Abstract: The present invention provides a technique for swapping data values within a data word. In particular, a single endian reverse instruction is provided to cause independent swap operations to be performed on particular sections of an input data word. The data processing apparatus of the present invention comprises a data processing unit for executing instructions which is responsive to the endian reverse instruction to apply an endian reverse operation to an input data word Rm comprising a plurality of data values.

Abstract: The present invention provides a technique for swapping data values within a data word. In particular, a single endian reverse instruction is provided to cause independent swap operations to be performed on particular sections of an input data word. The data processing apparatus of the present invention comprises a data processing unit for executing instructions which is responsive to the endian reverse instruction to apply an endian reverse operation to an input data word Rm comprising a plurality of data values.

Abstract: A data processing apparatus and method is provided, wherein in a first mode of operation, data of a first data type is processed, and in a second mode of operation, data of a second data type consisting of an even multiple of data words is processed. The data processing apparatus comprises a register bank having a plurality of data slots for storing data words of data of said first type data and data words of data of said second type data, and transfer logic, responsive to a store instruction, to control the storing of the data words in the register bank to a memory. Further, a format register is provided for storing format data indicating the distribution in the register bank of data words of data of said first data type and data words of data of said second data type.

Abstract: A data processing system is described utilizes a multiplier-accumulator 108 that performs both a first class of multiply-accumulate instructions and a second class of multiply-accumulate instructions. The first class of multiply-accumulate instructions are of the form N*N+N.fwdarw.N and the second class of multiply-accumulate instructions are of the form N*N+2N.fwdarw.2N. The second class of multiply-accumulate instructions provide a greater precision of arithmetic in a single instruction and avoid the use of excessive instruction set space by being constrained that the result is written back into the two registers from which the 2N-bit accumulate value was taken. The multiplier-accumulator also provides N*N.fwdarw.N and N*N.fwdarw.2N multiplication operations.

Abstract: A multiply-accumulate circuit is described in which upon each multiply iteration some of the accumulate value bits are incorporated into the result with lower order subsequently non-changing bits being latched. In this way, a wide accumulate value can be dealt with without incurring a correspondingly wide data path through the multiply accumulate circuit. Initialisation of the multiply accumulate circuit with one of the carry value and save value as the first partial summand and the other as at least part of the accumulate value is performed to reduce the total number of iterative cycles required to produce the result.

Abstract: An apparatus for mapping a logical pixel value 2 defining pixel appearance to a plurality of physical appearance component values for driving a display device is described. Read addresses for a plurality of palettes 4, 6, 8 and 10 are derived from bits of the logical pixel value. The portions of the logical pixel value which are used to provide these read addresses overlap. Multiple storage of given physical appearance values GPV0, GPV1, . . . within the palettes is provided so as to ensure the appropriate output irrespective of what particular value a bit has that is non-significant for that palette. Three component color palettes 4, 6 and 8 addressed with 8-bit addresses are provided together with an effects palette 10 addressed by a 4-bit address. In the case of a 16-bit logical pixel value, the system has the flexibility to support any of 6-5-5, 5-6-5 or 5-5-6 depending upon what is stored within the color palettes.