heap.c File Reference

#include <miniOS/mm/heap.h>
#include <miniOS/mm/pmm.h>
#include <miniOS/mm/vmm.h>
#include <miniOS/types.h>
#include <miniOS/arch/x86_64/spinlock.h>

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Classes
struct	heap_hdr
struct	heap_ftr

Macros
#define	HEAP_START   0xFFFF820000000000ULL
#define	HEAP_MAX   (HEAP_START + 64ULL * 1024 * 1024) /* 64MB limit */
#define	HDR_SIZE   16ULL /* sizeof aligned header */
#define	FTR_SIZE   8ULL /* sizeof footer */
#define	OVERHEAD   (HDR_SIZE + FTR_SIZE)
#define	MIN_BLOCK   32ULL /* minimum allocation unit (8 bytes of usable payload) */

Functions
static struct heap_ftr *	blk_ftr (struct heap_hdr *hdr)
static struct heap_hdr *	blk_next (struct heap_hdr *hdr)
static void *	blk_payload (struct heap_hdr *hdr)
static struct heap_hdr *	hdr_from_payload (void *ptr)
static void	blk_init (uint64_t addr, size_t payload_size, uint8_t used)
static struct heap_hdr *	heap_expand (void)
void	heap_init (void)
	Maps the first heap page at HEAP_START via vmm_map_page() and writes the initial free-block boundary tag covering the entire heap region. Must be called exactly once during boot before any call to kmalloc(). Called by kernel_main() after vmm setup.
void *	kmalloc (size_t size)
	Uses a first-fit boundary-tag strategy. Acquires heap_lock (spinlock_irqsave) before scanning. Maps additional pages via vmm_map_page() if the current heap extent is exhausted (up to HEAP_MAX).
void	kfree (void *ptr)
	Marks the block free in its boundary tag and coalesces adjacent free blocks (forward and backward). Acquires heap_lock before modifying heap state.
size_t	heap_free_bytes (void)
	Walks the boundary-tag chain and sums the sizes of all free blocks. O(n) in the number of heap blocks. Intended for diagnostic/debug output only.

Variables
static uint64_t	heap_top = 0
static spinlock_t	heap_lock = SPINLOCK_INIT

Macro Definition Documentation

FTR_SIZE

#define FTR_SIZE   8ULL /* sizeof footer */

HDR_SIZE

#define HDR_SIZE   16ULL /* sizeof aligned header */

HEAP_MAX

#define HEAP_MAX   (HEAP_START + 64ULL * 1024 * 1024) /* 64MB limit */

HEAP_START

#define HEAP_START   0xFFFF820000000000ULL

MIN_BLOCK

#define MIN_BLOCK   32ULL /* minimum allocation unit (8 bytes of usable payload) */

OVERHEAD

#define OVERHEAD   (HDR_SIZE + FTR_SIZE)

Function Documentation

blk_ftr()

struct heap_ftr * blk_ftr ( struct heap_hdr * hdr )

inlinestatic

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blk_init()

void blk_init ( uint64_t addr, size_t payload_size, uint8_t used )

static

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blk_next()

struct heap_hdr * blk_next ( struct heap_hdr * hdr )

inlinestatic

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blk_payload()

void * blk_payload ( struct heap_hdr * hdr )

inlinestatic

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hdr_from_payload()

struct heap_hdr * hdr_from_payload ( void * ptr )

inlinestatic

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heap_expand()

struct heap_hdr * heap_expand ( void )

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Variable Documentation

heap_lock

spinlock_t heap_lock = SPINLOCK_INIT

static

heap_top

uint64_t heap_top = 0

static