fs/fcb: Enable FCB to work with non-0xff erase value flash
The FCB has been strongly tied to 0xff erased flash devices and this commit adds support for other erase values. Signed-off-by: Dominik Ermel <dominik.ermel@nordicsemi.no>
This commit is contained in:
Dominik Ermel
Carles Cufí
parent
53fd687344
commit
4832fe43e0
5 changed files with 84 additions and 24 deletions
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@ -1,5 +1,5 @@
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/*
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* Copyright (c) 2017 Nordic Semiconductor ASA
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* Copyright (c) 2017-2020 Nordic Semiconductor ASA
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* Copyright (c) 2015 Runtime Inc
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*
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* SPDX-License-Identifier: Apache-2.0
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@ -12,6 +12,8 @@
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#include "fcb_priv.h"
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#include "string.h"
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#include <errno.h>
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#include <device.h>
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#include <drivers/flash.h>
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uint8_t
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fcb_get_align(const struct fcb *fcb)
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@ -99,6 +101,8 @@ fcb_init(int f_area_id, struct fcb *fcb)
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int oldest = -1, newest = -1;
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struct flash_sector *oldest_sector = NULL, *newest_sector = NULL;
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struct fcb_disk_area fda;
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const struct device *dev = NULL;
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const struct flash_parameters *fparam;
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if (!fcb->f_sectors || fcb->f_sector_cnt - fcb->f_scratch_cnt < 1) {
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return -EINVAL;
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@ -109,6 +113,10 @@ fcb_init(int f_area_id, struct fcb *fcb)
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return -EINVAL;
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}
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dev = device_get_binding(fcb->fap->fa_dev_name);
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fparam = flash_get_parameters(dev);
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fcb->f_erase_value = fparam->erase_value;
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align = fcb_get_align(fcb);
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if (align == 0U) {
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return -EINVAL;
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@ -194,16 +202,33 @@ fcb_is_empty(struct fcb *fcb)
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/**
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* Length of an element is encoded in 1 or 2 bytes.
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* 1 byte for lengths < 128 bytes, and 2 bytes for < 16384.
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*
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* The storage of length has been originally designed to work with 0xff erasable
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* flash devices and gives length 0xffff special meaning: that there is no value
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* written; this is smart way to utilize value in non-written flash to figure
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* out where data ends. Additionally it sets highest bit of first byte of
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* the length to 1, to mark that there is second byte to be read.
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* Above poses some problems when non-0xff erasable flash is used. To solve
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* the problem all length values are xored with not of erase value for given
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* flash:
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* len' = len ^ ~erase_value;
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* To obtain original value, the logic is reversed:
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* len = len' ^ ~erase_value;
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*
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* In case of 0xff erased flash this does not modify data that is written to
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* flash; in case of other flash devices, e.g. that erase to 0x00, it allows
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* to correctly use the first bit of byte to figure out how many bytes are there
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* and if there is any data at all or both bytes are equal to erase value.
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*/
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int
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fcb_put_len(uint8_t *buf, uint16_t len)
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fcb_put_len(const struct fcb *fcb, uint8_t *buf, uint16_t len)
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{
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if (len < 0x80) {
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buf[0] = len;
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buf[0] = len ^ ~fcb->f_erase_value;
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return 1;
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} else if (len < FCB_MAX_LEN) {
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buf[0] = (len & 0x7f) | 0x80;
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buf[1] = len >> 7;
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buf[0] = (len | 0x80) ^ ~fcb->f_erase_value;
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buf[1] = (len >> 7) ^ ~fcb->f_erase_value;
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return 2;
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} else {
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return -EINVAL;
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@ -211,18 +236,20 @@ fcb_put_len(uint8_t *buf, uint16_t len)
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}
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int
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fcb_get_len(uint8_t *buf, uint16_t *len)
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fcb_get_len(const struct fcb *fcb, uint8_t *buf, uint16_t *len)
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{
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int rc;
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if (buf[0] & 0x80) {
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if (buf[0] == 0xff && buf[1] == 0xff) {
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if ((buf[0] ^ ~fcb->f_erase_value) & 0x80) {
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if ((buf[0] == fcb->f_erase_value) &&
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(buf[1] == fcb->f_erase_value)) {
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return -ENOTSUP;
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}
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*len = (buf[0] & 0x7f) | (buf[1] << 7);
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*len = ((buf[0] ^ ~fcb->f_erase_value) & 0x7f) |
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((uint8_t)(buf[1] ^ ~fcb->f_erase_value) << 7);
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rc = 2;
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} else {
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*len = buf[0];
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*len = (uint8_t)(buf[0] ^ ~fcb->f_erase_value);
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rc = 1;
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}
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return rc;
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@ -237,9 +264,9 @@ fcb_sector_hdr_init(struct fcb *fcb, struct flash_sector *sector, uint16_t id)
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struct fcb_disk_area fda;
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int rc;
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fda.fd_magic = fcb->f_magic;
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fda.fd_magic = fcb_flash_magic(fcb);
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fda.fd_ver = fcb->f_version;
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fda._pad = 0xff;
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fda._pad = fcb->f_erase_value;
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fda.fd_id = id;
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rc = fcb_flash_write(fcb, sector, 0, &fda, sizeof(fda));
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@ -268,10 +295,10 @@ int fcb_sector_hdr_read(struct fcb *fcb, struct flash_sector *sector,
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if (rc) {
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return -EIO;
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}
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if (fdap->fd_magic == 0xffffffff) {
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if (fdap->fd_magic == MK32(fcb->f_erase_value)) {
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return 0;
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}
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if (fdap->fd_magic != fcb->f_magic) {
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if (fdap->fd_magic != fcb_flash_magic(fcb)) {
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return -ENOMSG;
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}
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return 1;
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@ -1,5 +1,5 @@
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/*
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* Copyright (c) 2017 Nordic Semiconductor ASA
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* Copyright (c) 2017-2020 Nordic Semiconductor ASA
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* Copyright (c) 2015 Runtime Inc
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*
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* SPDX-License-Identifier: Apache-2.0
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@ -65,7 +65,7 @@ fcb_append(struct fcb *fcb, uint16_t len, struct fcb_entry *append_loc)
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int rc;
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uint8_t tmp_str[8];
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cnt = fcb_put_len(tmp_str, len);
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cnt = fcb_put_len(fcb, tmp_str, len);
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if (cnt < 0) {
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return cnt;
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}
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@ -34,7 +34,7 @@ fcb_elem_crc8(struct fcb *fcb, struct fcb_entry *loc, uint8_t *c8p)
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return -EIO;
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}
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cnt = fcb_get_len(tmp_str, &len);
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cnt = fcb_get_len(fcb, tmp_str, &len);
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if (cnt < 0) {
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return cnt;
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}
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@ -1,5 +1,5 @@
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/*
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* Copyright (c) 2017 Nordic Semiconductor ASA
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* Copyright (c) 2017-2020 Nordic Semiconductor ASA
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* Copyright (c) 2015 Runtime Inc
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*
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* SPDX-License-Identifier: Apache-2.0
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@ -17,6 +17,31 @@ extern "C" {
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#define FCB_ID_GT(a, b) (((int16_t)(a) - (int16_t)(b)) > 0)
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#define MK32(val) ((((uint32_t)(val)) << 24) | \
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(((uint32_t)((val) & 0xff)) << 16) | \
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(((uint32_t)((val) & 0xff)) << 8) | \
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(((uint32_t)((val) & 0xff))))
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/* @brief Gets magic value in flash formatted version
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*
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* Magic, the fcb->f_magic, prior to being written to flash, is xored with
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* binary inversion of fcb->f_erase_value to avoid it matching a 4 consecutive
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* bytes of flash erase value, which is used to recognize end of records,
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* by accident. Only the value of 0xFFFFFFFF will be always written as
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* 4 bytes of erase value.
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*
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* @param fcb pointer to initialized fcb structure
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*
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* @return uin32_t formatted magic value
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*/
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static inline uint32_t fcb_flash_magic(const struct fcb *fcb)
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{
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const uint8_t ev = fcb->f_erase_value;
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return (fcb->f_magic ^ ~MK32(ev));
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}
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struct fcb_disk_area {
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uint32_t fd_magic;
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uint8_t fd_ver;
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@ -24,8 +49,8 @@ struct fcb_disk_area {
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uint16_t fd_id;
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};
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int fcb_put_len(uint8_t *buf, uint16_t len);
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int fcb_get_len(uint8_t *buf, uint16_t *len);
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int fcb_put_len(const struct fcb *fcb, uint8_t *buf, uint16_t len);
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int fcb_get_len(const struct fcb *fcb, uint8_t *buf, uint16_t *len);
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static inline int fcb_len_in_flash(struct fcb *fcb, uint16_t len)
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{
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