Abstract: A method and apparatus for handling events, such as those which occur in a processor. An event vector is formed by combining event type information indicating a type of event in the processor and mode information indicating an operating mode of the processor. A microcode event handler vector is generated therefrom, for example, by referencing a lookup table. The microcode event handler vector is then used for invoking a microcode event handler to handle occurrence of these events in the processor. By the formation of an event vector, and the microcode event handler vector, execution performance is increased due to avoiding conditional branching within the processor, such as modem high performance architectures, including those which execute instructions in and out-of-order.

Abstract: A microprocessor contains an address generation unit, including a segment block, for loading descriptor data and a segment selector in a segment register. Two descriptor loads from a global descriptor table (GDT) and a local descriptor table (LDT) are executed. A 64 bit global descriptor from the GDT is loaded into a temporary register, and a 64 bit local descriptor from the LDT is also loaded into a separate temporary register. If a table indicator bit in the segment selector indicates use of the GDT, then the descriptor data from the GDT is selected. Alternatively, if the table indicator bit in the segment selector indicates the use of the LDT, then the descriptor data from the LDT is selected. The segment block splits the 64 bit descriptor data selected into two 32 bit quantities. The two 32 bit data quantities are input to a test programmable logic array (PLA). The test PLA checks for permission violations, or faults, and detects the need for special handling of the register segment load operation.