Added new list-based memory allocator

include/Makefile.am

@@ -1,2 +1,2 @@
 nobase_include_HEADERS = libmalloc/bitmap_alloc.h libmalloc/buddy_alloc.h \
-    libmalloc/memmap.h libmalloc/common.h
+    libmalloc/list_alloc.h libmalloc/memmap.h libmalloc/common.h

include/libmalloc/list_alloc.h

@@ -0,0 +1,27 @@
+#ifndef _LIBMALLOC_LISTALLOC_H
+#define _LIBMALLOC_LISTALLOC_H
+
+#include "memmap.h"
+#include "common.h"
+
+typedef struct list_block_t
+{
+    unsigned long free;
+    unsigned long size;
+    struct list_block_t *prev;
+    struct list_block_t *next;
+} list_block_t;
+
+typedef struct list_alloc_descriptor_t
+{
+    list_block_t head;
+    list_block_t *current_block;
+} list_alloc_descriptor_t;
+
+void *list_alloc_reserve(list_alloc_descriptor_t *heap, unsigned long size);
+
+void list_alloc_free(list_alloc_descriptor_t *heap, void *p);
+
+int list_alloc_init(list_alloc_descriptor_t *heap, memory_map_t *map);
+
+#endif

src/Makefile.am

@@ -1,4 +1,4 @@
 lib_LIBRARIES = libmalloc.a
-libmalloc_a_SOURCES = buddy_alloc.c bitmap_alloc.c memmap.c
+libmalloc_a_SOURCES = buddy_alloc.c bitmap_alloc.c list_alloc.c memmap.c
 
 libmalloc_a_CFLAGS = -I$(prefix)/include

src/list_alloc.c

@@ -0,0 +1,134 @@
+#include "libmalloc/list_alloc.h"
+#include <stddef.h>
+#include <stdio.h>
+
+#define MIN_BLOCK_SIZE (4 * sizeof(list_block_t))
+
+static list_block_t *block_end_ptr(list_block_t *p)
+{
+    return (list_block_t*)((void*)p + p->size - sizeof(list_block_t));
+}
+
+static list_block_t *block_start_ptr(list_block_t *p)
+{
+    return (list_block_t*)((void*)p - p->size + sizeof(list_block_t));
+}
+
+static void set_block_tag(list_block_t *p, unsigned long free)
+{
+    p->free = free;
+    block_end_ptr(p)->free = free;
+}
+
+static void set_block_size(list_block_t *p, unsigned long size)
+{
+    p->size = size;
+    block_end_ptr(p)->size = size;
+}
+
+static void set_block_next(list_block_t *p, list_block_t *next)
+{
+    p->next = next;
+    block_end_ptr(p)->next = next;
+}
+
+static void set_block_prev(list_block_t *p, list_block_t *prev)
+{
+    p->prev = prev;
+    block_end_ptr(p)->prev = prev;
+}
+
+static void set_block(list_block_t *p, unsigned long tag, unsigned long size,
+    list_block_t *next, list_block_t *prev)
+{
+    set_block_size(p, size);
+    set_block_tag(p, tag);
+    set_block_next(p, next);
+    set_block_prev(p, prev);
+}
+
+void *list_alloc_reserve(list_alloc_descriptor_t *heap, unsigned long size)
+{
+    size += sizeof(unsigned long) - 1;
+    size -= size % sizeof(unsigned long);
+    list_block_t *p = heap->current_block;
+    do
+    {
+        if(p->size >= (size + 2 * sizeof(list_block_t) + MIN_BLOCK_SIZE))
+        {
+            printf("Reserving partial block.\n");
+            unsigned long new_size = p->size - size - (2 * sizeof(list_block_t));
+            list_block_t *new_block = (void*)p + new_size;
+            set_block(new_block, 0, size + 2 * sizeof(list_block_t), 0, 0);
+            set_block_tag(p, 1);
+            set_block_size(p, new_size);
+            heap->current_block = p;
+            return (void*)new_block + sizeof(list_block_t);
+        }
+        else if(p->size >= (size + 2 * sizeof(list_block_t)))
+        {
+            printf("Reserving whole block.\n");
+            set_block_next(p->prev, p->next);
+            set_block_prev(p->next, p->prev);
+            heap->current_block = p->next;
+            set_block(p, 0, p->size, 0, 0);
+            return (void*)p + sizeof(list_block_t);
+        }
+        p = p->next;
+    } while(p != heap->current_block);
+    return NOMEM;
+}
+
+void list_alloc_free(list_alloc_descriptor_t *heap, void *p)
+{
+    list_block_t *block = (list_block_t*)(p - sizeof(list_block_t));
+
+    list_block_t *lhs = block_start_ptr(block - 1);
+    if(lhs->free == 1)
+    {
+        printf("Merging left.\n");
+        set_block_next(lhs->prev, lhs->next);
+        set_block_prev(lhs->next, lhs->prev);
+        unsigned long new_size = block->size + lhs->size;
+        block = (void*)block - lhs->size;
+        block->size = new_size;
+    }
+
+    list_block_t *rhs = (block_end_ptr(block) + 1);
+    if(rhs->free == 1)
+    {
+        printf("Merging right.\n");
+        set_block_next(rhs->prev, rhs->next);
+        set_block_prev(rhs->next, rhs->prev);
+        block->size += rhs->size;
+    }
+
+    set_block(block, 1, block->size, &heap->head, heap->head.prev);
+    set_block_next(heap->head.prev, block);
+    set_block_prev(&heap->head, block);
+    heap->current_block = block;
+}
+
+int list_alloc_init(list_alloc_descriptor_t *heap, memory_map_t *map)
+{
+    heap->head.free = 0;
+    heap->head.size = sizeof(heap->head);
+    heap->head.prev = &heap->head;
+    heap->head.next = &heap->head;
+    heap->current_block = &heap->head;
+    for(int i = 0; i < map->size; i++)
+    {
+        if(map->array[i].type != M_AVAILABLE 
+            || map->array[i].size < MIN_BLOCK_SIZE)
+        {
+            continue;
+        }
+        list_block_t *new_block = ((list_block_t*)map->array[i].location) + 1;
+        set_block(new_block, 1, map->array[i].size - sizeof(list_block_t) * 2, &heap->head, heap->head.prev);
+        set_block_next(heap->head.prev, new_block);
+        set_block_prev(&heap->head, new_block);
+        (new_block - 1)->free = 0;
+        (block_end_ptr(new_block) + 1)->free = 0;
+    }
+    return 0;
+}

tests/Makefile.am

@@ -1,9 +1,12 @@
 if BUILD_TESTS
-    noinst_PROGRAMS = test_bitmapalloc test_buddyalloc
+    noinst_PROGRAMS = test_bitmapalloc test_buddyalloc test_listalloc
 
     test_bitmapalloc_SOURCES = test_bitmapalloc.c
     test_bitmapalloc_LDADD = ../src/libmalloc.a
 
     test_buddyalloc_SOURCES = test_buddyalloc.c
     test_buddyalloc_LDADD = ../src/libmalloc.a
+
+    test_listalloc_SOURCES = test_listalloc.c
+    test_listalloc_LDADD = ../src/libmalloc.a
 endif

tests/test_listalloc.c

@@ -0,0 +1,109 @@
+#include "libmalloc/list_alloc.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <assert.h>
+
+typedef struct memblock_t
+{
+    unsigned long size;
+    void *p;
+} memblock_t;
+
+void check_block_list(void *heap, unsigned long heap_size, memblock_t *blocks, unsigned long count)
+{
+    for (int j = 0; j < count; j++)
+    {
+        if (blocks[j].size > 0)
+        {
+            assert(blocks[j].p >= heap);
+            assert(blocks[j].p + blocks[j].size <= heap + heap_size);
+            for (int k = j + 1; k < count; k++)
+            {
+                if (blocks[k].size > 0)
+                {
+                    // printf("j = (%p, %lu), k = (%p, %lu)\n", blocks[j].p, blocks[j].size, blocks[k].p, blocks[k].size);
+                    assert(blocks[k].p < blocks[j].p || blocks[k].p >= blocks[j].p + blocks[j].size);
+                    assert(blocks[j].p < blocks[k].p || blocks[j].p >= blocks[k].p + blocks[k].size);
+                }
+            }
+        }
+    }
+}
+
+int main(int argc, char** argv)
+{
+    unsigned int max_block_count = 0;
+    unsigned int heap_size = 0;
+    unsigned int passes = 0;
+
+    char c;
+    while((c = getopt(argc, argv, "m:b:c:")) != -1)
+    {
+        if(c == 'm')
+        {
+            sscanf(optarg, "%i", &heap_size);
+            heap_size *= 1024;
+        }
+        else if(c == 'b')
+        {
+            sscanf(optarg, "%i", &max_block_count);
+        }
+        else if(c == 'c')
+        {
+            sscanf(optarg, "%i", &passes);
+        }
+    }
+
+    printf("Running test with %i byte heap, %i blocks, %i passes.\n",
+        heap_size, max_block_count, passes);
+
+    void *heap = malloc(heap_size);
+    memory_map_t map = {
+        .array = malloc(sizeof(unsigned long) * 16),
+        .capacity = 16,
+        .size = 0
+    };
+    memmap_insert_region(&map, heap, heap_size, M_AVAILABLE);
+
+    list_alloc_descriptor_t desc;
+    list_alloc_init(&desc, &map);
+    memblock_t *blocks = calloc(max_block_count, sizeof(memblock_t));
+
+    for(int i = 0; i < passes; i++)
+    {
+        int index = rand() % max_block_count;
+        if(blocks[index].size == 0)
+        {
+            unsigned long size = rand() % 65536 + 1;
+            blocks[index].p = list_alloc_reserve(&desc, size);
+            //printf("Reserved %lu bytes.\n", size);
+            if(blocks[index].p != NOMEM)
+            {
+                blocks[index].size = size;
+            }
+            else
+            {
+                printf("Out of memory trying to reserve %lu bytes\n", size);
+            }
+        }
+        else
+        {
+            list_alloc_free(&desc, blocks[index].p);
+            //printf("Freed %p\n", blocks[index].p);
+            blocks[index].size = 0;
+        }
+        check_block_list(heap, heap_size, blocks, max_block_count);
+    }
+
+    for(int i = 0; i < max_block_count; i++)
+    {
+        if(blocks[i].size != 0)
+        {
+            list_alloc_free(&desc, blocks[i].p);
+            blocks[i].size = 0;
+        }
+    }
+
+    return 0;
+}