denormal.hpp File Reference

#include <cmath>
#include <cstddef>
#include <cstdint>

Go to the source code of this file.

Classes
struct	pulp::signal::SnapChunk
	One chunk of a block: samples [begin, end). More...
class	pulp::signal::SnapChunks
	The chunks of [0, num_samples), consecutive and at most kSnapChunkSamples long, as a range. More...
class	pulp::signal::SnapChunks::iterator

Namespaces
namespace	pulp
namespace	pulp::signal

Macros
#define	PULP_DSP_ENABLE_SNAP_TO_ZERO   1
	Denormal-flushing utility.

Functions
template<typename T>
constexpr T	pulp::signal::snap_threshold ()
	Threshold in absolute value below which a sample is treated as zero.
template<typename T>
T	pulp::signal::snap_to_zero (T x)
	Returns 0 if |x| < snap_threshold, else x.
template<typename T>
T	pulp::signal::snap_recursion_state (T x)
	Snap a per-sample recursion's state: snap_to_zero() where subnormals are slow, the identity where kSubnormalsAreFree.
template<typename T>
void	pulp::signal::snap_to_zero (T *samples, int n)
	Snap an entire buffer in place.
constexpr SnapChunks	pulp::signal::snap_chunks (std::size_t num_samples) noexcept
template<typename T>
bool	pulp::signal::is_denormal (T x)
	Return true if x is a denormal (subnormal) float.

Variables
constexpr bool	pulp::signal::kSubnormalsAreFree
	Whether subnormal arithmetic runs at full speed on this target.
constexpr std::size_t	pulp::signal::kSnapChunkSamples = 64
	Samples a block path runs between denormal snaps of its recursive state.

Macro Definition Documentation

PULP_DSP_ENABLE_SNAP_TO_ZERO

#define PULP_DSP_ENABLE_SNAP_TO_ZERO   1

Denormal-flushing utility.

Denormal floating-point values cause severe CPU stalls on x86 when they enter recursive paths like IIR filter state or reverb feedback. snap_to_zero returns 0 when the input is below a threshold whose magnitude is large enough to catch denormals (and very-quiet tails) but small enough not to be audible. The threshold is 1e-15 (~-300 dB FS for float; see snap_threshold() below) — the single source of truth for the magnitude quoted here.

Use at the end of each recursive state update in IIR / SVF / TPT / Ladder / Ballistics / Reverb feedback paths.

last_out_ = pulp::signal::snap_to_zero(coef * last_out_ + input);

Build-time toggle: define PULP_DSP_ENABLE_SNAP_TO_ZERO=0 to compile out the check (the function becomes the identity). Default: ON.