entropy_health_test

Run OpenTitan Repetition, Adaptive Proportion, and Markov health tests with a unified status byte.

enable_i selects which tests run; window_wrap_pulse_i closes each window. The block exposes raw repetition/APT/Markov counts and apt_fail_hi_o/apt_fail_lo_o pulses.

status_o bits:

[0] Repetition failure
[3] APT high/low
[4] Markov above threshold
[5] Markov below threshold
[1,2,6,7] reserved

count_err_o sets when a health-test counter's duplicate copies disagree (prim_count fault detection), independent of threshold trips; callers must route it to the alert path because a glitched counter can stop reporting real failures.

Parameters

Table 1. Parameters
Name	Type	Default	Description
`DATA_WIDTH`	`int unsigned`	`32`	Number of parallel entropy bit streams tested, one counter set per bit.

Ports

Table 2. Ports
Name	Direction	Type	Description
`clk_i`	input	`logic`	System clock.
`rst_ni`	input	`logic`	Active-low reset.
`entropy_i`	input	`logic [DATA_WIDTH-1:0]`	Entropy word; each bit is tested as its own stream.
`entropy_valid_i`	input	`logic`	Qualifies entropy_i for one sample.
`enable_i`	input	`logic [2:0]`	Per-test enables: bit 0 repetition, bit 1 APT, bit 2 Markov; a clear bit holds that test's counters cleared.
`repetition_limit_i`	input	`logic [7:0]`	Repetition-count failure threshold: a bit repeating this many consecutive samples fails.
`proportion_limit_1bit_i`	input	`logic [15:0]`	APT high threshold; fails when the largest per-bit ones count in a window exceeds it.
`proportion_limit_lo_i`	input	`logic [15:0]`	APT low threshold; fails when the smallest per-bit ones count in a window falls below it.
`markov_prob_01_threshold_i`	input	`logic [15:0]`	Markov high threshold; fails when the largest per-bit 01/10 pair count exceeds it.
`markov_prob_10_threshold_i`	input	`logic [15:0]`	Markov low threshold; fails when the smallest per-bit 01/10 pair count falls below it.
`window_wrap_pulse_i`	input	`logic`	End-of-window strobe that evaluates and restarts the APT and Markov counts.
`ctr_repetition_o`	output	`logic [15:0]`	Longest current run of identical samples across all bit streams.
`apt_pattern_count_1bit_o`	output	`logic [15:0]`	Largest per-bit ones count in the current APT window.
`apt_pattern_count_2bit_o`	output	`logic [15:0]`	Smallest per-bit ones count in the current APT window.
`count_01_o`	output	`logic [15:0]`	Largest per-bit Markov 01/10 pair count in the current window.
`count_10_o`	output	`logic [15:0]`	Smallest per-bit Markov 01/10 pair count in the current window.
`apt_fail_hi_o`	output	`logic`	Single-cycle pulse at a window end where the APT high threshold is exceeded.
`apt_fail_lo_o`	output	`logic`	Single-cycle pulse at a window end where the APT low threshold is undershot.
`status_o`	output	`logic [7:0]`	Health-test failure pulses, encoded as listed above.
`count_err_o`	output	`logic`	Redundant-counter disagreement in any of the three tests.