Hi Shubham,
SYS/BIOS has a Hwi dispatcher which takes control of the interrupt vector table. The dispatcher will make sure the context switches (from Hwi, Task, Swi, etc) are performed correctly.
From your previous posts, I see you are using a Tiva device. If you do not want to use the dispatcher; the Hwi module supports TM4C "zero latency" interrupt on this device. To use zero latency interrupts, the peripheral interrupt must be enabled with a priority greater than disablePriority. More info in the SYS/BIOS API (ti.sysbios.family.arm.m3.Hwi).
SYSBIOS is designed to support several devices; so we do not ship a single file wherein you write the ISRs. The ISRs can be written anywhere in your code (as long as it is accessible to the particular Hwi Create).
Thanks,
Emmanuel