Method and apparatus for data alignment

An apparatus for the synchronization of an F.sub.-- port receiver on a Fibre Channel switch with an N.sub.-- port that transmits a stream of transmission characters including periodic four byte ordered sets that include a 10 bit comma character as the first byte, comprising:

• detection circuitry that detects the presence and position of a comma character within one of the four-byte ordered sets, said detection circuitry comprising a four stage transmission character register bank for storing transmission characters in four registers and a four stage comma presence register bank that generates a one-bit flag in one of four registers corresponding to the register in the transmission character register bank that contains a comma character;
• alignment circuitry that aligns the detected comma character such that it is positioned as the first byte in the four byte ordered set;
• a comma presence multiplexor that receives the four outputs of the comma presence register bank;
• a transmission character register bank multiplexor that receives the four outputs of the transmission character register bank;
• and
• control logic synchronized by a clock enable system synch pulse, wherein the control logic ascertains whether the detected comma character is located as the left most register in the transmission character register bank, wherein, if more than one comma character is identified, the control logic locks onto the last comma character entering the transmission character register bank such that the receiver is synchronized and a stream of data arrives having comma characters at regular intervals.

A method for transmission character alignment in a Fibre Channel receiver in which a GLM/OLC transceiver provides a stream of transmission characters, comprising the method steps of:

• grouping the incoming stream of transmission characters into four-byte words within a transmission character register bank,
• detecting comma characters within the transmission character register bank,
• aligning comma characters such that there is only one comma character and it occurs as the left most byte within the register bank, and
• in response to detecting excessive comma characters during the detecting step, masking out the excessive comma characters.

An apparatus for the synchronization of an F.sub.-- port receiver on a Fibre Channel switch with an N.sub.-- port that transmits a stream of transmission characters including periodic ordered sets that include a comma character in a specified position in the ordered set, comprising:

• a transmission character register bank for storing transmission characters in registers;
• a comma presence register bank that generates a one-bit flag in a register indicating one register in the transmission character register bank that contains a comma character;
• alignment circuitry that aligns the detected comma character such that it is positioned in the specified position in the ordered set;
• a comma presence multiplexor that receives the one-bit flag from the comma presence register bank;
• a transmission character register bank multiplexor that receives the stored transmission characters from the transmission character register bank;
• and
• control logic synchronized by a clock enable system synch pulse, wherein the control logic ascertains whether the detected comma character is located in the specified position in the transmission character register bank, wherein, if more than one comma character is identified, the control logic positions the last comma character entering the transmission character register bank into the specified position such that the receiver is synchronized to the last comma character and a stream of data arrives having comma characters at regular intervals.