Methods and apparatus for the intelligent association of control symbols
Methods and apparatus for the intelligent association of control symbols with special symbols that are transmitted over a network. In one embodiment, the association is utilized to improve DC-balance on a transmission medium. In an exemplary variant, the special symbols originate from line codes such as the 8B/10B line code, which format a digital signal so that is optimized for transmission over a given physical channel. These control symbols are divided up according to a first criterion, while the special symbols are further divided up according to a second criterion. The divided control symbols are then allocated to the divided special symbols using a pre-designated allocation algorithm, which may or may not include a scrambling algorithm. The allocation of the control symbols improves signal characteristics and electromagnetic interference (EMI) when various ones of control symbols are ultimately transmitted over a given transmission medium.
1. A method of processing data transmitted on a high-speed bus of a computerized device so as to mitigate electromagnetic interference, the data comprising both control data and payload data, the method comprising:
scrambling at least a portion of the payload data according to a first scheme; and
scrambling at least a portion of the control data according to a second scheme, the second scheme comprising:
dividing the control data into at least two groups, the dividing being based at least in part on a value of a parameter associated with individual ones of the control data;
selectively scrambling at least portions of the at least two groups according to a scrambling algorithm;
looking up a value in a table using a result of the selective scrambling; and
transmitting the value onto the high-speed bus;
wherein the selective scrambling reduces a level of electromagnetic interference when the control data is transmitted on the bus; and
wherein the first scheme comprises a different scheme than the second scheme.
2. The method of claim 1 , wherein the parameter relates to the level of electromagnetic interference created by the individual ones of the control data.
3. The method of claim 1 , wherein the parameter relates to a frequency of occurrence of the individual ones of the control data.
4. The method of claim 1 , wherein at least the payload data is carried according to a packet protocol, and the high-speed bus comprises one compliant with a DisplayPort Standard.
5. The method of claim 1 , further comprising 8B10B encoding at least portions of the control data and payload data.
6. A method for associating a control symbol with a transmitted encoded control code, the method comprising:
determining an index value for the control symbol;
for a subset of control symbols, the subset determined by an expected frequency of use, executing a logical function on the index value to create an encoded value;
associating an encoded control code with the encoded value; and
transmitting the encoded control code over a physical medium;
wherein electromagnetic interference associated with the medium is reduced when the encoded control code is transmitted with other encoded control codes.
7. The method of claim 6 , wherein the control symbol comprises a DisplayPort control symbol, and the encoded control code comprises an 8B10B code.
8. The method of claim 6 , wherein the logical function comprises an exclusive OR (XOR) function.
9. A method for associating a control function associated with an audiovisual implementation with a Direct Current (DC)-balanced control code, the method comprising:
determining a grouping for the control function based at least in part on a frequency of occurrence of the control function;
associating an index value for the control function based at least in part on the determination of the grouping; and
when the grouping for the control function comprises a first group:
executing a logical function on the index value to create an encoded value;
associating the encoded value with the DC-balanced control code; and
transmitting the DC-balanced control code onto a network bus;
when the grouping for the control function comprises a second group:
associating the index value with the DC-balanced control code; and
transmitting the DC-balanced control code onto the network bus.
10. The method of claim 9 , wherein the logical function comprises an exclusive OR (XOR) function, and the DC-balanced control code comprises a constant-weight line code.
11. The method of claim 9 , wherein the act of determining a grouping for the control function comprises determining one of a first group and a second group, the first group having a larger population than the second group.
12. A method of processing control data transmitted on a bus of a computerized device, the control data being associated with payload data, the method comprising:
dividing the control data into at least two groups based at least in part on a criterion associated with individual ones of the control data;
selectively scrambling at least a portion of at least one of the two groups according to a scrambling algorithm;
looking up a value in a table using a result of the selective scrambling; and
transmitting the value onto the bus;
wherein the selective scrambling reduces a level of electromagnetic interference when the control data is transmitted on the bus; and
wherein the criterion relates to a frequency of occurrence of the individual ones of the control data.
13. The method of claim 12 , wherein the criterion relates to a level of electromagnetic interference created by the individual ones of the control data.
14. The method of claim 12 , wherein the scrambling algorithm comprises an exclusive OR (XOR) function.