Abstract: A microcomputer is provided with an upper clip circuit for comparing digital values output from an AD converting circuit 1 with a high level reference value A, and replacing a digital value larger than the reference value A with the reference value A; and a lower clip circuit for comparing digital values output from the upper clip circuit with a reference value B, and replacing a digital value smaller than the reference value B with the reference value B. Irregular signal waveforms can be removed by replacing with the reference values A, B, thereby enhancing the reliability of operation results.

Abstract: A plurality of units identified by respective addresses are disposed in a register file. Each of the units has a data register for storing data representative of a result of an arithmetic operation, a register for storing an overflow flag indicating the presence or absence of an occurrence of overflow in the arithmetic operation, and a register for storing a sign flag providing an indication of which one of a positive and a negative saturation value should replace the arithmetic operation result in the presence of an occurrence of overflow in the arithmetic operation. Each of the flags is updated in response to a write signal concerning its corresponding register. If at the moment when a data register is fed a read signal, a corresponding overflow flag is set, then either a positive or a negative saturation value, whichever corresponds to the sign flag, is generated on the input side of an arithmetic unit.

Abstract: A process is for determining an overflow to the format of the result of an arithmetic operation carried out by an arithmetic unit on two operands A and B and an input carry digit Cin. This process is executed in parallel to the processing done by the AU on operands A and B, before the AU has determined the result S of the operation.

Abstract: A data processing system is provided for supporting saturating arithmetic using input operands of the Q31 and Q15 type. In order to accommodate this type of operation applied to multiply accumulate or multiply subtract instructions, additional instructions QDADD, QDSUB and QDRSB are provided, QDADD provides the function of double/saturate/add/saturate. QDSUB and QDRSB provide respective operand orderings of double/saturate/subtract/saturate operations. Providing these special purpose instructions within the instruction set allows the required saturation and adjustments to be provided for Q31 and Q15 operands whilst not imposing additional delays and complication onto the main data paths required for the rest of the processing operations.

Abstract: An apparatus that performs arithmetic logic and carry-lookahead logic in parallel on two N-nary operands, including saturating or unsaturating, signed or unsigned, addition or subtraction. The operands may be selectably partitioned into 8-bit, 16-bit, 32-bit, or 64-bit operands. For multiple partitions, carry propagation is interrupted on partition boundaries. Each selectable feature may be implemented singly, or in combination with other selectable features.

Abstract: An apparatus and method for performing saturating addition or subtraction on two signed or unsigned operands using N-NARY logic. The two operands may be selectably partitioned into 8-bit, 16-bit, 32-bit, or 64-bit operands. For multiple partitions, carry propagation is interrupted on partition boundaries so that partitions may be saturated independently.

Abstract: A plurality of units identified by respective addresses are disposed in a register file. Each of the units has a data register for storing data representative of a result of an arithmetic operation, a register for storing an overflow flag indicating the presence or absence of an occurrence of overflow in the arithmetic operation, and a register for storing a sign flag providing an indication of which one of a positive and a negative saturation value should replace the arithmetic operation result in the presence of an occurrence of overflow in the arithmetic operation. Each of the flags is updated in response to a write signal concerning its corresponding register. If at the moment when a data register is fed a read signal, a corresponding overflow flag is set, then either a positive or a negative saturation value, whichever corresponds to the sign flag, is generated on the input side of an arithmetic unit.

Abstract: A method for detecting overflow in an add operation on first and second decoded bit-vectors is provided, the method including generating a one-ahead vector using the first decoded bit-vector. The method also includes selecting an overflow bit from bits of the one-ahead vector using the second decoded bit-vector.

Abstract: A multiplier capable of performing signed and unsigned scalar and vector multiplication is disclosed. The multiplier is configured to receive signed or unsigned multiplier and multiplicand operands in scalar or packed vector form. An effective sign for the multiplier and multiplicand operands may be calculated and used to create and select a number of partial products according to Booth's algorithm. Once the partial products have been created and selected, they may be summed and the results may be output. The results may be signed or unsigned, and may represent vector or scalar quantities. When a vector multiplication is performed, the multiplier may be configured to generate and select partial products so as to effectively isolate the multiplication process for each pair of vector components. The multiplier may also be configured to sum the products of the vector components to form the vector dot product. The final product may be output in segments so as to require fewer bus lines.

Abstract: A processor which executes positive conversion processing, which converts coded data into uncoded data, and saturation calculation processing, which rounds a value to an appropriate number of bits, at high speed. When a positive conversion saturation calculation instruction “MCSST D1” is decoded, the sum-product result register 6 outputs its held value to the path P1. The comparator 22 compares the magnitude of the held value of the sum-product result register 6 with the coded 32-bit integer “0x0000_00FF”. The polarity judging unit 23 judges whether the eighth bit of the value held by the sum-product result register 6 is “ON”. The multiplexer 24 outputs one of the maximum value “0x0000_00FF” generated by the constant generator 21, the zero value “0x0000_0000” generated by the zero generator 25, and the held value of the sum-product result register 6 to the data bus 18.

Abstract: A method and apparatus for detecting an overflow in a data stream include processing that begins by monitoring content of a stream of data. As the content of the stream of data is being monitored, the processing provides a word length signal that has a rate corresponding to a word rate of the stream of data. When the content of the stream of data is in a first logic state for an interval between the word length signal and a previous word length signal, the processing provides an overflow indication.

Abstract: A method is disclosed for detecting overflow and underflow conditions using a status register having a main status field and first and second alternate status fields. The first and second alternate status fields are set to chop and wre modes, respectively, and chop and wre results are determined for an arithmetic operation using the first and second alternate status fields. The chop and wre results are tested against test values to determine whether an overflow or underflow condition exists.

Abstract: A digital signal processor having an ALU and accumulating register small in bit number. The digital signal processor adds r-bit rounding bits to an N-bit data(wherein r<N) and adds g-bit guard bits to the high-order bits of the data using bit alignment units each being implemented with a wiring, when N bit data is processed. The data added by the guard bits and the rounding bits is operated by means of the accumulator. The operated data is selectively rounded by a rounding processor. Also, the selectively rounded data is selectively saturated by a saturation processor.

Abstract: Two related extended precision operand formats provide for efficient multiply/accumulate operations in a SIMD data processing system. Each format utilizes a group of “b” bit elements in a vector register. Each of the elements provides “m” bits of precision, with b>m. The remaining b−m bits in each element accumulate overflows and carries across multiple additions and subtractions. Existing SIMD multiply-sum instructions can be used to efficiently take input operands from the first format and produce output results in the second extended precision format when b2=2b1 and m2=2m1.

Abstract: An improved method and apparatus for saturation detection in floating point to integer conversions is described. A floating point number is tested for saturation conditions based on an integer field size. From testing the saturation conditions on the floating point number, the present invention predicts whether a floating point number can be converted into an integer value having the given integer field size, or whether the integer field would be saturated. In one embodiment, the saturation conditions are tested on the floating point number in parallel with a floating point to integer conversion.

Abstract: A programmable function block comprises a core logic circuit having a first argument input group consisting of first through fourth argument input terminals, a second argument input group consisting of first through fourth argument input terminals, first through third configuration input terminals, a core logic carry output terminal, a core logic carry generation output terminal, a core logic carry propagation output terminal, a ripple-core logic carry input terminal, and a sum output terminal. Connected to interconnection wires and the first and the second argument input groups, an input block includes eighth input selection units for selecting, as eight input selected signals, eight ones of signals on the interconnection wires, a fixed logic value of “1”, and a fixed logic value of “0”. Connected to the first through the third configuration input terminals, respectively, first through third memory circuits stores, as first through third stored logic values, a logic value of one bit.

Abstract: A first adder-subtracter combines the first input with the largest positive number capable of being represented by the number of bits in the datapath. A second adder-subtracter operating in parallel with the first adder-subtracter combines the first input with the largest negative number capable of being represented by the number of bits in the datapath. A third adder-subtracter combines the first, second, and third inputs and operates in parallel with the first and second adder-subtracters. A carry/sign detector circuit operating in parallel with all three adder-subtracters determines the sign and the carry of the sum of the second and third inputs.

Abstract: Disclosed is a method and circuit for detecting overflow when multiplying operands. The disclosed method and circuit is configured to operate in parallel with a multiplier configured to multiply first and second n bit operands. In general, the multiplier circuit generates result operand which represents a multiplication of the first and second n bit operands. An overflow detection circuit is coupled to the multiplier circuit and configured to generate an overflow signal which indicates that the multiplication of the first and second n bit operands results in an overflow condition. The multiplier circuit comprises a compression circuit configured to generate the first and second 2n bit partial product operands as a function of the first and second n bit operands. An addition of the first and second 2n bit partial product operands produces the result operand.

Abstract: A scalable overflow clamp for controlling the level of allowable digital signal overflow in a gain scaler/summer having an initial full-scale range and a feedback path for establishing a feedback gain. The clamp includes a range scaler for determining the feedback gain and generating a modified full-scale range relative to the feedback gain. The modified full-scale range defines a substantially constant overflow capability relative to the feedback gain. An overflow detector senses the overflow conditions and a selector responsive to the overflow detector utilizes the modified full-scale range when overflow conditions are sensed.

Abstract: An integrated circuit, e.g. an AC '97 conforming audio codec, includes a digital filter and gain module including multiple channels of gain control and multiple channels of digital filtering. A gain control module includes an overflow check of data samples requiring differing lengths of clamping. Each channel of the digital filter includes a finite impulse response (FIR) filter, and an infinite impulse response (IIR) filter. The digital filtering is implemented largely in hardware independent of the number of channels required and/or independent of the required order of the filtering. Thus, filter channels can be added or additional filtering implemented merely by increasing the clock speed without changing the digital filter design. The FIR filter is capable of being reset each frame to prevent a DC buildup at internal nodes. The IIR filter performs a plurality of 2.sup.nd order biquadratic equations in an overall average of as few as four clock cycles per 2.sup.nd order biquad.

Abstract: A numerical processing method on a computer system in which an instruction having at least one operand and a type control is retrieved, and the operand is converted to a precision specified by the type control. The instruction is executed in the precision specified by the type control to obtain a result, and when the destination precision differs from the precision specified by the type control, the result is converted to the destination precision using a second instruction.

Abstract: A microprocessor 1 has an instruction fetch/decode unit 10a-c, a plurality of execution units, including an arithmetic and load/store unit D1, a multiplier M1, an ALU/shifter unit S1, an arithmetic logic unit ("ALU") L1, a shared multiport register file 20a from which data are read and to which data are written, and a memory 22. Execution unit M1 has circuitry for multiplying two operands, shifting the resulting product and saturating the product if an overflow is detected in two execution phase of an instruction execution pipeline.

Abstract: An apparatus and method for performing integer division in a microprocessor are provided. The apparatus includes translation logic, floating point execution logic, and integer execution logic. The translation logic decodes an integer divide instruction into an integer divide micro instruction sequence and an overflow detection micro instruction sequence. The integer divide micro instruction sequence is routed to and executed by the floating point execution logic. The overflow detection micro instruction sequence is routed to and executed by the integer execution logic. The integer execution logic and the floating point execution logic execute the overflow detection micro instruction sequence and the integer divide micro instruction sequence concurrently.

Abstract: A 3-D graphics accelerator for performing lighting operations using operands within a given fixed point numeric range. The 3-D graphics accelerator includes a first computational unit which is configured to compute a value of an attenuation factor usable for performing said lighting operation for local lights. The attenuation factor is represented in floating point format. The first computational unit is also configured to represent the attenuation factor in an intermediate format including a first intermediate value (a scaled attenuation factor value within the given fixed point numeric range), and a second intermediate value (a shift count usable to convert the scaled attenuation factor value back to the original attenuation factor value). The 3-D graphics accelerator further includes a lighting unit coupled to said first computational unit. The first computational unit is further configured to convey the intermediate representation of the attenuation factor to the lighting unit.

Abstract: An apparatus and a method for indicating the computational adder overflow status of bit-variable data employing a pipelining adder. An adder is provided with a first input port and a second input port, for adding a multiple-bit data input from the second input port. A plurality of shift registers receive and store in parallel a plurality of multiple-bit data output from the adder, and sequentially output the plurality of multiple-bit data to the second input port of the adder in response to a clock signal. A comparing circuit simultaneously receives and compares a multiple-bit data output from the adder and a multiple-bit data output from a plurality of shift registers. An overflow arbitrating unit arbitrates the overflow status of each multiple-bit data in accordance with a comparing result from the comparing circuit as well as a selective signal.

Abstract: A processor which executes positive conversion processing, which converts coded data into uncoded data, and saturation calculation processing, which rounds a value to an appropriate number of bits, at high speed. When a positive conversion saturation calculation instruction "MCSST D1" is decoded, the sum-product result register 6 outputs its held value to the path P1. The comparator 22 compares the magnitude of the held value of the sum-product result register 6 with the coded 32-bit integer "0x0000.sub.-- 00FF". The polarity judging unit 23 judges whether the eighth bit of the value held by the sum-product result register 6 is "ON". The multiplexer 24 outputs one of the maximum value "0x0000.sub.-- 00FF" generated by the constant generator 21, the zero value "0x0000.sub.-- 0000" generated by the zero generator 25, and the held value of the sum-product result register 6 to the data bus 18.

Abstract: A sum-of-products arithmetic unit includes a coefficient register, a data register, a multiplier, an adder, and a data bus used for the transfer of data to and from an external unit. Provision is made to allow addresses in the data register in which sum-of-products arithmetic data is to be stored to be specified without externally specifying an individual address in the data register for each piece of arithmetic data. This provision comprises an automatic data batch storage section, automatic address setting section, or address setting section.