Output Ports

Port Name

Required

Description

Comments

q[]

Yes

Data output from csfifo.

Output port LPM_WIDTH wide.

full

No

Indicates that csfifo is full.

 

empty

No

Indicates that csfifo is empty.

 

threshold

No

Indicates that csfifo contains greater than the threshlevel[] number of words.

 

usedw

No

The number of csfifo words that are currently being used.

Output port with width [CEIL(LOG2(LPM_NUMWORDS))-1..0].

If the value of LPM_NUMWORDS is a power of 2, you can use the full output as an extra bit and append it to usedw[].

The following table shows the difference between using only the usedw[] output and using the full output with the usedw[] output. In this example, LPM_NUMWORDS = 256.

csfifo status

usedw[]

(full, usedw[])

empty (0 used words)

0

0

3 used words

3

3

200 used words

200

200

full (256 used words)

0

256

The csfifo must contain at least one word before it is able to read the word and must have at least one unused word before it is able to write a word.