Abstract: A processor (100) is provided that is a programmable fixed point digital signal processor (DSP) with variable instruction length, offering both high code density and easy programming. 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. The processor includes an instruction buffer unit (106), a program flow control unit (108), an address/data flow unit (110), a data computation unit (112), and multiple interconnecting busses. Dual multiply-accumulate blocks improve processing performance. A memory interface unit (104) provides parallel access to data and instruction memories. The instruction buffer is operable to buffer single and compound instructions pending execution thereof. A decode mechanism is configured to decode instructions from the instruction buffer. The use of compound instructions enables effective use of the bandwidth available within the processor.

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 processor (100) is provided that is a programmable digital signal processor (DSP) with variable instruction length. A trace FIFO (800) is provided for tracing a sequence of instruction addresses to assist with software or hardware debugging. In order to conserve space, only the addresses of an instruction just before (M+K, P+Q) and just after (P, R) a discontinuity are stored in the trace FIFO. A sequence of instruction lengths (SEC13LPC) is also stored in the trace FIFO so that the sequence of instruction addresses can be reconstructed by interpolating between two discontinuity points (P to P+Q).