Toggle a Pin in always@() ?

Does the following verilog correctly pulse a reset pin?

input [15:0]shadow;

input tach;

input carry_in;

output [15:0]active;

output reset;

reg [15:0]active;

reg reset;

always@(negedge tach)

begin

active = shadow;

reset = 1;

reset = 0;

end

Please help?

Additonally, Is there an overall better way to do this?

Basically I am trying to count the total time a input square wave is high. So when it goes high, I start my counter. The above module does not show the counter, just the output transition module. As it transitions back to low, I want to 1.) copy the count from the counter 'shadow' to another register 'active' 2.) clear the counter to 0

Any advice?