hw/char: riscv_htif: Avoid using magic numbers

The Spike HTIF is poorly documented. The only relevant info we can
get from the internet is from Andrew Waterman at [1].

Add a comment block before htif_handle_tohost_write() to explain
the tohost register format, and use meaningful macros instead of
magic numbers in the codes.

While we are here, correct 2 multi-line comment blocks that have
wrong format.

Link: https://github.com/riscv-software-src/riscv-isa-sim/issues/364#issuecomment-607657754 [1]
Signed-off-by: Bin Meng <bmeng@tinylab.org>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20221229091828.1945072-2-bmeng@tinylab.org>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

0 files changed, 0 insertions, 0 deletions