buddy.c

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/**************************************************************************
 * Conditional Compilation Options
 **************************************************************************/
#define USE_DEBUG 0
 
/**************************************************************************
 * Included Files
 **************************************************************************/
#include <stdio.h>
#include <stdlib.h>
 
#include "buddy.h"
#include "list.h"
 
/**************************************************************************
 * Public Definitions
 **************************************************************************/
#define MIN_ORDER 12
#define MAX_ORDER 20
 
#define PAGE_SIZE (1<<MIN_ORDER)
/* page index to address */
#define PAGE_TO_ADDR(page_idx) (void *)((page_idx*PAGE_SIZE) + g_memory)
 
/* address to page index */
#define ADDR_TO_PAGE(addr) ((unsigned long)((void *)addr - (void *)g_memory) / PAGE_SIZE)
 
/* find buddy address */
#define BUDDY_ADDR(addr, o) (void *)((((unsigned long)addr - (unsigned long)g_memory) ^ (1<<o)) \
                                     + (unsigned long)g_memory)
 
#if USE_DEBUG == 1
#  define PDEBUG(fmt, ...) \
    fprintf(stderr, "%s(), %s:%d: " fmt,            \
        __func__, __FILE__, __LINE__, ##__VA_ARGS__)
#  define IFDEBUG(x) x
#else
#  define PDEBUG(fmt, ...)
#  define IFDEBUG(x)
#endif
 
/**************************************************************************
 * Public Types
 **************************************************************************/
typedef struct {
    struct list_head list;
    /* TODO: DECLARE NECESSARY MEMBER VARIABLES */
} page_t;
 
/**************************************************************************
 * Global Variables
 **************************************************************************/
/* free lists*/
struct list_head free_area[MAX_ORDER+1];
 
/* memory area */
char g_memory[1<<MAX_ORDER];
 
/* page structures */
page_t g_pages[(1<<MAX_ORDER)/PAGE_SIZE];
 
/**************************************************************************
 * Public Function Prototypes
 **************************************************************************/
 
/**************************************************************************
 * Local Functions
 **************************************************************************/
 
void buddy_init()
{
    int i;
    int n_pages = (1<<MAX_ORDER) / PAGE_SIZE;
    for (i = 0; i < n_pages; i++) {
        /* TODO: INITIALIZE PAGE STRUCTURES */
    }
 
    /* initialize freelist */
    for (i = MIN_ORDER; i <= MAX_ORDER; i++) {
        INIT_LIST_HEAD(&free_area[i]);
    }
 
    /* add the entire memory as a freeblock */
    list_add(&g_pages[0].list, &free_area[MAX_ORDER]);
}
 
void *buddy_alloc(int size)
{
    /* TODO: IMPLEMENT THIS FUNCTION */
    return NULL;
}
 
void buddy_free(void *addr)
{
    /* TODO: IMPLEMENT THIS FUNCTION */
}
 
void buddy_dump()
{
    int o;
    for (o = MIN_ORDER; o <= MAX_ORDER; o++) {
        struct list_head *pos;
        int cnt = 0;
        list_for_each(pos, &free_area[o]) {
            cnt++;
        }
        printf("%d:%dK ", cnt, (1<<o)/1024);
    }
    printf("\n");
}