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- UID
- 83191
- 性别
- 男
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| 这是个状态机的子程序，不知道它实现了什么功能，请帮我看看，要是能画出状态转换图，那就太感谢了。
process (clk, rst) -- huge state machine
begin
if rst = '1' then
state <= 255 ;
lxclkout_d <= '1' ;
lxdir <= '0' ;
lxdir_int <= '0' ;
shift_tx <= '0' ;
gcnt <= "0000" ;
tx_ack_bad <= '0' ;
rxtoen <= '0' ;
enablewr <= '0' ;
disablewr <= '0' ;
mux <= '0' ;
pcount <= "000000" ;
elsif clk'event and clk = '1' then
lxdir <= lxdir_int ;
gcnt <= gcnt + 1 ;
case state is
when 255 => lxdir_int <= '0' ; lxclkout_d <= not rxbp ; pcount <= "000000" ;
gcnt <= "0000" ; shift_tx <= '0' ; -- reset state
if lxclkintp = '0' and rxbp = '0' then -- goto receiver stuff
state <= 100 ; enablewr <= '1' ;
elsif txreq = '1' then state <= 2 ; -- goto transmitter stuff
else state <= 255 ;
end if ; -- else hang around here
when 2 => if lxclkintp = '0' then
state <= 2 ; lxclkout_d <= '1' ; -- tx requested, wait for lxclkin high
elsif gcnt < "1011" then
state <= 2 ; lxclkout_d <= '0' ; -- hold lxclkout low for 6 cycles
else state <= 3 ; shift_tx <= '1' ;
end if ;
when 3 => state <= 13 ; lxclkout_d <= '0' ; shift_tx <= '1' ;
lxdir_int <= '1' ; gcnt <= "0000" ;
when 13 => if gcnt = "0111" then
state <= 13 ; tx_ack_bad <= lxclkintp ;
if psize = '0' then
pcount <= pcount + 1 ;
end if ;
lxclkout_d <= not gcnt(0) ; shift_tx <= '1' ;
elsif gcnt < "1101" then
state <= 13 ; lxclkout_d <= not gcnt(0) ;
shift_tx <= '1' ;
elsif verein = '1' and gcnt = "1101" then
state <= 13 ; lxclkout_d <= not gcnt(0) ;
shift_tx <= '1' ;
elsif verein = '1' and gcnt = "1110" then
state <= 13 ; lxclkout_d <= not gcnt(0) ;
shift_tx <= '0' ;
elsif verein = '0' and gcnt = "1101" then
state <= 32 ; lxclkout_d <= not gcnt(0) ;
shift_tx <= '1' ;
else
state <= 32 ; lxclkout_d <= not gcnt(0) ;
shift_tx <= '0' ; mux <= '1' ;
end if ;
when 32 => lxclkout_d <= '1' ; mux <= '0' ;
if lxclkintp = '0' then
state <= 34 ; shift_tx <= '0' ; -- wait for receiver ready
elsif txreq = '1' and psize = '1' then
state <= 33 ; shift_tx <= '1' ;
elsif txreq = '1' and psize = '0' and pcount > "000000" then
state <= 33 ; shift_tx <= '1' ;
else
state <= 33 ; shift_tx <= '0' ;
end if ;
when 33 => gcnt <= "0000" ; lxclkout_d <= '0' ;
if txreqd = '1' and psize = '1' then
state <= 13 ; shift_tx <= '1' ; -- transmit next word
elsif txreqd = '1' and psize = '0' and pcount > "000000" then
state <= 13 ; shift_tx <= '1' ; -- transmit next word
else
state <= 45 ; shift_tx <= '0' ;
end if ;
when 34 => gcnt <= "0000" ; lxclkout_d <= '0' ;
if lxclkintp = '0' then state <= 34 ;
else state <= 3 ; shift_tx <= '1' ;
end if ;
when 45 => lxclkout_d <= '1' ; state <= 46 ;
lxdir_int <= '0' ; gcnt <= "0000" ; -- no tx request, try to pass token
when 46 => if gcnt < "1000" then state <= 46 ;
elsif gcnt = "1000" and txreq = '1' -- tx req arrived, service it
and (psize = '1' or (psize = '0' and pcount > "000000")) then
state <= 47 ; lxclkout_d <= '0' ; gcnt <= "0000" ;
elsif gcnt = "1100" then
state <= 255 ; enablewr <= '0' ;
elsif lxclkintp = '0' then -- request from other end
state <= 100 ; enablewr <= '1' ;
else
state <= 46 ;
end if ;
when 47 => if gcnt < "0011" then state <= 47 ;
elsif lxclkintp = '0' then state <= 47 ;
else state <= 3 ; lxclkout_d <= '0' ; shift_tx <= '1' ; -- tx req, regret token
end if ;
when 100 => gcnt <= "0000" ; pcount <= "000000" ;
if localenablewr_rt = '1' then state <= 101 ;
lxclkout_d <= '0' ; rxtoen <= '1' ;
else state <= 100 ;
end if ;
when 101 => lxclkout_d <= '0' ;
if gcnt = "0010" then state <= 105 ; enablewr <= '0' ;
else state <= 101 ;
end if ;
when 105 => if ackflag_rt = '1' and rxbp = '1' then
state <= 106 ; lxclkout_d <= '0' ;
elsif lxcounthflag = '1' then state <= 200 ; disablewr <= '1' ;
elsif localenablewr_rt = '1' then
-- state <= 105 ; lxclkout_d <= not(rxbp or ackflag_rt) ;
state <= 105 ; lxclkout_d <= '1' ; --not ackflag_rt ;
else state <= 255 ;
end if ;
when 106 => if lxcounthflag = '1' then state <= 200 ; disablewr <= '1' ;
elsif rxbp = '1' then state <= 106 ; lxclkout_d <= '0' ;
else state <= 105 ; lxclkout_d <= '1' ;
end if ;
when 200 => gcnt <= "0000" ; disablewr <= '0' ; rxtoen <= '0' ;
if txreq = '0' and lxclkintp = '1' then
state <= 255 ; -- no txreq
elsif txreq = '0' and lxclkintp = '0' then
state <= 100 ; enablewr <= '1' ; -- then go and receive
else lxclkout_d <= '0' ; state <= 201 ; -- potential token pass
end if ;
when 201 => if lxclkintp = '0' then state <= 100 ;
lxclkout_d <= '1' ; enablewr <= '1' ; -- regret from other end
elsif gcnt < "0110" then state <= 201 ; -- wait
else state <= 3 ; shift_tx <= '1' ; -- OK, become transmitter
end if ;
when others => state <= 255 ;
end case ;
end if ;
end process ; |
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