Fixes https://github.com/libopencm3/libopencm3/issues/476
Sets USB_COUNTn_RX reg fields : bits <14:10> are NUM_BLOCK; bit 15 is BL_SIZE.
- When (size <= 62), BL_SIZE must be 0 and NUM_BLOCK set to (size / 2).
- When (size > 62), BL_SIZE must be 1 and NUM_BLOCK=((size / 32) - 1).
Previous code improperly set NUM_BLOCK and assumed the requested size was set.
Now, we use the next largest legal buffer size. Examples:
size BL_SIZE NUM_BLOCK => Actual bufsize
0 0 0 ??? (illegal !)
1 0 1 2
63 1 1 64
Algo is valid for F102, F103 and F0 devices (USB_FS peripheral).
In addition, the new usb_set_ep_rx_bufsize() function returns the actual
size set.
Tested-by: Karl Palsson <karlp@tweak.net.au>
01f33f47b7