Squash commits for public release

libs/libc/malloc/slab.c

@@ -0,0 +1,79 @@
+#include "malloc.h"
+#include <stdbool.h>
+#include <string.h>
+#include <sys/mman.h>
+
+// Fast allocator for sizes 16, 32, 48, 64 bytes
+
+malloc_header_t* free_blocks[5];
+
+void prepare_free_blocks(size_t size)
+{
+    int block_id = size >> 4;
+    const size_t alloc_size = MALLOC_DEFAULT_BLOCK_SIZE;
+    intptr_t ret = (intptr_t)mmap(NULL, alloc_size, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
+    if (ret < 0) {
+        free_blocks[block_id] = NULL;
+        return;
+    }
+
+    void* raw_area = (void*)ret;
+    const size_t sizeof_block_with_header = size + sizeof(malloc_header_t);
+    size_t passed = 0;
+
+    free_blocks[block_id] = (malloc_header_t*)raw_area;
+    malloc_header_t* prev_header = NULL;
+
+    while (passed + sizeof_block_with_header <= alloc_size) {
+        malloc_header_t* current = (malloc_header_t*)raw_area;
+
+        current->flags = FLAG_SLAB | FLAG_ALLOCATED;
+        current->next = NULL;
+        current->prev = prev_header;
+        current->size = size;
+
+        prev_header = current;
+        raw_area += sizeof_block_with_header;
+        passed += sizeof_block_with_header;
+    }
+
+    malloc_header_t* next_header = NULL;
+    while (prev_header) {
+        prev_header->next = next_header;
+        prev_header = prev_header->prev;
+    }
+}
+
+void _slab_init()
+{
+    prepare_free_blocks(16);
+    prepare_free_blocks(32);
+    prepare_free_blocks(48);
+    prepare_free_blocks(64);
+}
+
+void* slab_alloc(size_t size)
+{
+    if (size > 64) {
+        return NULL;
+    }
+    int block_id = ((size + 15) >> 4);
+    malloc_header_t* zone = free_blocks[block_id];
+    if (!zone) {
+        return NULL;
+    }
+
+    free_blocks[block_id] = zone->next;
+    return (void*)&((malloc_header_t*)zone)[1];
+}
+
+void slab_free(malloc_header_t* mem_header)
+{
+    malloc_header_t* next = free_blocks[((mem_header->size) >> 4)];
+    free_blocks[((mem_header->size) >> 4)] = mem_header;
+    mem_header->next = next;
+    mem_header->prev = NULL;
+    if (next) {
+        next->prev = mem_header;
+    }
+}