TM4C123GH6PM: using Tiva C on edge timing mode

Hello , i have an issue with the timer on tiva c when using it on edge timing mode ,  according to the datasheet counter starts counting until a rising edge is detected and then moves the value of the counter currently to the GPTMTnR register , 

i am running my code at the moment and debugging to see whats going on , i know i should use the tivaware API but i like going down to register level 

my problem is this , since i'm using timer module 0 A then i should be using the PB pin 6 or PF Pin 0 as my rising edge detectors this what i understood from reading the timer part in the data sheet so is this correct ? because if it is, its not working accordingly the timer keeps running but doesn't move its current value to the designated register ever weather PB6 or PF0 are high or not  

so here is my code:

#include "tm4c123gh6pm.h"

void Timer0Init(void);

int main(void)
{
	int i=0;
	Timer0Init();
	while(1){
		for(i=0;i<100000;i++){
		}
	}
	return 0;
}

void Timer0Init(void)
{
	//initialize PORT B
	volatile unsigned long  delay;
	SYSCTL_RCGC2_R |= 0x00000002;      // 1) B clock
  delay = SYSCTL_RCGC2_R;            // delay to allow clock to stabilize     
  GPIO_PORTB_AMSEL_R &= 0x00;        // 2) disable analog function
  GPIO_PORTB_PCTL_R &= 0x00000000;   // 3) GPIO clear bit PCTL  
  GPIO_PORTB_DIR_R &= 0x00;          // 4.2) PB all input
  GPIO_PORTB_AFSEL_R &= 0x40;        // 5) no alternate function
  GPIO_PORTB_DEN_R |= 0xFF;          // 7) enable digital pins PF4-PF1
	GPIO_PORTB_PCTL_R = 7;
	//timer clock
	SYSCTL_RCGCTIMER_R |=0x01;
	delay = SYSCTL_RCGCTIMER_R;
//1. Ensure the timer is disabled (the TnEN bit is cleared) before making any changes.
	TIMER0_CTL_R &= 0xFE;
//2. Write the GPTM Configuration (GPTMCFG) register with a value of 0x0000.0004.
	TIMER0_CFG_R= 0x00000004;
//3. In the GPTM Timer Mode (GPTMTnMR) register, write the TnCMR field to 0x1 and the TnMR field to 0x3.
	TIMER0_TAMR_R= TIMER0_TAMR_R | 0x007;
//4. Configure the type of event that the timer captures by writing the TnEVENT field of the GPTM Control (GPTMCTL) register.
	TIMER0_CTL_R = TIMER0_CTL_R & 0xFFFFFFF3;
//5. If a prescaler is to be used, write the prescale value to the GPTM Timer n Prescale Register (GPTMTnPR).
	//no prescaler for now
//6. Load the timer start value into the GPTM Timer n Interval Load (GPTMTnILR) register.
	TIMER0_TAILR_R = 0xFF;
//7. If interrupts are required, set the CnEIM bit in the GPTM Interrupt Mask (GPTMIMR) register.
//no interrupts required	
//8. Set the TnEN bit in the GPTM Control (GPTMCTL) register to enable the timer and start counting.
	TIMER0_CTL_R= TIMER0_CTL_R & 0x00000001;
	TIMER0_CTL_R |= 0x01;
//9. Poll the CnERIS bit in the GPTMRIS register or wait for the interrupt to be generated (if enabled). In both cases,
//the status flags are cleared by writing a 1 to the CnECINT bit of the GPTM Interrupt Clear (GPTMICR) register.
//The time at which the event happened can be obtained by reading the GPTM Timer n (GPTMTnR) register.

/*In Input Edge Timing mode, the timer continues running after an edge event has been detected,
but the timer interval can be changed at any time by writing the GPTMTnILR register. The change
takes effect at the next cycle after the write.*/
}

Thanks in advance.