Flipdot-display/src/esp32/logic/frame_check.cpp

#include "logic/frame_check.h"

#include <string.h>

#include "config.h"

static int hexDigit(char c)
{
	if (c >= '0' && c <= '9')
		return c - '0';
	if (c >= 'A' && c <= 'F')
		return c - 'A' + 10;
	if (c >= 'a' && c <= 'f')
		return c - 'a' + 10;
	return -1;
}

void FrameCheck::reset(uint32_t now)
{
	_pending = false;
	_checked_any = false;
	_replied = false;
	_problem = false;
	// Switching on sends the whole image anyway
	_last_resync = now;
}

bool FrameCheck::due(uint32_t frames_sent, uint32_t now) const
{
	// A repair is coming anyway: no need to count the same problem again
	if (_pending || _problem)
		return false;
	if (!_checked_any)
		return true;
	return frames_sent != _checked_frames && now - _last_check >= FRAME_CHECK_INTERVAL;
}

void FrameCheck::sent(uint16_t expected, uint32_t frames_sent, uint32_t now)
{
	_pending = true;
	_expected = expected;
	_sent_at = now;
	_checked_any = true;
	_checked_frames = frames_sent;
	_last_check = now;
}

void FrameCheck::line(const char *text, uint32_t now)
{
	(void)now;
	size_t len = strlen(text);
	while (len && (text[len - 1] == '\r' || text[len - 1] == ' '))
		len--;

	if (len == 6 && text[0] == 'C' && text[1] == ' ')
	{
		int value = 0;
		for (int i = 2; i < 6; i++)
		{
			int d = hexDigit(text[i]);
			if (d < 0)
				return;
			value = value << 4 | d;
		}
		_replied = true;
		if (!_pending)
			return; // late answer to a check that already timed out
		_pending = false;
		if (value == _expected)
			_stats.checks++;
		else
		{
			_stats.mismatches++;
			_problem = true;
		}
		return;
	}
	if (strncmp(text, "ERR", 3) == 0)
	{
		_replied = true;
		_stats.errors++;
		size_t n = len < sizeof(_stats.last_error) - 1 ? len : sizeof(_stats.last_error) - 1;
		memcpy(_stats.last_error, text, n);
		_stats.last_error[n] = '\0';
		return;
	}
	if (len >= 5 && strncmp(text, "READY", 5) == 0)
	{
		// The Nano restarted while it was on: its image is gone
		_replied = true;
		_stats.restarts++;
		_pending = false;
		_problem = true;
	}
}

bool FrameCheck::resyncNow(uint32_t now, uint32_t resync_ms)
{
	if (_pending && now - _sent_at >= FRAME_CHECK_TIMEOUT)
	{
		_pending = false;
		_stats.no_reply++;
		// Only when answers can arrive at all (old Nano firmware, TX not wired: never)
		if (_replied)
			_problem = true;
	}
	if (_problem && now - _last_resync >= FRAME_REPAIR_MIN_GAP)
	{
		_problem = false;
		_stats.repairs++;
		_last_resync = now;
		return true;
	}
	if (resync_ms && now - _last_resync >= resync_ms)
	{
		_last_resync = now;
		return true;
	}
	return false;
}