VHDL Code For Ultrasonic Distance Sensor HC-SR04

Yes I realized that mistake. I edited my code accordingly this way, but it still does not work. It either shows 99 or 00 after each reprograming the FPGA. Also I don't know how to write the testbench:( I would appreciate if you write it for me( I believe it is quite easy for a given code, otherwise I wouldn't ask such a thing.). The new code is:

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.NUMERIC_STD.ALL;
entity sonar is
    Port ( clk : in STD_LOGIC;
           trig : out STD_LOGIC;--trigger
           echo : in STD_LOGIC;
           cm1 : out unsigned(3 downto 0); --most significant bit of distance in binary form
           cm0 : out unsigned(3 downto 0));
end sonar;
architecture sonar_arch of sonar is
begin
    process(clk)
    variable count: integer range 0 to 10000;
    variable tmpcm1: unsigned(3 downto 0) := "0000";
    variable tmpcm0 : unsigned(3 downto 0) := "0000";
    variable sendTrig: std_logic := '1';
    variable echoPrev: std_logic:= '0';
    variable echoCurrent : std_logic:= '0';
    begin
        if rising_edge(clk) then
            if sendTrig = '1' then -- send 10us trig
                if count = 1000 then -- 10 us trig is completed, reset tmp signals for the new calculation
                    trig <= '0';
                    sendTrig := '0';
                    count := 0;
                    tmpcm0 := "0000";
                    tmpcm1 := "0000";
                else
                    trig <= '1';
                    count := count + 1;
                end if; 
            else -- stop sending trig, do the calculation (5800 clk cycle = 1cm)(count enters here as 0)
                if echo = '1' then -- we can start calculating the width of the echo
                    if count = 5799 then--we measuered 1 cm
                        if tmpcm0 = "1001" then
                            if tmpcm1 = "1001" then
                                sendTrig := '1';--max distance to be measured(100 cm), stop measuring, re-send the trig(also update the output)
                                cm0 <= tmpcm0;
                                cm1 <= tmpcm1;
                            else
                                tmpcm1 := tmpcm1 + "0001";
                                tmpcm0 := "0000";
                            end if;
                        else
                            tmpcm0 := tmpcm0 + "0001";
                        end if;
                        count := 0;
                    else
                        count := count + 1;
                    end if;
                    if echoPrev = '1' and echoCurrent = '0' then --falling edge of echo, edit the output, start sending new trigger
                        sendTrig := '1';
                        cm0 <= tmpcm0;
                        cm1 <= tmpcm1;
                    end if;                              
                end if;                        
            end if;
            echoPrev := echoCurrent;
            echoCurrent := echo;
        end if;      
    end process;
     
end sonar_arch;