Computer and method for performing immediate calculation by utilizing the computer

A computer for performing an immediate calculation, comprising:

• a calculation instruction for storing a first operation code which represents a general calculation, a plurality of register numbers, and a first immediate value, the calculation instruction representing an immediate calculation instruction for executing the immediate calculation in cases where one of the register numbers is a first specific number;
• an immediate prefixed instruction for storing a second operation code which represents no effective calculation, a second specific register number, and a second immediate value;
• register file means for storing first and second source operands and a calculation result in prescribed registers which are designated by the register numbers stored in the calculation instruction;
• instruction registering means for storing the immediate prefixed instruction and the calculation instruction in turn;
• immediate value generating means for generating a new immediate value by concatinating the first immediate value stored in the immediate calculation instruction with the second immediate value stored in the immediate prefixed instruction;
• and
• immediate calculation performing means for
• (1) performing the general calculation according to the first operation code stored in the calculation instruction by utilizing both the first and second source operands stored in the register file means
• (2) performing the immediate calculation according to the first operation code stored in the immediate calculation instruction by utilizing both the first source operand stored in the register file means and the new immediate value generated in the immediate value generating means in cases where the instruction registering means stores the first specific register number and
• (3) performing no effective calculation according to the second operation code stored in the immediate prefixed instruction in cases where the instruction registering means stores the second specific register number.

A method for performing an immediate calculation to execute an immediate calculation instruction which is a type of calculation instruction by utilizing a computer, comprising:

• storing either the calculation instruction incorporating a first immediate value or an immediate prefixed instruction containing a second immediate value in an instruction register, the immediate prefixed instruction being executed prior to the execution of the immediate calculation instruction;
• interpreting whether the instruction stored in the instruction register is the calculation instruction or the immediate prefixed instruction in an instruction decoder;
• registering the second immediate value contained in the immediate prefixed instruction in a second immediate register in cases where the instruction decoder interprets the instruction stored in the instruction register to be the immediate prefixed instruction;
• setting a flag in a prefix state flag when the second immediate value in the immediate prefixed instruction is stored in the second immediate register and resetting the flag when the execution of the calculation instruction is finished;
• concatenating first serial bits forming the first immediate value in the calculation instruction stored in the instruction register with second serial bits forming the second immediate value in the immediate prefixed instruction in a concatenation unit in cases where the flag in the prefix state flag is set;
• generating the immediate value concatenated in the concatenation unit as a first constant;
• extending the number of bits represented by the first immediate value which is contained in the immediate calculation instruction stored in the instruction register to the number of bits represented by the first constant without changing the first immediate value in a bit extender in cases where the instruction decoder interprets the instruction stored in the instruction register to be the calculation instruction;
• generating the first immediate value extended by the bit extender as a second constant;
• selecting the first constant generated in the concatenation unit in a constant selector in cases where the flag in the prefix state flag is set and selecting the second constant generated in the bit extender in the constant selector in cases where the flag in the prefix state flag is reset;
• judging whether or not the instruction stored in the instruction register is the immediate calculation instruction in a judgement unit;
• and
• performing the immediate calculation to process the constant selected in the constant selector in cases where the judgement unit judges that the immediate calculation instruction is stored in the instruction register.