Remove the sendUSBPacket maxLen param because this greatly confused the compiler.
It also fixes a bug where the length provided to the hardware may not match the length of the packet.
sendUSBPacket now panics if the sent packet is too big.
I also fixed some of the string descriptor logic where we could create a packet without fully populating it.
RP2* systems might require some more work since they are implemented very differently?
I don't have any of those to test with yet, so maybe someone can deal with them in a seperate PR?
The reason is that allocating without a heap is usually more visible
than using an uninitialized random generator which is subtle and may
lead to security vulnerabilities.
Based on suggestion from @eliasnaur
Signed-off-by: deadprogram <ron@hybridgroup.com>
The data to write is specififed in words, not in bytes.
This fix is needed for correctness. Without it, a
`machine.Flash.WriteAt` call can result in **data loss** since it will
overwrite more data than it should.
Now that the drivers repo and friends are intended to target the most
recent release version of TinyGo instead of the development version,
this trigger does not serve any puppose to trigger a build that will have
already been tested.
Signed-off-by: deadprogram <ron@hybridgroup.com>
ahocorasick no longer times out during interp. I don't believe
this is because we fixed a bug in interp but rather because "something"
(garbage collector fixes?) has moved the tree building to runtime.
Instead of looping over each block, we can use bit hacks to operate on an entire state byte.
I deinterleaved the state bits in order to enable these tricks.
Sweep used to count free/freed allocations/blocks.
I managed to move/remove all of these counters:
- The free space is now calculated in buildFreeRanges by adding the range lengths.
- ReadMemStats counts freed objects by subtracting live objects from allocated objects.
- gcFreedBlocks was never necessary because MemStats.HeapAlloc is the same as MemStats.HeapInUse.
The allocator originally just looped through the blocks until it found a sufficiently-long range.
This is simple, but it fragments very easily and can degrade to a full heap scan for long requests.
Instead, we now maintain a sorted nested list of free ranges by size.
The allocator will select the shortest sufficient-length range, generally reducing fragmentation.
This data structure can find a range in time directly proportional to the requested length.
This updates the stack slot pass to include callers of external functions which may access non-argument memory.
Wiithout this change, a use-after-free could occur on WASM when calling a reentrant function or switching to another goroutine.
Enabling USB consumes a lot of power. So it's better to keep it disabled
by default when the serial port is set to something other than "usb"
(USB-CDC).
On my nice!nano clone, it reduces current consumption from 1mA to
0.13mA (and most of the rest is probably consumed by a connected SCD41
sensor).
This change might break some expectations, when a board uses USB but not
USB-CDC (I think this is rare, but I didn't check specifically).
The setjmp code sets r24 to 0 and checks if it is still 0 when it finishes.
This usually works because tinygo_longjmp stores the lower half of the stack pointer into r24.
However, r24 will be set to 0 if the stack is aligned to 256 bytes when entering the setjmp.
Manually set r24 to 1 in tinygo_longjmp to fix this issue.
Loop over valid pointer locations in heap objects instead of checking if each location is valid.
The conservative scanning code is now shared between markRoots and the heap scan.
This also removes the ending alignment requirement from markRoots, since the new scan* functions do not require an aligned length.
This requirement was occasionally violated by the linux global marking code.
This saves some code space and has negligible impact on performance.
The blocks GC originally used a fixed-size stack to hold objects to scan.
When this stack overflowed, the GC would fully rescan all marked objects.
This could cause the GC to degrade to O(n^2) when scanning large linked data structures.
Instead of using a fixed-size stack, we now add a pointer field to the start of each object.
This pointer field is used to implement an unbounded linked stack.
This also consolidates the heap object scanning into one place, which simplifies the process.
This comes at the cost of introducing a pointer field to the start of the object, plus the cost of aligning the result.
This translates to:
- 16 bytes of overhead on x86/arm64 with the conservative collector
- 0 bytes of overhead on x86/arm64 with the precise collector (the layout field cost gets aligned up to 16 bytes anyway)
- 8 bytes of overhead on other 64-bit systems
- 4 bytes of overhead on 32-bit systems
- 2 bytes of overhead on AVR
VDDH is typically connected to USB (~5V) or directly to a battery.
Measuring the voltage on VDDH is a way to measure the current battery
voltage, which in turn can be useful to determine how much power is left
in the battery.
I've special cased the nrf52840 in a somewhat unusual way, maybe there
is a better way, feel free to comment!
In order to scan stacks, the GC preempts all other threads and has them scan their own stack.
This is somewhat expensive since all of these threads have to fight over a single lock.
Instead, save the stack bounds and let the GC thread perform the scan.
This also fixes a few other bugs I ran into:
1. The GC starts scanning before the world stops. This can cause it to miss some objects (and mistakenly free them) if memory is modified while stopping.
2. The GC does not wait for threads to resume. This can cause notifications to be misinterpreted due to signal nesting if the GC is re-run before all threads wake.
This fixes a bug where runtime.alloc would not clear the padding from rounding the allocation up to a multiple of the block size.
The GC still has to scan this, and this could result in permanent false positives (and therefore memory leaks).
It also handles overflow in the size calculation.
Flash operations must go through the SoftDevice if it is enabled,
otherwise they will crash the chip. (And even then the SoftDevice
doesn't guarantee they'll succeed, depending on advertisement frequency
etc). But this patch makes sure to call the appropriate APIs so that
flash is usable while using Bluetooth.
Ideally we'd use something like
https://github.com/tinygo-org/tinygo/pull/5016 but that's a bit more
involved. As a quick improvement, call gosched() instead.
Example where I use this: a custom WS2812 driver that uses SPI to
transfer the data. It's useful to be able to switch back to the main
goroutine during the transfer to render the next LED update.
Writing the pointer of a buffer to memory-mapped I/O will normally cause
it to escape, which forces the compiler to heap-allocate the buffer. But
we do know how long the value stays alive, so we can tell the compiler
to keep it alive exactly until it is not needed anymore - and tell it to
not treat the pointer-to-uintptr cast as escaping.
This fixes the "gc: world already stopped" check by moving it before gcMarkReachable.
Previously the check did not work because gcMarkReachable would hang while waiting for activeTaskLock.
Previously, we created joinable threads.
As a result, all threads would be kept alive after completion so that pthread_join could wait for them.
We never call pthread_join, so threads would never get cleaned up.
Additionally, the thread creation error check was performed after waiting for the thread to start.
If pthread_create failed, the caller would get stuck waiting for a thread that was never created.
The compiler needs to know whether a defer is in a loop to determine whether to allocate stack or heap memory.
Previously, this performed a DFS of the CFG every time a defer was found.
This resulted in time complexity jointly proportional to the number of defers and the number of blocks in the function.
Now, the compiler will instead use Tarjan's strongly connected components algorithm to find cycles in linear time.
The search is performed lazily, so this has minimal performance impact on functions without defers.
In order to implement Tarjan's SCC algorithm, additional state needed to be attached to the blocks.
I chose to merge all of the per-block state into a single slice to simplify memory management.
Nia Waldvogel
Damian Gryski
deadprogram
MakKi (makki_d)
Ayke van Laethem
Michael Smith
cjpeterson
sivchari
Ben Krieger