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Fix simpleuart baud rate calculation #162

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Fix simpleuart baud rate calculation #162

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Commits on May 5, 2020

  1. Fix simpleuart baud rate calculation 

    This patch fixes the baud rate calculation so that the behavior of
simpleuart is in line with the description in picosoc/README.md:

> The UART Clock Divider Register must be set to the system clock
> frequency divided by the baud rate.

Previously, the effective behavior of simpleuart was

    divisor = (clock frequency / baud rate) - 2

The fix is done basically by comparing `*_divcnt + 1 >= cfg_divider`
instead of the old `*_divcnt > cfg_divider`. A special case is needed in
the receive logic for the case where the divider is equal to 1, where at
the next cycle we want to read the first bit (jumping straight to a
`recv_state` of 2).

This patch also makes some minor stylistic changes that fix Verilator
lint errors.
    @anishathalye
    anishathalye committed May 5, 2020
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