membuddy.c & makefile

makefile

#http://en.wikipedia.org/wiki/Buddy_memory_allocation
#This is a dummy code for Buddy memory allocation implementation.

CFLAGS=-DHAVE_DEV_SYS
LDFLAGS=
CFILES=membuddy.c
OBJS=$(CFILES:.c=.o)
BINNAME=membuddy

all: $(BINNAME)

.c.o:
	$(CC) -c $< $(CFLAGS)

$(BINNAME): $(OBJS)
	$(CC) -o $@ $^ $(LDFLAGS)

run: $(BINNAME)
	./$^

clean:
	rm -f $(OBJS)

membuddy.c

#ifdef HAVE_DEV_SYS
    #include <stdio.h>
    #include <stdlib.h>
    #define BOS_PRINTF printf
#else
    #define BOS_PRINTF printf
    typedef unsigned int size_t;
#endif

void *__bos_mem_heap_base_adr = 0;
size_t __bos_mem_heap_size = 0;

struct bos_mem_bluk {
    void *addr;
    size_t size;
    struct bos_mem_bluk *next;
};

struct bos_mem_map {
    void *baseaddr; /* system reserved a big block memeory */
    struct bos_mem_bluk *bluk_head;
    size_t free_size;
    size_t size;
};


struct bos_mem_map __bos_mem_map;
static struct bos_mem_map *pm = &__bos_mem_map;

void
bos_free(void *ptr);

void *
bos_malloc(size_t size);

void __bos_mem_init(void *ptr, size_t size)
{
        pm->baseaddr = __bos_mem_heap_base_adr;
        pm->size = __bos_mem_heap_size;
        pm->free_size = pm->size;
        pm->bluk_head = NULL;
}

#define bluk_max_size 1024
static struct bos_mem_bluk __bos_membluks[bluk_max_size];
static struct bos_mem_bluk *pb_head = __bos_membluks;

void
bos_free(void *ptr)
{
        BOS_PRINTF("bos_free dummy.\n");
}

struct bos_mem_bluk* get_mem_empty_bluk()
{
    struct bos_mem_bluk *p = pb_head;
    struct bos_mem_bluk *pend = pb_head + sizeof(__bos_membluks);
    for(;p < pend && p->addr; p++) ;
    if (p < pend) return p;
    return NULL;
}

void *
bos_malloc(size_t size)
{
        struct bos_mem_bluk *bluk = get_mem_empty_bluk();
        if (!bluk) return NULL;

        /* TBM: with buddy allocation */
        bluk->addr = (void *)( pm->baseaddr + size );
        bluk->size = size;

        BOS_PRINTF("bos_malloc %p.\n", bluk->addr);
        return bluk->addr;
}

size_t
__bos_total_used(void)
{
        return pm->size - pm->free_size;
}

size_t
__bos_total_free(void)
{
        return pm->free_size;
}

#ifdef HAVE_DEV_SYS
int main()
{
    __bos_mem_heap_size = 4096*1024;
    __bos_mem_heap_base_adr = malloc(__bos_mem_heap_size);
    __bos_mem_init(__bos_mem_heap_base_adr, __bos_mem_heap_size);

    void *p16a = bos_malloc(16);
    void *p16b = bos_malloc(16);
    bos_free(p16a);
    bos_free(p16b);
    size_t total_used_mem = __bos_total_used();

    BOS_PRINTF("Free: %08lx Used: %08lx\n", __bos_total_free(), total_used_mem);
    if (total_used_mem == 0) {
        BOS_PRINTF("test buddy system: passed\n");
        return 0;
    } else {
        BOS_PRINTF("test buddy system: failed\n");
    }
    return 1;
}
#endif