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Update freelist

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Imbus 2025-09-08 09:16:40 +02:00
parent d583dbaced
commit ca0b25d110
2 changed files with 22 additions and 31 deletions
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33
kern/libkern/freelist.c
View file

@ -4,23 +4,15 @@
#include <stdint.h> #include <stdint.h>
#include <stdio.h> #include <stdio.h>
#include <stdlib.h> #include <stdlib.h>
#include <string.h>
/* Fiddle these around according to your need. */ struct FreeListBlock {
#ifdef FREELIST_NOALIGN struct FreeListBlock *next;
#define ALIGN(x) (x) };
#else // FREELIST_NOALIGN
/* Align to nearest multiple of sizeof(void*) */
static inline size_t align_up(size_t n) {
return (n + sizeof(void *) - 1) & ~(sizeof(void *) - 1);
}
#define ALIGN(x) (align_up(x))
#endif // FREELIST_NOALIGN
/* Initialize the FreeList */ /* Initialize the FreeList */
int fl_init(FreeList *fl, uintptr_t start, uintptr_t end, size_t itemsize) { int fl_init(FreeList *fl, uintptr_t start, uintptr_t end, size_t itemsize) {
size_t size = ALIGN(itemsize + sizeof(FreeListBlock)); size_t size = ALIGN(itemsize);
if (!fl || end <= start) if (!fl || end <= start)
return EXIT_FAILURE; return EXIT_FAILURE;
@ -33,7 +25,6 @@ int fl_init(FreeList *fl, uintptr_t start, uintptr_t end, size_t itemsize) {
FreeListBlock *block = (FreeListBlock *)start; FreeListBlock *block = (FreeListBlock *)start;
for (size_t i = 0; i < fl_capacity(fl); i++) { for (size_t i = 0; i < fl_capacity(fl); i++) {
block->next = (FreeListBlock *)((void *)block + size); block->next = (FreeListBlock *)((void *)block + size);
block->block_state = FL_FREE;
block = block->next; block = block->next;
} }
@ -45,16 +36,16 @@ int fl_init(FreeList *fl, uintptr_t start, uintptr_t end, size_t itemsize) {
/* Allocate some memory from the FreeList */ /* Allocate some memory from the FreeList */
void *fl_alloc(FreeList *fl) { void *fl_alloc(FreeList *fl) {
if (!fl->free || fl->free->block_state != FL_FREE) if (!fl->free)
return NULL; return NULL;
FreeListBlock *m = fl->free; FreeListBlock *m = fl->free;
m->block_state = FL_USED;
fl->free = fl->free->next; fl->free = fl->free->next;
fl->allocated++; fl->allocated++;
return ((void *)m) + sizeof(FreeListBlock); memset((void *)m, 0, sizeof(FreeListBlock));
return ((void *)m);
} }
/* Return some memory to the FreeList */ /* Return some memory to the FreeList */
@ -63,13 +54,8 @@ int fl_free(FreeList *fl, void *ptr) {
return EXIT_FAILURE; /* We cant free memory we do not own */ return EXIT_FAILURE; /* We cant free memory we do not own */
} }
FreeListBlock *block = (FreeListBlock *)((uintptr_t)ptr - sizeof(FreeListBlock)); FreeListBlock *block = (FreeListBlock *)(uintptr_t)ptr;
if (block->block_state != FL_USED) {
return EXIT_FAILURE; /* Block must be used */
}
block->block_state = FL_FREE;
block->next = fl->free; block->next = fl->free;
fl->free = block; fl->free = block;
fl->allocated--; fl->allocated--;
@ -109,7 +95,6 @@ size_t fl_check(FreeList *fl) {
while (cursor->next != NULL) { while (cursor->next != NULL) {
avail++; avail++;
assert(cursor->block_state == FL_FREE);
cursor = cursor->next; cursor = cursor->next;
} }

20
kern/libkern/freelist.h
View file

@ -5,18 +5,24 @@
#include <stdint.h> #include <stdint.h>
#include <stdlib.h> #include <stdlib.h>
#define FL_FREE ((uint8_t)0x00) /* Align to nearest multiple of align */
#define FL_USED ((uint8_t)0x01) static inline size_t align_up_to(size_t n, size_t align) {
return (n + align - 1) & ~(align - 1);
}
typedef struct FreeListBlock { /* Fiddle these around according to your need. Delete or check makefile */
struct FreeListBlock *next; #ifdef FREELIST_ALIGN
uint8_t block_state; #define ALIGN(x) (align_up_to(x, sizeof(void *)))
} FreeListBlock; #else
#define ALIGN(x) (x)
#endif
typedef struct FreeListBlock FreeListBlock;
typedef struct { typedef struct {
FreeListBlock *free;
uintptr_t start; uintptr_t start;
uintptr_t end; uintptr_t end;
FreeListBlock *free;
size_t size; size_t size;
size_t allocated; size_t allocated;
} FreeList; } FreeList;