Abstract: A method and system of executing computer instructions is described. Each instruction defines first and second operands and an operation to be carried out on said operands. Each instruction also contains an address field of a predetermined bit length which identifies a test register holding a plurality of test bits greater than the predetermined bit length. The test register holds a test code defining a test condition. The test condition is checked against at least one condition code and the operation is selectively carried out in dependence on whether the condition code satisfies the test condition. In one embodiment, the condition codes are set on a lane-by-lane basis for packed operands.

Abstract: A method of executing instructions in a computer system on operands containing a plurality of packed objects in respective lanes of the operand is described. Each instruction defines an operation and contains a condition setting indicator settable independently of the operation. The status of the condition setting indicator determines whether or not multibit condition codes are set. When they are to be set, they are set depending on the results for carrying out the operation for each lane.

Abstract: A method of executing instructions in a computer system on operands containing a plurality of packed objects in respective lanes of the operand is described. Each instruction defines an operation and contains a condition setting indicator settable independently of the operation. The status of the condition setting indicator determines whether or not multibit condition codes are set. When they are to be set, they are set depending on the results of carrying out the operation for each lane.

Abstract: A method and system of executing computer instructions is described. Each instruction defines first and second operands and an operation to be carried out on said operands. Each instruction also contains an address field of a predetermined bit length which identifies a test register holding a plurality of test bits greater than the predetermined bit length. The test register holds a test code defining a test condition. The test condition is checked against at least one condition code and the operation is selectively carried out in dependence on whether the condition code satisfies the test condition. In one embodiment, the condition codes are set on a lane-by-lane basis for packed operands.

Abstract: There is disclosed a technique for accessing a register file which comprises defining a first register address as a plurality of bits and using said first register address to access said register file generating a second register address by using a sequence of said plurality of bits with at least one of said plurality of bits supplied via a unitary operator, the unitary operator being effective to selectively alter the logical value of said bit depending on its logical value in the first register address, and using said second register address to access said register file. A computer system for carrying out such a technique is also enclosed.

Abstract: An execution unit and a new set of instructions for performing Viterbi decoding are provided. The instructions can be built into an execution unit which executes other instructions, or in their own execution unit. In an example implementation, the new set of instructions are used in implementing a modem for a high bit rate single-pair high speed digital subscriber line (“SHDSL”) system. In the example implementation, the execution unit includes registers to hold the input metrics, so the same metrics do not need to be supplied for each instruction that uses them. The execution unit also includes registers to accumulate decision values, so that as many can be retrieved at once as makes best use of the data path out of the execution unit. The instructions may employ modulo arithmetic to avoid the necessity to rescale the state metrics.

Abstract: An execution unit and method for performing Viterbi decoding is provided. The instruction may be built into an execution unit which executes other instructions, or in its own execution unit. In an example implementation, the instruction is used in implementing the central-office modem (ATU-C) of an asymmetric digital subscriber line (“ADSL”) system. In the example implementation, the new instruction takes as input eight input metrics and eight state metrics, and returns as output eight updated state metrics and eight decision bytes. The decision bytes contain: two ‘path’ bits to enable the previous state to be quickly identified; bits to enable the input bits to be quickly identified; and a carry bit to allow the full value of a state metric to be reconstructed, even though during the calculation only the bottom bits are calculated.

Abstract: A memory access system is described which generates two memory addresses from a single memory access instruction which identifies a register holding at least two packed objects. In the preferred embodiment, the contents of a base register is combined respectively with each of two or more packed objects in an offset register.

Abstract: There is disclosed a technique for accessing a register file which comprises defining a first register address as a plurality of bits and using said first register address to access said register file generating a second register address by using a sequence of said plurality of bits with at least one of said plurality of bits supplied via a unitary operator, the unitary operator being effective to selectively alter the logical value of said bit depending on its logical value in the first register address, and using said second register address to access said register file. A computer system for carrying out such a technique is also enclosed.

Abstract: A method of and device for performing a data expansion operation on a plurality of input data objects to generate expanded output data objects is disclosed. The method comprises receiving and decoding a data manipulation instruction defining a data expansion operation, a portion of the data manipulation instruction indicating an expansion operation from a number of predetermined types of data manipulation operations. The method includes generating one or more expansion objects responsive to the indication of an expansion operation, said expansion objects being for use in extending an input data object. The input data objects are manipulated according to control information expansion objects programmed to produce a set of expanded output data objects.

Abstract: A memory access system is described which generates two memory addresses from a single memory access instruction which identifies a register holding at least two packed objects. In the preferred embodiment, the contents of a base register is combined respectively with each of two or more packed objects in an offset register.

Abstract: A method of decompressing data words of an instruction set includes:

Abstract: A method is provided of processing data representing pixel colour having a luminance component and colour difference components. The data is divided into first and second data portions, the first data portion comprising the luminance components and the second data portion comprising the colour difference components. First and second instructions from a combined instruction word, and the first and second date portions are processed in parallel using first and second parallel processors within a processor architecture, the first and second parallel processors operating according to the first and second instructions, respectively. The processed first and second data portions are combined to provide processed pixel colour data. This method uses parallel processor sections to process the luminance and colour difference components. The parallel processor sections can then use instructions suited to the type of data being processed, providing an efficient method of processing the graphics data.

Abstract: A memory access system is described which generates two memory addresses from a single memory access instruction which identifies a register holding at least two packed objects. In the preferred embodiment, the contents of a base register is combined respectively with each of two or more packed objects in an offset register.

Abstract: A method of decompressing data words of an instruction set includes: A. filling a primary dictionary with at least one primary data word of the instruction set, each of the at least one primary data word being stored in the primary dictionary in a location associated with a distinct primary dictionary index; B. filling at least one secondary dictionary with at least one difference bit stream, each of the at least one difference bit stream being stored in one of the at least one secondary dictionary in a location associated with a distinct secondary dictionary index; C. receiving a code word, the code word comprising: a. a header which identifies the primary dictionary and a specific one of the at least one secondary dictionary; b. a first bit stream; and c. a second bit stream; wherein the first bit stream comprises the distinct primary dictionary index and the second bit stream comprises the distinct secondary dictionary index; D.

Abstract: There is disclosed a technique for accessing a register file which comprises defining a first register address as a plurality of bits and using said first register address to access said register file generating a second register address by using a sequence of said plurality of bits with at least one of said plurality of bits supplied via a unitary operator, the unitary operator being effective to selectively alter the logical value of said bit depending on its logical value in the first register address, and using said second register address to access said register file. A computer system for carrying out such a technique is also enclosed.

Abstract: A memory access system is described which generates two memory addresses from a single memory access instruction which identifies a register holding at least two packed objects. In the preferred embodiment, the contents of a base register is combined respectively with each of two or more packed objects in an offset register.

Abstract: A method of and device for performing a data expansion operation on a plurality of input data objects to generate expanded output data objects is disclosed. The method comprises receiving and decoding a data manipulation instruction defining a data expansion operation, a portion of the data manipulation instruction indicating an expansion operation from a number of predetermined types of data manipulation operations. The method includes generating one or more expansion objects responsive to the indication of an expansion operation, said expansion objects being for use in extending an input data object. The input data objects and said expansion objects are manipulated according to control information programmed to produce a set of expanded output data objects.

Abstract: A method of decompressing data words of an instruction set includes:

Abstract: A method and system of executing computer instructions is described. Each instruction defines first and second operands and an operation to be carried out on said operands. Each instruction also contains an address field of a predetermined bit length which identifies a test register holding a plurality of test bits greater than the predetermined bit length. The test register holds a test code defining a test condition. The test condition is checked against at least one condition code and the operation is selectively carried out in dependence on whether the condition code satisfies the test condition. In one embodiment, the condition codes are set on a lane-by-lane basis for packed operands.