= p->s.ptr && (bp > p || bp < p->s.ptr))
			break;	/* freed block at start or end of arena */

	if (bp + bp->s.size == p->s.ptr) {	/* join to upper nbr */
		bp->s.size += p->s.ptr->s.size;
		bp->s.ptr = p->s.ptr->s.ptr;
	} else {
		bp->s.ptr = p->s.ptr;
	}

	if (p + p->s.size == bp) {		/* join to lower nbr */
		p->s.size += bp->s.size;
		p->s.ptr = bp->s.ptr;
	} else {
		p->s.ptr = bp;
	}

	freep = p;
	//printk("%s(): next = 0x%x, size = %d\n", __FUNCTION__, freep->s.ptr, freep->s.size);
}

/* vmalloc_init: initialize heap area */
void vmalloc_init(void)
{
	unsigned long nunits = HEAP_SIZE / sizeof(Header);

	/* It's clear. But it's take some times */
#if 0
	memset(HEAP_BASE, 0x00, HEAP_SIZE);
#endif

	freep = (Header *)HEAP_BASE;
	freep->s.ptr = freep;
	freep->s.size = nunits;
}