Rralglib is a portable, quality-aware peak detection library for embedded biosignal processing. It implements a real-time processing block designed for robust peak detection and signal quality assessment in physiological signals (e.g., respiration, heart rate). The library uses a multi-stage approach optimized for performance on embedded systems: Detrending: Single-pole low-pass filter subtraction to remove baseline wander and prevent integer overflows. Bandpass Filtering: Dual biquad IIR filters (Direct Form 1) to isolate the frequency band of interest. SRMAC Stage: A performance-optimized real-time peak detection algorithm using three exponentially weighted moving average (EWMA) filters (fast, slow, and cross). Zero-Crossing Detection: Extracts peaks from the centered SRMAC output using a dynamic threshold (0.0625 * average peak height). Signal Quality Index (SQI): Calculates morphological similarity using the Pearson correlation coefficient between individual peaks and the average peak shape. More details in the README.md