Electrical computers and digital processing systems: processing – Processing control – Branching
Patent
1999-01-19
2000-01-11
An, Meng-Ai T.
Electrical computers and digital processing systems: processing
Processing control
Branching
712231, 712234, 712239, 712241, G06F 934
Patent
active
060147415
ABSTRACT:
A superscalar microprocessor implements a microcode instruction unit that predicts the end of microcode loops. The microcode instruction unit detects a microcode loop and begins counting the number of iterations of the loop. The microcode sequence that implements the loop includes a microcode instruction that uses the string count as an operand and/or a result. The microcode instruction unit captures the string count when it is available on either an operand or address bus. The string count is compared to the number of iterations of the string loop to determine when to terminate the microcode loop. If the string count is not captured prior to the microcode instruction unit dispatching more microcode instructions than necessary, the microcode instruction unit notifies other components via a cancel bus. In this manner, the end of a loop is detected prior to the functional unit detecting a mispredicted branch instruction within the microcode loop.
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Advanced Micro Devices , Inc.
An Meng-Ai T.
El-Hady Nabil
Merkel Lawrence J.
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