Electronic stream processing circuit with test access

An electronic signal processing circuit, comprising:

• a plurality of chained stream processing circuits, each having a stream input and a stream output, for inputting and outputting an input and output stream of successive sample values;
• linking multiplexing circuits, each linking a respective pair of stream processing circuits, each linking multiplexing circuit being individually switchable to a normal mode and to a replacement mode, the linking multiplexing circuit, when in the normal mode, providing a continuous connection for passing a first stream of samples values between the stream processing circuits in the respective pair;
• a shareable communication structure coupled to the linking multiplexing circuits, each linking multiplexing circuit, when in the replacement mode, providing a continuous connection for supplying successive sample values from a second stream from the communication structure to a receiving one of the stream processing circuits in the respective pair of the linking multiplexing circuit;
• a control circuit coupled to the linking multiplexing circuits, arranged to keep a selectable one of the multiplexing circuits in the replacement mode so that the selectable one of the linking multiplexing circuits passes a stream of successive sample from the second stream to the receiving one of the processing circuits in the respective pair of linking multiplexing circuit, while keeping at least part of the other linking multiplexing circuits in the normal mode.