TMS570LC4357: Unable to execute interrupts in Boot code

I have been trying to implement a bootloader using the bootloader provided for Hercules Microcontrollers https://git.ti.com/cgit/hercules_examples/hercules_examples/tree/Bootloaders?h=master. I am using TMS570LC4357 microcontroller. I am able to successfully bootload and run my application code using the given bootloader, and now as I am trying to implement a delay in the boot code before jumping to the application code, the RTI timer interrupt is not working. I have observed that the counter itself isn't working when I call the "_enable_IRQ_interrupt_()" function. When I don't call it, the counter is up and running but it does not trigger an interrupt. I have also observed that when I modify the "_enable_IRQ_interrupt_()" function as per the Technical Reference Manual of the controller as

"IRQENABLE .equ 0x80

FIQENABLE .equ 0x40

Enable_Irq

MRS R1, CPSR

BIC R1, R1, #IRQENABLE

MSR CPSR, R1

MOV PC, LR"

the specific statement causing the running of counter was "BIC R1,R1, #IRQENABLE"

The counter is running properly when I put an other value instead of #80 at the address of #IRQENABLE, similar thing is happening for FIQ, when I put the address other than #40. Please help me with working with interrupts properly. I am going to try generating an SCI interrupt and update you with the result. Please help me if I am doing anything incorrect.

I have also observed that when I make the changes you have mentioned in the exception vector table in the application report of CAN bootloader for Hercules Microcontrollers, I have observed that the counter is running properly but the interrupt is not being triggered. I think I am unable to figure out the usage of interrupt vector table of boot code and application code. 

Thank You

Regards,

T. Sharath Chandra