Current way of having a globally, but weakly defined static buffer has
several shortcomings:
- It forces user to have a certain "magic" byte array variable if
they want to have a control buffer of different size.
- Having a globally defined static array and a separate function to
tell USB core about its size is error prone.
- Its inner workings are not easily understandable form cursory look
at API and one needs to go and look at the implementation code to
connect all the pieces into a solid picture of how it works
This commit adds two parameters to 'usbd_init' call that allow user to
specify the pointer to the area of memory and a size of that memory
which would be used by the USB core to store the data received during
DATA stage of control requests. This approach, while further
complicating the prototype of 'usbd_init', provides user with more
flexibility allowing for any custom area of memory of any size to be
used as control buffer. It also forces user to provide both address
and memory size at the same time thus avoiding the possibility of user
redefining 'usbd_control_buffer', but not calling
'usbd_set_control_buffer_size' after that.
This commit refactors USB string code, making it, hopefully, less
buggy and more easier to understand. It also removes "magic" bit
manipulation and "magic" numbers;
This commits adds a new error code that can be return from a
registered control callback: USBD_REQ_NEXT_CALLBACK. This return code
signifies that the callback is done processing the data successfully,
but user would like to have all matching callbacks down the callback
chain to be executed too.
This change allows for example to intercept standard requests like
GET_DESCRIPTOR, do some small action upon receiving of one, but still
have the standard callback executed and do it's job. This way user
doesn't have to re-implement standard GET_DESCRIPTOR functionality if
they want to intercept that request to do some small thing.
This commit add an extra field to the _usbd_device, that allows to
keep track of the number of USB strings which allows simplify
boundaries checking code in usb_standard_get_descriptor.
This commit also changes the index base for strings in
usb_standard_get_descriptor which allows to get rid of necessity to
have a dummy one-character string in a strings array.
All #includes now explicitly use the "<libopencm3/stm32/rcc.h>" format.
If you want to get rid of the "libopencm3" prefix in your local project you
can add a respective -I entry in your Makefile (not recommended though).
All .ld files and .a libs are installed in $(TOOLCHAIN_DIR)/lib
directly (as before), but are now renamed to avoid potential
conflicts now or in the future. Examples:
libopencm3_lpc13xx.a
libopencm3_lpc13xx.ld
libopencm3_stm32.a
libopencm3_stm32.ld
