esp_littlefs：用于ESP-IDF的LittleFS端口.zip

LittleFS for ESP-IDF. # What is LittleFS? [LittleFS](https://github.com/ARMmbed/littlefs) is a small fail-safe filesystem for microcontrollers. We ported LittleFS to esp-idf (specifically, the ESP32) because SPIFFS was too slow, and FAT was too fragile. # How to Use In your project, add this as a submodule to your `components/` directory. ``` git submodule add https://github.com/joltwallet/esp_littlefs.git git submodule update --init --recursive ``` The library can be configured via `make menuconfig` under `Component config->LittleFS`. ### Example User @wreyford has kindly provided a demo repo showing the use of `esp_littlefs`: https://github.com/wreyford/demo_esp_littlefs # Documentation See the official ESP-IDF SPIFFS documentation, basically all the functionality is the same; just replace `spiffs` with `littlefs` in all function calls. Also see the comments in `include/esp_littlefs.h` Slight differences between this configuration and SPIFFS's configuration is in the `esp_vfs_littlefs_conf_t`: 1. `max_files` field doesn't exist since we removed the file limit, thanks to @X-Ryl669 2. `partition_label` is not allowed to be `NULL`. You must specify the partition name from your partition table. This is because there isn't a define `littlefs` partition subtype in `esp-idf`. The subtype doesn't matter. # Performance Here are some naive benchmarks to give a vague indicator on performance. Formatting a ~512KB partition: ``` FAT: 963,766 us SPIFFS: 10,824,054 us LittleFS: 2,067,845 us ``` Writing 5 88KB files: ``` FAT: 13,601,171 us SPIFFS*: 118,883,197 us LittleFS**: 6,582,045 us LittleFS***: 5,734,811 us *Only wrote 374,784 bytes instead of the benchmark 440,000, so this value is extrapolated **CONFIG_LITTLEFS_CACHE_SIZE=128 ***CONFIG_LITTLEFS_CACHE_SIZE=512 (default value) ``` In the above test, SPIFFS drastically slows down as the filesystem fills up. Below is the specific breakdown of file write times for SPIFFS. Not sure what happens on the last file write. ``` SPIFFS: 88000 bytes written in 1325371 us 88000 bytes written in 1327848 us 88000 bytes written in 5292095 us 88000 bytes written in 19191680 us 22784 bytes written in 74082963 us ``` Reading 5 88KB files: ``` FAT: 3,111,817 us SPIFFS*: 3,392,886 us LittleFS**: 3,425,796 us LittleFS***: 3,210,140 us *Only read 374,784 bytes instead of the benchmark 440,000, so this value is extrapolated **CONFIG_LITTLEFS_CACHE_SIZE=128 ***CONFIG_LITTLEFS_CACHE_SIZE=512 (default value) ``` Deleting 5 88KB files: ``` FAT: 934,769 us SPIFFS*: 822,730 us LittleFS**: 31,502 us LittleFS***: 20,063 us *The 5th file was smaller, did not extrapolate value. **CONFIG_LITTLEFS_CACHE_SIZE=128 ***CONFIG_LITTLEFS_CACHE_SIZE=512 (default value) ``` # Tips, Tricks, and Gotchas * LittleFS operates on blocks, and blocks have a size of 4096 bytes on the ESP32. * A freshly formatted LittleFS will have 2 blocks in use, making it seem like 8KB are in use. # Running Unit Tests To flash the unit-tester app and the unit-tests, run ``` make tests ``` To test on an encrypted partition, add the `encrypted` flag to the `flash_test` partition in `partition_table_unit_test_app.csv`. I.e. ``` flash_test, data, spiffs, , 512K, encrypted ``` Also make sure that `CONFIG_SECURE_FLASH_ENC_ENABLED=y` in `menuconfig`. The unit tester can then be flashed via the command: ``` make TEST_COMPONENTS='src' encrypted-flash monitor ``` # Breaking Changes * July 22, 2020 - Changed attribute type for file timestamp from `0` to `0x74` ('t' ascii value). # Acknowledgement This code base was heavily modeled after the SPIFFS esp-idf component.