is in order let a given processor have a register file set labeled ri_x where x is a value between 0 through n u2212 1 and n is the total number of datapath registers let the processor also have a typical risc like instruction set and a sequential controller that executes a specified loop for example an add instruction is of the form add src 1 src 2 dst where src 1 is source operand 1 src 2 is source operand 2 and dst is the destination register all the three operands are drawn from the register file normally an instruction like add ri_ 0 ri_ 1 ri_ 2 would simply add up the contents of register in location 0 of the register file with register in location 1 and store the results in location 2 in a c language notation this would be written as ri 2 ri 0 ri 1 in these examples all addressing is implicit and static fixed in time pointer modified addressing works slightly differently pointer modified addressing is a form of indirect addressing an additional register set the pointer register set is maintained to map the address of a datapath register with the contents of the corresponding pointer register set thus let the pointer register set be called rd_x an instruction like add ri_ 0 ri_ 1 ri_ 2 is actually translated to mean ri rd 2 ri rd 0 ri rd 1 thus the operands of the instruction are the data registers whose addresses are contained in the rd_x register set if the contents of the pointer register set were such that rd_x x then the behavior under the pointer modified addressing would be exactly the same as that of the.