+++ /dev/null
-/* malloc(), realloc(), free() - simple memory allocation routines
- *
- * This is a very small and simple minded malloc Author: Kees J. Bot
- * implementation. Ideal for things like a 29 Jan 1994
- * bootstrap program, or for debugging. Six times
- * slower than any good malloc.
- */
-#define nil 0
-
-#define sbrk _sbrk
-#include <stddef.h>
-#include <stdlib.h>
-#include <unistd.h>
-#include <string.h>
-#include <limits.h>
-#if !DEBUG
-#define NDEBUG 1
-#define debug(expr) ((void) 0)
-#else
-#define debug(expr) expr
-#endif
-#include <assert.h>
-
-typedef struct cell {
- size_t size; /* Size of a malloc()'ed object. */
-#if DEBUG
- unsigned magic; /* To recognize a cell. */
-#endif
- struct cell *next; /* Next cell on the free list. */
-#if DEBUG
- unsigned sacred; /* Don't touch while unallocated. */
-#endif
-} cell_t;
-
-#if UINT_MAX <= 0xFFFF
-#define MAGIC 0x537B
-#else
-#define MAGIC 0x537BC0D8
-#endif
-
-/* Size of the header of an object. */
-#define HDR_SIZE offsetof(cell_t, next)
-
-/* An offset from a cell pointer to a next cell. */
-#define offset(cp, size) ((cell_t *) ((char *) (cp) + (size)))
-
-/* Address of the object in a cell and back. */
-#define cell2obj(cp) ((void *) ((char *) (cp) + HDR_SIZE))
-#define obj2cell(op) ((cell_t *) ((char *) (op) - HDR_SIZE))
-
-/* The free list. */
-static cell_t *freelist;
-
-void *malloc(size_t size)
-/* Allocate an object of at least the given size. */
-{
- cell_t **pcp, *cp;
-
- size += HDR_SIZE;
- if (size < sizeof(cell_t)) size= sizeof(cell_t);
-
- /* Align to a word. Use a real malloc if you need better alignment. */
- size= (size + sizeof(int) - 1) & ~(sizeof(int) - 1);
-
- /* Space for a magic number at the end of the chunk. */
- debug(size += sizeof(unsigned));
-
- for (;;) {
- /* Do a first fit search. */
- pcp= &freelist;
- while ((cp= *pcp) != nil) {
- cell_t *next= cp->next;
-
- assert(cp->magic == MAGIC);
- assert(cp->sacred == MAGIC);
-
- if (offset(cp, cp->size) == next) {
- /* Join adjacent free cells. */
- assert(next->magic == MAGIC);
- assert(next->sacred == MAGIC);
-
- cp->size+= next->size;
- cp->next= next->next;
-
- continue; /* Try again. */
- }
- if (size <= cp->size) break; /* Big enough. */
-
- /* Next cell. */
- pcp= &cp->next;
- }
-
- if (cp != nil) break; /* Found a big enough chunk. */
-
- /* Allocate a new chunk at the break. */
- if ((cp= (cell_t *) sbrk(size)) == (cell_t *) -1) {
- return nil;
- }
-
- cp->size= size;
- cp->next= nil;
- debug(cp->magic= MAGIC);
- debug(cp->sacred= MAGIC);
- *pcp= cp;
- }
-
- /* We've got a cell that is big enough. Can we break it up? */
- if (cp->size >= size + sizeof(cell_t)) {
- cell_t *next= offset(cp, size);
-
- next->size= cp->size - size;
- next->next= cp->next;
- debug(next->magic= MAGIC);
- debug(next->sacred= MAGIC);
- cp->size= size;
- cp->next= next;
- }
-
- /* Unchain the cell we've found and return an address in it. */
- *pcp= cp->next;
- debug(memset(cell2obj(cp), 0xAA, cp->size - HDR_SIZE));
- debug(((unsigned *) offset(cp, cp->size))[-1]= MAGIC);
-
- return cell2obj(cp);
-}
-
-void free(void *op)
-/* Deallocate an object. */
-{
- cell_t **prev, *next, *cp;
-
- if (op == nil) return; /* Aaargh. */
-
- cp= obj2cell(op);
- assert(cp->magic == MAGIC);
- assert(((unsigned *) offset(cp, cp->size))[-1] == MAGIC);
- debug(cp->sacred= MAGIC);
-
- /* Find the spot where the object belongs. */
- prev= &freelist;
- while ((next= *prev) != nil && next < cp) {
- assert(next->magic == MAGIC);
- assert(next->sacred == MAGIC);
- prev= &next->next;
- }
-
- /* Put the new free cell in the list. */
- *prev= cp;
- cp->next= next;
-
-#if DEBUG
- /* Check the rest of the list. */
- while (next != nil) {
- assert(next->magic == MAGIC);
- assert(next->sacred == MAGIC);
- next= next->next;
- }
-#endif
-}
-
-void *realloc(void *op, size_t size)
-/* Change the size of an object. Don't bother being smart, just copy it. */
-{
- size_t oldsize;
- void *new;
-
- oldsize= op == nil ? 0 : obj2cell(op)->size - HDR_SIZE;
-
- new= malloc(size);
- memcpy(new, op, oldsize > size ? size : oldsize);
- free(op);
- return new;
-}
-
-/*
- * $PchId: malloc.c,v 1.4 1996/02/22 09:15:56 philip Exp $
- */