Method of implementing fast 486TM microprocessor compatible string operations

A method of repetitively implementing a string operation to compare a first block of data stored in a first memory location with a second block of data stored in a second memory location, comprising:

• reading a portion of the first block of data from the first memory location;
• updating and committing a value of a first register which indicates an address of a next portion of the first block of data to be read from the first memory location;
• setting an indicator corresponding to the first register to indicate that the first register is in an inconsistent state;
• reading a portion of the second block of data from the second memory location;
• updating and committing a value of a second register which indicates an address of a next portion of the second block of data to be read from the second memory location;
• setting an indicator corresponding to the second register to indicate that the second register is in an inconsistent state.
• comparing the portion of the first block of data to the portion of the second block of data;
• and
• repeating the above steps of the method until the entire first and second blocks of data have been compared with each other, wherein the method steps are stopped when the portion of the first block of data is unequal to the portion of the second block of data, and further, wherein if an exception occurs during the method steps, the method further comprises:
• executing an exception handling routine which checks the state of the indicators corresponding to the first and second registers;
• and
• restoring the values of the first and second registers to values they had prior to the occurrence of the exception by appropriately incrementing or decrementing the register values if the registers are in an inconsistent state.

A method of repetitively implementing a string operation to process a block of data stored in memory, comprising:

• performing a data processing operation on a portion of the block of data;
• updating and committing a register value of a register which indicates an address of a next portion of the block of data to be processed by performing the data processing operation on it;
• setting an indicator corresponding to the register to indicate that the register is in an inconsistent state;
• and
• repeating the above steps of the method until the data processing operation has been performed on the entire block of data, wherein if an exception occurs during the method steps, the method further comprises:
• executing an exception handling routine which checks the state of the indicator;
• and
• restoring the register value to a value it had prior to the occurrence of the exception by appropriately incrementing or decrementing the register value if the register is in an inconsistent state.