The "word" referred to by BYTES_PER_WORD is actually the size of mp_obj_t
which is not always the same as the size of a pointer on the target
architecture. So rename this config value to better reflect what it
measures, and also prefix it with MP_.
For uses of BYTES_PER_WORD in setting the stack limit this has been
changed to sizeof(void *), because the stack usually grows with
machine-word sized values (eg an nlr_buf_t has many machine words in it).
Signed-off-by: Damien George <damien@micropython.org>
It's only used in one location, to test if << or >> will overflow when
shifting mp_uint_t. For such a test it's clearer to use sizeof(lhs_val),
which will be valid even if the type of lhs_val changes.
Signed-off-by: Damien George <damien@micropython.org>
This should be enabled when the mp_raw_code_save_file function is needed.
It is enabled for mpy-cross, and a check for defined(__APPLE__) is added to
cover Mac M1 systems.
Adds a new compile-time option MICROPY_EMIT_THUMB_ARMV7M which is enabled
by default (to get existing behaviour) and which should be disabled (set to
0) when building native emitter support (@micropython.native) on ARMv6M
targets.
Newer GCC versions are able to warn about switch cases that fall
through. This is usually a sign of a forgotten break statement, but in
the few cases where a fall through is intended we annotate it with this
macro to avoid the warning.
On ports where normal heap memory can contain executable code (eg ARM-based
ports such as stm32), native code loaded from an .mpy file may be reclaimed
by the GC because there's no reference to the very start of the native
machine code block that is reachable from root pointers (only pointers to
internal parts of the machine code block are reachable, but that doesn't
help the GC find the memory).
This commit fixes this issue by maintaining an explicit list of root
pointers pointing to native code that is loaded from an .mpy file. This
is not needed for all ports so is selectable by the new configuration
option MICROPY_PERSISTENT_CODE_TRACK_RELOC_CODE. It's enabled by default
if a port does not specify any special functions to allocate or commit
executable memory.
A test is included to test that native code loaded from an .mpy file does
not get reclaimed by the GC.
Fixes#6045.
Signed-off-by: Damien George <damien@micropython.org>
The syntax matches CPython and the semantics are equivalent except that,
unlike CPython, MicroPython allows using := to assign to comprehension
iteration variables, because disallowing this would take a lot of code to
check for it.
The new compile-time option MICROPY_PY_ASSIGN_EXPR selects this feature and
is enabled by default, following MICROPY_PY_ASYNC_AWAIT.
Older implementations deal with infinity/negative zero incorrectly. This
commit adds generic fixes that can be enabled by any port that needs them,
along with new tests cases.
Note: the uncrustify configuration is explicitly set to 'add' instead of
'force' in order not to alter the comments which use extra spaces after //
as a means of indenting text for clarity.
TimeoutError was added back in 077812b2ab for
the cc3200 port. In f522849a4d the cc3200
port enabled use of it in the socket module aliased to socket.timeout. So
it was never added to the builtins. Then it was replaced by
OSError(ETIMEDOUT) in 047af9b10b.
The esp32 port enables this exception, since the very beginning of that
port, but it could never be accessed because it's not in builtins.
It's being removed: 1) to not encourage its use; 2) because there are a lot
of other OSError subclasses which are not defined at all, and having
TimeoutError is a bit inconsistent.
Note that ports can add anything to the builtins via MICROPY_PORT_BUILTINS.
And they can also define their own exceptions using the
MP_DEFINE_EXCEPTION() macro.
Implements Task and TaskQueue classes in C, using a pairing-heap data
structure. Using this reduces RAM use of each Task, and improves overall
performance of the uasyncio scheduler.
To enable lazy loading of submodules (among other things), which is very
useful for MicroPython libraries that want to have optional subcomponents.
Disabled explicitly on minimal ports.
This commit adds micropython.heap_locked() which returns the current
lock-depth of the heap, and can be used by Python code to check if the heap
is locked or not. This new function is configured via
MICROPY_PY_MICROPYTHON_HEAP_LOCKED and is disabled by default.
This commit also changes the return value of micropython.heap_unlock() so
it returns the current lock-depth as well.
This should reclaim *most* code space added to handle f-strings.
However, there may be some small code growth as parse_string_literal
takes a new parameter (which will always be 0, so hopefully the optimizer
eliminates it)
Functions like mp_keyboard_interrupt() may need to be called from an IRQ
handler and may need to be in a special memory section, so provide a
generic wrapping macro for a port to do this. The macro name is chosen to
be MICROPY_WRAP_<function name in uppercase> so that (in the future with
more wrappers) each function could potentially be handled separately.
This option (enabled by default for object representation A, B, C) makes
None/False/True objects immediate objects, ie they are no longer a concrete
object in ROM but are rather just values, eg None=0x6 for representation A.
Doing this saves a considerable amount of code size, due to these objects
being widely used:
bare-arm: -392 -0.591%
minimal x86: -252 -0.170% [incl +52(data)]
unix x64: -624 -0.125% [incl -128(data)]
unix nanbox: +0 +0.000%
stm32: -1940 -0.510% PYBV10
cc3200: -1216 -0.659%
esp8266: -404 -0.062% GENERIC
esp32: -732 -0.064% GENERIC[incl +48(data)]
nrf: -988 -0.675% pca10040
samd: -564 -0.556% ADAFRUIT_ITSYBITSY_M4_EXPRESS
Thanks go to @Jongy aka Yonatan Goldschmidt for the idea.
This commit adjusts the definition of qstr encoding in all object
representations by taking a single bit from the qstr space and using it to
distinguish between qstrs and a new kind of literal object: immediate
objects. In other words, the qstr space is divided in two pieces, one half
for qstrs and the other half for immediate objects.
There is still enough room for qstr values (29 bits in representation A on
a 32-bit architecture, and 19 bits in representation C) and the new
immediate objects can be used for things like None, False and True.
This commit adds backward-word, backward-kill-word, forward-word,
forward-kill-word sequences for the REPL, with bindings to Alt+F, Alt+B,
Alt+D and Alt+Backspace respectively. It is disabled by default and can be
enabled via MICROPY_REPL_EMACS_WORDS_MOVE.
Further enabling MICROPY_REPL_EMACS_EXTRA_WORDS_MOVE adds extra bindings
for these new sequences: Ctrl+Right, Ctrl+Left and Ctrl+W.
The features are enabled on unix micropython-coverage and micropython-dev.
Instances of the slice class are passed to __getitem__() on objects when
the user indexes them with a slice. In practice the majority of the time
(other than passing it on untouched) is to work out what the slice means in
the context of an array dimension of a particular length. Since Python 2.3
there has been a method on the slice class, indices(), that takes a
dimension length and returns the real start, stop and step, accounting for
missing or negative values in the slice spec. This commit implements such
a indices() method on the slice class.
It is configurable at compile-time via MICROPY_PY_BUILTINS_SLICE_INDICES,
disabled by default, enabled on unix, stm32 and esp32 ports.
This commit also adds new tests for slice indices and for slicing unicode
strings.
For the 3 ports that already make use of this feature (stm32, nrf and
teensy) this doesn't make any difference, it just allows to disable it from
now on.
For other ports that use pyexec, this decreases code size because the debug
printing code is dead (it can't be enabled) but the compiler can't deduce
that, so code is still emitted.
This commit implements automatic module weak links for all built-in
modules, by searching for "ufoo" in the built-in module list if "foo"
cannot be found. This means that all modules named "ufoo" are always
available as "foo". Also, a port can no longer add any other weak links,
which makes strict the definition of a weak link.
It saves some code size (about 100-200 bytes) on ports that previously had
lots of weak links.
Some changes from the previous behaviour:
- It doesn't intern the non-u module names (eg "foo" is not interned),
which saves code size, but will mean that "import foo" creates a new qstr
(namely "foo") in RAM (unless the importing module is frozen).
- help('modules') no longer lists non-u module names, only the u-variants;
this reduces duplication in the help listing.
Weak links are effectively the same as having a set of symbolic links on
the filesystem that is searched last. So an "import foo" will search
built-in modules first, then all paths in sys.path, then weak links last,
importing "ufoo" if it exists. Thus a file called "foo.py" somewhere in
sys.path will still have precedence over the weak link of "foo" to "ufoo".
See issues: #1740, #4449, #5229, #5241.
This commit adds support for sys.settrace, allowing to install Python
handlers to trace execution of Python code. The interface follows CPython
as closely as possible. The feature is disabled by default and can be
enabled via MICROPY_PY_SYS_SETTRACE.
Enabled via MICROPY_PY_URE_DEBUG, disabled by default (but enabled on unix
coverage build). This is a rarely used feature that costs a lot of code
(500-800 bytes flash). Debugging of regular expressions can be done
offline with other tools.
As per PEP 485, this function appeared in for Python 3.5. Configured via
MICROPY_PY_MATH_ISCLOSE which is disabled by default, but enabled for the
ports which already have MICROPY_PY_MATH_SPECIAL_FUNCTIONS enabled.
This patch implements a new sys.atexit function which registers a function
that is later executed when the main script ends. It is configurable via
MICROPY_PY_SYS_ATEXIT, disabled by default.
This is not compliant with CPython, rather it can be used to implement a
CPython compatible "atexit" module if desired (similar to how
sys.print_exception can be used to implement functionality of the
"traceback" module).
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.
This allows figuring out the number of bytes in the memoryview object as
len(memview) * memview.itemsize.
The feature is enabled via MICROPY_PY_BUILTINS_MEMORYVIEW_ITEMSIZE and is
disabled by default.
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).
This optimisation eliminates the need to create a temporary normal dict.
The optimisation is enabled via MICROPY_COMP_CONST_LITERAL which is enabled
by default (although only has an effect if OrderdDict is enabled).
Thanks to @pfalcon for the initial idea and implementation.
This feature is controlled at compile time by MICROPY_PY_URE_SUB, disabled
by default.
Thanks to @dmazzella for the original patch for this feature; see #3770.
This feature is controlled at compile time by
MICROPY_PY_URE_MATCH_SPAN_START_END, disabled by default.
Thanks to @dmazzella for the original patch for this feature; see #3770.
This feature is controlled at compile time by MICROPY_PY_URE_MATCH_GROUPS,
disabled by default.
Thanks to @dmazzella for the original patch for this feature; see #3770.
As mentioned in #4450, `websocket` was experimental with a single intended
user, `webrepl`. Therefore, we'll make this change without a weak
link `websocket` -> `uwebsocket`.
Python defines warnings as belonging to categories, where category is a
warning type (descending from exception type). This is useful, as e.g.
allows to disable warnings selectively and provide user-defined warning
types. So, implement this in MicroPython, except that categories are
represented just with strings. However, enough hooks are left to implement
categories differently per-port (e.g. as types), without need to patch each
and every usage.
If MICROPY_PERSISTENT_CODE_LOAD or MICROPY_ENABLE_COMPILER are enabled then
code gets enabled that calls file reading functions which may be disabled
if no readers have been implemented.
To fix this, introduce a MICROPY_HAS_FILE_READER variable, which is
automatically set if MICROPY_READER_POSIX or MICROPY_READER_VFS is set but
can also be manually set if a custom reader is being implemented. Then
disable the file reading calls if this is not set.
Changes to the layout of the bytecode header meant that this debug code was
no longer compiling. This is now fixed and a new compile-time option is
introduced, MICROPY_DEBUG_VM_STACK_OVERFLOW, to turn on this feature (which
is disabled by default). This option is needed because more than one file
needs to cooperate to make this check work.
It's more robust to have the version defined statically in a header file,
rather than dynamically generating it via git using a git tag. In case
git doesn't exist, or a different source control tool is used, it's
important to still have the uPy version number available.
SHORT, INT, LONG, LONGLONG, and unsigned (U*) variants are being defined.
This is done at compile using GCC-style predefined macros like
__SIZEOF_INT__. If the compiler doesn't have such defines, no such types
will be defined.
A new option MICROPY_GC_STACK_ENTRY_TYPE is added to select a custom type
instead of size_t for the gc_stack array items. This can be beneficial for
small devices, especially those that are low on memory anyway. If a device
has 1MB or less of heap (and 16-byte GC blocks) then this type can be
uint16_t, saving 128 bytes of RAM.
Configurable via MICROPY_MODULE_GETATTR, disabled by default. Among other
things __getattr__ for modules can help to build lazy loading / code
unloading at runtime.
Configurable via MICROPY_PY_BUILTINS_STR_COUNT. Default is enabled.
Disabled for bare-arm, minimal, unix-minimal and zephyr ports. Disabling
it saves 408 bytes on x86.
This commit adds the math.factorial function in two variants:
- squared difference, which is faster than the naive version, relatively
compact, and non-recursive;
- a mildly optimised recursive version, faster than the above one.
There are some more optimisations that could be done, but they tend to take
more code, and more storage space. The recursive version seems like a
sensible compromise.
The new function is disabled by default, and uses the non-optimised version
by default if it is enabled. The options are MICROPY_PY_MATH_FACTORIAL
and MICROPY_OPT_MATH_FACTORIAL.
This patch in effect renames MICROPY_DEBUG_PRINTER_DEST to
MICROPY_DEBUG_PRINTER, moving its default definition from
lib/utils/printf.c to py/mpconfig.h to make it official and documented, and
makes this macro a pointer rather than the actual mp_print_t struct. This
is done to get consistency with MICROPY_ERROR_PRINTER, and provide this
macro for use outside just lib/utils/printf.c.
Ports are updated to use the new macro name.
This feature is controlled at compile time by MICROPY_PY_URE_SUB, disabled
by default.
Thanks to @dmazzella for the original patch for this feature; see #3770.
This feature is controlled at compile time by
MICROPY_PY_URE_MATCH_SPAN_START_END, disabled by default.
Thanks to @dmazzella for the original patch for this feature; see #3770.
This feature is controlled at compile time by MICROPY_PY_URE_MATCH_GROUPS,
disabled by default.
Thanks to @dmazzella for the original patch for this feature; see #3770.
Allow including crypto consts based on compilation settings. Disabled by
default to reduce code size; if one wants extra code readability, can
enable them.
The API follows guidelines of https://www.python.org/dev/peps/pep-0272/,
but is optimized for code size, with the idea that full PEP 0272
compatibility can be added with a simple Python wrapper mode.
The naming of the module follows (u)hashlib pattern.
At the bare minimum, this module is expected to provide:
* AES128, ECB (i.e. "null") mode, encrypt only
Implementation in this commit is based on axTLS routines, and implements
following:
* AES 128 and 256
* ECB and CBC modes
* encrypt and decrypt
Via the config value MICROPY_PY_UHASHLIB_SHA256. Default to enabled to
keep backwards compatibility.
Also add default value for the sha1 class, to at least document its
existence.
A user class derived from IOBase and implementing readinto/write/ioctl can
now be used anywhere a native stream object is accepted.
The mapping from C to Python is:
stream_p->read --> readinto(buf)
stream_p->write --> write(buf)
stream_p->ioctl --> ioctl(request, arg)
Among other things it allows the user to:
- create an object which can be passed as the file argument to print:
print(..., file=myobj), and then print will pass all the data to the
object via the objects write method (same as CPython)
- pass a user object to uio.BufferedWriter to buffer the writes (same as
CPython)
- use select.select on a user object
- register user objects with select.poll, in particular so user objects can
be used with uasyncio
- create user files that can be returned from user filesystems, and import
can import scripts from these user files
For example:
class MyOut(io.IOBase):
def write(self, buf):
print('write', repr(buf))
return len(buf)
print('hello', file=MyOut())
The feature is enabled via MICROPY_PY_IO_IOBASE which is disabled by
default.
This patch is a code optimisation, trading text bytes for speed. On
pyboard it's an increase of 0.06% in code size for a gain (in pystone
performance) of roughly 6.5%.
The patch optimises load/store/delete of attributes in user defined classes
by not looking up special accessors (@property, __get__, __delete__,
__set__, __setattr__ and __getattr_) if they are guaranteed not to exist in
the class.
Currently, if you do my_obj.foo() then the runtime has to do a few checks
to see if foo is a property or has __get__, and if so delegate the call.
And for stores things like my_obj.foo = 1 has to first check if foo is a
property or has __set__ defined on it.
Doing all those checks each and every time the attribute is accessed has a
performance penalty. This patch eliminates all those checks for cases when
it's guaranteed that the checks will always fail, ie no attributes are
properties nor have any special accessor methods defined on them.
To make this guarantee it checks all attributes of a user-defined class
when it is first created. If any of the attributes of the user class are
properties or have special accessors, or any of the base classes of the
user class have them, then it sets a flag in the class to indicate that
special accessors must be checked for. Then in the load/store/delete code
it checks this flag to see if it can take the shortcut and optimise the
lookup.
It's an optimisation that's pretty widely applicable because it improves
lookup performance for all methods of user defined classes, and stores of
attributes, at least for those that don't have special accessors. And, it
allows to enable descriptors with minimal additional runtime overhead if
they are not used for a particular user class.
There is one restriction on dynamic class creation that has been introduced
by this patch: a user-defined class cannot go from zero special accessors
to one special accessor (or more) after that class has been subclassed. If
the script attempts this an AttributeError is raised (see addition to
tests/misc/non_compliant.py for an example of this case).
The cost in code space bytes for the optimisation in this patch is:
unix x64: +528
unix nanbox: +508
stm32: +192
cc3200: +200
esp8266: +332
esp32: +244
Performance tests that were done:
- on unix x86-64, pystone improved by about 5%
- on pyboard, pystone improved by about 6.5%, from 1683 up to 1794
- on pyboard, bm_chaos (from CPython benchmark suite) improved by about 5%
- on esp32, pystone improved by about 30% (but there are caching effects)
- on esp32, bm_chaos improved by about 11%
This VFS component allows to mount a host POSIX filesystem within the uPy
VFS sub-system. All traditional POSIX file access then goes through the
VFS, allowing to sandbox a uPy process to a certain sub-dir of the host
system, as well as mount other filesystem types alongside the host
filesystem.
This patch changes 2 things in the endianness detection:
1. Don't assume that __BYTE_ORDER__ not being __ORDER_LITTLE_ENDIAN__ means
that the machine is big endian, so add an explicit check that this macro
is indeed __ORDER_BIG_ENDIAN__ (same with __BYTE_ORDER, __LITTLE_ENDIAN
and __BIG_ENDIAN). A machine could have PDP endianness.
2. Remove the checks which base their autodetection decision on whether any
little or big endian macros are defined (eg __LITTLE_ENDIAN__ or
__BIG_ENDIAN__). Just because a system defines these does not mean it
has that endianness.
See issue #3760.
.. defaulting to off for circuitpython-supported boards, on for others.
.. fixing up the tests that fail when it is turned off, so that they skip
instead of failing
So far, implements just append() and popleft() methods, required for
a normal queue. Constructor doesn't accept an arbitarry sequence to
initialize from (am empty deque is always created), so an empty tuple
must be passed as such. Only fixed-size deques are supported, so 2nd
argument (size) is required.
There's also an extension to CPython - if True is passed as 3rd argument,
append(), instead of silently overwriting the oldest item on queue
overflow, will throw IndexError. This behavior is desired in many
cases, where queues should store information reliably, instead of
silently losing some items.
The micropython.stack_use() function is useful to query the current C stack
usage, and it's inclusion in the micropython module doesn't need to be tied
to the inclusion of mem_info()/qstr_info() because it doesn't rely on any
of the code from these functions. So this patch introduces the config
option MICROPY_PY_MICROPYTHON_STACK_USE which can be used to independently
control the inclusion of stack_use(). By default it is enabled if
MICROPY_PY_MICROPYTHON_MEM_INFO is enabled (thus not changing any of the
existing ports).
The new option is MICROPY_ENABLE_EXTERNAL_IMPORT and is enabled by default
so that the default behaviour is the same as before. With it disabled
import is only supported for built-in modules, not for external files nor
frozen modules. This allows to support targets that have no filesystem of
any kind and that only have access to pre-supplied built-in modules
implemented natively.
This feature is not often used so is guarded by the config option
MICROPY_PY_BUILTINS_RANGE_BINOP which is disabled by default. With this
option disabled MicroPython will always return false when comparing two
range objects for equality (unless they are exactly the same object
instance). This does not match CPython so if (in)equality between range
objects is needed then this option should be enabled.
Enabling this option costs between 100 and 200 bytes of code space
depending on the machine architecture.
This patch combines the compiler optimisation code for double and triple
tuple-to-tuple assignment, taking it from two separate if-blocks to one
combined if-block. This can be done because the code for both of these
optimisations has a lot in common. Combining them together reduces code
size for ports that have the triple-tuple optimisation enabled (and doesn't
change code size for ports that have it disabled).
This implements .pend_throw(exc) method, which sets up an exception to be
triggered on the next call to generator's .__next__() or .send() method.
This is unlike .throw(), which immediately starts to execute the generator
to process the exception. This effectively adds Future-like capabilities
to generator protocol (exception will be raised in the future).
The need for such a method arised to implement uasyncio wait_for() function
efficiently (its behavior is clearly "Future" like, and normally would
require to introduce an expensive Future wrapper around all native
couroutines, like upstream asyncio does).
py/objgenerator: pend_throw: Return previous pended value.
This effectively allows to store an additional value (not necessary an
exception) in a coroutine while it's not being executed. uasyncio has
exactly this usecase: to mark a coro waiting in I/O queue (and thus
not executed in the normal scheduling queue), for the purpose of
implementing wait_for() function (cancellation of such waiting coro
by a timeout).
The nan-boxing representation has an extra 16-bits of space to store
small-int values, and making use of it allows to create and manipulate full
32-bit positive integers (ie up to 0xffffffff) without using the heap.
This patch introduces the MICROPY_ENABLE_PYSTACK option (disabled by
default) which enables a "Python stack" that allows to allocate and free
memory in a scoped, or Last-In-First-Out (LIFO) way, similar to alloca().
A new memory allocation API is introduced along with this Py-stack. It
includes both "local" and "nonlocal" LIFO allocation. Local allocation is
intended to be equivalent to using alloca(), whereby the same function must
free the memory. Nonlocal allocation is where another function may free
the memory, so long as it's still LIFO.
Follow-up patches will convert all uses of alloca() and VLA to the new
scoped allocation API. The old behaviour (using alloca()) will still be
available, but when MICROPY_ENABLE_PYSTACK is enabled then alloca() is no
longer required or used.
The benefits of enabling this option are (or will be once subsequent
patches are made to convert alloca()/VLA):
- Toolchains without alloca() can use this feature to obtain correct and
efficient scoped memory allocation (compared to using the heap instead
of alloca(), which is slower).
- Even if alloca() is available, enabling the Py-stack gives slightly more
efficient use of stack space when calling nested Python functions, due to
the way that compilers implement alloca().
- Enabling the Py-stack with the stackless mode allows for even more
efficient stack usage, as well as retaining high performance (because the
heap is no longer used to build and destroy stackless code states).
- With Py-stack and stackless enabled, Python-calling-Python is no longer
recursive in the C mp_execute_bytecode function.
The micropython.pystack_use() function is included to measure usage of the
Python stack.
This function was implemented as an experiment, and was enabled only in
unix port. To remind, it allows to access arbitrary files frozen as
source modules (vs bytecode).
However, further experimentation showed that the same functionality can
be implemented with frozen bytecode. The process requires more steps, but
with suitable toolset it doesn't matter patch. This process is:
1. Convert binary files into "Python resource module" with
tools/mpy_bin2res.py.
2. Freeze as the bytecode.
3. Use micropython-lib's pkg_resources.resource_stream() to access it.
In other words, the extra step is using tools/mpy_bin2res.py (because
there would be wrapper for uio.resource_stream() anyway).
Going frozen bytecode route allows more flexibility, and same/additional
efficiency:
1. Frozen source support can be disabled altogether for additional code
savings.
2. Resources could be also accessed as a buffer, not just as a stream.
There're few caveats too:
1. It wasn't actually profiled the overhead of storing a resource in
"Python resource module" vs storing it directly, but it's assumed that
overhead is small.
2. The "efficiency" claim above applies to the case when resource
file is frozen as the bytecode. If it's not, it actually will take a
lot of RAM on loading. But in this case, the resource file should not
be used (i.e. generated) in the first place, and micropython-lib's
pkg_resources.resource_stream() implementation has the appropriate
fallback to read the raw files instead. This still poses some distribution
issues, e.g. to deployable to baremetal ports (which almost certainly
would require freezeing as the bytecode), a distribution package should
include the resource module. But for non-freezing deployment, presense
of resource module will lead to memory inefficiency.
All the discussion above reminds why uio.resource_stream() was implemented
in the first place - to address some of the issues above. However, since
then, frozen bytecode approach seems to prevail, so, while there're still
some issues to address with it, this change is being made.
This change saves 488 bytes for the unix x86_64 port.
This patch introduces a new compile-time config option to disable multiple
inheritance at the Python level: MICROPY_MULTIPLE_INHERITANCE. It is
enabled by default.
Disabling multiple inheritance eliminates a lot of recursion in the call
graph (which is important for some embedded systems), and can be used to
reduce code size for ports that are really constrained (by around 200 bytes
for Thumb2 archs).
With multiple inheritance disabled all tests in the test-suite pass except
those that explicitly test for multiple inheritance.
Macros to convert big-endian values to host byte order and vice-versa.
These were defined in adhoc way for some ports (e.g. esp8266), allow
reuse, provide default implementations, while allow ports to override.
