System and method for 32 bit code branching to 64 bit targets

Abstract

A system and method for converting 32 bit addresses into 64 bit addresses and enabling the 32 bit address to include a region index. The region index is stored in low order bits of the 32 bit address. In some architectures, namely the Intel IA-64 architecture, the low order bits are not used in entry point addresses because each entry point is on a 16 byte boundary. In the case of the IA-64 architecture, the low 4 bits of a 64 bit module entry point address are ignored. The region index in a 64 bit IA-64 address is stored in the high 3 bits of the address. Region index information is stored in the low order bits of the 32 bit address and copied to the high order bits for the corresponding 64 bit address. In this manner, the 32 bit address can include memory region index information without compromising the normal 4 gigabyte address space for a 32 bit address. By storing the memory index information, the 32 bit address is able to address a module entry point in any of the eight memory regions found in the IA-64 architecture. In addition, an additional bit in the 32 bit address is usable to further expand the addressable range of the 32 bit address when converted to operate in a 64 bit environment.

Dependencies are inferred from the claim text.