US 6,983,361 B1 | ||
Apparatus and method for implementing switch instructions in an IA64 architecture | ||
Geoffrey Owen Blandy, Austin, Tex. (US) | ||
Assigned to International Business Machines Corporation, Armonk, N.Y. (US) | ||
Filed on Sep. 28, 2000, as Appl. No. 9/671,973. | ||
Int. Cl. G06F 9/00 (2006.01) |
U.S. Cl. 712—236 | 26 Claims |
1. A method of implementing a switch instruction in an IA64 architecture based data processing device, comprising:
receiving a call to the switch instruction, the call including one or more parameters for the switch instruction, wherein
the one or more parameters includes a range of branch address, the range being defined by a high value and a low value;
loading a plurality of predicate registers with values associated with a plurality of branch addresses based on the one or
more parameters;
calling an instruction associated with one of the plurality of branch addresses based on the values of the plurality of predicate
registers;
determining if the low value is lower than a lowpredicate;
setting a first register value to 2**(lowpredicate-low value) if the low value is lower than the lowpredicate; and
setting the first register value to 2**(lowpredicate) if the low value is not zero, where lowpredicate is a predicate register
number of a lowest numbered predicate register.
|