Measuring pulse width using TImer 1

[figdungiven]

Anyone know code for measuring a pulse from a 555 timer?
Any help would be much appreciated?
Below is the code i have at the minute. I am using PIC 16F874 and programming in C

#include <16f874.h>
#use delay (clock = 4000000)
#byte PORTC = 7
#bit INPUT = PORTC.0
setup_timer_1(T1_INTERNAL , T1_DIV_BY_1);
long int PERIOD;
main()
{
set_tris_c (0x01); // setting up ports
PERIOD= 0;
while(INPUT==0)
set_timer1(0);
while(INPUT==1);

PERIOD = get_timer1();