Instruction operation and operand memory location determined based on preceding instruction operation and operand memory location

Abstract

A repeat instruction (RPT) operates on one or more operands, but the RPT instruction includes only an opcode and does not specify locations of the operand or operands. The type of operation to be performed when the RPT instruction is executed depends upon an initial instruction. If, for example, the initial instruction is an ADD, then the RPT instruction causes an ADC operation to be performed, thereby facilitating efficient coding of an extended precision addition operation. The locations of the operands for the RPT instruction are assumed to be in predetermined memory locations. When coding a repeated operation, rather than following the initial instruction with one or more instructions of the same form, the initial instruction is followed by one or more of the shorter RPT instructions, thereby conserving memory space and facilitating backward compatibility with an instruction set that does not have the RPT instruction.