This provides a more consistent C-level API to raise exceptions, ie moving
away from nlr_raise towards mp_raise_XXX. It also reduces code size by a
small amount on some ports.
Most types are in rodata/ROM, and mp_obj_base_t.type is a constant pointer,
so enforce this const-ness throughout the code base. If a type ever needs
to be modified (eg a user type) then a simple cast can be used.
The struct member "dest" should never be less than "destStart", so their
difference is never negative. Cast as such to make the comparison
explicitly unsigned, ensuring the compiler produces the correct comparison
instruction, and avoiding any compiler warnings.
Move webrepl support code from ports/esp8266/modules into extmod/webrepl
(to be alongside extmod/modwebrepl.c), and use frozen manifests to include
it in the build on esp8266 and esp32.
A small modification is made to webrepl.py to make it work on non-ESP
ports, i.e. don't call dupterm_notify if not available.
The size of the event ringbuf was previously fixed to compile-time config
value, but it's necessary to sometimes increase this for applications that
have large characteristic buffers to read, or many events at once.
With this commit the size can be set via BLE.config(rxbuf=512), for
example. This also resizes the internal event data buffer which sets the
maximum size of incoming data passed to the event handler.
Protocols are nice, but there is no way for C code to verify whether
a type's "protocol" structure actually implements some particular
protocol. As a result, you can pass an object that implements the
"vfs" protocol to one that expects the "stream" protocol, and the
opposite of awesomeness ensues.
This patch adds an OPTIONAL (but enabled by default) protocol identifier
as the first member of any protocol structure. This identifier is
simply a unique QSTR chosen by the protocol designer and used by each
protocol implementer. When checking for protocol support, instead of
just checking whether the object's type has a non-NULL protocol field,
use `mp_proto_get` which implements the protocol check when possible.
The existing protocols are now named:
protocol_framebuf
protocol_i2c
protocol_pin
protocol_stream
protocol_spi
protocol_vfs
(most of these are unused in CP and are just inherited from MP; vfs and
stream are definitely used though)
I did not find any crashing examples, but here's one to give a flavor of what
is improved, using `micropython_coverage`. Before the change,
the vfs "ioctl" protocol is invoked, and the result is not intelligible
as json (but it could have resulted in a hard fault, potentially):
>>> import uos, ujson
>>> u = uos.VfsPosix('/tmp')
>>> ujson.load(u)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: syntax error in JSON
After the change, the vfs object is correctly detected as not supporting
the stream protocol:
>>> ujson.load(p)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
OSError: stream operation not supported
This allows the user to explicitly select the behaviour of the write to the
remote peripheral. This is needed for peripherals that have
characteristics with WRITE_NO_RESPONSE set (instead of normal WRITE). The
function's signature is now:
BLE.gattc_write(conn_handle, value_handle, data, mode=0)
mode=0 means write without response, while mode=1 means write with
response. The latter was the original behaviour so this commit is a change
in behaviour of this method, and one should specify 1 as the 4th argument
to get back the old behaviour.
In the future there could be more modes supported, such as long writes.
The default protection for the BLE ringbuf is to use
MICROPY_BEGIN_ATOMIC_SECTION, which disables all interrupts. On stm32 it
only needs to disable the lowest priority IRQ, pendsv, because that's the
IRQ level at which the BLE stack is driven.
This removes the limit on data coming in from a BLE.gattc_read() request,
or a notify with payload (coming in to a central). In both cases the data
coming in to the BLE callback is now limited only by the available data in
the ringbuf, whereas before it was capped at (default hard coded) 20 bytes.
Instead of enqueue_irq() inspecting the ringbuf to decide whether to
schedule the IRQ callback (if ringbuf is empty), maintain a flag that knows
if the callback is on the schedule queue or not. This saves about 150
bytes of code (for stm32 builds), and simplifies all uses of enqueue_irq()
and schedule_ringbuf().
The address, adv payload and uuid fields of the event are pre-allocated by
modbluetooth, and reused in the IRQ handler. Simplify this and move all
storage into the `mp_obj_bluetooth_ble_t` instance.
This now allows users to hold on to a reference to these instances without
crashes, although they may be overwritten by future events. If they want
to hold onto the values longer term they need to copy them.
Remove existing scan result events from the ringbuf if the ringbuf is full
and we're trying to enqueue any other event. This is needed so that events
such as SCAN_COMPLETE are always put on the ringbuf.
This commit removes the Makefile-level MICROPY_FATFS config and moves the
MICROPY_VFS_FAT config to the Makefile level to replace it. It also moves
the include of the oofatfs source files in the build from each port to a
central place in extmod/extmod.mk.
For a port to enabled VFS FAT support it should now set MICROPY_VFS_FAT=1
at the level of the Makefile. This will include the relevant oofatfs files
in the build and set MICROPY_VFS_FAT=1 at the C (preprocessor) level.
POSIX poll should always return POLLERR and POLLHUP in revents, regardless
of whether they were requested in the input events flags.
See issues #4290 and #5172.
POSIX poll should always return POLLERR and POLLHUP in revents, regardless
of whether they were requested in the input events flags.
See issues #4290 and #5172.
- Adds an explicit way to set the size of a value's internal buffer,
replacing `ble.gatts_write(handle, bytes(size))` (although that
still works).
- Add an "append" mode for values, which means that remote writes
will append to the buffer.
This commit adds helper functions to call readblocks/writeblocks with a
fourth argument, the byte offset within a block.
Although the mp_vfs_blockdev_t struct has grown here by 2 machine words, in
all current uses of this struct within this repository it still fits within
the same number of GC blocks.
For consistency with "umachine". Now that weak links are enabled
by default for built-in modules, this should be a no-op, but allows
extension of the bluetooth module by user code.
Also move registration of ubluetooth to objmodule rather than
port-specific.
NimBLE doesn't actually copy this data, it requires it to stay live.
Only dereference when we register a new set of services.
Fixes#5226
This will allow incrementally adding services in the future, so
rename `reset` to `append` to make it clearer.
Internally change the representation of UUIDs to LE uint8* to simplify this.
This allows UUIDs to be easily used in BLE payloads (such as advertising).
Ref: #5186
This avoids a confusing ENOMEM raised from gap_advertise if there is
currently an active connection. This refers to the static connection
buffer pre-allocated by Nimble (nothing to do with MicroPython heap
memory).
This is to more accurately match the BLE spec, where intervals are
configured in units of channel hop time (625us). When it was
specified in ms, not all "valid" intervals were able to be
specified.
Now that we're also allowing configuration of scan interval, this
commit updates advertising to match.
This adds two additional optional kwargs to `gap_scan()`:
- `interval_us`: How long between scans.
- `window_us`: How long to scan for during a scan.
The default with NimBLE is a 11.25ms window with a 1.28s interval.
Changing these parameters is important for detecting low-frequency
advertisements (e.g. beacons).
Note: these params are in microseconds, not milliseconds in order
to allow the 625us granularity offered by the spec.
On other ports (e.g. ESP32) they provide a complete Nimble implementation
(i.e. we don't need to use the code in extmod/nimble). This change
extracts out the bits that we don't need to use in other ports:
- malloc/free/realloc for Nimble memory.
- pendsv poll handler
- depowering the cywbt
Also cleans up the root pointer management.
With this patch alignment is done relative to the start of the buffer that
is being unpacked, not the raw pointer value, as per CPython.
Fixes issue #3314.
As per the README.md of the upstream source at
https://github.com/B-Con/crypto-algorithms, this source code was released
into the public domain, so make that explicit in the copyright line in the
header.
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.
The helper function exec_user_callback executes within the context of an
lwIP C callback, and the user (Python) callback to be scheduled may want to
perform further TCP/IP actions, so the latter should be scheduled to run
outside the lwIP context (otherwise it's effectively a "hard IRQ" and such
callbacks have lots of restrictions).
If tcp_write returns ERR_MEM then it's not a fatal error but instead means
the caller should retry the write later on (and this is what lwIP's netconn
API does).
This fixes problems where a TCP send would raise OSError(ENOMEM) in
situations where the TCP/IP stack is under heavy load. See eg issues #1897
and #1971.
Setting MICROPY_PY_USSL and MICROPY_SSL_MBEDTLS at the Makefile-level will
now build mbedTLS from source and include it in the build, with the ussl
module using this TLS library. Extra settings like MBEDTLS_CONFIG_FILE may
need to be provided by a given port.
If a port wants to use its own mbedTLS library then it should not set
MICROPY_SSL_MBEDTLS at the Makefile-level but rather set it at the C level,
and provide the library as part of the build in its own way (see eg esp32
port).
In d5f0c87bb9 this call to tcp_poll() was
added to put a timeout on closing TCP sockets. But after calling
tcp_close() the PCB may be freed and therefore invalid, so tcp_poll() can
not be used at that point. As a fix this commit calls tcp_poll() before
closing the TCP PCB. If the PCB is subsequently closed and freed by
tcp_close() or tcp_abort() then the PCB will not be on any active list and
the callback will not be executed, which is the desired behaviour (the
_lwip_tcp_close_poll() callback only needs to be called if the PCB remains
active for longer than the timeout).
Commit 2848a613ac introduced a bug where
lwip_socket_free_incoming() accessed pcb.tcp->state after the PCB was
closed. The state may have changed due to that close call, or the PCB may
be freed and therefore invalid. This commit fixes that by calling
lwip_socket_free_incoming() before the PCB is closed.
For example: i2c.writevto(addr, (buf1, buf2)). This allows to efficiently
(wrt memory) write data composed of separate buffers, such as a command
followed by a large amount of data.
It consists of:
1. "do_handhake" param (default True) to wrap_socket(). If it's False,
handshake won't be performed by wrap_socket(), as it would be done in
blocking way normally. Instead, SSL socket can be set to non-blocking mode,
and handshake would be performed before the first read/write request (by
just returning EAGAIN to these requests, while instead reading/writing/
processing handshake over the connection). Unfortunately, axTLS doesn't
really support non-blocking handshake correctly. So, while framework for
this is implemented on MicroPython's module side, in case of axTLS, it
won't work reliably.
2. Implementation of .setblocking() method. It must be called on SSL socket
for blocking vs non-blocking operation to be handled correctly (for
example, it's not enough to wrap non-blocking socket with wrap_socket()
call - resulting SSL socket won't be itself non-blocking). Note that
.setblocking() propagates call to the underlying socket object, as
expected.
For this, add wrap_socket(do_handshake=False) param. CPython doesn't have
such a param at a module's global function, and at SSLContext.wrap_socket()
it has do_handshake_on_connect param, but that uselessly long.
Beyond that, make write() handle not just MBEDTLS_ERR_SSL_WANT_WRITE, but
also MBEDTLS_ERR_SSL_WANT_READ, as during handshake, write call may be
actually preempted by need to read next handshake message from peer.
Likewise, for read(). And even after the initial negotiation, situations
like that may happen e.g. with renegotiation. Both
MBEDTLS_ERR_SSL_WANT_READ and MBEDTLS_ERR_SSL_WANT_WRITE are however mapped
to the same None return code. The idea is that if the same read()/write()
method is called repeatedly, the progress will be made step by step anyway.
The caveat is if user wants to add the underlying socket to uselect.poll().
To be reliable, in this case, the socket should be polled for both POLL_IN
and POLL_OUT, as we don't know the actual expected direction. But that's
actually problematic. Consider for example that write() ends with
MBEDTLS_ERR_SSL_WANT_READ, but gets converted to None. We put the
underlying socket on pull using POLL_IN|POLL_OUT but that probably returns
immediately with POLL_OUT, as underlyings socket is writable. We call the
same ussl write() again, which again results in MBEDTLS_ERR_SSL_WANT_READ,
etc. We thus go into busy-loop.
So, the handling in this patch is temporary and needs fixing. But exact way
to fix it is not clear. One way is to provide explicit function for
handshake (CPython has do_handshake()), and let *that* return distinct
codes like WANT_READ/WANT_WRITE. But as mentioned above, past the initial
handshake, such situation may happen again with at least renegotiation. So
apparently, the only robust solution is to return "out of bound" special
sentinels like WANT_READ/WANT_WRITE from read()/write() directly. CPython
throws exceptions for these, but those are expensive to adopt that way for
efficiency-conscious implementation like MicroPython.
In CPython the random module is seeded differently on each import, and so
this new macro option MICROPY_PY_URANDOM_SEED_INIT_FUNC allows to implement
such a behaviour.
Since commit da938a83b5 the tcp_arg() that is
set for the new connection is the new connection itself, and the parent
listening socket is found in the pcb->connected entry.
Use uos.dupterm for REPL configuration of the main USB_VCP(0) stream on
dupterm slot 1, if USB is enabled. This means dupterm can also be used to
disable the boot REPL port if desired, via uos.dupterm(None, 1).
For efficiency this adds a simple hook to the global uos.dupterm code to
work with streams that are known to be native streams.
Some users of this module may require the LwIP stack to run at an elevated
priority, to protect against concurrency issues with processing done by the
underlying network interface. Since LwIP doesn't provide such protection
it must be done here (the other option is to run LwIP in a separate thread,
and use thread protection mechanisms, but that is a more heavyweight
solution).
The bug polling for readability was: if alloc==0 and tcp.item==NULL then
the code would incorrectly check tcp.array[iget] which is an invalid
dereference when alloc==0. This patch refactors the code to use a helper
function lwip_socket_incoming_array() to return the correct pointer for the
incomming connection array.
Fixes issue #4511.
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`.
Previously crypto-algorithms impl was included even if MICROPY_SSL_MBEDTLS
was in effect, thus we relied on the compiler/linker to cut out the unused
functions.
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.
This header is deprecated as of mbedtls 2.8.0, as shipped with Ubuntu
18.04. Leads to #warning which is promoted to error with uPy compile
options.
Note that the current version of mbedtls is 2.14 at the time of writing.
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.
The recent implementation of the listen backlog meant that the logic to
test for readability of such a socket changed, and this commit updates the
logic to work again.
Array to hold waiting connections is in-place if backlog=1, else is a
dynamically allocated array. Incoming connections are processed FIFO
style to maintain fairness.
sizeof() can work in two ways: a) calculate size of already instantiated
structure ("sizeof variable") - in this case we already no layout; b) size
of structure decsription ("sizeof type"). In the latter case, LAYOUT_NATIVE
was assumed, but there should possibility to calculate size for other
layouts too. So, with this patch, there're now 2 forms:
uctypes.sizeof(struct)
uctypes.sizeof(struct_desc, layout)
This value is unused. It was an artifact of early draft design, but
bitfields were optimized to use scalar one-word encoding, to allow
compact encoding of typical multiple bitfields in MCU control
registers.
Since mbedtls 2.7.0 new digest functions were introduced with a "_ret"
suffix to allow the functions to return an error message (eg, if the
underlying hardware acceleration failed). These new functions must be used
instead of the old ones to prevent deprecation warnings, or link errors for
missing functions, depending on the mbedtls configuration.
This removes the need for a separate axtls build stage, and builds all
axtls object files along with other code. This simplifies and cleans up
the build process, automatically builds axtls when needed, and puts the
axtls object files in the correct $(BUILD) location.
The MicroPython axtls configuration file is provided in
extmod/axtls-include/config.h
Commit 95e70cd0ea 'time: Use 1970 epoch' changed epoch for the time
module, but not for other users. This patch does the same for the only
other core timeutils user: extmod/vfs_fat.c:fat_vfs_stat().
Other timeutils users: cc3200, esp8266 and stm32, are not changed.
Ports that don't use long ints, will still get wrong time values from
os.stat().
This saves code space in builds which use link-time optimization.
The optimization drops the untranslated strings and replaces them
with a compressed_string_t struct. It can then be decompressed to
a c string.
Builds without LTO work as well but include both untranslated
strings and compressed strings.
This work could be expanded to include QSTRs and loaded strings if
a compress method is added to C. Its tracked in #531.
The underlying socket can handling polling, and any other transparent ioctl
requests. Note that CPython handles the case of polling an ssl object by
polling the file descriptor of the underlying socket file, and that
behaviour is emulated here.
Otherwise they may be called on a socket that no longer exists.
For example, if the GC calls the finaliser on the socket and then reuses
its heap memory, the "callback" entry of the old socket may contain invalid
data. If lwIP then calls the TCP callback the code may try to call the
user callback object which is now invalid. The lwIP callbacks must be
deregistered during the closing of the socket, before all the pcb pointers
are set to NULL.
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.
This will allow implementations other than axTLS.
This commit includes additions of checks and clarifications of exceptions
related to user input.
To make the interface cleaner, I've disallowed switching from encrypt to
decrypt in the same object, as this is not always possible with other
crypto libraries (not all libraries have AES_convert_key like axTLS).
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
With this patch objects are only checked that they have the stream protocol
at the start of their use as a stream, and afterwards the efficient
mp_get_stream() helper is used to extract the stream protocol C methods.
This patch changes dupterm to call the native C stream methods on the
connected stream objects, instead of calling the Python readinto/write
methods. This is much more efficient for native stream objects like UART
and webrepl and doesn't require allocating a special dupterm array.
This change is a minor breaking change from the user's perspective because
dupterm no longer accepts pure user stream objects to duplicate on. But
with the recent addition of uio.IOBase it is possible to still create such
classes just by inheriting from uio.IOBase, for example:
import uio, uos
class MyStream(uio.IOBase):
def write(self, buf):
# existing write implementation
def readinto(self, buf):
# existing readinto implementation
uos.dupterm(MyStream())
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.
For consistency with other modules, and to help avoid clashes with the
actual underlying functions that do the hashing (eg
crypto-algorithms/sha256.c:sha256_update).
Following other C-level protocols, this VFS protocol is added to help
abstract away implementation details of the underlying VFS in an efficient
way. As a starting point, the import_stat function is put into this
protocol so that the VFS sub-system does not need to know about every VFS
implementation in order to do an efficient stat for importing files.
In the future it might be worth adding other functions to this protocol.
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.
If mbedtls_ctr_drbg_seed() is available in the mbedtls bulid then so should
be mbedtls_entropy_func(). Then it's up to the port to configure a valid
entropy source, eg via MBEDTLS_ENTROPY_HARDWARE_ALT.
Otherwise the "sock" member may have an undefined value if wrap_socket
fails with an exception and exits early, and then if the finaliser runs it
will try to close an invalid stream object.
Fixes issue #3828.
This matches CPython behaviour on Linux: a socket that is new and not
listening or connected is considered "hung up".
Thanks to @rkojedzinszky for the initial patch, PR #3457.
Textualy, the files in lib/uzlib/src were identical to the ones committed
in extmod/uzlib so there should be no behavioral change possible as a
result of this commit.
.. this maybe should be subject to MICROPY_CPYTHON_COMPAT, except that
is not defined in the main circuitpython ports so it would be a change
that makes no difference.
The order of function calls in an arithmetic expression is undefined and so
they must be written out as sequential statements.
Thanks to @dv-extrarius for reporting this issue, see issue #3690.
.. this maybe should be subject to MICROPY_CPYTHON_COMPAT, except that
is not defined in the main circuitpython ports so it would be a change
that makes no difference.
The 2nd and 3rd args of the ternary operator are treated like they are in
the same expression and must have similar types. void is not compatible
with int so that's why the compiler is complaining.
This patch moves the implementation of stream closure from a dedicated
method to the ioctl of the stream protocol, for each type that implements
closing. The benefits of this are:
1. Rounds out the stream ioctl function, which already includes flush,
seek and poll (among other things).
2. Makes calling mp_stream_close() on an object slightly more efficient
because it now no longer needs to lookup the close method and call it,
rather it just delegates straight to the ioctl function (if it exists).
3. Reduces code size and allows future types that implement the stream
protocol to be smaller because they don't need a dedicated close method.
Code size reduction is around 200 bytes smaller for x86 archs and around
30 bytes smaller for the bare-metal archs.
These allow accessing the filesystem label. For instance,
in boot.py, you can set the label on the built-in storage with:
storage.remount('/', False)
storage.getmount('/').label = "NEWLABEL"
storage.remount('/', True)
Users with multiple CIRCUITPY boards may find it desirable to
choose a different label for each board they own.
CPython doesn't allow SEEK_CUR with non-zero offset for files in text mode,
and uPy inherited this behaviour for both text and binary files. It makes
sense to provide full support for SEEK_CUR of binary-mode files in uPy, and
to do this in a minimal way means also allowing to use SEEK_CUR with
non-zero offsets on text-mode files. That seems to be a fair compromise.
This patch takes the software SPI implementation from extmod/machine_spi.c
and moves it to a dedicated file in drivers/bus/softspi.c. This allows the
SPI driver to be used independently of the uPy runtime, making it a more
general component.
This patch eliminates heap allocation in the VFS FAT disk IO layer, when
calling the underlying readblocks/writeblocks methods. The bytearray
object that is passed to these methods is now allocated on the C stack
rather than the heap (it's only 4 words big).
This means that these methods should not retain a pointer to the buffer
object that is passed in, but this was already a restriction because the
original heap-allocated bytearray had its buffer passed by reference.
This patch just moves the definition of the wrapper object fat_vfs_open_obj
to the location of the definition of its function, which matches how it's
done in most other places in the code base.
The fat_vfs_ilistdir2() function was only used by fat_vfs_ilistdir_func()
so moving the former into the same file as the latter allows it to be
placed directly into the latter function, thus saving code size.
CPython doesn't allow SEEK_CUR with non-zero offset for files in text mode,
and uPy inherited this behaviour for both text and binary files. It makes
sense to provide full support for SEEK_CUR of binary-mode files in uPy, and
to do this in a minimal way means also allowing to use SEEK_CUR with
non-zero offsets on text-mode files. That seems to be a fair compromise.
Dramatically improves TCP sending throughput because without an explicit
call to tcp_output() the data is only sent to the lower layers via the
lwIP slow timer which (by default) ticks every 500ms.
Before this patch MP_BINARY_OP_IN had two meanings: coming from bytecode it
meant that the args needed to be swapped, but coming from within the
runtime meant that the args were already in the correct order. This lead
to some confusion in the code and comments stating how args were reversed.
It also lead to 2 bugs: 1) containment for a subclass of a native type
didn't work; 2) the expression "{True} in True" would illegally succeed and
return True. In both of these cases it was because the args to
MP_BINARY_OP_IN ended up being reversed twice.
To fix these things this patch introduces MP_BINARY_OP_CONTAINS which
corresponds exactly to the __contains__ special method, and this is the
operator that built-in types should implement. MP_BINARY_OP_IN is now only
emitted by the compiler and is converted to MP_BINARY_OP_CONTAINS by
swapping the arguments.
It's possible to use the methods (eg ilistdir) of a VFS FatFS object
without it being mounted in the VFS itself. This previously worked but
only because FatFS was "mounting" the filesystem automatically when any
function (eg f_opendir) was called. But it didn't work for ports that used
synchronisation objects (_FS_REENTRANT) because they are only initialised
via a call to f_mount. So, call f_mount explicitly when creating a new
FatFS object so that everything is set up correctly. Then also provide a
finaliser to do the f_umount call, but only if synchronisation objects are
enabled (since otherwise the f_umount call does nothing).
This patch simplifies the str creation API to favour the common case of
creating a str object that is not forced to be interned. To force
interning of a new str the new mp_obj_new_str_via_qstr function is added,
and should only be used if warranted.
Apart from simplifying the mp_obj_new_str function (and making it have the
same signature as mp_obj_new_bytes), this patch also reduces code size by a
bit (-16 bytes for bare-arm and roughly -40 bytes on the bare-metal archs).
The SHA1 hashing functionality is provided via the "axtls" library's
implementation, and hence is unavailable when the "axtls" library is not being
used. This change provides the same SHA1 hashing functionality when using the
"mbedtls" library by using its implementation instead.
Introduction of ports subdirectory where all ports are moved to
The main change in this release is the introduction of a "ports/"
subdirectory at the top-level of the repository, and all of the ports are
moved here. In the process the "stmhal" port is renamed to "stm32" to
better reflect the MCU that it targets. In addition, the STM32 CMSIS and
HAL sources are moved to a new submodule called "stm32lib".
The bytecode has changed in this release, compared to the previous release,
and as a consequence the .mpy version number has increased to version 3.
This means that scripts compiled with the previous mpy-cross must be
recompiled to work with this new version.
There have also been various enhancements and optimisations, such as:
check for valid UTF-8 when creating str objects, support for reverse
special binary operations like __radd__, full domain checking in the math
module, support for floor-division and modulo in the viper emitter,
and addition of stack overflow checking when executing a regex.
The stm32 port sees improved support for F7 MCUs, addition of a new board
B_L475E_IOT01A based on the STM32L475, and support for the Wiznet W5500
chipset along with improved socket behaviour.
A detailed list of changes follows.
py core:
- objstr: startswith, endswith: check arg to be a string
- nlrx86,x64: replace #define of defined() with portable macro usage
- objtype: handle NotImplemented return from binary special methods
- objtype: mp_obj_class_lookup: improve debug logging
- map: remove unused new/free functions
- make m_malloc_fail() have void return type, since it doesn't return
- modstruct: in struct.pack, stop converting if there are no args left
- modstruct: check and prevent buffer-read overflow in struct unpacking
- modstruct: check and prevent buffer-write overflow in struct packing
- nlrthumb: get working again on standard Thumb arch (ie not Thumb2)
- objfloat: fix binary ops with incompatible objects
- obj: fix comparison of float/complex NaN with itself
- objtype: implement fallback for instance inplace special methods
- objtuple: properly implement comparison with incompatible types
- objstr: add check for valid UTF-8 when making a str from bytes
- objlist: properly implement comparison with incompatible types
- runtime0.h: move relational ops to the beginning of mp_binary_op_t
- runtime0.h: move MP_BINARY_OP_DIVMOD to the end of mp_binary_op_t
- objtype: make sure mp_binary_op_method_name has full size again
- runtime0.h: put inplace arith ops in front of normal operations
- builtinhelp: simplify code slightly by extracting object type
- runtime: implement dispatch for "reverse op" special methods
- nlrx86: fix building for Android/x86
- builtinhelp: change signature of help text var from pointer to array
- runtime.h: change empty mp_warning macro so var-args are non empty
- modbuiltins: implement abs() by dispatching to MP_UNARY_OP_ABS
- {objfloat,objcomplex}: optimise MP_UNARY_OP_ABS by reusing variables
- mpconfig.h: add note that using computed gotos in VM is not C99
- objstr: strip: don't strip "\0" by default
- objexcept: prevent infinite recursion when allocating exceptions
- stream: remove unnecessary checks for NULL return from vstr_add_len
- vstr: raise a RuntimeError if fixed vstr buffer overflows
- vm: use lowercase letter at start of exception message
- persistentcode: define mp_raw_code_save_file() for any unix target
- add config option to print warnings/errors to stderr
- objfloat: support raising a negative number to a fractional power
- objset: simplify set and frozenset by separating their locals dicts
- objset: check that RHS of a binary op is a set/frozenset
- objset: include the failed key in a KeyError raised from set.remove
- objtype: change type of enum-to-qstr table to uint16_t to save space
- objstr: make empty bytes object have a null-terminating byte
- mpprint: only check for null string printing when NDEBUG not defined
- objtype: clean up unary- and binary-op enum-to-qstr mapping tables
- persistentcode: bump .mpy version number to version 3
- bc: update opcode_format_table to match the bytecode
- modmath: add full checks for math domain errors
- modmath: convert log2 macro into a function
- formatfloat: don't print the negative sign of a NaN value
- formatfloat: use standard isinf, isnan funcs instead of custom ones
- modbuiltins: use existing utf8_get_char helper in builtin ord func
- emitnative: implement floor-division and modulo for viper emitter
- objtype: use CPython compatible method name for sizeof
- objtype: fit qstrs for special methods in byte type
- objtype: define all special methods if requested
- objtype: introduce MICROPY_PY_ALL_INPLACE_SPECIAL_METHODS
extmod:
- modubinascii: only include uzlib/tinf.h when it's really needed
- modussl_mbedtls: allow to compile with MBEDTLS_DEBUG_C disabled
- machine_pinbase: put PinBase singleton in ROM
- re1.5: upgrade to v0.8.2, adds hook for stack overflow checking
- modure: add stack overflow checking when executing a regex
- uos_dupterm: update uos.dupterm() and helper funcs to have index
- uos_dupterm: swallow any errors from dupterm closing the stream
- vfs: replace VLA in proxy func with small, static sized array
- modussl: add finaliser support for ussl objects
- modussl_mbedtls: allow to compile with unix coverage build
lib:
- add new submodule, stm32lib containing STM32 CMSIS and HAL source
- embed/abort_: use mp_raise_msg helper function
- libm: fix tanhf so that it correctly handles +/- infinity args
- libm: remove implementation of log2f, use MP_NEED_LOG2 instead
- axtls: update, support for SSL_EAGAIN return code
- berkeley-db-1.xx: update, allow to override MINCACHE, DEFPSIZE
drivers:
- memory/spiflash: change from hard-coded soft SPI to generic SPI
- display/ssd1306.py: improve performance of graphics methods
- nrf24l01: make nRF24L01 test script more portable
- display/ssd1306: implement SSD1306_I2C poweron method
- display/ssd1306: make poweron() work the same with SSD1306_SPI
- wiznet5k: improve the performance of socket ops with threading
- wiznet5k: get low-level W5500 driver working
tools:
- upip: upgrade to 1.2.2
- pyboard: use repr() when quoting data in error messages
- pyboard: update docstring for additional device support
tests:
- object_new: better messages, check user __new__() method
- class_new: add checks for __init__ being called and other improvements
- class_new: add another testcase for __new__/__init__ interaction
- class_inplace_op: test for inplace op fallback to normal one
- run-bench-tests: update locations of executables, now in ports/
- class_reverse_op: test for reverse arith ops special methods
- run-tests: skip class_inplace_op for minimal profile
- run-tests: fix copy-paste mistake in var name
- cpydiff: add cases for locals() discrepancies
- extmod: add test for ure regexes leading to infinite recursion
- extmod: add test for '-' in character class in regex
- run-tests: close device under test using "finally"
- net_inet: update tls test to work with CPython and incl new site
unix port:
- rename modsocket.c to modusocket.c
- modusocket: remove #if MICROPY_SOCKET_EXTRA code blocks
- enable MICROPY_PY_REVERSE_SPECIAL_METHODS
stm32 port:
- modmachine: make machine.bootloader() work when MPU is enabled
- modmachine: improve support for sleep/deepsleep on F7 MCUs
- compute PLL freq table during build instead of at run time
- modmachine: for F7 MCU, save power by reducing internal volt reg
- boards/pllvalues.py: make script work with both Python 2 and 3
- Makefile: use lib/stm32lib instead of local cmsis and hal files
- remove cmsis and hal files, they are now a submodule
- Makefile: automatically fetch stm32lib submodule if needed
- update to new STM Cube HAL library
- fix clock initialisation of L4 MCUs
- rename stmhal port directory to stm32
- remove unused usbd_msc.c file
- boards: change remaining stm32f4xx_hal_conf.h to unix line ending
- boards: change linker scripts to use "K" instead of hex byte size
- boards: fix I2C1 pin mapping on NUCLEO_F401RE/F411RE boards
- i2c: when scanning for I2C devices only do 1 probe per address
- modnwwiznet5k: release the GIL on blocking network operations
- boards: add new board B_L475E_IOT01A based on STM32L475
- make-stmconst.py: make sure mpz const data lives in ROM
- timer: make pyb.Timer() instances persistent
- mpconfigport.h: add configuration for max periphs on L4 series
- usbdev: make the USBD callback struct const so it can go in ROM
- usbdev: change static function variable to non-static
- usbdev: put all CDC state in a struct
- usbdev: put all HID state in a struct
- usbdev: simplify CDC tx/rx buffer passing
- usbdev: simplify HID tx/rx buffer passing
- usbdev/core: add state parameter to all callback functions
- usbdev: put all state for the USB device driver in a struct
- usbdev: simplify pointers to MSC state and block dev operations
- usbdev: merge all global USB device state into a single struct
- usbdev: make device descriptor callbacks take a state pointer
- usbdev: move all the USB device descriptor state into its struct
- timer: enable ARPE so that timer freq can be changed smoothly
- modnwwiznet5k: get the IP address of an established socket
- boards: fix typos in stm32f767_af.csv table
- usbd_cdc_interface: don't reset CDC output buf on initialisation
- modnwwiznet5k: implement WIZNET5K.isconnected() method
- modusocket: make getaddrinfo() work when passed an IP address
- modusocket: return OSError(-2) if getaddrinfo fails
- mpconfigport.h: add MICROPY_THREAD_YIELD() macro
- modnwwiznet5k: add support for W5500 Ethernet chip
- modnwwiznet5k: increase SPI bus speed to 42MHz
- modnwwiznet5k: implement stream ioctl for the Wiznet driver
- mphalport: improve efficiency of mp_hal_stdout_tx_strn_cooked
- make uos.dupterm() conform to specs by using extmod version
cc3200 port:
- enable micropython.kbd_intr() method
- use standard implementation of keyboard interrupt
esp8266 port:
- rename axtls_helpers.c to posix_helpers.c
- posix_helpers: set ENOMEM on memory alloc failure
- set DEFPSIZE=1024, MINCACHE=3 for "btree" module
- esp_mphal: send data in chunks to mp_uos_dupterm_tx_strn
- modnetwork: add "bssid" keyword arg to WLAN.connect() method
- modules/webrepl_setup: add info about allowed password length
zephyr port:
- Makefile: revamp "test" target after ports were moved to ports/
- use CONFIG_NET_APP_SETTINGS to setup initial network addresses
- switch to interrupt-driven pull-style console
pic16bit port:
- add definition of SEEK_SET to unistd.h
docs:
- pyboard/tutorial: add "timeout=0" to UART in pass-through example
- more xrefs to "MicroPython port" in glossary
- library/network: fix ref to "socket" module (should be "usocket")
- machine.Signal: improve style/grammar and add usage example
- library: add description of "index" parameter to uos.dupterm()
- library/micropython: fix typo in RST formatting
- library/framebuf.rst: generalise constructor to all colour formats
- btree: describe page caching policy of the underlying implementation
- esp8266/tutorial: update neopixel with example of using 4 bbp
- library/network: clarify usage of "bssid" arg in connect() method
- pyboard/quickref: add info for Switch, RTC, CAN, Accel classes
- pyboard/tutorial: update now that yellow LED also supports PWM
- esp8266/quickref: add quickref info for RTC class
- library: add missing cross-ref links for classes in pyb module
- library/network: update docs to state that W5500 is supported
- uselect: document one-shot polling mode
- usocket: elaborate descriptions
- usocket: document inet_ntop(), inet_pton()
- library/network: add dhcp_hostname parameter
- reference/isr_rules: minor typo correction
- ussl: fix module name refs and use "MicroPython port" term
- esp8266/general: add section on TLS limitations
- usocket: document that settimeout() isn't supported by all ports
- ure: add "|" (alternative) to the list of supported operators
- reference/isr_rules.rst: add tutorial on use of micropython.schedule()
travis:
- use --upgrade when pip is installing cpp-coveralls
- update build command now that stm32 Wiznet config has changed
examples:
- hwconfig_console: add .on()/.off() methods
all:
- convert mp_uint_t to mp_unary_op_t/mp_binary_op_t where appropriate
- convert remaining "mp_uint_t n_args" to "size_t n_args"
- make new ports/ sub-directory and move all ports there
- update Makefiles and others to build with new ports/ dir layout
- remove inclusion of internal py header files
- use NULL instead of "" when calling mp_raise exception helpers
README:
- update "Dependencies" section
- add explicit section on contributing
- add gcc and arm-none-eabi-newlib to list of required components
.gitattributes:
- remove obsolete entries for stmhal/hal, stmhal/cmsis
- add entries for files that will move to ports/ dir
If SSL_EAGAIN is returned (which is a feature of MicroPython's axTLS fork),
return EAGAIN.
Original axTLS returns SSL_OK both when there's no data to return to user
yet and when the underlying stream returns EAGAIN. That's not distinctive
enough, for example, original module code works well for blocking stream,
but will infinite-loop for non-blocking socket with EAGAIN. But if we fix
non-blocking case, blocking calls to .read() will return few None's initially
(while axTLS progresses thru handshake).
Using SSL_EAGAIN allows to fix non-blocking case without regressing the
blocking one.
Note that this only handles case of non-blocking reads of application data.
Initial handshake and writes still don't support non-blocking mode and must
be done in the blocking way.
* Introduce a python script to generate the USB descriptor instead of
a bunch of C macros. In the future, we can use this dynamically in
CircuitPython.
* Add support for detecting read-only mass storage mounts.
Fixes#377
Per the comment found here
https://github.com/micropython/micropython-esp32/issues/209#issuecomment-339855157,
this patch adds finaliser code to prevent memory leaks from ussl objects,
which is especially useful when memory for a ussl context is allocated
outside the uPy heap. This patch is in-line with the finaliser code found
in many modsocket implementations for various ports.
This feature is configured via MICROPY_PY_USSL_FINALISER and is disabled by
default because there may be issues using it when the ussl state *is*
allocated on the uPy heap, rather than externally.
VLAs can be expensive on stack usage due to stack alignment requirements,
and also the fact that extra local variables are needed to track the
dynamic size of the stack. So using fixed-size arrays when possible can
help to reduce code size and stack usage.
In this particular case, the maximum value of n_args in the VLA is 2 and so
it's more efficient to just allocate this array with a fixed size. This
reduces code size by around 30 bytes on Thumb2 and Xtensa archs. It also
reduces total stack usage of the function: on Thumb2 the usage with VLA is
between 40 and 48 bytes, which is reduced to 32; on Xtensa, VLA usage is
between 64 and 80 bytes, reduced to 32; on x86-64 it's at least 88 bytes
reduced to 80.
Without this the board will crash when deactivating a stream that doesn't
have a close() method (eg UART) or that raises an exception within the
method (eg user-defined function).
The uos.dupterm() signature and behaviour is updated to reflect the latest
enhancements in the docs. It has minor backwards incompatibility in that
it no longer accepts zero arguments.
The dupterm_rx helper function is moved from esp8266 to extmod and
generalised to support multiple dupterm slots.
A port can specify multiple slots by defining the MICROPY_PY_OS_DUPTERM
config macro to an integer, being the number of slots it wants to have;
0 means to disable the dupterm feature altogether.
The unix and esp8266 ports are updated to work with the new interface and
are otherwise unchanged with respect to functionality.
Header files that are considered internal to the py core and should not
normally be included directly are:
py/nlr.h - internal nlr configuration and declarations
py/bc0.h - contains bytecode macro definitions
py/runtime0.h - contains basic runtime enums
Instead, the top-level header files to include are one of:
py/obj.h - includes runtime0.h and defines everything to use the
mp_obj_t type
py/runtime.h - includes mpstate.h and hence nlr.h, obj.h, runtime0.h,
and defines everything to use the general runtime support functions
Additional, specific headers (eg py/objlist.h) can be included if needed.
Allow literal minus in char classes to be in trailing position, e.g. [a-c-].
(Previously, minus was allowed only at the start.)
This increases ARM Thumb2 code size by 8 bytes.
This patch also removes the empty type "pinbase_type" (which crashes if
accessed) and uses "machine_pinbase_type" instead as the type of the
PinBase singleton.
With MBEDTLS_DEBUG_C disabled the function mbedtls_debug_set_threshold()
doesn't exist. There's also no need to call mbedtls_ssl_conf_dbg() so a
few bytes can be saved on disabling that and not needing the mbedtls_debug
callback.
The unary-op/binary-op enums are already defined, and there are no
arithmetic tricks used with these types, so it makes sense to use the
correct enum type for arguments that take these values. It also reduces
code size quite a bit for nan-boxing builds.
This implementation ignores invalid characters in the input. This allows
it to decode the output of b2a_base64, and also mimics the behavior of
CPython.
- Changed: ValueError, TypeError, NotImplementedError
- OSError invocations unchanged, because the corresponding utility
function takes ints, not strings like the long form invocation.
- OverflowError, IndexError and RuntimeError etc. not changed for now
until we decide whether to add new utility functions.
Since the stride is specified in pixels, in a 4-bit horizontal format it
has to always be even, otherwise the computation is wrong and we can
write outside of the buffer sometimes.
The code conventions suggest using header guards, but do not define how
those should look like and instead point to existing files. However, not
all existing files follow the same scheme, sometimes omitting header guards
altogether, sometimes using non-standard names, making it easy to
accidentally pick a "wrong" example.
This commit ensures that all header files of the MicroPython project (that
were not simply copied from somewhere else) follow the same pattern, that
was already present in the majority of files, especially in the py folder.
The rules are as follows.
Naming convention:
* start with the words MICROPY_INCLUDED
* contain the full path to the file
* replace special characters with _
In addition, there are no empty lines before #ifndef, between #ifndef and
one empty line before #endif. #endif is followed by a comment containing
the name of the guard macro.
py/grammar.h cannot use header guards by design, since it has to be
included multiple times in a single C file. Several other files also do not
need header guards as they are only used internally and guaranteed to be
included only once:
* MICROPY_MPHALPORT_H
* mpconfigboard.h
* mpconfigport.h
* mpthreadport.h
* pin_defs_*.h
* qstrdefs*.h
Fixes for stmhal USB mass storage, lwIP bindings and VFS regressions
This release provides an important fix for the USB mass storage device in
the stmhal port by implementing the SCSI SYNCHRONIZE_CACHE command, which
is now require by some Operating Systems. There are also fixes for the
lwIP bindings to improve non-blocking sockets and error codes. The VFS has
some regressions fixed including the ability to statvfs the root.
All changes are listed below.
py core:
- modbuiltins: add core-provided version of input() function
- objstr: catch case of negative "maxsplit" arg to str.rsplit()
- persistentcode: allow to compile with complex numbers disabled
- objstr: allow to compile with obj-repr D, and unicode disabled
- modsys: allow to compile with obj-repr D and PY_ATTRTUPLE disabled
- provide mp_decode_uint_skip() to help reduce stack usage
- makeqstrdefs.py: make script run correctly with Python 2.6
- objstringio: if created from immutable object, follow copy on write policy
extmod:
- modlwip: connect: for non-blocking mode, return EINPROGRESS
- modlwip: fix error codes for duplicate calls to connect()
- modlwip: accept: fix error code for non-blocking mode
- vfs: allow to statvfs the root directory
- vfs: allow "buffering" and "encoding" args to VFS's open()
- modframebuf: fix signed/unsigned comparison pendantic warning
lib:
- libm: use isfinite instead of finitef, for C99 compatibility
- utils/interrupt_char: remove support for KBD_EXCEPTION disabled
tests:
- basics/string_rsplit: add tests for negative "maxsplit" argument
- float: convert "sys.exit()" to "raise SystemExit"
- float/builtin_float_minmax: PEP8 fixes
- basics: convert "sys.exit()" to "raise SystemExit"
- convert remaining "sys.exit()" to "raise SystemExit"
unix port:
- convert to use core-provided version of built-in import()
- Makefile: replace references to make with $(MAKE)
windows port:
- convert to use core-provided version of built-in import()
qemu-arm port:
- Makefile: adjust object-file lists to get correct dependencies
- enable micropython.mem_*() functions to allow more tests
stmhal port:
- boards: enable DAC for NUCLEO_F767ZI board
- add support for NUCLEO_F446RE board
- pass USB handler as parameter to allow more than one USB handler
- usb: use local USB handler variable in Start-of-Frame handler
- usb: make state for USB device private to top-level USB driver
- usbdev: for MSC implement SCSI SYNCHRONIZE_CACHE command
- convert from using stmhal's input() to core provided version
cc3200 port:
- convert from using stmhal's input() to core provided version
teensy port:
- convert from using stmhal's input() to core provided version
esp8266 port:
- Makefile: replace references to make with $(MAKE)
- Makefile: add clean-modules target
- convert from using stmhal's input() to core provided version
zephyr port:
- modusocket: getaddrinfo: Fix mp_obj_len() usage
- define MICROPY_PY_SYS_PLATFORM (to "zephyr")
- machine_pin: use native Zephyr types for Zephyr API calls
docs:
- machine.Pin: remove out_value() method
- machine.Pin: add on() and off() methods
- esp8266: consistently replace Pin.high/low methods with .on/off
- esp8266/quickref: polish Pin.on()/off() examples
- network: move confusingly-named cc3200 Server class to its reference
- uos: deconditionalize, remove minor port-specific details
- uos: move cc3200 port legacy VFS mounting functions to its ref doc
- machine: sort machine classes in logical order, not alphabetically
- network: first step to describe standard network class interface
examples:
- embedding: use core-provided KeyboardInterrupt object
Boot will only run once now before USB is started. Its output goes to
boot_out.txt. After main and REPL will run with VM and hardware resets
between each.
VfsFat no longer has the listdir() method. Rather, if listdir()
functionality is needed then one should use uos.listdir() which will call
VfsFat.ilistdir().
This patch allows mounting of VFS objects right at the root directory, eg
os.mount(vfs, '/'). It still allows VFS's to be mounted at a path within
the root, eg os.mount(vfs, '/flash'), and such mount points will override
any paths within a VFS that is mounted at the root.
Peer-closed socket is both readable and writable: read will return EOF,
write - error. Without this poll will hang on such socket.
Note that we don't return POLLHUP, based on argumentation in
http://www.greenend.org.uk/rjk/tech/poll.html that it should apply to
deeper disconnects, for example for networking, that would be link layer
disconnect (e.g. WiFi went down).
A shorter name takes less code size, less room in scripts and is faster to
type at the REPL.
Tests and HW-API examples are updated to reflect the change.
This implements the orginal idea is that Signal is a subclass of Pin, and
thus can accept all the same argument as Pin, and additionally, "inverted"
param. On the practical side, it allows to avoid many enclosed parenses for
a typical declararion, e.g. for Zephyr:
Signal(Pin(("GPIO_0", 1))).
Of course, passing a Pin to Signal constructor is still supported and is the
most generic form (e.g. Unix port will only support such form, as it doesn't
have "builtin" Pins), what's introduces here is just practical readability
optimization.
"value" kwarg is treated as applying to a Signal (i.e. accounts for possible
inversion).
MONO_xxx is much easier to read if you're not familiar with the code.
MVLSB is deprecated but kept for backwards compatibility, for the time
being.
This patch also updates the associated docs and tests.
This follows the pattern of how all other headers are now included, and
makes it explicit where the header file comes from. This patch also
removes -I options from Makefile's that specify the mp-readline/timeutils/
netutils directories, which are no longer needed.
Allows to get event time for a head item in the queue. The usecase
if waiting for the next event *OR* I/O completion. I/O completion may
happen before event triggers, and then wait should continue for the
remaining event time (or I/O completion may schedule another earlier
event altogether).
The new function has a strongly provisional status - it may be converted
to e.g. peek() function returning all of the event fields, not just time.
GIL behaviour should be handled by the port. And ports probably want to
define sleep_us so that it doesn't release the GIL, to improve timing
accuracy.
