High CPU consumption

[mh1412]

Overview

Running the library will consume 70% CPU time on an i7 10th Gen CPU.
Library need to be optimized to to consume less CPU resource

How to reproduce

• Start point cloud viewer server using tau-lidar-camera module
• Start activity monitor (on Mac computer)
• Observe Python process is consuming 70% CPU

[vsemi]

I thought Zheng mentioned solved by he modifying the javascript in UI. Or not?

[ziguana]

I am not a Python expert, but I think the issue is in _calcCrc32Uint32(crc, data). When crc is shifted left, it needs to be truncated with & 0xFFFFFFFF, or it gets turned into a big int and grows quite large.

tau-lidar-camera/TauLidarCamera/crc.py

Lines 8 to 15 in a70b24e

	def _calcCrc32Uint32(crc, data) :
	crc = crc ^ data
	for i in range(32) :
	if crc & 0x80000000 :
	crc = (crc << 1) ^ POLYNOM
	else :
	crc = crc << 1
	return(crc)

I traced the value of crc on a 10-byte command and it topped out at 9041709683971943732904854826748712756544968371426423194332838811441949002642410130889108712225116206824332. I imagine the issue is much worse on larger messages.