Equalizing FIFO buffer with adaptive watermark
AssigneeRacal Airtech Limited
InventorKevin John Baker
Life of this patent
Estimating the term…
Abstract
Disclosed is a frame processing device (10) for processing frames having a plurality of data bits, a plurality of flag bits and a plurality of zero bits inserted within the data bits to avoid there being a pattern of the data bits which coincide with the pattern of flag bits, the frame processing device (10) comprising a host interface (16) for receiving and transmitting said frames having a first data rate, an encryptor (22) and decryptor (28) for encrypting and decrypting the data bits respectively, a network interface (26) for transmitting and receiving encrypted data bits having a second data rate, and an adaptive first-in first out (FIFO) buffers (22 and 30) for compensating for the difference between said first data rate and second data rate.
Claims16
A method of buffering received frames of data bits comprising:
- inputting the data bits into a first-in first-out buffer at a first data rate;
- outputting the data bits from the buffer at a second data rate when a complete frame of the data bits has been received by the buffer or the amount of the data bits received by the buffer reaches a watermark;
- detecting when the buffer has an underrun condition or an overrun condition;
- detecting when the buffer has an underrun condition or an overrun condition;
- increasing the watermark by a first predetermined amount when the underrun condition is detected;
- decreasing the watermark by a second predetermined amount when the overrun condition is detected;
- and
- monitoring the buffer for a predetermined period of time to determine whether the underrun condition occurs during the predetermined period of time and decreasing the watermark by a third predetermined amount upon not detecting the underrun condition during the predetermined time period.
A frame processing device for processing received frames of data bits comprising means for receiving said data bits with a first data rate;
- data manipulation means being operable for changing the amount of said data bits;
- means for transmitting said data bits with a second data rate;
- first-in first-out (FIFO) buffer means for compensating for a rate difference between said first data rate and said second data rate;
- and said FIFO buffer means including output means for outputting said data bits from said FIFO buffer means when a complete frame of said data bits has been received by said FIFO buffer means or amount of said data bits received by said FIFO buffer reaches a watermark and detection means for detection when said FIFO has an underrun condition of an overrun condition, wherein the improvement is characterized by:
- said FIFO buffer means including underrun means for increasing said watermark by a first predetermined amount when said detection means detects said underrun condition;
- said FIFO buffer means including overrun means for decreasing said watermark by a second predetermined amount when said detection means detects said overrun condition;
- and
- said FIFO buffer means includes watermark adjustment means for decreasing said watermark by a third predetermined amount upon said detection means not detecting an underrun condition during a predetermined time period.
Dependencies are inferred from the claim text.