摘要:
A processor including instruction support for implementing large-operand multiplication may issue, for execution, programmer-selectable instructions from a defined instruction set architecture (ISA). The processor may include an instruction execution unit comprising a hardware multiplier datapath circuit, where the hardware multiplier datapath circuit is configured to multiply operands having a maximum number of bits M. In response to receiving a single instance of a large-operand multiplication instruction defined within the ISA, wherein at least one of the operands of the large-operand multiplication instruction includes more than the maximum number of bits M, the instruction execution unit is configured to multiply operands of the large-operand multiplication instruction within the hardware multiplier datapath circuit to determine a result of the large-operand multiplication instruction without execution of programmer-selected instructions within the ISA other than the large-operand multiplication instruction.
摘要:
A pipelined circuit for performing a divide operation on small operand sizes. The circuit includes a plurality of stages connected together in a series to perform a subtractive divide algorithm based on iterative subtractions and shifts. Each stage computes two quotient bits and outputs a partial remainder value to the next stage in the series. The first and last stages utilize a radix-4 serial architecture with edge modifications to increase efficiency. The intermediate stages utilize a radix-4 parallel architecture. The divide architecture is pipelined such that input operands can be applied to the divider on each clock cycle.
摘要:
A processing unit, system, and method for performing a multiply operation in a multiply-add pipeline. To reduce the pipeline latency, the unrounded result of a multiply-add operation is bypassed to the inputs of the multiply-add pipeline for use in a subsequent operation. If it is determined that rounding is required for the prior operation, then the rounding will occur during the subsequent operation. During the subsequent operation, a Booth encoder not utilized by the multiply operation will output a rounding correction factor as a selection input to a Booth multiplexer not utilized by the multiply operation. When the Booth multiplexer receives the rounding correction factor, the Booth multiplexer will output a rounding correction value to a carry save adder (CSA) tree, and the CSA tree will generate the correct sum from the rounding correction value and the other partial products.
摘要:
Determining an effective address of a memory with a three-operand add operation in single execution cycle of a multithreaded processor that can access both segmented memory and non-segmented memory. During that cycle, the processor determines whether a memory segment base is zero. If the segment base is zero, the processor can access a memory location at the effective address without adding the segment base. If the segment base is not zero, such as when executing legacy code, the processor consumes another cycle to add the segment base to the effective address. Similarly, the processor consumes another cycle if the effective address or the linear address is misaligned. An integer execution unit that performs the three-operand add using a carry-save adder coupled to a carry look-ahead adder. If the segment base is not zero, the effective address is fed back through the integer execution unit to add the segment base.
摘要:
A processor including instruction support for implementing hash algorithms may issue, for execution, programmer-selectable hash instructions from a defined instruction set architecture (ISA). The processor may include a cryptographic unit that may receive instructions for execution. The instructions include hash instructions defined within the ISA. In addition, the hash instructions may be executable by the cryptographic unit to implement a hash that is compliant with one or more respective hash algorithm specifications. In response to receiving a particular hash instruction defined within the ISA, the cryptographic unit may retrieve a set of input data blocks from a predetermined set of architectural registers of the processor, and generate a hash value of the set of input data blocks according to a hash algorithm that corresponds to the particular hash instruction.
摘要:
A processor including instruction support for implementing the Kasumi block cipher algorithm may issue, for execution, programmer-selectable instructions from a defined instruction set architecture (ISA). The processor may include a cryptographic unit that may receive instructions for execution. The instructions include one or more Kasumi instructions defined within the ISA. In addition, the Kasumi instructions may be executable by the cryptographic unit to implement portions of a Kasumi cipher that is compliant with 3rd Generation Partnership Project (3GPP) Technical Specification TS 35.202 version 8.0.0. In response to receiving a Kasumi FL( )-operation instruction defined within the ISA, the cryptographic unit may perform an FL( ) operation, as defined by the Kasumi cipher, upon a data input operand and a subkey operand in which the data input operand and subkey operand may be specified by the Kasumi FL( )-operation instruction.
摘要:
A processor including instruction support for implementing the Data Encryption Standard (DES) block cipher algorithm may issue, for execution, programmer-selectable instructions from a defined instruction set architecture (ISA). The processor may include a cryptographic unit that may receive instructions for execution. The instructions include one or more DES instructions defined within the ISA. In addition, the DES instructions may be executable by the cryptographic unit to implement portions of an DES cipher that is compliant with Federal Information Processing Standards Publication 46-3 (FIPS 46-3). In response to receiving a DES key expansion instruction defined within the ISA, the cryptographic unit may generate one or more expanded cipher keys of the DES cipher key schedule from an input key.
摘要:
An apparatus and method for floating-point special case handling. In one embodiment, a processor may include a first execution unit configured to execute a longer-latency floating-point instruction, and a second execution unit configured to execute a shorter-latency floating-point instruction. In response to the longer-latency floating-point instruction being issued to the first execution unit, the second execution unit may be further configured to detect whether a result of the longer-latency floating-point instruction is determinable from one or more operands of the longer-latency floating-point instruction independently of the first execution unit executing the longer-latency floating-point instruction. In response to detecting that the result is determinable, the second execution unit may be further configured to flush the longer-latency floating-point instruction from the first execution unit and to determine the result.
摘要:
In one embodiment, a processor is configured to execute a window swap instruction. The processor comprises a register file (that comprises a plurality of registers) and first and second execution units coupled to the register file. A first pipeline associated with the first execution unit has a first number of pipeline stages, and a second pipeline associated with the second execution unit has a second number of pipeline stages. The first execution unit is configured to change the current register window from the first register window to the second register window in the register file in response to the instruction. The second execution unit is configured to perform an operation defined by the instruction and write the result to the register file. The second number of pipeline stages exceeds the first number, whereby the second register window is established in the register file prior to writing the result.
摘要:
A method of enabling a single instruction stream multiple data stream operation and a double precision floating point operation within a single floating point execution unit which includes providing a floating point unit with a two way aligner and a two way normalizer, selectively aligning a value based upon whether a single instruction stream multiple data stream operation is to be performed or a double precision operation is to be performed, and selectively normalizing a value based upon whether a single instruction stream multiple data stream operation is to be performed or a double precision operation is to be performed.