Initial commit of block device interface and emulated block device

lfs_bd.h

@@ -0,0 +1,56 @@
+/*
+ * Block device interface
+ *
+ * Copyright (c) 2017 Christopher Haster
+ * Distributed under the MIT license
+ */
+#ifndef LFS_BD_H
+#define LFS_BD_H
+
+#include "lfs_config.h"
+
+
+// Description of block devices
+struct lfs_bd_info {
+    lfs_size_t read_size;   // Size of readable block
+    lfs_size_t write_size;  // Size of programmable block
+    lfs_size_t erase_size;  // Size of erase block
+
+    lfs_lsize_t total_size; // Total size of the device
+};
+
+// Block device operations
+//
+// The little file system takes in a pointer to an opaque type
+// and this struct, all operations are passed the opaque pointer
+// which can be used to reference any state associated with the
+// block device
+struct lfs_bd_ops {
+    // Read a block
+    lfs_error_t (*read)(void *bd, uint8_t *buffer,
+            lfs_ino_t ino, lfs_off_t off, lfs_size_t size);
+
+    // Program a block
+    //
+    // The block must have previously been erased.
+    lfs_error_t (*write)(void *bd, const uint8_t *buffer,
+            lfs_ino_t ino, lfs_off_t off, lfs_size_t size);
+
+    // Erase a block
+    //
+    // A block must be erased before being programmed. The
+    // state of an erased block is undefined.
+    lfs_error_t (*erase)(void *bd,
+            lfs_ino_t ino, lfs_off_t off, lfs_size_t size);
+
+    // Sync the block device
+    lfs_error_t (*sync)(void *bd);
+
+    // Get a description of the block device
+    //
+    // Any unknown information may be left as zero
+    lfs_error_t (*info)(void *bd, struct lfs_bd_info *info);
+};
+
+
+#endif