- Use compiler-rt and picolibc instead of avr-libc.
- Use ld.lld instead of avr-ld (or avr-gcc).
This makes it much easier to get started with TinyGo on AVR because
installing these extra tools (gcc-avr, avr-libc) can be a hassle.
It also opens the door for future improvements such as ThinLTO.
There is a code size increase but I think it's worth it in the long run.
The code size increase can hopefully be reduced with improvements to the
LLVM AVR backend and to compiler-rt.
This prefix isn't actually used and only adds noise, so remove it.
It may have been useful on Linux that makes a distinction between
/dev/ttyACM* and /dev/ttyUSB* but it isn't now. Also, it's unlikely that
the same vid/pid pair will be shared between an acm and usb driver
anyway.
This matches the flash-command and is generally a bit easier to work
with.
This commit also prepares for allowing multiple formats to be used in
the emulator command, which is necessary for the esp32.
This makes it possible to flash a board even when there are multiple
different kinds of boards attached, e.g. an Arduino Uno and a Circuit
Playground Express. You can find the VID/PID pair in several ways:
1. By running `lsusb` before and after attaching the board and looking
at the new USB device.
2. By grepping for `usb_PID` and `usb_VID` in the TinyGo source code.
3. By checking the Arduino IDE boards.txt from the vendor.
Note that one board may have multiple VID/PID pairs:
* The bootloader and main program may have a different PID, so far
I've seen that the main program generally has the bootloader PID
with 0x8000 added.
* The software running on the board may have an erroneous PID, for
example from a different board. I've seen this happen a few times.
* A single board may have had some revisions which changed the PID.
This is particularly true for the Arduino Uno.
As a fallback, if the given VID/PID pair isn't found, the whole set of
serial ports will be used.
There are many boards which I haven't included yet simply because I
couldn't test them.
Instead of specifying the emulator command in atmega328p.json, specify
it in the two boards based on it (arduino and arduino-nano). This makes
the configuration consistent with the machine package, which only
defines the CPUFrequency function in the board files (and not in
machine_atmega328p.json).
On Windows, it is common that there is a colon in the path. avrdude will
treat that as a separator and everything behind it as the file format
specifier instead of defaulting to Intel hex format.
By explicitly specifying the Intel hex format (with `:i`), this issue
should be fixed.
Setting the linker script as one property (instead of as part of the
generic ldflags property) allows it to be overriden.
This is important for the SoftDevice on Nordic chips, because the
SoftDevice takes up a fixed part of the flash/RAM and the application
must be flashed at a different position. With this linkerscript option,
it is possible to create (for example) a pca10040-s132v6 that overrides
the default linker script.
Instead of specifying explicit commands, most of these commands have
been replaced by more specific properties.
This is work that will be necessary for an eventual -programmer flag to
the compiler, with which it is possible to select which programmer to
use to flash or debug a chip. That's not very useful for boards that
already include a programmer or bootloader for that purpose, but is very
useful for novel boards or single-purpose boards that are not already
included in TinyGo.
* all: add support for specifying target CPU in target config
* avr: specify the chip name in the target CPU
This reduces code size by a large margin. For examples/blinky, it
reduces code size from 1360 to 1266 when compiling for the Arduino Uno
(94 bytes, or ~7%).
This allows the use of some compiler-generated builtins that are
hopefully compatible with LLVM. Example: println(uint8(foo))
Code size is unchanged normally but of course compiler builtins will
increase code size when actually used (for example with division).
