I ran into an issue where I did a method call on a nil interface and it
resulted in a HardFault. Luckily I quickly realized what was going on so
I could fix it, but I think undefined behavior is definitely the wrong
behavior in this case. This commit therefore changes such calls to cause
a nil panic instead of introducing undefined behavior.
This does have a code size impact. It's relatively minor, much lower
than I expected. When comparing the before and after of the drivers
smoke tests (probably the most representative sample available), I found
that most did not change at all and those that did change, normally not
more than 100 bytes (16 or 32 byte changes are typical).
Right now the pattern is the following:
switch typecode {
case 1:
call method 1
case 2:
call method 2
default:
nil panic
}
I also tried the following (in the hope that it would be easier to
optimize), but it didn't really result in a code size reduction:
switch typecode {
case 1:
call method 1
case 2:
call method 2
case 0:
nil panic
default:
unreachable
}
Some code got smaller, while other code (the majority) got bigger. Maybe
this can be improved once range[1] is finally allowed[2] on function
parameters, but it'll probably take a while before that is implemented.
[1]: https://llvm.org/docs/LangRef.html#range-metadata
[2]: https://github.com/rust-lang/rust/issues/50156
This is a common case, but it also complicates the code. Removing this
special case does have a negative effect on code size in rare cases, but
I don't think it's worth keeping around (and possibly causing bugs) for
such uncommon cases.
This should not result in functional changes, although the output (as
stated above) sometimes changes a little bit.
There were a few cases left where a named type would cause a crash in
the compiler. While going through enough code would have found them
eventually, I specifically looked for the `Type().(` pattern: a Type()
call that is then used in a type assert. Most of those were indeed bugs,
although for some I couldn't come up with a reproducer so I left them
as-is.
This commit replaces the existing ad-hoc package loader with a package
loader that uses the x/tools/go/packages package to find all
to-be-loaded packages.
This commit changes the way that packages are looked up. Instead of
working around the loader package by modifying the GOROOT variable for
specific packages, create a new GOROOT using symlinks. This GOROOT is
cached for the specified configuration (Go version, underlying GOROOT
path, TinyGo path, whether to override the syscall package).
This will also enable go module support in the future.
Windows is a bit harder to support, because it only allows the creation
of symlinks when developer mode is enabled. This is worked around by
using symlinks and if that fails, using directory junctions or hardlinks
instead. This should work in the vast majority of cases. The only case
it doesn't work, is if developer mode is disabled and TinyGo, the Go
toolchain, and the cache directory are not all on the same filesystem.
If this is a problem, it is still possible to improve the code by using
file copies instead.
As a side effect, this also makes diagnostics use a relative file path
only when the file is not in GOROOT or in TINYGOROOT.
This is needed to make it available to more packages, for caching
purposes.
For caching, the version itself may not be enough during development.
But for regular releases, the version provides some protection against
accidentally using a cache entry that is invalid in a newer version.
This is necessary to avoid a circular dependency in the loader (which
soon will need to read the Go version) and because it seems like a
better place anyway.
This makes it possible to use Bluetooth on the BBC micro:bit.
Note that you need to use -programmer=cmsis-dap otherwise the SoftDevice
will be erased while flashing something that uses Bluetooth.
The RAM base address is needed during SoftDevice initialization. So far,
the same magic value has been used in aykevl/go-bluetooth and in TinyGo,
but this should be configured in only one place.
This will have additional benefits in the future:
* It is currently set to 0x39c0, which is around 14.5kB. Most nrf51822
chips have only 16kB of RAM, so this is way too much for those
chips.
* LLD in LLVM 11 allows expressions in the MEMORY part of linker
scripts, which will allow overriding the SoftDevice RAM area with a
linker flag, which might come in handy.
Eventually we might want to start using the FPU, but the easy option
right now is to simply disable it everywhere. Previously, it depended on
whether Clang was built as part of TinyGo or it was an external binary.
By setting the floating point mode explicitly, such inconsistencies are
avoided.
This commit creates a new cortex-m4 target which can be the central
place for setting FPU-related settings across all Cortex-M4 chips.
This commit refactors both determining the current time and sleeping for
a given time. It also improves precision for many chips.
* The nrf chips had a long-standing TODO comment about a slightly
inaccurate clock. This should now be fixed.
* The SAM D2x/D5x chips may have a slightly more accurate clock,
although probably within the error margin of the RTC. Also, by
working with RTC ticks and converting in the least number of places,
code size is often slightly reduced (usually just a few bytes, up to
around 1kB in some cases).
* I believe the HiFive1 rev B timer was slightly wrong (32768Hz vs
30517.6Hz). Because the datasheet says the clock runs at 32768Hz,
I've used the same conversion code here as in the nrf and sam cases.
* I couldn't test both stm32 timers, so I kept them as they currently
are. It may be possible to make them more efficient by using the
native tick frequency instead of using microseconds everywhere.
All the AVRs that I've looked at had the same pin/port structure, with
the possible states being input/floating, input/pullup, low, and high
(with the same PORT/DDR registers). The main difference is the number of
available ports and pins. To reduce the amount of code and avoid
duplication (and thus errors) I decided to centralize this, following
the design used by the atmega2560 but while using a trick to save
tracking a few registers.
In the process, I noticed that the Pin.Get() function was incorrect on
the atmega2560 implementation. It is now fixed in the unified code.
Previously, we implemented individual bytealg functions via linknaming, and had to update them every once in a while when we hit linker errors.
Instead, this change reimplements the bytealg package in pure Go.
If something is missing, it will cause a compiler error rather than a linker error.
This is easier to test and maintain.
This commit changes pin numbering for atmega328 based boards (Uno, Nano)
to use the standard format, where pin number is determined by the
pin/port. Previously, pin numbers were based on what the Uno uses, which
does not seem to have a clear pattern.
One difference is that counting starts at port B, as there is no port A.
So PB0 is 0, PB1 is 1… PC0 is 8.
This commit also moves PWM code to the atmega328 file, as it may not be
generic to all ATmega chips.
Yannis Huber
sago35
Ayke van Laethem
deadprogram
Brad Peabody
Brad Peabody
Lucas Teske
cebernardi
Jaden Weiss
cornelk