Closed-loop reading of index registers using wide read and narrow write for multi-threaded system

A configurable computer system comprising:

• a central processing unit (CPU) for executing instructions;
• a controller chip having an index register and a plurality of data registers, the index register selecting, as a selected data register, one of the plurality of data registers for access;
• a bus connecting the CPU with the controller chip;
• a first program executing on the CPU, the first program including:
• first means for writing a desired index to the index register;
• second means for reading a stored index from the index register while simultaneously reading the selected data register in the plurality of data registers;
• compare means for comparing the desired index to the stored index;
• and
• repeat means, coupled to the compare means, for repeating actions of the first means and the second means when the compare means determines that the desired index does not match the stored index;
• whereby the first program detects when the wrong data is read by simultaneously reading the index register and the data register from the controller chip.

A computer-program product comprising:

• a computer-usable medium having computer-readable program code means embodied therein for accessing indexed registers in a multi-threaded environment, the computer-readable program code means in the computer-program product comprising:
• execution means for executing a single-width write instruction in a processor;
• index-write means for writing a desired index value to an index register in a controller chip when the single-width write instruction is executed, the desired index value having the single width of bits;
• second execution means for executing a double-width read instruction in the processor;
• double-width means for reading from the controller chip when the double-width read instruction is executed:
• 1) a stored index from the index register and
• 2) selected data from a selected data register;
• wherein the selected data register is identified by the stored index from the index register;
• compare means for comparing the stored index to the desired index value;
• and
• repeat means for re-executing the single-width write instruction and the double-width read instruction when the stored index does not match the desired index value,
• whereby the stored index is read with the selected data from the selected data register that is selected by the stored index to determine when to re-execute reading the indexed registers.