Hardware function generator support in a DSP
View Patent ↗The present invention relates to digital signal processors with an integrated module configured to compute a Coordinate Rotation Digital Computer (CORDIC) in a pipeline. The pipelined module can advantageously complete computation of one CORDIC computation for each clock pulse applied to the CORDIC module, thereby providing a CORDIC computation for each clock pulse. One embodiment advantageously computes a first portion of a computation with a lookup table and a second portion in accordance with a CORDIC algorithm. Advantageously, data in a CORDIC pipeline is automatically advanced in response to read instructions and can be automatically advanced from the beginning of the pipeline to the end of the pipeline to reinitialize the pipeline. This allows information to be retrieved from the CORDIC pipeline with relatively little overhead. The automatic starting and stopping of the CORDIC pipeline advantageously allows the retrieval of computations from efficient pipeline architectures on an as-needed basis.
1. A method of generating a function in a digital signal processor (DSP), the method comprising:
receiving a first instruction, where the first instruction initiates a computation according to a Coordinate Rotation Digital Computer (CORDIC) algorithm;
computing the CORDIC algorithm in a pipeline;
automatically discontinuing further computations of the CORDIC algorithm in the pipeline when a computed output is ready;
providing the computed output of the CORDIC algorithm in response to a second instruction;
predicting a desired time when a computation of the CORDIC algorithm is desired; and
initiating the computation of the CORDIC algorithm before the desired time such that the computation is completed by the desired time.
2. The method as defined in claim 1 , wherein the CORDIC algorithm is initiated before the desired time by an amount of time substantially equal to an initial latency period of the computation.
3. A control circuit for a pipelined Coordinate Rotation Digital Computer (CORDIC) comprising:
a reset circuit adapted to reset at least a portion of the pipelined stages of the pipelined CORDIC;
a first sequencing unit adapted to automatically enable clock pulses to the pipelined CORDIC such that a new calculation progress from a beginning of the pipelined CORDIC to an end of the pipelined CORDIC and to automatically disable the automatic application of clock pulses to the pipelined CORDIC when the computation is available at the end of the pipelined CORDIC;
and a second sequencing unit adapted to provide a clock pulse to the pipelined CORDIC to advance a calculation from one stage to another where the second sequencing unit is configured to provide the clock pulse in response to an instruction to read an output of the pipelined CORDIC, wherein the first sequencing unit comprises a counter that is reset in response to a detection of a start instruction, where the first sequencing unit enables clock pulses when a count maintained by the counter is in a first range of counts, and where the first sequencing unit disables the automatic application of clock pulses when the count maintained by the counter is in a second range of count.
4. The control circuit as defined in claim 3 , where the counter is incremented in response to an advancing of data from one pipelined stage to another, and the number of pipelined stages of the pipelined CORDIC determines the count at which the control circuit enables and disables the automatic application of clock pulses to the pipelined CORDIC.