Abstract: A processor (100) is provided that is a programmable digital signal processor (DSP) with variable instruction length, offering both high code density and easy programming. Instructions may be executed during delay slots after program branching while an execution pipeline is being restarted. Architecture and instruction set are optimized for low power consumption and high efficiency execution of DSP algorithms, such as for wireless telephones, as well as pure control tasks. A software breakpoint instruction is provided for debugging purposes. In order to correctly emulate the operation of the instruction pipeline when a software breakpoint instruction is executed during a delay slot, the width (1110-1115) of the software breakpoint is the same as the replaced instruction. A limited number of breakpoint instruction length formats (1100, 1102) are combined with non-operational instructions (NOP, NOP—16) to form a large number of combination instructions that match any instruction length format.

Abstract: A computer system having a central processing unit (CPU) execution pipeline and a floating point unit (FPU) execution pipeline, the CPU pipeline including a plurality of pipestages and the FPU pipeline including a plurality of pipestages, wherein each CPU pipestage in the CPU pipeline has a corresponding pipestage in the FPU pipeline, a method of synchronizing operation of the CPU pipeline and the FPU pipeline, the method including the steps of (a) receiving an instruction in a first CPU pipestage, (b) receiving the instruction in a corresponding first FPU pipestage, (c) processing the instruction in the first CPU pipestage, (d) processing the instruction in the first FPU pipestage, (e) generating, by the first CPU pipestage, a first signal indicating that the instruction has been processed by first CPU pipestage and is ready to proceed to a second pipestage in the CPU pipeline, (f) generating by the first FPU pipestage, a second signal indicating that the instruction has been processed by the first FPU pipes

Abstract: An improved Agree branch predictor is provided. The branch predictor biasing bit is generated by a static predictor that makes a static prediction. The static predictor maintains a register storing an instruction preceding a conditional branch instruction for which the prediction is to be made. The static predictor makes the static prediction based upon a table of predetermined combinations of the preceding instruction type and upon a test type specifying a condition upon which the conditional branch instruction will be taken. In addition, the static predictor makes the static prediction based upon the sign of a displacement for calculating a target address of the branch. The static prediction is correlated with an Agree/Disagree prediction generated by a history table of previous outcomes of conditional branch instructions.