block_guard.hpp

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// sbl/dsp/primitives/block_guard.hpp — Did a non-finite sample get into this block?
//
// A widget with feedback cannot let a NaN or an Inf recirculate. Summing
// every sample the block produced (and any state that feeds back) and
// testing the sum once catches a burst anywhere in the block — NaN and Inf
// both survive a sum — for the cost of an add per sample.
 
#ifndef SBL_DSP_PRIMITIVES_BLOCK_GUARD_HPP_
#define SBL_DSP_PRIMITIVES_BLOCK_GUARD_HPP_
 
#include <cmath>
 
namespace sbl::dsp::primitives {
 
class BlockGuard {
public:
    /// @note All public methods are ISR-safe — bounded computation, no I/O.
 
    void begin() { sum_ = 0.0f; }
    void add(float v) { sum_ += v; }
 
    /// True if anything added since begin() was non-finite.
    bool tripped() const { return !std::isfinite(sum_); }
 
private:
    float sum_ = 0.0f;
};
 
} // namespace sbl::dsp::primitives
 
#endif // SBL_DSP_PRIMITIVES_BLOCK_GUARD_HPP_