Apparatus for decoding frames from a data link
First Claim
1. Apparatus for decoding frames from a data link, each frame having multiple data characters, said apparatus comprising:
- a frame input connected to said data link for the receipt thereon of a received frame from the data link;
an expect/mask buffer, having a first portion for storing a reproduction of expected characters expected to be in said received frame, and a second portion for storing a mask indicating which bits of the characters of said received frame are to be compared to corresponding bits of said expected characters in the first portion;
compare means for comparing characters of said received frame to corresponding expected characters in the first portion of said expect/mask buffer as masked by said second portion;
a compare register connected to said compare means for storing the results of the comparison of said compare means;
a header buffer having multiple entries and being connected to said frame input, each entry thereof for storing characters of one of the frames received by said frame input; and
a compare buffer having multiple entries and being connected to said compare register, each entry thereof for storing the contents of said compare register resulting from the comparison by said compare means for the corresponding frame entry in said header buffer.
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Accused Products
Abstract
An apparatus for decoding frames from a data link including a multiple entry expect/mask buffer an input for receiving multiple character frames, a comparator for comparing characters received from the data link with expected characters in the expect/mask buffer as masked by a mask also in the expect/mask buffer, a multiple entry header buffer for storing characters of frames received by the input, and a multiple entry compare buffer for storing in an entry the results of the comparison of the characters stored in the corresponding entry in the header buffer to expected characters as masked by the mask in a corresponding entry of the expect/mask buffer. Storage into the header buffer and the compare buffer is stopped by terminating events which are detected by a state machine. A data frame recognition circuit is provided which detects a variety of data frames from among the frames transmitted over the data link to the input of the apparatus.
56 Citations
13 Claims
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1. Apparatus for decoding frames from a data link, each frame having multiple data characters, said apparatus comprising:
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a frame input connected to said data link for the receipt thereon of a received frame from the data link; an expect/mask buffer, having a first portion for storing a reproduction of expected characters expected to be in said received frame, and a second portion for storing a mask indicating which bits of the characters of said received frame are to be compared to corresponding bits of said expected characters in the first portion; compare means for comparing characters of said received frame to corresponding expected characters in the first portion of said expect/mask buffer as masked by said second portion; a compare register connected to said compare means for storing the results of the comparison of said compare means; a header buffer having multiple entries and being connected to said frame input, each entry thereof for storing characters of one of the frames received by said frame input; and a compare buffer having multiple entries and being connected to said compare register, each entry thereof for storing the contents of said compare register resulting from the comparison by said compare means for the corresponding frame entry in said header buffer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification