International Business Machines Corporation

Werner Soell

Dieter F Wendel

Rolf B Hilgendorf

Hartmut R Schwermer

Friedrich-Christian Wernicke

The invention provides an apparatus and a method for converting instructions of a code A to instructions of a code B. Said conversion is performed by obtaining rearrangement information, which corresponds to the instruction that is to be converted, from a table. Said rearrangement information is then used to rearrange the instruction elements of the initial instruction, in order to generate instructions of code B, which functionally corresponds to said initial instruction. Said rearrangement can be performed by multiplexing means, which use said instruction elements of the initial code A instruction as input, and which select one of said instruction elements, or the content of another register, and forward this selected data to the instruction that is to be generated. Said rearrangement information is directly used to control the selection performed by said multiplexers.

Dynamic conversion between different instruction codes by recombination

The invention relates to a circular buffer containing a sequence of entries, and in particular to determining a sequential priority among entries which both fulfill a given condition and are contained in said sequence. This problem is not straightforward, because said sequence of entries may wrap-around in said circular buffer, which means that said sequence of entries extends beyond the last entry position of the buffer. According to the invention, first, a number of virtual entry positions, which is at least equal to the number of real entry positions in the buffer, is added to the non-occupied part of the buffer. In a second step, each entry which fulfills the given condition blocks a certain number of adjacent entries, including said virtual entries. One entry will remain which is not blocked, and which also fulfills the given condition. This entry is the entry with sequential priority.

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Schonaich, Germany

Werner Soell