* File Name: buffer.c
* Author: Zhao Yanbai
* 2023-06-20 19:30:33 Tuesday CST
- * Description: none
+ * Description: 目前只支持只读，因此可以先写得简单一点
* ------------------------------------------------------------------------
*/
#include <buffer.h>
+#define MAX_BBUFFER_CNT 985
+
#define BLOCK_BUFFER_HASH_TABLE_SIZE 211
// atomic_t hash_cnt;
-bbuffer_t *block_buffer_hash_table[BLOCK_BUFFER_HASH_TABLE_SIZE] = {
+list_head_t block_buffer_hash_table[BLOCK_BUFFER_HASH_TABLE_SIZE] = {
0,
};
-int hash(dev_t dev, uint32_t block) { return ((~dev) ^ block) % BLOCK_BUFFER_HASH_TABLE_SIZE; }
+typedef struct bbuffer_store {
+ int blocksize;
+ list_head_t cache_list;
+ list_head_t free_list;
+} bbuffer_store_t;
+
+// 1024, 2048, 4096
+bbuffer_store_t store[3] = {0};
+
+int hashfn(dev_t dev, uint32_t block) { return ((dev) ^ block) % BLOCK_BUFFER_HASH_TABLE_SIZE; }
bbuffer_t *get_hash_block_buffer(dev_t dev, uint32_t block, uint16_t size) {}
-void init_buffer() {}
+kmem_cache_t *bbufer_kmem_cache = 0;
+
+bbuffer_t *bread(dev_t dev, uint64_t block, uint32_t size) {
+ assert(size == 1024 || size == 2048 || size == 4096);
+
+ // 暂时先只支持hard disk
+ assert(DEV_MAJOR(dev) == DEV_MAJOR_DISK);
+
+ // 先尝试从hash里分配
+ list_head_t *p = 0;
+ uint32_t hash = hashfn(dev, block);
+ list_for_each(p, block_buffer_hash_table + hash) {
+ bbuffer_t *b = list_entry(p, bbuffer_t, node);
+ if (b->dev != dev) {
+ continue;
+ }
+ if (b->block == block) {
+ continue;
+ }
+
+ break;
+ }
+
+ // 如果找到了就直接返回
+ if (0 != p) {
+ bbuffer_t *b = list_entry(p, bbuffer_t, node);
+ assert(0 != b);
+ assert(0 != b->data);
+ return b;
+ }
+
+ // 如果没找到，则从store的cached_list里尝试找
+
+ // 如果没找到，则尝试从store里的free_list里尝试分配
+
+ // 如果free_list为空，且cached_list不为空，
+}
+
+void init_buffer() {
+ for (int i = 0; i < BLOCK_BUFFER_HASH_TABLE_SIZE; i++) {
+ list_init(block_buffer_hash_table + i);
+ }
+
+ bbufer_kmem_cache = kmem_cache_create("bbuffer", sizeof(bbuffer_t), 4);
+ if (0 == bbufer_kmem_cache) {
+ panic("no memory for bbufer kmem cache");
+ }
+
+ printk("bbufer kmem cache %08x\n", bbufer_kmem_cache);
+
+ for (int i = 0; i < 3; i++) {
+ int blocksize = 1 << (10 + i);
+
+ store[i].blocksize = blocksize;
+ list_init(&store[i].cache_list);
+ list_init(&store[i].free_list);
+
+ int page_left_space = 0;
+ void *data = 0;
+ page_t *page = 0;
+ for (int j = 0; j < MAX_BBUFFER_CNT; j++) {
+ if (page_left_space < blocksize) {
+ data = (void *)(alloc_one_page(0));
+ page = va2page(data);
+ }
+
+ bbuffer_t *b = kmem_cache_alloc(bbufer_kmem_cache, 0);
+ assert(b != 0);
+
+ b->block = 0;
+ b->block_size = blocksize;
+ b->ref_count = 0;
+ b->data = data + j * blocksize;
+ b->dev = 0;
+ b->page = page;
+ list_init(&b->node);
+
+ assert(0 != b->data);
+
+ list_add(&b->node, &store[i].free_list);
+
+ page_left_space -= blocksize;
+ }
+ }
+}