software pwm width set question

[whung.john]

hi:
today i read custom form content follow as :
but i dont understand width value ,how to culcuate.
please help me to solve,thanks u.

#include <16F877>
#fuses XT, NOWDT, NOPROTECT, BROWNOUT, PUT, NOLVP
#use delay(clock = 4000000)

#define PWM_PIN PIN_B1

#define LOOPCNT 39

int8 width;

//-------------------------------
#INT_RTCC
void tick_interrupt(void);

//====================================
main()
{
width = 10;

setup_counters(RTCC_INTERNAL, RTCC_DIV_1);
enable_interrupts(INT_RTCC);
enable_interrupts(GLOBAL);

while(1);
}

//====================================
#INT_RTCC
void tick_interrupt(void)
{
static int8 loop = LOOPCNT;
static int8 pulse;

if(--loop == 0)
{
loop = LOOPCNT;
pulse = width;
}

if(pulse)
{
output_high(PWM_PIN);
pulse--;
}
else
{
output_low(PWM_PIN);
}

}

[PCM programmer]

The width value can be from 0 to LOOPCNT. This corresponds to 0%
and 100% duty cycle. In the example below, the width = 0 for 0% duty
cycle and the width = 39 for 100% duty cycle.

[whung.john]

thanks u very much for programmer:
but if ithink use software pwm make a frequency.
how much (MAX frequency AND min frequency) can make from software pwm RTCC OR TIMER1 OR timer2.
can u teach me how to culcuate? thanks u .