Added initial superblock definition

Really started working out how the internal structure of the driver
will be organized. There are a few hazy lines between the intended
data structures with the goal of code reuse, so the function boundaries
may end up a bit weird.

lfs.c

@@ -29,6 +29,49 @@ static uint32_t lfs_crc(const uint8_t *data, lfs_size_t size, uint32_t crc) {
 static lfs_error_t lfs_alloc(lfs_t *lfs, lfs_ino_t *ino);
 static lfs_error_t lfs_free(lfs_t *lfs, lfs_ino_t ino);
 
+// Disk structures
+//lfs_disk_struct lfs_disk_free {
+//    lfs_ino_t head;
+//    uint32_t ioff;
+//    uint32_t icount;
+//    uint32_t rev;
+//};
+//
+//lfs_disk_struct lfs_disk_dir {
+//    uint32_t rev;
+//    uint32_t count;
+//    lfs_ino_t tail[2];
+//    struct lfs_disk_free free;
+//};
+//
+//lfs_disk_struct lfs_disk_dirent {
+//    uint16_t type;
+//    uint16_t len;
+//};
+//
+//lfs_disk_struct lfs_disk_superblock {
+//    struct lfs_disk_dir dir;
+//    struct lfs_disk_dirent header;
+//    char magic[4];
+//    uint32_t read_size;
+//    uint32_t write_size;
+//    uint32_t erase_size;
+//    uint32_t erase_count;
+//};
+//
+//lfs_disk_struct lfs_disk_dirent_file {
+//    struct lfs_disk_dirent header;
+//    lfs_ino_t head;
+//    lfs_size_t size;
+//    char name[LFS_NAME_MAX];
+//};
+//
+//lfs_disk_struct lfs_disk_dirent_dir {
+//    struct lfs_disk_dirent header;
+//    lfs_ino_t ino[2];
+//    char name[LFS_NAME_MAX];
+//};
+
 
 // Next index offset
 static lfs_off_t lfs_inext(lfs_t *lfs, lfs_off_t ioff) {
@@ -114,21 +157,220 @@ static lfs_error_t lfs_iappend(lfs_t *lfs, lfs_ino_t *headp,
 
 // Memory managment
 static lfs_error_t lfs_alloc(lfs_t *lfs, lfs_ino_t *ino) {
-    lfs_error_t err = lfs_ifind(lfs, lfs->free.head,
-            lfs->free.icount, lfs->free.ioff, ino);
+    // TODO save slot for freeing?
+    lfs_error_t err = lfs_ifind(lfs, lfs->free.d.head,
+            lfs->free.d.icount, lfs->free.d.ioff, ino);
     if (err) {
         return err;
     }
 
-    lfs->free.ioff = lfs_inext(lfs, lfs->free.ioff);
+    lfs->free.d.ioff = lfs_inext(lfs, lfs->free.d.ioff);
 
     return lfs->ops->erase(lfs->bd, *ino, 0, lfs->info.erase_size);
 }
 
 static lfs_error_t lfs_free(lfs_t *lfs, lfs_ino_t ino) {
-    return lfs_iappend(lfs, &lfs->free.head, &lfs->free.icount, ino);
+    return lfs_iappend(lfs, &lfs->free.d.head, &lfs->free.d.icount, ino);
+}
+
+// create a dir
+// create entry
+// update entry
+
+
+//static lfs_error_t lfs_dir_alloc(lfs_t *lfs, lfs_dir_t *dir);
+//static lfs_error_t lfs_dir_update(lfs_t *lfs, lfs_dir_t *dir, lfs_entry_t *entry);
+//static lfs_error_t lfs_dir_destroy(lfs_t *lfs, lfs_dir_t *dir);
+//static lfs_error_t lfs_entry_alloc(lfs_t *lfs, lfs_dir_t *dir, lfs_entry_t *entry);
+//static lfs_error_t lfs_entry_update(lfs_t *lfs, lfs_entry_t *entry);
+//static lfs_error_t lfs_entry_destroy(lfs_t *lfs, lfs_dir_t *dir);
+
+// Directory operations
+static lfs_error_t lfs_dir_alloc(lfs_t *lfs, lfs_dir_t *dir) {
+    // Allocate pair of dir blocks
+    for (int i = 0; i < 2; i++) {
+        int err = lfs_alloc(lfs, &dir->dno[i]);
+        if (err) {
+            return err;
+        }
+    }
+
+    // Rather than clobbering one of the blocks we just pretend
+    // the revision may be valid
+    int err = lfs->ops->read(lfs->bd, (void*)&dir->d.rev, dir->dno[1], 0, 4);
+    if (err) {
+        return err;
+    }
+    dir->d.rev += 1;
+
+    // Other defaults
+    dir->d.size = sizeof(struct lfs_disk_dir);
+    dir->d.tail[0] = 0;
+    dir->d.tail[1] = 0;
+    dir->d.parent[0] = 0;
+    dir->d.parent[1] = 0;
+    return 0;
+}
+
+lfs_error_t lfs_dir_update(lfs_t *lfs, lfs_dir_t *dir, lfs_entry_t *entry) {
+    // TODO flush this
+    dir->d.free = lfs->free.d;
+
+    // Start by erasing target block
+    int err = lfs->ops->erase(lfs->bd, dir->dno[0], 0, lfs->info.erase_size);
+
+    // Write header and start calculating crc
+    uint32_t crc = lfs_crc((void*)&dir->d, sizeof(dir->d), 0xffffffff);
+    err = lfs->ops->write(lfs->bd, (void*)&dir->d,
+        dir->dno[0], 0, sizeof(dir->d));
+    if (err) {
+        return err;
+    }
+
+    // Copy over entries and write optional entry update
+    // TODO handle optional entry
+    for (lfs_off_t i = sizeof(dir->d); i < lfs->info.erase_size-4; i += 4) {
+        uint32_t data;
+        err = lfs->ops->read(lfs->bd, (void*)&data, dir->dno[1], i, 4);
+        if (err) {
+            return err;
+        }
+
+        crc = lfs_crc((void*)&data, 4, crc);
+        err = lfs->ops->write(lfs->bd, (void*)&data, dir->dno[0], i, 4);
+        if (err) {
+            return err;
+        }
+    }
+
+    // Write resulting crc
+    err = lfs->ops->write(lfs->bd, (void*)&crc,
+            dir->dno[0], lfs->info.erase_size-4, 4);
+    if (err) {
+        return err;
+    }
+
+    // Flip dnos to indicate next write of the dir pair
+    lfs_ino_t temp = dir->dno[0];
+    dir->dno[0] = dir->dno[1];
+    dir->dno[1] = temp;
+
+    return 0;
 }
 
+
+//static lfs_error_t lfs_dir_alloc(lfs_t *lfs, lfs_dir_t *dir) {
+//    memset(dir, 0, sizeof(lfs_dir_t));
+//
+//    for (int i = 0; i < 2; i++) {
+//        int err = lfs_alloc(lfs, &dir->dno[i]);
+//        if (err) {
+//            return err;
+//        }
+//    }
+//
+//    // Rather than clobbering one of the blocks we just pretend
+//    // the revision may be valid
+//    int err = lfs->ops->read(lfs->bd, (void*)&dir->rev, dir->dno[1], 0, 4);
+//    if (err) {
+//        return err;
+//    }
+//    dir->rev += 1;
+//
+//    // TODO move this to a flush of some sort?
+//    struct lfs_disk_dir disk_dir = {
+//        .rev = dir->rev,
+//        .count = dir->len,
+//        .tail[0] = dir->tail[0],
+//        .tail[1] = dir->tail[1],
+//        .free.head = lfs->free.head,
+//        .free.ioff = lfs->free.ioff,
+//        .free.icount = lfs->free.icount,
+//        .free.rev = lfs->free.rev,
+//    };
+//
+//    err = lfs->ops->write(lfs->bd, (void*)&disk_dir,
+//        dir->dno[0], 0, sizeof(struct lfs_disk_dir));
+//    if (err) {
+//        return err;
+//    }
+//
+//    uint32_t crc = 0xffffffff;
+//    for (lfs_off_t i = 0; i < lfs->info.erase_size-4; i += 4) {
+//        uint32_t data;
+//        err = lfs->ops->read(lfs->bd, (void*)&data, dir->dno[0], i, 4);
+//        if (err) {
+//            return err;
+//        }
+//
+//        crc = lfs_crc((void*)&data, 4, crc);
+//    }
+//
+//    err = lfs->ops->write(lfs->bd, (void*)&crc,
+//            dir->dno[0], lfs->info.erase_size-4, 4);
+//    if (err) {
+//        return err;
+//    }
+//
+//    lfs_ino_t temp = dir->dno[0];
+//    dir->dno[0] = dir->dno[1];
+//    dir->dno[1] = temp;
+//
+//    return 0;
+//}
+
+//lfs_error_t lfs_dir_update(lfs_t *lfs, lfs_dir_t *dir,
+//        lfs_dirent_t *ent, const char *name) {
+//
+//
+//
+//    struct lfs_disk_dir disk_dir = {
+//        .rev = dir->rev,
+//        .count = dir->len,
+//        .tail[0] = dir->tail[0],
+//        .tail[1] = dir->tail[1],
+//        // TODO flush this?
+//        .free.head = lfs->free.head,
+//        .free.ioff = lfs->free.ioff,
+//        .free.icount = lfs->free.icount,
+//        .free.rev = lfs->free.rev,
+//    };
+//
+//    err = lfs->ops->write(lfs->bd, (void*)&disk_dir,
+//        dir->dno[0], 0, sizeof(struct lfs_disk_dir));
+//    if (err) {
+//        return err;
+//    }
+//
+//    if (ent) {
+//        // TODO update entry
+//    }
+//
+//    uint32_t crc = 0xffffffff;
+//    for (lfs_off_t i = 0; i < lfs->info.erase_size-4; i += 4) {
+//        uint32_t data;
+//        err = lfs->ops->read(lfs->bd, (void*)&data, dir->dno[0], i, 4);
+//        if (err) {
+//            return err;
+//        }
+//
+//        crc = lfs_crc((void*)&data, 4, crc);
+//    }
+//
+//    err = lfs->ops->write(lfs->bd, (void*)&crc,
+//            dir->dno[0], lfs->info.erase_size-4, 4);
+//    if (err) {
+//        return err;
+//    }
+//
+//    lfs_ino_t temp = dir->dno[0];
+//    dir->dno[0] = dir->dno[1];
+//    dir->dno[1] = temp;
+//
+//    return 0;
+//}
+
+
 // Little filesystem operations
 lfs_error_t lfs_create(lfs_t *lfs, lfs_bd_t *bd, const struct lfs_bd_ops *ops) {
     lfs->bd = bd;
@@ -157,10 +399,10 @@ lfs_error_t lfs_format(lfs_t *lfs) {
     // TODO make sure that erase clobbered blocks
 
     {   // Create free list
-        lfs->free.head = 4;
-        lfs->free.ioff = 1;
-        lfs->free.icount = 1;
-        lfs->free.rev = 1;
+        lfs->free.d.head = 4;
+        lfs->free.d.ioff = 1;
+        lfs->free.d.icount = 1;
+        lfs->free.d.rev = 1;
 
         lfs_size_t block_count = lfs->info.total_size / lfs->info.erase_size;
         for (lfs_ino_t i = 5; i < block_count; i++) {
@@ -171,68 +413,66 @@ lfs_error_t lfs_format(lfs_t *lfs) {
         }
     }
 
+    lfs_dir_t root;
     {
         // Write root directory
-        struct __attribute__((packed)) {
-            lfs_word_t rev;
-            lfs_size_t len;
-            lfs_ino_t  tail[2];
-            struct lfs_free_list free;
-        } header = {1, 0, {0, 0}, lfs->free};
-        err = lfs->ops->write(lfs->bd, (void*)&header, 2, 0, sizeof(header));
+        int err = lfs_dir_alloc(lfs, &root);
         if (err) {
             return err;
         }
 
-        uint32_t crc = lfs_crc((void*)&header, sizeof(header), 0xffffffff);
+        err = lfs_dir_update(lfs, &root, 0);
+        if (err) {
+            return err;
+        }
+    }
 
-        for (lfs_size_t i = sizeof(header); i < info.erase_size-4; i += 4) {
-            uint32_t data;
-            err = lfs->ops->read(lfs->bd, (void*)&data, 2, i, 4);
+    {
+        // Write superblocks
+        lfs_ino_t sno[2] = {0, 1};
+        lfs_superblock_t superblock = {
+            .d.rev = 1,
+            .d.count = 0,
+            .d.root = {root.dno[0], root.dno[1]},
+            .d.magic = {"littlefs"},
+            .d.block_size = info.erase_size,
+            .d.block_count = info.total_size / info.erase_size,
+        };
+
+        for (int i = 0; i < 2; i++) {
+            err = lfs->ops->erase(lfs->bd, sno[i], 0, info.erase_size);
             if (err) {
                 return err;
             }
 
-            crc = lfs_crc((void*)&data, 4, crc);
-        }
+            err = lfs->ops->write(lfs->bd, (void*)&superblock.d,
+                    sno[i], 0, sizeof(superblock.d));
+            if (err) {
+                return err;
+            }
 
-        err = lfs->ops->write(lfs->bd, (void*)&crc, 2, info.erase_size-4, 4);
-        if (err) {
-            return err;
-        }
-    }
+            uint32_t crc = lfs_crc((void*)&superblock.d,
+                    sizeof(superblock.d), 0xffffffff);
 
-    {
-        // Write superblock
-        struct __attribute__((packed)) {
-            lfs_word_t rev;
-            lfs_word_t len;
-            lfs_word_t tail[2];
-            struct lfs_free_list free;
-            char magic[4];
-            struct lfs_bd_info info;
-        } header = {1, 0, {2, 3}, {0}, {"lfs"}, info};
-        err = lfs->ops->write(lfs->bd, (void*)&header, 0, 0, sizeof(header));
-        if (err) {
-            return err;
-        }
+            for (lfs_size_t i = sizeof(superblock);
+                    i < info.erase_size-4; i += 4) {
+                uint32_t data;
+                err = lfs->ops->read(lfs->bd, (void*)&data, 0, i, 4);
+                if (err) {
+                    return err;
+                }
 
-        uint32_t crc = lfs_crc((void*)&header, sizeof(header), 0xffffffff);
+                crc = lfs_crc((void*)&data, 4, crc);
+            }
 
-        for (lfs_size_t i = sizeof(header); i < info.erase_size-4; i += 4) {
-            uint32_t data;
-            err = lfs->ops->read(lfs->bd, (void*)&data, 0, i, 4);
+            err = lfs->ops->write(lfs->bd, (void*)&crc,
+                    sno[i], info.erase_size-4, 4);
             if (err) {
                 return err;
             }
-
-            crc = lfs_crc((void*)&data, 4, crc);
         }
 
-        err = lfs->ops->write(lfs->bd, (void*)&crc, 0, info.erase_size-4, 4);
-        if (err) {
-            return err;
-        }
+        // TODO verify superblocks written correctly
     }
 
 

lfs.h

@@ -10,22 +10,81 @@
 #include "lfs_config.h"
 #include "lfs_bd.h"
 
-struct lfs_free_list {
-    lfs_ino_t head;
-    lfs_word_t ioff;
-    lfs_word_t icount;
-    lfs_word_t rev;
-};
 
+// Data structures
+typedef struct lfs_free {
+    lfs_disk_struct lfs_disk_free {
+        lfs_ino_t head;
+        lfs_word_t ioff;
+        lfs_word_t icount;
+        lfs_word_t rev;
+    } d;
+} lfs_free_t;
+
+typedef struct lfs_dir {
+    lfs_ino_t dno[2];
+
+    lfs_disk_struct lfs_disk_dir {
+        lfs_word_t rev;
+        lfs_size_t size;
+        lfs_ino_t tail[2];
+        lfs_ino_t parent[2];
+
+        struct lfs_disk_free free;
+    } d;
+} lfs_dir_t; 
+
+typedef struct lfs_entry {
+    lfs_ino_t dir[2];
+    lfs_off_t off;
+
+    lfs_disk_struct lfs_disk_entry {
+        uint16_t type;
+        uint16_t len;
+        union {
+            lfs_disk_struct {
+                lfs_ino_t head;
+                lfs_size_t size;
+                char name[LFS_NAME_MAX];
+            } file;
+            lfs_disk_struct {
+                lfs_ino_t dir[2];
+                char name[LFS_NAME_MAX];
+            } dir;
+            lfs_disk_struct {
+                char magic[4];
+                uint32_t read_size;
+                uint32_t write_size;
+                uint32_t erase_size;
+                uint32_t erase_count;
+            } superblock;
+        } value;
+    } d;
+} lfs_entry_t;
+
+typedef struct lfs_superblock {
+    lfs_disk_struct lfs_disk_superblock {
+        uint32_t rev;
+        uint32_t count;
+        lfs_ino_t root[2];
+        char magic[8];
+        uint32_t block_size;
+        uint32_t block_count;
+    } d;
+} lfs_superblock_t;
+
+// Little filesystem type
 typedef struct lfs {
     lfs_bd_t *bd;
     const struct lfs_bd_ops *ops;
 
-    struct lfs_free_list free;
+    lfs_free_t free;
     struct lfs_bd_info info;
 } lfs_t;
 
+// Functions
 lfs_error_t lfs_create(lfs_t *lfs, lfs_bd_t *bd, const struct lfs_bd_ops *bd_ops);
 lfs_error_t lfs_format(lfs_t *lfs);
+lfs_error_t lfs_mount(lfs_t *lfs);
 
 #endif

lfs_config.h

@@ -42,4 +42,7 @@ static inline lfs_word_t lfs_npw2(lfs_word_t a) {
     return 32 - __builtin_clz(a-1);
 }
 
+// Attributes
+#define lfs_disk_struct struct __attribute__((packed))
+
 #endif