malloc.c

ADS下的bios工程

#include <bios/malloc.h>
#include <bios/system.h>
#include <bios/stdio.h>

#undef DEBUG
#ifdef DEBUG
#define PRINTF(fmt, args...) printf("%s-%s()[%d]: " fmt, __FILE__, \
      __FUNCTION__, __LINE__, ##args)
#else
#define PRINTF(fmt, args...)
#endif

struct free {
    int    size;
    struct free    *next;
};

#define ALLOC_SIZE	0x4000

static struct free    *free_list;
static unsigned char    alloc_buf[ALLOC_SIZE];

void 
malloc_init(void)
{
    free_list = (struct free *)alloc_buf;

    free_list -> next = NULL;
    free_list -> size = ALLOC_SIZE;
    PRINTF("BIOS free mem start(0x%x) \n", free_list);
    PRINTF("BIOS free mem size(%d Kbytes)\n ", free_list -> size / 1024);
}

void *
malloc(int size)
{
    struct free    *tf;
    void    *ptr;
    flags_t    flags;

    ptr = (void *)NULL;

    /* aligned memage */
    size = (size + 19) & ~15;
    PRINTF("will malloc %d bytes\n", size);

    save_flags(flags);
    cli();

    tf = free_list;

    PRINTF("alloced block at 0x%p size %d, next(0x%x)\n", tf, 
           tf -> size, tf -> next);
    if (tf -> size >= size + sizeof(struct free)) {
        tf -> next = (struct free *)((int)tf + (size + sizeof(struct free)));
        free_list = tf -> next;
        free_list -> next = NULL;
        free_list -> size = tf -> size - size;
        tf -> size = size;
        ptr = tf;
    } 
    else {
        PRINTF("%s", "exact!\n");
        return  0;
    }

    ptr += sizeof(struct free);

    restore_flags(flags);

    PRINTF("will malloced %p \n", ptr);

    return  ptr;
}

void
free(void *ptr)
{
    struct free    *tf, *nf, *ff;
    flags_t    flags;

    if (!ptr) 
        return ;

    tf = (struct free *)((int)ptr - 8);	/* current free buffer point */
    nf = (struct free *)alloc_buf;

    PRINTF("freeing %p (block at %p, size %d, next 0x%x)\n", ptr, tf, 
          tf -> size, tf -> next);

    save_flags(flags);
    cli();

    ff = (struct free *)tf -> next;		/* next free buffer point */

    if (tf == (struct free *)alloc_buf) {
        if (!(ff -> next)) { 
            tf -> size += (int)(ff -> size);
            free_list = (struct free *)alloc_buf;
        }
    } 
    else {
        nf -> size += tf -> size;
        if (!(ff -> next)) {
            nf -> size += ff -> size;
            free_list = (struct free *)alloc_buf;
        }
    }

    tf -> next = NULL;

    restore_flags(flags);
}