Blank bit and processor instructions employing the blank bit

摘要

Reading a value into a register, checking to see if the value is a NULL, and then jumping out of a loop if the value is a NULL is a common task that processors perform. To speed performance of such a task, a novel “blank bit” is added to the flag register of a processor. When a first instruction (arithmetic, logic or load) is executed, the instruction operands are checked to see if any is a NULL character value. Information on the result of the check is stored in the blank bit. Execution of a second instruction uses the information stored in the blank bit to determine whether or not a second operation (for example, a jump) will be performed. By using the first and second instructions in a loop, the number of instructions executed to check for NULLs at the end of strings and arrays is reduced.

主权项

1. A method comprising:
(a) executing a first instruction, comprising:
storing a first value in a bit if a first operand of the first instruction is equal to zero, otherwise storing a second value in the bit; andafter the storing in (a) performing a first operation associated with the first instruction using the first operand; and (b) executing a second instruction, comprising:
performing a second operation associated with the second instruction if the bit is storing the first value, otherwise not performing the second operation.