Boosted performance, board.json metadata, more mimxrt, rp2, samd features
This release of MicroPython sees a boost to the overall performance of the
VM and runtime. This is achieved by the addition of an optional cache to
speed up general hash table lookups, as well as a fast path in the VM for
the LOAD_ATTR opcode on instance types. The new configuration options are
MICROPY_OPT_MAP_LOOKUP_CACHE and MICROPY_OPT_LOAD_ATTR_FAST_PATH. As part
of this improvement the MICROPY_OPT_CACHE_MAP_LOOKUP_IN_BYTECODE option has
been removed, which provided a similar map caching mechanism but with the
cache stored in the bytecode, which made it not useful on bare metal ports.
The new mechanism is measured to be at least as good as the old one,
applies to more map lookups, has a constant RAM overhead, and applies to
native code as well as bytecode.
These performance options are enabled on the esp32, mimxrt, rp2, stm32 and
unix ports. For esp32 and mimxrt some code is also moved to RAM to further
boost performance. On stm32, performance increases by about 20% for
benchmarks that are heavy on name lookups, like misc_pystone.py and
misc_raytrace.py. On esp32 performance can increase by 2-3x, and on mimxrt
it is up to 6x.
All boards in all ports now have a board.json metadata file, which is used
to automatically build firmware and generate a webpage for that board
(among other possibilities). Auto-build scripts have been added for this
purpose and they build all esp32, mimxrt, rp2, samd and stm32 boards. The
generated output is available at https://micropython.org/download.
Support for FROZEN_DIR and FROZEN_MPY_DIR has been deprecated for some time
and was finally removed in this release. Instead of these, FROZEN_MANIFEST
can be used. The io.resource_stream() function is also removed, replaced
by the pure Python version in micropython-lib.
The search order for importing frozen Python modules is now controlled by
the ".frozen" entry in sys.path. This string is added by default in the
second position in sys.path. User code should adjust sys.path depending on
the desired behaviour. Putting ".frozen" first in sys.path will speed up
importing frozen modules.
A bug in multiple precision integers with bitwise of -0 was fixed in commit
2c139bbf4e.
The platform module has been added to allow querying the compiler and
underlying SDK/HAL/libc version. This is enabled on esp32, mimxrt and
stm32 ports.
The mpremote tool now supports seek, flush, mkdir and rmdir on PC-mounted
filesystems. And a help command has been added.
The documentation has seen many additions and improvements thanks (for a
second time) to the Google Season of Docs project. The rp2 documentation
now includes a reference for PIO assembly instructions, a PIO quick
reference and a PIO tutorial. The random and stm modules have been
documented, along with sys.settrace, manifest.py files and mpremote. There
is also now more detail about the differences between MicroPython and
standard Python 3.5 and above.
The esp32 port sees support for ESP32-S3 SoCs, and new boards GENERIC_S3,
ESP32_S2_WROVER, LOLIN_S2_MINI, LOLIN_S2_PICO and UM_FEATHERS2NEO. The PWM
driver has been improved and now supports all PWM timers and channels, and
the duty_u16() and duty_ns() methods, and it keeps the duty constant when
changing frequency. The machine.bitstream() function has been improved to
use RMT, with an option to select the original bit-banging implementation.
The mimxrt port gained new hardware features: SDRAM and SD card support, as
well as network integration with a LAN driver. The machine.WDT class was
added along with the machine.reset_cause(), machine.soft_reset(),
machine.unique_id() add machine.bitstream() functions. DHT sensor support
was added, and f-strings were enabled.
The rp2 port now has support for networking, and bluetooth using NimBLE.
The Nina-W10 WiFi/BT driver is fully integrated and supported by the new
Arduino Nano RP2040 connect board. I2S protocol support is added along
with a machine.bitstream() driver and DHT sensor support. The PWM driver
had a bug fix with the accuracy of setting/getting the frequency, and the
duty value is now retained when changing the frequency.
On the samd port there is now support for the internal flash being a block
device, and for filesystems and the os module. Pin and LED classes have
been implemented. There are more time functions, more Python features
enabled, and the help() function is added. SEEED_WIO_TERMINAL and
SEEED_XIAO board definitions are now available.
The stm32 port now has support for F427, F479 and H7A3(Q)/H7B3(Q) MCUs, and
new board definitions for VCC_GND_H743VI, OLIMEX_H407, MIKROE_QUAIL,
GARATRONIC_PYBSTICK26_F411, STM32H73B3I_DK. A bug was fixed in the SPI
driver where a SPI transfer could fail if the CYW43 WiFi driver was also
active at the same time.
On the windows port the help() function has been enabled, and support for
build variants added, to match the unix port.
The zephyr port upgraded Zephyr to v2.7.0.
The change in code size since the previous release for various ports is
(absolute and percentage change in the text section):
bare-arm: -1520 -2.605%
minimal x86: -2256 -1.531%
unix x64: -457 -0.089%
unix nanbox: -925 -0.204%
stm32: +312 +0.079% PYBV10
cc3200: -176 -0.096%
esp8266: +532 +0.076% GENERIC
esp32: +27096 +1.820% GENERIC
nrf: -212 -0.121% pca10040
rp2: +9904 +2.051% PICO
samd: +35332 +33.969% ADAFRUIT_ITSYBITSY_M4_EXPRESS
The changes that dominate these numbers are:
- bare-arm, minimal: use of new MICROPY_CONFIG_ROM_LEVEL_MINIMUM option and
subsequent disabling of remaining optional features
- unix, cc3200, nrf: general code size reductions of the core
- stm32: performance improvements, addition of platform module
- esp8266: enabling f-strings
- esp32: use of -O2 instead of -Os
- rp2: machine.I2S and other new hardware features
- samd: filesystem support and other new hardware features
Thanks to everyone who contributed to this release: Alan Dragomirecký,
Alexey Shvetsov, Andrew Leech, Andrew Scheller, Antoine Aubert, Boris
Vinogradov, Chris Boudacoff, Chris Fiege, Christian Decker, Damien George,
Daniel Gorny, Dave Hylands, David Michieli, Emilie Feral, Frédéric Pierson,
gibbonsc, Henk Vergonet, iabdalkader, Ihor Nehrutsa, Jan Hrudka, Jan Staal,
jc_.kim, Jim Mussared, Jonathan Hogg, Laurens Valk, leo chung, Lorenzo
Cappelletti, Magnus von Wachenfeldt, Matt Trentini, Matt van de Werken,
Maureen Helm, Michael Bentley, Michael Buesch, Mike Causer, Mike Teachman,
Mike Wadsten, Ned Konz, NitiKaur, oli, patrick, Patrick Van Oosterwijck,
Peter Boin, Peter Hinch, Peter van der Burg, Philipp Ebensberger, Pooya
Moradi, retsyo, robert-hh, roland van straten, Scott Armitage, Sebastian
Wicki, Seon Rozenblum, Sergei Silnov, Simon Baatz, Stewart Bonnick, stijn,
Tobias Thyrrestrup, Tomas Vanek, YoungJoon Chun.
What follows is a detailed list of changes, generated from the git commit
history, and organised into sections.
Main components
===============
all:
- remove MICROPY_OPT_CACHE_MAP_LOOKUP_IN_BYTECODE
- update Python formatting to latest Black version 21.12b0
- remove support for FROZEN_DIR and FROZEN_MPY_DIR
py core:
- parse: simplify parse nodes representing a list
- emitnative: ensure load_subscr does not clobber existing REG_RET
- mpconfig.h: define initial templates for "feature levels"
- vm: add a fast path for LOAD_ATTR on instance types
- map: add an optional cache of (map+index) to speed up map lookups
- builtinimport: forward all debug printing to MICROPY_DEBUG_PRINTER
- add wrapper macros so hot VM functions can go in fast code location
- runtime: fix crash when exc __new__ doesn't return an exc instance
- mpconfig.h: define the "extra" feature level
- mpconfig.h: revert MICROPY_REPL_INFO to disabled at all levels
- gc: add hook to run code during time consuming GC operations
- showbc: print unary-op string when dumping bytecode
- modsys: replace non-ASCII quote char with ASCII char
- runtime: allow types to use both .attr and .locals_dict
- lexer: support nested [] and {} characters within f-string params
- objfun.h: remove obsolete comments about entries in extra_args
- builtinimport: refactor module importing
- showbc: fix printing of raw bytecode header on nanbox builds
- modio: remove io.resource_stream function
- only search frozen modules when '.frozen' is found in sys.path
- mkrules.cmake: set frozen preprocessor defs early
- runtime: allow initialising sys.path/argv with defaults
- mpstate.h: only include sys.path/argv objects in state when enabled
- mpz: fix bugs with bitwise of -0 by ensuring all 0's are positive
- qstr: reset mpstate.qstr_last_chunk before raising an error
- modbuiltins: add additional macro for extending builtins
- mpconfig.h: define MICROPY_PY_USSL_FINALISER only if not defined
extmod:
- machine_i2c: make SoftI2C configurable via macro option
- machine_spi: make SoftSPI configurable via macro option
- modonewire: make _onewire module configurable via macro option
- machine_pwm: factor out machine.PWM bindings to common code
- move modnetwork and modusocket from stm32 to extmod
- modnetwork: add STA_IF and AP_IF constants
- modnetwork: add extended socket state
- modusocket: add read/write stream methods to socket object
- modnetwork: define network interfaces in port config files
- network_cyw43: make consistent use of STA and AP constants
- modnetwork: remove STM32 references
- modnetwork: remove modnetwork socket u_state member
- mpbthci.h: add mp_bluetooth_hci_uart_any prototype
- nimble: add nimble CMake fragment file
- add platform module
- moduplatform: improve implementation for PC ports
- vfs_posix_file: support MP_STREAM_POLL in vfs_posix_file_ioctl
- modbluetooth: add connection interval to gap_connect
- nimble: update to NimBLE v1.4
- nimble: remove workaround for OS_ENOMEM
- uasyncio: fix gather returning exceptions from a cancelled task
- uplatform: remove unused definitions
- uplatform: use generic custom platform string
- network_ninaw10: fix scan list order to match other NICs
- modbluetooth: support gap_connect(None) to cancel a connection
- modure: redirect regex debug printing to mp_printf
- network_ninaw10: fix config of AP mode
- network_ninaw10: disable active connections before connecting
- network_ninaw10: make NIC state persistent
- network_ninaw10: return -1 on timeout from recv/send
- network_ninaw10: make recv/recvfrom interchangeable
- moduplatform: detect xtensa arch
- modusocket: allow setting timeout on unbound sockets
- modusocket: initialise accepted socket state
- network_ninaw10: use socket timeout preset in modusocket
- modbluetooth: fix conditional compilation of ringbuf_put_uuid
- modbluetooth: put declaration of connect_cancel in correct place
shared:
- libc/string0: don't include string.h, and provide __memcpy_chk
- runtime/pyexec: cleanup EXEC_FLAG flag constants
drivers:
- ninaw10: add ublox Nina-W10 WiFi/BT module driver
- lsm6dsox: add LSM6DSOX driver and examples
- neopixel: avoid heap alloc in fill()
- ninaw10: fix BSSID byte order, and add null byte to ESSID
- ninaw10/nina_wifi_drv: fix DNS resolution
mpy-cross: no changes specific to this component/port
lib:
- mynewt-nimble: switch to the MicroPython fork of NimBLE
- asf4: point submodule to latest commit on circuitpython branch
- update pico-sdk to 1.3.0 and tinyusb to 0.12.0
- stm32lib: update library for L4 v1.17.0, new G4, WL, and MMC fixes
- stm32lib: update library for fix to F7 USB HS
Support components
==================
docs:
- library/os.rst: clarify littlefs requirements for block erase
- library/bluetooth.rst: update incorrect link to gatts_write
- make.bat: change Windows output dir from '_build' to 'build'
- library/machine.I2S.rst: specify that I2S.shift args are kw-only
- esp32: explain ESP32 PWM modes, timers, and channels
- rp2: add reference for PIO assembly instructions, and PIO tutorial
- library/random.rst: document the random module
- reference/mpremote.rst: add docs for mpremote
- reference/manifest.rst: add docs for manifest.py files
- library/stm.rst: document the stm module
- esp32/tutorial: add an example of peripheral control via regs
- rp2/general.rst: fix typo with missing spaces
- library/framebuf.rst: adjust dimensions in example
- library/rp2.rst: update function asm_pio_encode to add sideset_opt
- reference/filesystem.rst: add detail on how to use littlefs fuse
- rp2/quickref.rst: add section on PIO
- library/sys.rst: add docs for sys.settrace
- esp8266/tutorial: fix comments of FrameBuffer examples
- library/uasyncio.rst: detail exception behaviour in cancel/timeout
- library/machine.Timer.rst: document 'id' as positional-only arg
- library/machine.SPI.rst: add example SPI usage
- library/machine.Timer.rst: document `period` and `callback` args
- library/machine.Pin.rst: add Pin.ANALOG mode constant
- remove trailing spaces and convert tabs to spaces
- library/sys.rst: add note about '.frozen' as an entry in sys.path
- differences: document details of new PEPs/features in Python 3.5+
- update copyright year range to include 2022
- esp32: update RMT quickref example to match latest code
examples: no changes specific to this component/port
tests:
- perf_bench: use math.log instead of math.log2
- basics: add tests for type-checking subclassed exc instances
- micropython/const.py: add comment about required config for test
- cpydiff: clarify f-string diffs regarding concatenation
- basics/int_big_cmp.py: add more tests for big-int comparison
- extmod: skip uselect_poll_udp when poll() is not available
tools:
- autobuild: add auto build for GENERIC_C3_USB
- ci.sh: use IDF v4.4 as part of esp32 CI and build GENERIC_S3
- autobuild: add the MIMXRT1010_EVK board to autobuild
- ci.sh: use a specific ESP IDF v4.4 commit
- autobuild: add script to generate website board metadata
- dfu.py: make tool work with python3 when parsing DFU files
- autobuild: automatically build all mimxrt, rp2 and samd boards
- autobuild: automatically build all stm32 boards
- mpremote: implement seek and flush in ioctl method
- autobuild: automatically build all esp32 boards
- upip.py: support == to specify exact package version
- makemanifest.py: make str conversion compatible with Python 2
- makemanifest.py: merge make-frozen.py
- mpremote: add mkdir and rmdir to RemoteFS
- mpremote: add help command
- mpremote: add link to mpremote docs URL in help message
- upip.py: skip '.frozen' entry in sys.path for install path
- autobuild: build esp8266 OTA image with GENERIC_1M board
- ci.sh: upgrade Zephyr docker image to v0.21.0
- ci.sh: build zephyr nucleo_wb55rg to test zephyr bluetooth build
CI:
- workflows: use Python 3.8 for macos workflow
- workflows: add new workflow to build ports download metadata
The ports
=========
all ports:
- add board.json for all boards
- add images, features and urls to board.json
- add '.frozen' as the first entry in sys.path
- move '.frozen' to second entry in sys.path
bare-arm port:
- mpconfigport.h: use MICROPY_CONFIG_ROM_LEVEL_MINIMUM
- mpconfigport.h: disable remaining optional features
cc3200 port: no changes specific to this component/port
esp8266 port:
- boards/GENERIC: enable f-strings
- extract qstr from object when comparing keys in config()
- etshal.h: remove unneeded function declarations
- allow building a board to any dest directory
esp32 port:
- boards: add new FeatherS2-Neo board definition
- machine_timer: use tx_update member for IDF 4.4 and above
- add support for ESP32-S3 SoCs
- boards: add new GENERIC_S3 board definition
- machine_hw_spi: fix hardware SPI DMA channels for S2/S3
- boards: add board definition for ESP32-S2-WROVER module
- boards: add LOLIN_S2_MINI ESP32-S2 board
- machine_pwm: add support for all PWM timers and channels
- README: updated readme with req IDF vers for ESP32-S2, C3 and S3
- usb: add USB host connection detection for CDC serial output
- machine_pin: block out IO16 and IO17 when using SPIRAM on ESP32
- mpthreadport: fix TCB cleanup function so thread_mutex is ready
- main: add option for a board to hook code into startup sequence
- split out WLAN code from modnetwork.c to network_wlan.c
- enable optimisations and move code to iRAM to boost performance
- usb: improve speed of USB CDC output
- add specific deploy_s2.md instructions for esp32-s2
- boards/LOLIN_S2_MINI: add image to board.json
- boards: update board and deploy metadata for UM_xxx boards
- usb: further improve speed of USB CDC output
- boards/LOLIN_S2_PICO: add LOLIN_S2_PICO board definition files
- boards/ESP32_S2_WROVER: link to specific deploy_s2 instructions
- support building with latest IDF v5
- in machine_i2s, send null samples in underflow situations
- in machine_i2s, make object reference arrays root pointers
- add SDCard support for S3, and a GENERIC_S3_SPIRAM board
- boards/GENERIC_S3: enable BLE on ESP32 S3
- machine_pwm: implement duty_u16() and duty_ns() PWM methods
- extract qstr from object when comparing keys in config()
- machine_pin: make GPIO 26 usable for S2,S3 if SPIRAM not config'd
- machine_hw_spi: fix SPI default pins reordering on ESP32-S2/S3
- machine_hw_spi: set proper default SPI(id=1) pins on S2,S3 and C3
- machine_hw_spi: set proper default SPI(id=2) pins on S2 and S3
- boards: remove SPI pin defaults from GENERIC S2/S3 boards
- modnetwork: synchronize WiFi AUTH_xxx constants with IDF values
- machine_pwm: keep duty constant when changing frequency
- machine_bitstream: replace bit-bang code with RMT-based driver
- machine_i2s: add support for ESP-IDF 4.4
- machine_bitstream: fix signal duplication on output pins
- esp32: enable platform module with IDF version
- boards/GENERIC_D2WD: build with -Os optimisation
- esp32_rmt: install RMT driver on core 1
- machine_bitstream: reinstate bitstream bit-bang implementation
javascript port: no changes specific to this component/port
mimxrt port:
- sdcard: implement SDCard driver
- machine_bitstream: add bitstream function to machine module
- rework flash configuration
- sdram: add SDRAM support
- eth: add LAN support and integrate the network module
- modmachine: implement machine.WDT() and machine.reset_cause()
- boards: fix the D14/D15 pin assignment of MIMXRT1050/60/64_EVK
- hal: remove duplicate definitions from flexspi_hyper_flash.h
- dma_channel: fix the DMA channel management
- fix cycle counter for time.ticks_cpu() and machine.bitstream()
- add dht_readinto() to the mimxrt module, and freeze dht.py
- extend the help() message and README.md
- mpconfigport.h: enable f-strings
- modmachine: implement soft_reset() and unique_id() functions
- boards/make-pins.py: allow empty lines and comments in pins.csv
- optimize the runtime speed
- enable the platform module
- boards: add the Seeed ARCH MIX board
- boards: update the board.json files and add deploy_xx.md files
- fix mp_hal_quiet_timing_enter()/exit() so timer still runs
- support PWM using the FLEXPWM and QTMR modules
- define UART 0 on MIMXRT boards
- support selection of PHY type and address
- re-enable eth checksum creation by HW
- fix a tiny unnoticed bug in sdcard.c
- add a driver for the DP83848 PHY device
- refactor the reading of the machine id
- enable ticks_cpu at boot time for NDEBUG builds only
- use -Og instead of -O0 for DEBUG builds
- tidy up the board flash related files
- hal: allow readSampleClkSrc to be configured by a board
- enable MICROPY_PY_USSL_FINALISER
minimal port:
- mpconfigport.h: use MICROPY_CONFIG_ROM_LEVEL_MINIMUM
- Makefile: don't force a 32-bit build
- mpconfigport.h: disable features that are not needed
nrf port:
- Makefile: improve Black Magic Probe commands
- main: use VFS helper function to mount fs and chdir
pic16bit port: no changes specific to this component/port
powerpc port: no changes specific to this component/port
qemu-arm port: no changes specific to this component/port
rp2 port:
- mpconfigport.h: enable heapq module
- add support for bluetooth module using NimBLE
- add framework for networking
- mpconfigport.h: use the "extra" feature level
- enable optimisations (comp goto, map cache, fast attr)
- machine_i2s: add I2S protocol support
- add support for Nina-W10 WiFi/BT module
- boards: add support for Arduino Nano RP2040
- machine_bitstream: implement the machine.bitstream driver
- boards: add neopixel.py to manifest.py
- rp2_pio: support exec with sideset
- boards/PIMORONI_PICOLIPO_16MB: fix 16MB flash size
- boards: add PYBSTICK26 RP2040 board definition
- machine_uart: handle and clear UART RX timeout IRQ
- boards/ARDUINO_NANO_RP2040_CONNECT: set default I2C pins
- machine_pwm: fix PWM frequency setting
- machine_pwm: keep duty value when changing the frequency
- add support for DHT11 and DHT22 sensors
- CMakeLists.txt: allow a board to override PICO_BOARD
- boards/GARATRONIC_PYBSTICK26_RP2040: use correct pico-sdk board cfg
samd port:
- integrate latest asf4, add help, more time funcs and uPy features
- samd_soc: allow a board to configure the low-level MCU config
- add internal flash block device, filesystem and uos support
- add Pin and LED classes, and machine.unique_id
- boards/ADAFRUIT_FEATHER_M0_EXPRESS: update for flash and pins
- boards/ADAFRUIT_ITSYBITSY_M4_EXPRESS: update for flash and pins
- boards/MINISAM_M4: update for flash and pins
- boards/ADAFRUIT_TRINKET_M0: update for flash and pins
- boards/SAMD21_XPLAINED_PRO: update for flash and pins
- boards/SEEED_WIO_TERMINAL: add new board definition
- boards/SEEED_XIAO: add new board definition
- README.md: update README to reflect new features and boards
stm32 port:
- pin: enable GPIO clock of pin if it's constructed without init
- main: don't unconditionally enable GPIO A,B,C,D clocks
- boards/VCC_GND_H743VI: add board definition for VCC_GND_H743VI
- boards/OLIMEX_E407: add Ethernet RMII support
- boards/LEGO_HUB_NO6: remove user paths from cc2564 init file
- boards: remove trailing spaces, and add newline at end of file
- add basic support for STM32H750
- add support for H7A3(Q)/H7B3(Q), and STM32H73B3I_DK board defn
- suggest putting code in main.py not boot.py
- boards/make-pins.py: allow a CPU pin to be hidden
- boards/make-pins.py: allow empty lines and comments in pins.csv
- dma: add functions for external users of DMA to enable clock
- enable LOAD_ATTR fast path, and map lookup caching on >M0
- boards: add OLIMEX H407 board definition
- enable platform module
- extended flash filesystem space to 512K on H743 boards
- boards/NUCLEO_H743ZI: enable VfsLfs2 on NUCLEO_H743ZI(2) boards
- boards: add PF11-BOOT0 to stm32f091_af.csv
- machine_i2c: use hardware I2C for STM32H7
- sdram: enforce gcc opt, and use volatile and DSB in sdram_test
- usbd_cdc_interface: allow a board to hook into USBD CDC RX events
- mpbthciport: allow a board to hook BT HCI poll functions
- pendsv: allow a board to add entries for pendsv_schedule_dispatch
- boards: add images to board.json for Adafruit and VCC_GND boards
- uart: fix race conditions and clearing status in IRQ handler
- mpconfigport.h: use the "extra" feature level
- in machine_i2s, send null samples in underflow situations
- in machine_i2s, make object reference arrays root pointers
- led: support an extra 2 LEDs in board configuration
- boards/MIKROE_CLICKER2_STM32: add more detail to board.json
- boards: add new board MikroElektronika Quail, and F427 support
- main: run optional frozen module at boot
- sdio: don't explicitly disable DMA2 on deinit of SDIO
- dma: make DMA2_Stream3 exclusive to SDIO when CYW43 enabled
- boards: build NUCLEO_WB55 and STM32F769DISC without mboot enabled
- boards: add PYBSTICK26 F411 board definition
- boards/NADHAT_PYBF405: rename board to GARATRONIC_NADHAT_F405
- usb: use a table of allowed values to simplify usb_mode get/set
- boards/NUCLEO_WB55: update rfcore_firmwre for new WS
- flashbdev: support generic flash storage config via link symbols
- boards: convert F413,F439,H743,L4xx,WB55 to new flash FS config
- add support for F479 MCUs
- include HAL MMC code in F4 builds
- boards/make-pins.py: use cpu pins to define static alt-fun macros
- boards/NUCLEO_WB55: fix LED ordering
- boards/LEGO_HUB_NO6: set filesystem label as HUB_NO6
- boards: remove stray '+' characters at start of lines in ld files
- boards: remove unused MICROPY_HW_ENABLE_TIMER config
- boards: enable MICROPY_HW_ENABLE_SERVO on various boards
- update L4 code to build with latest stm32lib and L4 HAL 1.17.0
- main: call sdcard_init when only MICROPY_HW_ENABLE_MMCARD enabled
- sdcard: support 8-bit wide SDIO bus
- sdcard: add config option to force MM card capacity
- factoryreset: init vfs flags before calling pyb_flash_init_vfs
- qspi: fix typo in address comment
- boards/make-pins.py: generate empty ADC table if needed
- boards/OLIMEX_H407: fix typo in OLIMEX H407 board.json
- network_wiznet5k: fix build error with wiznet5k and lwip enabled
- enable MICROPY_PY_USSL_FINALISER
teensy port:
- switch to use manifest.py instead of FROZEN_DIR
unix port:
- enable LOAD_ATTR fast path, and map lookup caching
- modusocket: support MP_STREAM_POLL in unix socket_ioctl
- modos: add support for uos.urandom(n)
- coverage: change remaining printf to mp_printf
- Makefile: use -Og instead of -O0 for debug builds
windows port:
- README: remove unsupported Python instructions for Cygwin
- mpconfigport.h: enable help and help("modules")
- add support for build variants to windows port
- run tests via Makefile
- appveyor: build both standard and dev variants
- appveyor: build mpy-cross only once for mingw-w64
- msvc: run qstr preprocessing phase in parallel
zephyr port:
- mphalport.h: remove unused and unimplemented C-level pin API
- increase minimum CMake version to 3.20.0
- update include path to reboot.h
- get UART console device from devicetree instead of Kconfig
- use CONFIG_USB_DEVICE_STACK for conditional USB device support
- upgrade to Zephyr v2.7.0
- modbluetooth_zephyr: provide dummy connect_cancel function
F-strings, new machine.I2S class, ESP32-C3 support and LEGO_HUB_NO6 board
This release of MicroPython adds support for f-strings (PEP-498), with a
few limitations compared to normal Python. F-strings are essentially
syntactic sugar for "".format() and make formatting strings a lot more
convenient. Other improvements to the core runtime include pretty printing
OSError when it has two arguments (an errno code and a string), scheduling
of KeyboardInterrupt on the main thread, and support for a single argument
to the optimised form of StopIteration.
In the machine module a new I2S class has been added, with support for
esp32 and stm32 ports. This provides a consistent API for transmit and
receive of audio data in blocking, non-blocking and asyncio-based
operation. Also, the json module has support for the "separators" argument
in the dump and dumps functions, and framebuf now includes a way to blit
between frame buffers of different formats using a palette. A new,
portable machine.bitstream function is also added which can output a stream
of bits with configurable timing, and is used as the basis for driving
WS2812 LEDs in a common way across ports.
There has been some restructuring of the repository directory layout, with
all third-party code now in the lib/ directory. And a new top-level
directory shared/ has been added with first-party code that was previously
in lib/ moved there.
The docs have seen further improvement with enhancements and additions to
the rp2 parts, as well as a new quick reference for the zephyr port.
The terms master/slave have been replaced with controller/peripheral,
mainly relating to I2C and SPI usage. And u-module references have been
replaced with just the module name without the u-prefix to help clear up
the intended usage of modules in MicroPython.
For the esp8266 and esp32 ports, hidden networks are now included in WLAN
scan results. On the esp32 the RMT class is enhanced with idle_level and
write_pulses modes. There is initial support for ESP32-C3 chips with
GENERIC_C3 and GENERIC_C3_USB boards.
The javascript port has had its Makefile and garbage collector
implementation reworked so it compiles and runs with latest the Emscripten
using asyncify.
The mimxrt port sees the addition of hardware I2C and SPI support, as well
as some additional methods to the machine module. There is also support
for Hyperflash chips.
The nrf port now has full VFS storage support, enables source-line on
traceback, and has .mpy features consistent with other ports.
For the rp2 port there is now more configurability for boards, and more
boards added.
The stm32 port has a new LEGO_HUB_NO6 board definition with detailed
information how to get this LEGO Hub running stock MicroPython. There is
also now support to change the CPU frequency on STM32WB MCUs. And USBD_xxx
descriptor options have been renamed to MICROPY_HW_USB_xxx.
Thanks to everyone who contributed to this release: Amir Gonnen, Andrew
Scheller, Bryan Tong Minh, Chris Wilson, Damien George, Daniel Mizyrycki,
David Lechner, David P, Fernando, finefoot, Frank Pilhofer, Glenn Ruben
Bakke, iabdalkader, Jeff Epler, Jim Mussared, Jonathan Hogg, Josh Klar,
Josh Lloyd, Julia Hathaway, Krzysztof Adamski, Matúš Olekšák, Michael
Weiss, Michel Bouwmans, Mike Causer, Mike Teachman, Ned Konz, NitiKaur,
oclyke, Patrick Van Oosterwijck, Peter Hinch, Peter Züger, Philipp
Ebensberger, robert-hh, Roberto Colistete Jr, Sashkoiv, Seon Rozenblum,
Tobias Thyrrestrup, Tom McDermott, Will Sowerbutts, Yonatan Goldschmidt.
What follows is a detailed list of changes, generated from the git commit
history, and organised into sections.
Main components
===============
all:
- fix signed shifts and NULL access errors from -fsanitize=undefined
- update to point to files in new shared/ directory
py core:
- mpstate: make exceptions thread-local
- mpstate: schedule KeyboardInterrupt on main thread
- mperrno: add MP_ECANCELED error code
- makeqstrdefs.py: don't include .h files explicitly in preprocessing
- mark unused arguments from bytecode decoding macros
- objexcept: pretty print OSError also when it has 2 arguments
- makeversionhdr: add --tags arg to git describe
- vm: simplify handling of MP_OBJ_STOP_ITERATION in yield-from opcode
- objexcept: make mp_obj_exception_get_value support subclassed excs
- support single argument to optimised MP_OBJ_STOP_ITERATION
- introduce and use mp_raise_type_arg helper
- modsys: optimise sys.exit for code size by using exception helpers
- objexcept: make mp_obj_new_exception_arg1 inline
- obj: fix formatting of comment for mp_obj_is_integer
- emitnative: reuse need_reg_all func in need_stack_settled
- emitnative: ensure stack settling is safe mid-branch
- runtime: fix bool unary op for subclasses of native types
- builtinimport: fix condition for including do_execute_raw_code()
- mkrules: automatically build mpy-cross if it doesn't exist
- implement partial PEP-498 (f-string) support
- lexer: clear fstring_args vstr on lexer free
- mkrules.mk: do submodule sync in "make submodules"
extmod:
- btstack: add missing call to mp_bluetooth_hci_uart_deinit
- btstack: check that BLE is active before performing operations
- uasyncio: get addr and bind server socket before creating task
- axtls-include: add axtls_os_port.h to customise axTLS
- update for move of crypto-algorithms, re1.5, uzlib to lib
- moduselect: conditionally compile select()
- nimble: fix leak in l2cap_send if send-while-stalled
- btstack/btstack.mk: use -Wno-implicit-fallthrough, not =0
- utime: always invoke mp_hal_delay_ms when >= to 0ms
- modbluetooth: clamp MTU values to 32->UINT16_MAX
- nimble: allow modbluetooth binding to hook "sent HCI packet"
- nimble: add "memory stalling" mechanism for l2cap_send
- uasyncio: in open_connection use address info in socket creation
- modujson: add support for dump/dumps separators keyword-argument
- modlwip: fix close and clean up of UDP and raw sockets
- modbluetooth: add send_update arg to gatts_write
- add machine.bitstream
- modframebuf: enable blit between different formats via a palette
lib:
- tinyusb: update to version 0.10.1
- pico-sdk: update to version 1.2.0
- utils/stdout_helpers: make mp_hal_stdout_tx_strn_cooked efficient
- axtls: switch to repo at micropython/axtls
- axtls: update to latest axtls 2.1.5 wih additional commits
- re1.5: move re1.5 code from extmod to lib
- uzlib: move uzlib code from extmod to lib
- crypto-algorithms: move crypto-algorithms code from extmod to lib
- update README's based on contents of these dirs
drivers:
- neopixel: add common machine.bitstream-based neopixel module
- neopixel: optimize fill() for speed
- neopixel: reduce code size of driver
- cyw43: fix cyw43_deinit so it can be called many times in a row
- cyw43: make wifi join fail if interface is not active
mpy-cross:
- disable stack check when building with Emscripten
Support components
==================
docs:
- library: document new esp32.RMT features and fix wait_done
- library: warn that ustruct doesn't handle spaces in format strings
- esp8266/tutorial: change flash mode from dio to dout
- replace master/slave with controller/peripheral in I2C and SPI
- rp2: enhance quickref and change image to Pico pinout
- rp2: update general section to give a brief technical overview
- library/utime.rst: clarify behaviour and precision of sleep ms/us
- library/uasyncio.rst: document stream readexactly() method
- library/machine.I2S.rst: fix use of sd pin in examples
- zephyr: add quick reference for the Zephyr port
- library/zephyr: add libraries specific to the Zephyr port
- templates: add unix and zephyr quickref links to top-index
- rename ufoo.rst to foo.rst
- replace ufoo with foo in all docs
- library/index.rst: clarify module naming and purpose
- library/builtins.rst: add module title
- library/network.rst: simplify socket import
- add docs for machine.bitstream and neopixel module
- library: fix usage of :term: for frozen module reference
- esp8266: use monospace for software tools
- reference: mention that slicing a memoryview causes allocation
examples: no changes specific to this component/port
tests:
- extmod: make uasyncio_heaplock test more deterministic
- cpydiff/modules_struct_whitespace_in_format: run black
- extmod/ujson: add tests for dump/dumps separators argument
- run-multitests.py: add broadcast and wait facility
- multi_bluetooth/ble_subscribe.py: add test for subscription
- extmod/vfs_fat_finaliser.py: ensure alloc at never-used GC blocks
- basics: split f-string debug printing to separate file with .exp
- pybnative: make while.py test run on boards without pyb.delay
tools:
- autobuild: add scripts to build release firmware
- remove obsolete build-stm-latest.sh script
- ci.sh: run apt-get update in ci_powerpc_setup
- makemanifest.py: allow passing flags to mpy-tool.py
- autobuild: add mimxrt port to build scripts for nightly builds
- pyboard.py: add cmd-line option to make soft reset configurable
- mpremote: swap order of PID and VID in connect-list output
- ci.sh: build unix dev variant as part of macOS CI
- ci.sh: build GENERIC_C3 board as part of esp32 CI
- autobuild: use separate IDF version to build newer esp32 SoCs
- autobuild: add FeatherS2 and TinyS2 to esp32 auto builds
- mpremote: add seek whence for mounted files
- mpremote: raise OSError on unsupported RemoteFile.seek
- autobuild: add the MIMXRT1050_EVKB board to the daily builds
- ci.sh: add mpy-cross build to nrf port
- codeformat.py: include ports/nrf/modules/nrf in code formatting
- gen-cpydiff.py: don't rename foo to ufoo in diff output
- autobuild: add auto build for Silicognition wESP32
- mpremote: fix connect-list in case VID/PID are None
- mpremote: add "devs" shortcut for "connect list"
- mpremote: remove support for pyb.USB_VCP in/out specialisation
- autobuild: don't use "-B" for make, it's already a fresh build
- pyboard.py: move --no-exclusive/--soft-reset out of mutex group
- pyboard.py: make --no-follow use same variable as --follow
- pyboard.py: add --exclusive to match --no-exclusive
- pyboard.py: make --no-soft-reset consistent with other args
- uncrustify: force 1 newline at end of file
- mpremote: bump version to 0.0.6
CI:
- workflows: add workflow to build and test javascript port
- workflows: switch from Coveralls to Codecov
- workflows: switch from lcov to gcov
- workflows: add workflow to build and test unix dev variant
The ports
=========
all ports:
- use common mp_hal_stdout_tx_strn_cooked instead of custom one
- update for move of crypto-algorithms, uzlib to lib
- rename USBD_VID/PID config macros to MICROPY_HW_USB_VID/PID
bare-arm port: no changes specific to this component/port
cc3200 port: no changes specific to this component/port
esp8266 port:
- add __len__ to NeoPixel driver to support iterating
- Makefile: add more libm files to build
- include hidden networks in WLAN.scan results
- replace esp.neopixel with machine.bitstream
- remove dead code for end_ticks in machine_bitstream
esp32 port:
- boards/sdkconfig.base: disable MEMPROT_FEATURE to alloc from IRAM
- add __len__ to NeoPixel driver to support iterating
- main: allow MICROPY_DIR to be overridden
- esp32_rmt: fix RMT looping in newer IDF versions
- esp32_rmt: enhance RMT with idle_level and write_pulses modes
- add new machine.I2S class for I2S protocol support
- machine_spi: calculate actual attained baudrate
- machine_hw_spi: use a 2 item SPI queue for long transfers
- machine_dac: add MICROPY_PY_MACHINE_DAC option, enable by default
- machine_i2s: add MICROPY_PY_MACHINE_I2S option, enable by default
- fix use of mp_int_t, size_t and uintptr_t
- add initial support for ESP32C3 SoCs
- boards/GENERIC_C3: add generic C3-based board
- modmachine: release the GIL in machine.idle()
- mphalport: always yield at least once in delay_ms
- machine_uart: add flow kw-arg to enable hardware flow control
- boards: add Silicognition wESP32 board configuration
- mpconfigport.h: enable reverse and inplace special methods
- include hidden networks in WLAN.scan results
- makeimg.py: get bootloader and partition offset from sdkconfig
- enable MICROPY_PY_FSTRINGS by default
- machine_hw_spi: release GIL during transfers
- machine_pin: make check for non-output pins respect chip variant
- replace esp.neopixel with machine.bitstream
- remove dead code for end_ticks in machine_bitstream
- boards: add GENERIC_C3_USB board with USB serial/JTAG support
javascript port:
- rework Makefile and GC so it works with latest Emscripten
- Makefile: suppress compiler errors from array bounds
- Makefile: change variable to EXPORTED_RUNTIME_METHODS
mimxrt port:
- move calc_weekday helper function to timeutils
- machine_spi: add the SPI class to the machine module
- moduos: seed the PRNG on boot using the TRNG
- boards: set vfs partition start to 1 MBbyte
- main: skip running main.py if boot.py failed
- main: extend the information returned by help()
- mimxrt_flash: remove commented-out code
- modmachine: add a few minor methods to the machine module
- machine_led: use mp_raise_msg_varg helper
- machine_i2c: add hardware-based machine.I2C to machine module
- add support for Hyperflash chips
- boards: add support for the MIMXRT1050_EVKB board
- machine_pin: implement ioctl for Pin
minimal port:
- Makefile: add support for building with user C modules
nrf port:
- modules: replace master/slave with controller/peripheral in SPI
- boards/common.ld: calculate unused flash region
- modules/nrf: add new nrf module with flash block device
- drivers: add support for using flash block device with SoftDevice
- mpconfigport.h: expose nrf module when MICROPY_PY_NRF is set
- README: update README.md to reflect internal file systems
- mpconfigport.h: tune FAT FS configuration
- Makefile: add _fs_size linker script override from make
- modules/uos: allow a board to configure MICROPY_VFS_FAT/LFS1/LFS2
- mpconfigport.h: enable MICROPY_PY_IO_FILEIO when an FS is enabled
- qstrdefsport.h: add entries for in-built FS mount points
- main: add auto mount and auto format hook for internal flash FS
- boards: enable needed features for FAT/LFS1/LFS2
- facilitate use of freeze manifest
- boards: set FROZEN_MANIFEST blank when SD present on nrf51 targets
- modules/scripts: add file system formatting script
- Makefile: set default manifest file for all targets
- mphalport: add dummy function for mp_hal_time_ns()
- boards: enable MICROPY_VFS_LFS2 for all target boards
- modules/uos: add ilistdir to uos module
- modules/nrf: add function to enable/disable DCDC
- enable source line on tracebacks
- set .mpy features consistent with documentation and other ports
pic16bit port: no changes specific to this component/port
powerpc port: no changes specific to this component/port
qemu-arm port: no changes specific to this component/port
rp2 port:
- use 0=Monday datetime convention in RTC
- machine_rtc: in RTC.datetime, compute weekday automatically
- CMakeLists.txt: suppress compiler errors for pico-sdk and tinyusb
- tusb_config.h: set CFG_TUD_CDC_EP_BUFSIZE to 256
- machine_uart: add hardware flow control support
- machine_uart: allow overriding default machine UART pins
- machine_i2c: allow boards to configure I2C pins using new macros
- machine_spi: allow boards to configure SPI pins using new macros
- machine_uart: fix poll ioctl to also check hardware FIFO
- machine_uart: fix read when FIFO has chars but ringbuf doesn't
- tusb_port: allow boards to configure USB VID and PID
- boards/ADAFRUIT_FEATHER_RP2040: configure custom VID/PID
- boards/ADAFRUIT_FEATHER_RP2040: configure I2C/SPI default pins
- boards/SPARKFUN_PROMICRO: configure UART/I2C/SPI default pins
- boards/SPARKFUN_THINGPLUS: configure I2C/SPI default pins
- boards: add Adafruit ItsyBitsy RP2040
- boards: add Adafruit QT Py RP2040
- boards: add Pimoroni Pico LiPo 4MB
- boards: add Pimoroni Pico LiPo 16MB
- boards: add Pimoroni Tiny 2040
- CMakeLists.txt: allow a board's cmake to set the manifest path
- enable MICROPY_PY_FSTRINGS by default
- Makefile: add "submodules" target, to match other ports
- rp2_flash: disable IRQs while calling flash_erase/program
- CMakeLists.txt: add option to enable double tap reset to bootrom
- mpconfigport.h: allow boards to add root pointers
samd port:
- add support for building with user C modules
stm32 port:
- softtimer: add soft_timer_reinsert() helper function
- mpbthciport: change from systick to soft-timer for BT scheduling
- provide a custom BTstack runloop that integrates with soft timer
- usb: make irq's default trigger enable all events
- boardctrl: skip running main.py if boot.py had an error
- sdio: fix undefined reference to DMA stream on H7
- dma: add DMAMUX configuration for H7 to fix dma_nohal_init
- main: call mp_deinit() at end of main
- adc: allow using ADC12 and ADC3 for H7
- adc: define the ADC instance used for internal channels
- adc: simplify and generalise how pin_adcX table is defined
- add new machine.I2S class for I2S protocol support
- boards/NUCLEO_F446RE: fix I2C1 pin assignment to match datasheet
- replace master/slave with controller/peripheral in I2C and SPI
- systick: always POLL_HOOK when delaying for milliseconds
- sdram: make SDRAM test cache aware, and optional failure with msg
- boards/NUCLEO_F446RE: enable CAN bus support
- boards: add support for SparkFun STM32 MicroMod Processor board
- uart: fix LPUART1 baudrate set/get
- uart: support low baudrates on LPUART1
- boards/STM32F429DISC: set correct UART2 pins and add UART3/6
- boards/NUCLEO_F439ZI: add board definition for NUCLEO_F439ZI
- boards/LEGO_HUB_NO6: add board definition for LEGO_HUB_NO6
- Makefile: update to only pull in used Bluetooth library
- README.md: update supported MCUs, and submodule and mboot use
- usbd_desc: rename USBD_xxx descriptor opts to MICROPY_HW_USB_xxx
- usbd_cdc_interface: rename USBD_CDC_xx opts to MICROPY_HW_USB_xx
- powerctrl: support changing frequency on WB MCUs
- boards/NUCLEO_H743ZI2: add modified version of NUCLEO_H743ZI
- mbedtls: fix compile warning about uninitialized val
- enable MICROPY_PY_FSTRINGS by default
- add implementation of machine.bitstream
- Makefile: allow GIT_SUBMODULES and LIBS to be extended
- stm32_it: support TIM17 IRQs on WB MCUs
- disable computed goto on constrained boards
- storage: make extended-block-device more configurable
- boards/LEGO_HUB_NO6: change SPI flash storage to use hardware SPI
- boards/LEGO_HUB_NO6: skip first 1MiB of SPI flash for storage
- boards/LEGO_HUB_NO6: add make commands to backup/restore firmware
teensy port: no changes specific to this component/port
unix port:
- modffi: add option to lock GC in callback, and cfun access
- Makefile: add back LIB_SRC_C to list of object files
- variants: enable help and help("modules") on standard and dev
- Makefile: disable error compression on arm-linux-gnueabi-gcc
windows port:
- Makefile: add .exe extension to executables name
- appveyor: update to VS 2017 and use Python 3.8 for build/test
zephyr port:
- machine_spi: add support for hardware SPI
uint types in viper mode can now be used for all binary operators except
floor-divide and modulo.
Fixes issue #1847 and issue #6177.
Signed-off-by: Damien George <damien@micropython.org>
The loop searches backwards for a target, but doesn't stop after finding
the first result, meaning that it'll always end up at the outermost
exception handler.
This previously made the native emitter incompatible with the bytecode
emitter, and mp_resume (and subsequently mp_obj_generator_resume) expects
the bytecode emitter behavior (i.e. throw==NULL).
In which case place the native function prelude in a bytes object, linked
from the const_table of that function. An architecture should define
N_PRELUDE_AS_BYTES_OBJ to 1 before including py/emitnative.c to emit
correct machine code, then enable MICROPY_EMIT_NATIVE_PRELUDE_AS_BYTES_OBJ
so the runtime can correctly handle the prelude being in a bytes object.
Such that args/return regs for the parent are different to args/return regs
for child calls. For an architecture to use this feature it should define
the REG_PARENT_xxx macros before including py/emitnative.c.
This patch compresses the second part of the bytecode prelude which
contains the source file name, function name, source-line-number mapping
and cell closure information. This part of the prelude now begins with a
single varible length unsigned integer which encodes 2 numbers, being the
byte-size of the following 2 sections in the header: the "source info
section" and the "closure section". After decoding this variable unsigned
integer it's possible to skip over one or both of these sections very
easily.
This scheme saves about 2 bytes for most functions compared to the original
format: one in the case that there are no closure cells, and one because
padding was eliminated.
The start of the bytecode prelude contains 6 numbers telling the amount of
stack needed for the Python values and exceptions, and the signature of the
function. Prior to this patch these numbers were all encoded one after the
other (2x variable unsigned integers, then 4x bytes), but using so many
bytes is unnecessary.
An entropy analysis of around 150,000 bytecode functions from the CPython
standard library showed that the optimal Shannon coding would need about
7.1 bits on average to encode these 6 numbers, compared to the existing 48
bits.
This patch attempts to get close to this optimal value by packing the 6
numbers into a single, varible-length unsigned integer via bit-wise
interleaving. The interleaving scheme is chosen to minimise the average
number of bytes needed, and at the same time keep the scheme simple enough
so it can be implemented without too much overhead in code size or speed.
The scheme requires about 10.5 bits on average to store the 6 numbers.
As a result most functions which originally took 6 bytes to encode these 6
numbers now need only 1 byte (in 80% of cases).
mpy-cross uses MICROPY_DYNAMIC_COMPILER and MICROPY_EMIT_NATIVE but does
not actually need to execute native functions, and does not need
mp_fun_table. This commit makes it so mp_fun_table and all its entries are
not built when MICROPY_DYNAMIC_COMPILER is enabled, significantly reducing
the size of the mpy-cross executable and allowing it to be built on more
machines/OS's.
Prior to this commit, building the unix port with `DEBUG=1` and
`-finstrument-functions` the compilation would fail with an error like
"control reaches end of non-void function". This change fixes this by
removing the problematic "if (0)" branches. Not all branches affect
compilation, but they are all removed for consistency.
This commit adds support for saving and loading .mpy files that contain
native code (native, viper and inline-asm). A lot of the ground work was
already done for this in the form of removing pointers from generated
native code. The changes here are mainly to link in qstr values to the
native code, and change the format of .mpy files to contain native code
blocks (possibly mixed with bytecode).
A top-level summary:
- @micropython.native, @micropython.viper and @micropython.asm_thumb/
asm_xtensa are now allowed in .py files when compiling to .mpy, and they
work transparently to the user.
- Entire .py files can be compiled to native via mpy-cross -X emit=native
and for the most part the generated .mpy files should work the same as
their bytecode version.
- The .mpy file format is changed to 1) specify in the header if the file
contains native code and if so the architecture (eg x86, ARMV7M, Xtensa);
2) for each function block the kind of code is specified (bytecode,
native, viper, asm).
- When native code is loaded from a .mpy file the native code must be
modified (in place) to link qstr values in, just like bytecode (see
py/persistentcode.c:arch_link_qstr() function).
In addition, this now defines a public, native ABI for dynamically loadable
native code generated by other languages, like C.
The new compile-time option is MICROPY_DEBUG_MP_OBJ_SENTINELS, disabled by
default. This is to allow finer control of whether this debugging feature
is enabled or not (because, for example, this setting must be the same for
mpy-cross and the MicroPython main code when using native code generation).
POP_BLOCK and POP_EXCEPT are now the same, and are always followed by a
JUMP. So this optimisation reduces code size, and RAM usage of bytecode by
two bytes for each try-except handler.
So these constant objects can be loaded by dereferencing the REG_FUN_TABLE
pointer instead of loading immediate values. This reduces the size of
generated native code (when such constants are used), and means that
pointers to these constants are no longer stored in the assembly code.
