Abstract: A program execution device with a small required memory storage capacity includes: a compressed code storing portion storing a code which has been compressed on a prescribed unit basis of a program described in a prescribed language; an expanding portion connected to the compressed code storing portion for expanding the compressed code stored in the compressed code storing portion; a code storing portion connected to the expanding portion for storing the code expanded by the expanding portion; and an interpreter portion connected to the code storing portion for interpreting and executing the expanded code.

Abstract: An adaptive difference computing element which consumes less power without any decrease in calculation accuracy includes: a first circuit receiving first and second data with the same bit lengths and each having bits at one and the other ends, determining if a prescribed relation is obtained between a bit string from each bit to the bit at one end of the first data and that of the second data for each bit of the first data and corresponding each bit of the second data, and replacing the each bit of the first data and the corresponding each bit of the second data with same predetermined bit values if the prescribed relation is obtained, and otherwise directly outputting the first and second data; and a subtracter having inputs connected to receive the first and second data from the first circuit, respectively.

Abstract: A motion estimation method capable of setting an optimum threshold value and allowing high speed processing includes the steps of: sequentially selecting one of blocks to be searched from a search range; sequentially calculating a difference between corresponding sample values of a reference block and one of blocks to be searched and accumulating an absolute value of difference; comparing an intermediate result of an accumulation value and a prescribed threshold value for a prescribed number of samples and interrupting the step of accumulating the absolute value of difference when the intermediate result exceeds the prescribed threshold value; and making one of blocks to be searched having a minimum final result of the accumulation value correspond to the reference block. The prescribed threshold value is dependent on the reference block. It is noted that the motion estimation apparatus is also disclosed.

Abstract: A data processing device includes a processor core, and a memory interface portion arranged between the processor core and an external memory mapped into a predetermined external memory space. The memory interface portion includes a fetch circuit for receiving an address value for access to the external memory space from the processor core, and fetching the data at the address in the external memory, a translator for translating the nonnative instruction fetched from the external memory into the native instruction, and a select circuit for selectively applying the data read from the external memory space and the instruction prepared by translating the instruction read from the external memory space by the translator to the processor core depending on whether the address value for the access to the external memory space is in a predetermined region or not.

Abstract: A data processor includes a hardware translator converting non-native code into a native code to a processor, a software translator converting non-native code into a native code to the processor by software, and a software interpreter sequentially interpreting a code that is non-native to the processor, and executing the interpreted code using a native code of the processor. The data processor includes a circuit selecting the hardware translator, software translator or software interpreter according to a predetermined criterion for operation.

Abstract: A data processor in accordance with the present invention makes it possible to perform pre-branch processing with respect to a return address in the initial stage of pipeline processing also on a subroutine return instruction, and therefore by providing a stack memory (PC stack) dedicated to a program counter (PC) for storing only return addresses of the subroutine return instruction, in executing a subroutine call instruction in an execution stage of a pipeline processing mechanism, the return address from the subroutine is pushed to the PC stack, and the pre-branch processing is performed to the address popped from the PC stack in decoding the subroutine return instruction in an instruction decoding stage.

Abstract: In a data processor, using a format field which specifies the number of operation fields of an instruction code and an order of execution of operations, the number of operations and the order of operation executions are flexibly controlled and the necessity of a null operation is reduced, and decoders operate in parallel each decoding only one operation having a specific function which has a dependency on an operation execution mechanism, so that the operation fields of the instruction code are decoded in parallel by a number of decoders. While the data processor is basically a VLIW type data processor, more types of operations can be specified by the operation fields, and coding efficiency of instructions is improved since the number of operation fields and the order of operation executions are flexibly controlled and the necessity of a null operation is reduced by means of the format field which specifies the number of the operation and the order of the operation executions.

Abstract: In a data processor, using a format field which specifies the number of operation fields of an instruction code and an order of execution of operations, the number of operations and the order of operation executions are-flexibly controlled and the necessity of a null operation is reduced, and decoders operate in parallel each decoding only one operation having a specific function which has a dependency on an operation execution mechanism, so that the operation fields of the instruction code are decoded in parallel by a number of decoders. While the data processor is basically a VLIW type data processor, more types of operations can be specified by the operation fields, and coding efficiency of instructions is improved since the number of operation fields and the order of operation executions are flexibly controlled and the necessity of a null operation is reduced by means of the format field which specifies the number of the operation and the order of the operation executions.

Abstract: When fetching an instruction from a plurality of memory banks, a first pipeline stage corresponding to selection of a memory bank and a second pipeline stage corresponding to instruction readout are generated to carry out a pipeline process. Only the selected memory bank can be precharged to allow reduction of power consumption. Since the first and second pipeline stages are effected in parallel, the throughput of the instruction memory can be improved.

Abstract: A semiconductor circuit device (encoder) is provided with: a functional block for carrying out an encoding process and for generating a first access signal for accessing a memory; a slave IF terminal for receiving a second access signal; and a first selector having a first connection mode for electrically connecting the functional block and the memory so as to supply the first access signal to the memory and a second connection mode for electrically connecting the slave IF terminal and the memory so as to supply the second access signal to the memory. Each of the first and second access signals has an address signal for specifying a storing position in the memory and a control signal for controlling the operation of the memory.

Abstract: A data processing device having a PC controlling part for executing an operation of branch which has a first register for holding a result of decoding in an instruction decode unit, a register for holding a description indicating an execution condition of the operation (a value of field for designating condition), and a register for holding the description indicating a time for executing the operation (an address value of PC), wherein the execution condition is started when a value held in the register is in agreement with a PC value in accordance with the description of the register; and if the condition is satisfied, the PC controlling part executes the operation based on a content held in the register, whereby it is possible to delay the time for judging the execution condition during this delay, to thereby increase a degree of freedom in scheduling instructions such that the branch instruction is positioned prior to the operation instruction for determining the execution condition in the program.

Abstract: In accordance with selection signals corresponding to an operation mode from a mode detection circuit, the voltage levels of back gate voltages applied to the back gates of MOS transistors included in internal circuitry are selected, by the selection signals, among the voltages from voltage generation circuits for generating a plurality of voltages having different voltage levels. The threshold voltage and the drive current of the MOS transistor are adjusted in accordance with the operation mode, and the semiconductor integrated circuit device which operates at high speed with low current consumption can be achieved.

Abstract: A microprocessor executes delayed instructions in which decoded results obtained at the instruction decoder unit 2 are stored in the ALU 361, the multiplier 363, the PC controller 365, the memory controller 367, and the shifter 369, and a program counter value related to a delayed value specified by a delayed instruction is stored into registers 362B, 364B, 366B and 370B.

Abstract: An MPEG2 decoder portion decodes an input bit stream and outputs a digital decoded image while extracting coding information and supplying the same to a control portion. An MPEG2 encoder portion re-encodes the digital decoded image output from the MPEG2 decoder portion. Coding information supplied from the control portion is reflected on a coding parameter in re-encoding. Transcoding between the MPEG2 standard and the DV standard can also be executed by arranging a decoder or an encoder corresponding to the DV standard in place of either the MPEG2 decoder portion or the MPEG2 encoder portion.

Abstract: The instruction translator includes a translator for reading out a corresponding instruction from the instruction memory in response to the received address to be executed by the processor and translating the instruction in a second instruction architecture into an instruction in a first instruction architecture, an instruction cache for temporarily holding the instruction in the first instruction architecture after the translation by the translator in association with the address in the instruction memory, and a selector for searching the instruction cache in response to the received address of an instruction to be executed by the processor, and based on a determination result of whether or not an instruction corresponding to the instruction of the address is held in the instruction cache, selectively outputting an instruction output by the translator, and the corresponding instruction in the first instruction architecture which has been held in the instruction cache.

Abstract: A microprocessor and a data processor therefor which have separate data and instruction buses, and wherein a data address and an instruction address are output over a single address bus in a time-shared manner, thereby allowing a data access and an instruction access to be pipelined without the need for separate address buses between the microprocessor and caches holding data and instructions.

Abstract: A data processor in accordance with the present invention makes it possible to perform pre-branch processing with respect to a return address in the initial stage of pipeline processing also on a subroutine return instruction, and therefore by providing a stack memory (PC stack) dedicated to a program counter (PC) for storing only return addresses of the subroutine return instruction, in executing a subroutine call instruction in an execution stage of a pipeline processing mechanism, the return address from the subroutine is pushed to the PC stack, and the pre-branch processing is performed to the address popped from the PC stack in decoding the subroutine return instruction in an instruction decoding stage.

Abstract: A data processor performs various types of EIT (exception, interrupt, trap) processing in connection with the execution of the preceding and following instructions in parallel. In one embodiment, an exception is detected resulting from processing the previous instruction in the pair being executed in parallel before completion of instruction processing where the exception requires re-execution. When the exception is detected a control means prevents the execution means from executing both preceding and following instructions. An additional feature is a control unit that controls when an interrupt is accepted during parallel execution. In another embodiment, a first decoder outputs suppressing information when the preceding instruction is a predetermined instruction having a possibility of causing a trap. A validity judgment circuit prevents the second decoded result from being issued when suppressing information is generated.

Abstract: In a data processor, using a format field which specifies the number of operation fields of an instruction code and an order of execution of operations, the number of operations and the order of operation executions are flexibly controlled and the necessity of a null operation is reduced, and decoders operate in parallel each decoding only one operation having a specific function which has a dependency on an operation execution mechanism, so that the operation fields of the instruction code are decoded in parallel by a number of decoders. While the data processor is basically a VLIW type data processor, more types of operations can be specified by the operation fields, and coding efficiency of instructions is improved since the number of operation fields and the order of operation executions are flexibly controlled and the necessity of a null operation is reduced by means of the format field which specifies the number of the operation and the order of the operation executions.

Abstract: In accordance with selection signals corresponding to an operation mode from a mode detection circuit, the voltage levels of back gate voltages applied to the back gates of MOS transistors included in internal circuitry are selected, by the selection signals, among the voltages from voltage generation circuits for generating a plurality of voltages having different voltage levels. The threshold voltage and the drive current of the MOS transistor are adjusted in accordance with the operation mode, and the semiconductor integrated circuit device which operates at high speed with low current consumption can be achieved.