All nrf chips have a cryptographically secure RNG on board. Therefore,
I've made the code more portable so that it works on all nrf chips.
I did remove a number of exported functions. I am of the opinion that
these should only be made available once we have an agreed upon API for
multiple chips. People who want to have greater control over the RNG
should use the device/nrf package directly instead.
I have also changed the behavior to always enable digital error
correction. Enabling it seems like a more conservative (and secure)
default to me. Again, people who would like to have it disabled can use
the device/nrf package directly.
The crypto/rand package is used for sensitive cryptographic operations.
Do not use the rp2040 RNG for this purpose, because it's not strong
enough for cryptography.
I think it is _possible_ to make use of the RP2040 RNG to create
cryptographically secure pseudo-random numbers, but it needs some
entropy calculation and secure hashing (blake2s or so) to make them
truly unpredictable.
The GC was originally designed for systems with a fixed amount of
memory, like baremetal systems. Therefore, it just used what it could
and ran a GC cycle when out of memory.
Other systems (like Linux or WebAssembly) are different. In those
systems, it is possible to grow the amount of memory on demand. But the
GC only actually grew the heap when it was really out of memory, not
when it was getting very close to being out of memory.
This patch fixes this by ensuring there is at least 33% headroom for the
GC. This means that programs can allocate around 50% more than what was
live in the last GC cycle. It should fix a performance cliff when a
program is almost, but not entirely, out of memory and the GC has to run
almost every heap allocation.
This documents memory constants. Somewhere, we should document what the
default memory size is (seems 2 pages so 128KB), as that determines the
initial heap size (which is a portion of that).
Signed-off-by: Adrian Cole <adrian@tetrate.io>
--allow-undefined can be a problem: it allows compiling code that will
fail when loaded. This change makes sure that if some symbols are
undefined, they are reported as an error by the linker.
Previously, people could get away with importing a function that was not
defined, like this:
func add(int a, int b) int
func test() {
println(add(3, 5))
}
This was always unintended but mostly worked. With this change, it isn't
possible anymore. Now every function needs to be marked with //export
explicitly:
//export add
func add(int a, int b) int
func test() {
println(add(3, 5))
}
As before, functions will be placed in the `env` module with the name
set from the `//export` tag. This can be overridden with
`//go:import-module`:
//go:import-module math
//export add
func add(int a, int b) int
func test() {
println(add(3, 5))
}
For the syscall/js package, I needed to give a list of symbols that are
undefined. This list is based on the JavaScript functions defined in
targets/wasm_exec.js.
This adds a summary of each wasm example, as before it was a bit unclear
how to do so. This also fixes the callback example which was broken.
Fixes#2568
Signed-off-by: Adrian Cole <adrian@tetrate.io>
This commit fixes two related issues:
1. CanInterface was unimplemented. It now uses the same check as is
used in Interface() itself.
This issue led to https://github.com/tinygo-org/tinygo/issues/3033
2. Allow making an interface out of a string char element.
Doing this in one commit (instead of two) because they are shown to be
correct with the same tests.
This commit adds support for time.NewTimer and time.NewTicker. It also
adds support for the Stop() method on time.Timer, but doesn't (yet) add
support for the Reset() method.
The implementation has been carefully written so that programs that
don't use these timers will normally not see an increase in RAM or
binary size. None of the examples in the drivers repo change as a result
of this commit. This comes at the cost of slightly more complex code and
possibly slower execution of the timers when they are used.
The Go tools only consider lowercase .s files to be assembly files. By
renaming these to uppercase .S files they won't be discovered by the Go
toolchain and listed as the SFiles to be assembled.
There is a difference between .s and .S: only uppercase .S will be
passed through the preprocessor. Doing that is normally safe, and
definitely safe in the case of these files.
Go 1.19 started reformatting code in a way that makes it more obvious
how it will be rendered on pkg.go.dev. It gets it almost right, but not
entirely. Therefore, I had to modify some of the comments so that they
are formatted correctly.
For write-only operations (in SPI displays for example), the transmit
speed is doubled with this relatively small change.
In the future, we should try to use DMA instead for larger buffers. But
this is already a significant improvement and will always be an
improvement for small buffer sizes.
