151 results about "Floating-point unit" patented technology

A microprocessor with a floating point unit configured to rapidly execute floating point compare (FCOMI) type instructions that are followed by floating point conditional move (FCMOV) type instructions is disclosed. FCOMI-type instructions, which normally store their results to integer status flag registers, are modified to store a copy of their results to a temporary register located within the floating point unit. If an FCMOV-type instruction is detected following an FCOMI-type instruction, then the FCMOV-type instruction's source for flag information is changed from the integer flag register to the temporary register. FCMOV-type instructions are thereby able to execute earlier because they need not wait for the integer flags to be read from the integer portion of the microprocessor. A computer system and method for rapidly executing FCOMI-type instructions followed by FCMOV-type instructions are also disclosed.

Portable smartcard devices, methods of operating smartcard devices, systems including a smartcard device and a terminal, and computer readable storage media including instructions for smartcard devices are provided. According to some embodiments, the smartcard includes a controller for executing commands received from a terminal, where execution of at least one command affects a power consumption of the smartcard device during subsequent execution of at least one other command. Optionally, the command which modifies smartcard power consumption is issued by the terminal in accordance with a power consumption decision. According to some embodiments, as an allowed power consumption of the smartcard device increases, the performance of the smartcard increases, and vice versa. According to some embodiments, the execution of the at least one command sets an operating parameter of the smartcard device, such as a clock frequency or a time of a non-volatile memory operation, thereby affecting the power consumption of the smartcard device during the subsequent executing. Alternatively or additionally, the execution of the at least one command enables or disables a functional unit of the smartcard device. Exemplary functional units include but are not limited to floating-point units and cryptographic units. Alternatively or additionally, the execution of the at least one command enables or disables memory such as non-volatile memory of the smartcard device. According to some embodiments, the execution of the at least one command sets an operating parameter of internal circuitry of the smartcard.

A floating point unit is provided with a register bank comprising 32 registers that may be used as either vector registers of scalar registers. A data processing instruction includes at least one register specifying field pointing to a register containing a data value to be used in that operation. An increase in the instruction bit space available to encode more opcodes or to allow for more registers is provided by encoding whether a register is to be treated as a vector or a scalar within the register field itself. Further, the register field for one register of the instruction may encode whether another register is a vector or a scalar. The registers can be initially accessed using the values within the register fields of the instruction independently of the opcode allowing for easier decode.

A processor core includes an instruction decode unit that may dispatch a same integer instruction stream to a plurality of integer execution units and may consecutively dispatch a same floating-point instruction stream to a floating-point unit. The integer execution units may operate in lock-step such that during each clock cycle, each respective integer execution unit executes the same integer instruction. The floating-point unit may execute the same floating-point instruction stream twice. Prior to the integer instructions retiring, compare logic may detect a mismatch between execution results from each of the integer execution units. In addition, prior to the results of the floating-point instruction stream transferring out of the floating-point unit, the compare logic may also detect a mismatch between results of execution of each consecutive floating-point instruction stream. Further, in response to detecting any mismatch, the compare logic may cause instructions causing the mismatch to be re-executed.

A more efficient method of handling instructions in a computer processor, by associating resource fields with respective program instructions wherein the resource fields indicate which of the processor hardware resources are required to carry out the program instructions, calculating resource requirements for merging two or more program instructions based on their resource fields, and determining resource availability for simultaneously executing the merged program instructions based on the calculated resource requirements. Resource vectors indicative of the required resource may be encoded into the resource fields, and the resource fields decoded at a later stage to derive the resource vectors. The resource fields can be stored in the instruction cache associated with the respective program instructions. The processor may operate in a simultaneous multithreading mode with different program instructions being part of different hardware threads. When the resource availability equals or exceeds the resource requirements for a group of instructions, those instructions can be dispatched simultaneously to the hardware resources. A start bit may be inserted in one of the program instructions to define the instruction group. The hardware resources may in particular be execution units such as a fixed-point unit, a load/store unit, a floating-point unit, or a branch processing unit.

A floating point unit capable of executing multiple instructions in a single clock cycle using a central window and a register map is disclosed. The floating point unit comprises: a plurality of translation units, a future file, a central window, a plurality of functional units, a result queue, and a plurality of physical registers. The floating point unit receives speculative instructions, decodes them, and then stores them in the central window. Speculative top of stack values are generated for each instruction during decoding. Top of stack relative operands are computed to physical registers using a register map. Register stack exchange operations are performed during decoding. Instructions are then stored in the central window, which selects the oldest stored instructions to be issued to each functional pipeline and issues them. Conversion units convert the instruction's operands to an internal format, and normalization units detect and normalize any denormal operands. Finally, the functional pipelines execute the instructions.

A fused multiply add floating point unit 1 includes multiplying circuitry 4 and adding circuitry 8. The multiply circuitry 4 multiplies operands B and C having N-bit significands to generate an unrounded product B*C. The unrounded product B*C has an M-bit significand, where M>N. The adding circuitry 8 receives an operand A that is input at a later processing cycle than a processing cycle at which the multiplying circuitry 4 receives operands B and C. The adding circuitry 8 commences processing of the operand A after the unrounded product B*C is generated by the multiplying circuitry 4. The adding circuitry 8 adds the operand A to the unrounded product B*C and outputs a rounded result A+B*C.

Disclosed is an apparatus which deactivates both the AC as well as the DC component of power for various functions in a CPU. The CPU partitions dataflow registers and arithmetic units such that voltage can be removed from the upper portion of dataflow registers when the software is not utilizing same. Clock signals are also prevented from being applied to these non-utilized components. As an example, if a 64 bit CPU (processor unit) is to be used with both 32 and 64 bit software, the mentioned components may be partitioned in equal sized upper and lower portions. The logic signal for activating the removal of voltage may be obtained from a software-accessible architected control register designated as a machine state register in some CPUs. The same logic may be used in connection with removing voltage and clocks from other specialized functional components such as the floating point unit when software instructions do not presently require same.

The invention proposes a Floating Point Unit (1) with fused multiply add, with one addend operand (eb, fb) and two multiplicand operands (ea, fa; ec, fc), with a shift amount logic (2) which based on the exponents of the operands (ea, eb and ec) computes an alignment shift amount, with an alignment logic (3) which uses the alignment shift amount to align the fraction (fb) of the addend operand, with a multiply logic (4) which multiplies the fractions of the multiplicand operands (fa, fc), with a adder logic (5) which adds the outputs of the alignment logic (3) and the multiply logic (4), with a normalization logic (6) which normalizes the output of the adder logic (5), which is characterized in that a leading zero logic (7) is provided which computes the number of leading zeros of the fraction of the addend operand (fb), and that a compare logic (8) is provided which based on the number of leading zeros and the alignment shift amount computes select signals that indicate whether the most significant bits of the alignment logic (3) output have all the same value in order to: a) control the carry logic of the adder logic (5) and/or b) control a stage of the normalization logic (6).

The invention relates to a parallel microprocessor and a corresponding realization method which are based on FPGA development. The parallel microprocessor comprises a CPU which is a 32-bit fixed-point CPU formed by a fetch decoding unit, a process management unit and an integer instruction execution unit; a communication module formed by a plurality of units of LINK channels and In/Out controllers; an arbitration controller used for arbitrating internal and external address buses and a data bus of the CPU; an external memory interface used for providing reading/writing time-sequence logic for an external memory; an interruption/time-sequence controller used for providing timing and interruption for the CPU; an internal memory used for providing the instructions of the CPU and quickly accessing data. The CPU is also provided with a floating point unit (FPU) combining the 32-bit fixed-point CPU to form a 64-bit floating point CPU. The 32-bit fixed-point parallel microprocessor and the 64-bit floating point parallel microprocessor provided by the invention work stably, bring convenience for system modification and debugging, accelerate verification speed and provide a low-cost operation platform for programs written in OccamII language.

A computing system capable of handling floating point operations during program code conversion is described, comprising a processor including a floating point unit and an integer unit. The computing system further comprises a translator unit arranged to receive subject code instructions including at least one instruction relating to a floating point operation and in response to generate corresponding target code for execution on said processor. To handle floating point operations a floating point status unit and a floating point control unit are provided within the translator. These units are cause the translator unit to generate either: target code for performing the floating point operations directly on the floating point unit; or target code for performing the floating point operations indirectly, for example using a combination of the integer unit and the floating point unit. In this way the efficiency of the computing system is improved.

A floating point unit 10 provides a multiply-accumulate operation to determine a result B+(A*C). The multiplier 20 takes several processing cycles to determine the product (A*C). Whilst the multiplier 20 and its subsequent carry-save-adder 26 operate, an aligned value B' of the addend B is generated by an alignment-shifter 34. The aligned-addend B' may only partially overlap with the product (A*C) to which it is to be added using an adder 44. Any high-order-portion HOP of the aligned-addend B' that does not overlap with the product (A*C) must be subsequently concatenated with the output of the adder 44 that sums the product (A*C) with the overlapping portion of the aligned-addend B'. If the sum performed by the adder 44 generates a carry then it is an incremented version IHOP of the high-order-portion that should be concatenated with the output of the adder 44. This incremented-high-order-portion is generated by the adder 44 during otherwise idle processing cycles present due to the multiplier 20 operating over multiple cycles.

Disclosed are a floating point execution unit, and a method of operating a floating point unit, to perform multiply/add operations using a plurality of operands from an instruction having a plurality of operand positions. The floating point unit comprises a multiplier for calculating a product of two of the operands, and an aligner for combining said product and a third of the operands. A first data path is used to supply to the multiplier operands from a first and a second of the operand positions of the instruction, and a second data path is used to supply the third operand to the aligner. The floating point unit further comprises a multiplexer on the second data path for selecting, for use by the aligner, either the operand from the second operand position or the operand from the third operand position of the instruction.

A floating point unit capable of executing multiple instructions in a single clock cycle using a central window and a register map is disclosed. The floating point unit comprises: a plurality of translation units, a future file, a central window, a plurality of functional units, a result queue, and a plurality of physical registers. The floating point unit receives speculative instructions, decodes them, and then stores them in the central window. Speculative top of stack values are generated for each instruction during decoding. Top of stack relative operands are computed to physical registers using a register map. Register stack exchange operations are performed during decoding. Instructions are then stored in the central window, which selects the oldest stored instructions to be issued to each functional pipeline and issues them. Conversion units convert the instruction's operands to an internal format, and normalization units detect and normalize any denormal operands. Finally, the functional pipelines execute the instructions.

One or more processor cores of a multiple-core processing device each can utilize a processing pipeline having a plurality of execution units (e.g., integer execution units or floating point units) that together share a pre-execution front-end having instruction fetch, decode and dispatch resources. Further, one or more of the processor cores each can implement dispatch resources configured to dispatch multiple instructions in parallel to multiple corresponding execution units via separate dispatch buses. The dispatch resources further can opportunistically decode and dispatch instruction operations from multiple threads in parallel so as to increase the dispatch bandwidth. Moreover, some or all of the stages of the processing pipelines of one or more of the processor cores can be configured to implement independent thread selection for the corresponding stage.

An apparatus and method for computing a rounded floating point number. A floating point unit (FPU) receives an instruction to round a floating point number to a nearest integral value and retrieves a binary source operand having an exponent of a fixed first number of bits and a mantissa of a fixed second number of bits. If the unbiased exponent value is greater than or equal to zero and less than the fixed second number, the FPU generates a mask having N consecutive ‘1’ bits beginning with the least significant bit and whose remaining bits have a value of ‘0’, where N is equal to the fixed second number minus the unbiased exponent value. The FPU computes a bitwise OR of the source operand with the mask, increments the result if the instruction is to round up, and computes a bitwise AND of the result with the inverse of the mask.

A floating point unit is provided which conveys the rounding mode in effect upon dispatch of a particular instruction with that particular instruction into the execution pipeline of the floating point unit. Upon dispatch of a control word update instruction into the execution pipeline, the rounding mode is updated according to the updated control word provided for the control word update instruction. Instructions subsequent to the control word update instruction thereby receive the updated rounding mode as those instructions are dispatched. The updated rounding mode is available to the subsequent instructions prior to retiring the control word update instruction. The rounding mode is therefore updated without serializing the update. If the control word update instruction modifies the value in a field other than the rounding mode, the instructions subsequent to the control word update instruction may be discarded and re-executed subsequent to updating the control word register with the updated control word. In this manner, the control word update is effectively serialized for cases in which a field other than the rounding mode is updated.

Multiple processor cores are implemented on a single integrated circuit chip, each having its own respective shareable functional units, which are preferably floating point units. A failure of a shareable unit in one processor causes that processor to share the corresponding unit in another processor on the same chip. Preferably, a functional unit is shared on a cycle interleaved basis.

One or more processor cores of a multiple-core processing device each can utilize a processing pipeline having a plurality of execution units (e.g., integer execution units or floating point units) that together share a pre-execution front-end having instruction fetch, decode and dispatch resources. Further, one or more of the processor cores each can implement dispatch resources configured to dispatch multiple instructions in parallel to multiple corresponding execution units via separate dispatch buses. The dispatch resources further can opportunistically decode and dispatch instruction operations from multiple threads in parallel so as to increase the dispatch bandwidth. Moreover, some or all of the stages of the processing pipelines of one or more of the processor cores can be configured to implement independent thread selection for the corresponding stage.

Apparatus for processing data includes processing circuitry 16, 18, 20, 22, 24, 26 and decoder circuitry 14 for decoding program instructions. The program instructions decoded include a floating point pre-conversion instruction which performs round-to-nearest ties to even rounding upon the mantissa field of an input floating number to generate an output floating point number with the same mantissa length but with the mantissa rounded to a position corresponding to a shorter mantissa field. The output mantissa field includes a suffix of zero values concatenated the rounded value. The decoder for circuitry 14 is also responsive to an integer pre-conversion instruction to quantise and input integer value using round-to-nearest ties to even rounding to form an output integer operand with a number of significant bits matched to the mantissa size of a floating point number to which the integer is later to be converted using an integer-to-floating point conversion instruction.

A microprocessor with a floating point unit configured to efficiently allocate multi-pipeline executable instructions is disclosed. Multi-pipeline executable instructions are instructions that are not forced to execute in a particular type of execution pipe. For example, junk ops are multi-pipeline executable. A junk op is an instruction that is executed at an early stage of the floating point unit's pipeline (e.g., during register rename), but still passes through an execution pipeline for exception checking. Junk ops are not limited to a particular execution pipeline, but instead may pass through any of the microprocessor's execution pipelines in the floating point unit. Multi-pipeline executable instructions are allocated on a per-clock cycle basis using a number of different criteria. For example, the allocation may vary depending upon the number of multi-pipeline executable instructions received by the floating point unit in a single clock cycle.