Christopher Haster
1d36fc606a
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.
500 lines
13 KiB
C
500 lines
13 KiB
C
/*
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* The little filesystem
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*
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* Copyright (c) 2017 Christopher Haster
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* Distributed under the MIT license
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*/
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#include "lfs.h"
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#include <string.h>
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#include <stdbool.h>
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static uint32_t lfs_crc(const uint8_t *data, lfs_size_t size, uint32_t crc) {
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static const uint32_t rtable[16] = {
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0x00000000, 0x1db71064, 0x3b6e20c8, 0x26d930ac,
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0x76dc4190, 0x6b6b51f4, 0x4db26158, 0x5005713c,
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0xedb88320, 0xf00f9344, 0xd6d6a3e8, 0xcb61b38c,
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0x9b64c2b0, 0x86d3d2d4, 0xa00ae278, 0xbdbdf21c,
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};
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for (lfs_size_t i = 0; i < size; i++) {
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crc = (crc >> 4) ^ rtable[(crc ^ (data[i] >> 0)) & 0xf];
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crc = (crc >> 4) ^ rtable[(crc ^ (data[i] >> 4)) & 0xf];
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}
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return crc;
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}
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static lfs_error_t lfs_alloc(lfs_t *lfs, lfs_ino_t *ino);
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static lfs_error_t lfs_free(lfs_t *lfs, lfs_ino_t ino);
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// Disk structures
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//lfs_disk_struct lfs_disk_free {
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// lfs_ino_t head;
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// uint32_t ioff;
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// uint32_t icount;
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// uint32_t rev;
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//};
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//
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//lfs_disk_struct lfs_disk_dir {
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// uint32_t rev;
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// uint32_t count;
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// lfs_ino_t tail[2];
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// struct lfs_disk_free free;
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//};
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//
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//lfs_disk_struct lfs_disk_dirent {
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// uint16_t type;
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// uint16_t len;
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//};
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//
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//lfs_disk_struct lfs_disk_superblock {
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// struct lfs_disk_dir dir;
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// struct lfs_disk_dirent header;
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// char magic[4];
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// uint32_t read_size;
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// uint32_t write_size;
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// uint32_t erase_size;
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// uint32_t erase_count;
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//};
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//
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//lfs_disk_struct lfs_disk_dirent_file {
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// struct lfs_disk_dirent header;
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// lfs_ino_t head;
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// lfs_size_t size;
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// char name[LFS_NAME_MAX];
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//};
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//
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//lfs_disk_struct lfs_disk_dirent_dir {
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// struct lfs_disk_dirent header;
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// lfs_ino_t ino[2];
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// char name[LFS_NAME_MAX];
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//};
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// Next index offset
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static lfs_off_t lfs_inext(lfs_t *lfs, lfs_off_t ioff) {
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ioff += 1;
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lfs_size_t wcount = lfs->info.erase_size/4;
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while (ioff % wcount == 0) {
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ioff += lfs_min(lfs_ctz(ioff/wcount + 1), wcount-1) + 1;
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}
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return ioff;
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}
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// Find index in index chain given its index offset
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static lfs_error_t lfs_ifind(lfs_t *lfs, lfs_ino_t head,
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lfs_size_t icount, lfs_off_t ioff, lfs_ino_t *ino) {
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lfs_size_t wcount = lfs->info.erase_size/4;
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lfs_off_t iitarget = ioff / wcount;
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lfs_off_t iicurrent = (icount-1) / wcount;
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while (iitarget != iicurrent) {
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lfs_size_t skip = lfs_min(
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lfs_min(lfs_ctz(iicurrent+1), wcount-1),
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lfs_npw2((iitarget ^ iicurrent)+1)-1);
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lfs_error_t err = lfs->ops->read(lfs->bd, (void*)&head,
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head, 4*skip, 4);
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if (err) {
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return err;
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}
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iicurrent -= 1 << skip;
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}
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return lfs->ops->read(lfs->bd, (void*)ino, head, 4*(ioff % wcount), 4);
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}
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// Append index to index chain, updates head and icount
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static lfs_error_t lfs_iappend(lfs_t *lfs, lfs_ino_t *headp,
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lfs_size_t *icountp, lfs_ino_t ino) {
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lfs_ino_t head = *headp;
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lfs_size_t ioff = *icountp - 1;
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lfs_size_t wcount = lfs->info.erase_size/4;
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ioff += 1;
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while (ioff % wcount == 0) {
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lfs_ino_t nhead;
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lfs_error_t err = lfs_alloc(lfs, &nhead);
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if (err) {
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return err;
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}
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lfs_off_t skips = lfs_min(lfs_ctz(ioff/wcount + 1), wcount-1) + 1;
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for (lfs_off_t i = 0; i < skips; i++) {
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err = lfs->ops->write(lfs->bd, (void*)&head, nhead, 4*i, 4);
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if (err) {
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return err;
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}
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if (head && i != skips-1) {
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err = lfs->ops->read(lfs->bd, (void*)&head, head, 4*i, 4);
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if (err) {
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return err;
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}
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}
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}
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ioff += skips;
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head = nhead;
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}
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lfs_error_t err = lfs->ops->write(lfs->bd, (void*)&ino,
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head, 4*(ioff % wcount), 4);
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if (err) {
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return err;
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}
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*headp = head;
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*icountp = ioff + 1;
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return 0;
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}
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// Memory managment
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static lfs_error_t lfs_alloc(lfs_t *lfs, lfs_ino_t *ino) {
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// TODO save slot for freeing?
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lfs_error_t err = lfs_ifind(lfs, lfs->free.d.head,
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lfs->free.d.icount, lfs->free.d.ioff, ino);
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if (err) {
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return err;
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}
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lfs->free.d.ioff = lfs_inext(lfs, lfs->free.d.ioff);
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return lfs->ops->erase(lfs->bd, *ino, 0, lfs->info.erase_size);
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}
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static lfs_error_t lfs_free(lfs_t *lfs, lfs_ino_t ino) {
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return lfs_iappend(lfs, &lfs->free.d.head, &lfs->free.d.icount, ino);
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}
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// create a dir
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// create entry
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// update entry
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//static lfs_error_t lfs_dir_alloc(lfs_t *lfs, lfs_dir_t *dir);
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//static lfs_error_t lfs_dir_update(lfs_t *lfs, lfs_dir_t *dir, lfs_entry_t *entry);
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//static lfs_error_t lfs_dir_destroy(lfs_t *lfs, lfs_dir_t *dir);
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//static lfs_error_t lfs_entry_alloc(lfs_t *lfs, lfs_dir_t *dir, lfs_entry_t *entry);
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//static lfs_error_t lfs_entry_update(lfs_t *lfs, lfs_entry_t *entry);
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//static lfs_error_t lfs_entry_destroy(lfs_t *lfs, lfs_dir_t *dir);
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// Directory operations
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static lfs_error_t lfs_dir_alloc(lfs_t *lfs, lfs_dir_t *dir) {
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// Allocate pair of dir blocks
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for (int i = 0; i < 2; i++) {
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int err = lfs_alloc(lfs, &dir->dno[i]);
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if (err) {
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return err;
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}
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}
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// Rather than clobbering one of the blocks we just pretend
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// the revision may be valid
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int err = lfs->ops->read(lfs->bd, (void*)&dir->d.rev, dir->dno[1], 0, 4);
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if (err) {
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return err;
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}
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dir->d.rev += 1;
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// Other defaults
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dir->d.size = sizeof(struct lfs_disk_dir);
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dir->d.tail[0] = 0;
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dir->d.tail[1] = 0;
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dir->d.parent[0] = 0;
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dir->d.parent[1] = 0;
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return 0;
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}
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lfs_error_t lfs_dir_update(lfs_t *lfs, lfs_dir_t *dir, lfs_entry_t *entry) {
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// TODO flush this
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dir->d.free = lfs->free.d;
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// Start by erasing target block
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int err = lfs->ops->erase(lfs->bd, dir->dno[0], 0, lfs->info.erase_size);
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// Write header and start calculating crc
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uint32_t crc = lfs_crc((void*)&dir->d, sizeof(dir->d), 0xffffffff);
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err = lfs->ops->write(lfs->bd, (void*)&dir->d,
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dir->dno[0], 0, sizeof(dir->d));
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if (err) {
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return err;
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}
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// Copy over entries and write optional entry update
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// TODO handle optional entry
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for (lfs_off_t i = sizeof(dir->d); i < lfs->info.erase_size-4; i += 4) {
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uint32_t data;
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err = lfs->ops->read(lfs->bd, (void*)&data, dir->dno[1], i, 4);
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if (err) {
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return err;
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}
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crc = lfs_crc((void*)&data, 4, crc);
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err = lfs->ops->write(lfs->bd, (void*)&data, dir->dno[0], i, 4);
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if (err) {
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return err;
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}
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}
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// Write resulting crc
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err = lfs->ops->write(lfs->bd, (void*)&crc,
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dir->dno[0], lfs->info.erase_size-4, 4);
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if (err) {
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return err;
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}
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// Flip dnos to indicate next write of the dir pair
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lfs_ino_t temp = dir->dno[0];
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dir->dno[0] = dir->dno[1];
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dir->dno[1] = temp;
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return 0;
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}
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//static lfs_error_t lfs_dir_alloc(lfs_t *lfs, lfs_dir_t *dir) {
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// memset(dir, 0, sizeof(lfs_dir_t));
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//
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// for (int i = 0; i < 2; i++) {
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// int err = lfs_alloc(lfs, &dir->dno[i]);
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// if (err) {
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// return err;
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// }
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// }
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//
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// // Rather than clobbering one of the blocks we just pretend
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// // the revision may be valid
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// int err = lfs->ops->read(lfs->bd, (void*)&dir->rev, dir->dno[1], 0, 4);
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// if (err) {
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// return err;
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// }
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// dir->rev += 1;
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//
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// // TODO move this to a flush of some sort?
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// struct lfs_disk_dir disk_dir = {
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// .rev = dir->rev,
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// .count = dir->len,
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// .tail[0] = dir->tail[0],
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// .tail[1] = dir->tail[1],
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// .free.head = lfs->free.head,
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// .free.ioff = lfs->free.ioff,
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// .free.icount = lfs->free.icount,
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// .free.rev = lfs->free.rev,
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// };
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//
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// err = lfs->ops->write(lfs->bd, (void*)&disk_dir,
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// dir->dno[0], 0, sizeof(struct lfs_disk_dir));
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// if (err) {
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// return err;
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// }
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//
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// uint32_t crc = 0xffffffff;
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// for (lfs_off_t i = 0; i < lfs->info.erase_size-4; i += 4) {
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// uint32_t data;
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// err = lfs->ops->read(lfs->bd, (void*)&data, dir->dno[0], i, 4);
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// if (err) {
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// return err;
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// }
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//
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// crc = lfs_crc((void*)&data, 4, crc);
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// }
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//
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// err = lfs->ops->write(lfs->bd, (void*)&crc,
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// dir->dno[0], lfs->info.erase_size-4, 4);
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// if (err) {
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// return err;
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// }
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//
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// lfs_ino_t temp = dir->dno[0];
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// dir->dno[0] = dir->dno[1];
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// dir->dno[1] = temp;
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//
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// return 0;
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//}
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//lfs_error_t lfs_dir_update(lfs_t *lfs, lfs_dir_t *dir,
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// lfs_dirent_t *ent, const char *name) {
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//
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//
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//
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// struct lfs_disk_dir disk_dir = {
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// .rev = dir->rev,
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// .count = dir->len,
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// .tail[0] = dir->tail[0],
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// .tail[1] = dir->tail[1],
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// // TODO flush this?
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// .free.head = lfs->free.head,
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// .free.ioff = lfs->free.ioff,
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// .free.icount = lfs->free.icount,
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// .free.rev = lfs->free.rev,
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// };
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//
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// err = lfs->ops->write(lfs->bd, (void*)&disk_dir,
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// dir->dno[0], 0, sizeof(struct lfs_disk_dir));
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// if (err) {
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// return err;
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// }
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//
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// if (ent) {
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// // TODO update entry
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// }
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//
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// uint32_t crc = 0xffffffff;
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// for (lfs_off_t i = 0; i < lfs->info.erase_size-4; i += 4) {
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// uint32_t data;
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// err = lfs->ops->read(lfs->bd, (void*)&data, dir->dno[0], i, 4);
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// if (err) {
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// return err;
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// }
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//
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// crc = lfs_crc((void*)&data, 4, crc);
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// }
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//
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// err = lfs->ops->write(lfs->bd, (void*)&crc,
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// dir->dno[0], lfs->info.erase_size-4, 4);
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// if (err) {
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// return err;
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// }
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//
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// lfs_ino_t temp = dir->dno[0];
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// dir->dno[0] = dir->dno[1];
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// dir->dno[1] = temp;
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//
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// return 0;
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//}
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// Little filesystem operations
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lfs_error_t lfs_create(lfs_t *lfs, lfs_bd_t *bd, const struct lfs_bd_ops *ops) {
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lfs->bd = bd;
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lfs->ops = ops;
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lfs_error_t err = lfs->ops->info(lfs->bd, &lfs->info);
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if (err) {
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return err;
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}
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return 0;
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}
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lfs_error_t lfs_format(lfs_t *lfs) {
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struct lfs_bd_info info;
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lfs_error_t err = lfs->ops->info(lfs->bd, &info);
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if (err) {
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return err;
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}
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err = lfs->ops->erase(lfs->bd, 0, 0, 5*info.erase_size);
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if (err) {
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return err;
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}
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// TODO make sure that erase clobbered blocks
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{ // Create free list
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lfs->free.d.head = 4;
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lfs->free.d.ioff = 1;
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lfs->free.d.icount = 1;
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lfs->free.d.rev = 1;
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lfs_size_t block_count = lfs->info.total_size / lfs->info.erase_size;
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for (lfs_ino_t i = 5; i < block_count; i++) {
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lfs_error_t err = lfs_free(lfs, i);
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if (err) {
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return err;
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}
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}
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}
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lfs_dir_t root;
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{
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// Write root directory
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int err = lfs_dir_alloc(lfs, &root);
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if (err) {
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return err;
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}
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err = lfs_dir_update(lfs, &root, 0);
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if (err) {
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return err;
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}
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}
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{
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// Write superblocks
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lfs_ino_t sno[2] = {0, 1};
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lfs_superblock_t superblock = {
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.d.rev = 1,
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.d.count = 0,
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.d.root = {root.dno[0], root.dno[1]},
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.d.magic = {"littlefs"},
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.d.block_size = info.erase_size,
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.d.block_count = info.total_size / info.erase_size,
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};
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for (int i = 0; i < 2; i++) {
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err = lfs->ops->erase(lfs->bd, sno[i], 0, info.erase_size);
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if (err) {
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return err;
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}
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err = lfs->ops->write(lfs->bd, (void*)&superblock.d,
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sno[i], 0, sizeof(superblock.d));
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if (err) {
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return err;
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}
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uint32_t crc = lfs_crc((void*)&superblock.d,
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sizeof(superblock.d), 0xffffffff);
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for (lfs_size_t i = sizeof(superblock);
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i < info.erase_size-4; i += 4) {
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uint32_t data;
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err = lfs->ops->read(lfs->bd, (void*)&data, 0, i, 4);
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if (err) {
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return err;
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}
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crc = lfs_crc((void*)&data, 4, crc);
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}
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err = lfs->ops->write(lfs->bd, (void*)&crc,
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sno[i], info.erase_size-4, 4);
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if (err) {
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return err;
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}
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}
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// TODO verify superblocks written correctly
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}
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|
|
|
// Sanity check
|
|
uint32_t crc = 0xffffffff;
|
|
for (lfs_size_t i = 0; i < info.erase_size; i += 4) {
|
|
uint32_t data;
|
|
err = lfs->ops->read(lfs->bd, (void*)&data, 0, i, 4);
|
|
if (err) {
|
|
return err;
|
|
}
|
|
|
|
crc = lfs_crc((void*)&data, 4, crc);
|
|
}
|
|
|
|
uint32_t data;
|
|
err = lfs->ops->read(lfs->bd, (void*)&data, 0, info.erase_size-4, 4);
|
|
if (err) {
|
|
return err;
|
|
}
|
|
|
|
return crc;
|
|
}
|
|
|