kern/libkern/freelist.c

@@ -1,55 +1,37 @@
 #include "freelist.h"
+#include "stddef.h"
+#include <assert.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
 
-/* Header block used to keep track of all the free blocks */
+struct FreeListBlock {
-struct __attribute__((packed)) FreeListBlock {
+    struct FreeListBlock *next;
-    uint16_t next_offset; /* May be 8, 16, 32, 64, whatever */
 };
 
-/* Align to nearest multiple of align */
-static inline size_t align_up_to(size_t n, size_t align) {
-    return (n + align - 1) & ~(align - 1);
-}
-
-/* Convert pointer -> 1-based offset (0 means NULL) */
-static inline uint32_t ptr_to_offset(FreeList *fl, void *ptr) {
-    if (!ptr)
-        return 0; // NULL maps to 0
-    uintptr_t diff = (uintptr_t)ptr - fl->start;
-    return (uint32_t)(diff / fl->size) + 1;
-}
-
-/* Convert 1-based offset -> pointer (0 means NULL) */
-static inline void *offset_to_ptr(FreeList *fl, uint32_t offset) {
-    if (offset == 0)
-        return NULL; // 0 = invalid/null
-    return (void *)(fl->start + (uintptr_t)(offset - 1) * fl->size);
-}
-
 /* Initialize the FreeList */
-int fl_init(FreeList *fl, uintptr_t start, size_t size_bytes, size_t itemsize) {
+int fl_init(FreeList *fl, uintptr_t start, uintptr_t end, size_t itemsize) {
-    /* Fiddle around according to your need, (void *) alignment seems to be enough,
+    size_t size = ALIGN(itemsize);
-     * but MAX_ALIGN_T is also an option. Especially for allocator implementation. */
-    size_t size = align_up_to(itemsize, sizeof(void *));
 
-    if (size < sizeof(FreeListBlock) || !fl)
+    if (!fl || end <= start)
-        return 0;
+        return EXIT_FAILURE;
 
     fl->start = start;
-    fl->end = start + size_bytes;
+    fl->end = end;
     fl->size = size;
     fl->allocated = 0;
 
     FreeListBlock *block = (FreeListBlock *)start;
-
+    for (size_t i = 0; i < fl_capacity(fl); i++) {
-    for (size_t offset = 1; offset < fl_capacity(fl) + 1; offset++) {
+        block->next = (FreeListBlock *)((void *)block + size);
-        block->next_offset = (int32_t)offset;
+        block = block->next;
-        block = offset_to_ptr(fl, offset);
     }
 
-    block->next_offset = 0; /* Last block */
+    block->next = NULL;
-    fl->free = (FreeListBlock *)start;
 
-    return 1;
+    fl->free = (FreeListBlock *)start;
+    return EXIT_SUCCESS;
 }
 
 /* Allocate some memory from the FreeList */
@@ -59,32 +41,26 @@ void *fl_alloc(FreeList *fl) {
 
     FreeListBlock *m = fl->free;
 
-    fl->free = offset_to_ptr(fl, fl->free->next_offset); /* May be null, which is fine */
+    fl->free = fl->free->next;
     fl->allocated++;
 
-    /* Wipe it before sending it out, could use memset
+    memset((void *)m, 0, sizeof(FreeListBlock));
-     * here, or even wiping the entire block */
-    m->next_offset = 0;
-
-    /* For reference: */
-    // memset((void *)m, 0, fl->size); /* Wipe entire block */
-    // memset((void *)m, 0, sizeof(FreeListBlock)); /* Wipe only header */
-
     return ((void *)m);
 }
 
 /* Return some memory to the FreeList */
 int fl_free(FreeList *fl, void *ptr) {
-    if (!fl_is_managed(fl, ptr))
+    if (!fl_is_managed(fl, ptr)) {
-        return 0; /* We cant free memory we do not own */
+        return EXIT_FAILURE; /* We cant free memory we do not own */
+    }
 
-    FreeListBlock *block = (FreeListBlock *)ptr;
+    FreeListBlock *block = (FreeListBlock *)(uintptr_t)ptr;
 
-    block->next_offset = ptr_to_offset(fl, fl->free); /* May be null, which is fine */
+    block->next = fl->free;
     fl->free = block;
     fl->allocated--;
 
-    return 1;
+    return EXIT_SUCCESS;
 }
 
 /* Returns how many slots are occupied */
@@ -104,13 +80,7 @@ size_t fl_capacity(FreeList *fl) {
 
 /* Check if a piece of memory is managed by the FreeList */
 int fl_is_managed(FreeList *fl, void *ptr) {
-    uintptr_t p = (uintptr_t)ptr;
+    return ((uintptr_t)ptr >= fl->start && (uintptr_t)ptr < fl->end);
-
-    if (p < fl->start || p >= fl->end) {
-        return 0; // outside pool
-    }
-
-    return ((p - fl->start) % fl->size) == 0; // aligned to block
 }
 
 /* Returns the ratio of metadata versus data as a scalar in range 0..1 */
@@ -123,16 +93,9 @@ size_t fl_check(FreeList *fl) {
     int            avail = 0;
     FreeListBlock *cursor = fl->free;
 
-    while (cursor) {
+    while (cursor->next != NULL) {
         avail++;
-
+        cursor = cursor->next;
-        if (!fl_is_managed(fl, cursor) || avail > fl_capacity(fl))
-            return 0;
-
-        if (cursor->next_offset == 0)
-            break;
-
-        cursor = offset_to_ptr(fl, cursor->next_offset);
     }
 
     return avail;

kern/libkern/freelist.h

@@ -5,6 +5,18 @@
 #include <stdint.h>
 #include <stdlib.h>
 
+/* Align to nearest multiple of align */
+static inline size_t align_up_to(size_t n, size_t align) {
+    return (n + align - 1) & ~(align - 1);
+}
+
+/* Fiddle these around according to your need. Delete or check makefile */
+#ifdef FREELIST_ALIGN
+#define ALIGN(x) (align_up_to(x, sizeof(void *)))
+#else
+#define ALIGN(x) (x)
+#endif
+
 typedef struct FreeListBlock FreeListBlock;
 
 typedef struct {
@@ -15,7 +27,7 @@ typedef struct {
     size_t         allocated;
 } FreeList;
 
-int    fl_init(FreeList *fl, uintptr_t start, size_t size_bytes, size_t itemsize);
+int    fl_init(FreeList *fl, uintptr_t start, uintptr_t end, size_t itemsize);
 int    fl_free(FreeList *fl, void *ptr);
 int    fl_is_managed(FreeList *fl, void *ptr);
 void  *fl_alloc(FreeList *fl);

kern/libkern/stdalign.h

@@ -1,7 +0,0 @@
-#ifndef STDALIGN_H
-#define STDALIGN_H
-
-#define ALIGN_UP(n, align)   (((n) + (align) - 1) & ~((align) - 1))
-#define ALIGN_DOWN(n, align) ((n) & ~((align) - 1))
-
-#endif // STDALIGN_H

kern/libkern/stddef.h

@@ -10,15 +10,4 @@
 #define size_t uint64_t
 #endif
 
-typedef struct {
-#if __riscv_xlen == 64
-    long double ld;
-#elif __riscv_xlen == 32
-    long long ll;
-#else
-    double d;
-#endif
-    void *p;
-} max_align_t;
-
 #endif // STDDEF_H

kern/libkern/stdint.h

@@ -24,11 +24,6 @@ typedef long  int64_t;
 typedef uint64_t size_t;
 typedef uint64_t uintptr_t;
 
-typedef int32_t  int_fast16_t;
-typedef int32_t  int_fast32_t;
-typedef uint32_t uint_fast16_t;
-typedef uint32_t uint_fast32_t;
-
 #define INT8_MIN  (-128)
 #define INT16_MIN (-32767 - 1)
 #define INT32_MIN (-2147483647 - 1)
@@ -44,20 +39,4 @@ typedef uint32_t uint_fast32_t;
 #define UINT32_MAX (4294967295U)
 #define UINT64_MAX (__UINT64_C(18446744073709551615))
 
-#define INT_FAST16_MIN INT32_MIN
-#define INT_FAST32_MIN INT32_MIN
-
-#define INT_FAST16_MAX INT32_MAX
-#define INT_FAST32_MAX INT32_MAX
-
-#define UINT_FAST16_MAX UINT32_MAX
-#define UINT_FAST32_MAX UINT32_MAX
-
-#define INTPTR_MIN  INT64_MIN
-#define INTPTR_MAX  INT64_MAX
-#define UINTPTR_MAX UINT64_MAX
-#define PTRDIFF_MIN INT64_MIN
-#define PTRDIFF_MAX INT64_MAX
-#define SIZE_MAX    UINT64_MAX
-
 #endif // STDINT_H