Abstract: A streaming engine employed in a digital data processor specifies a fixed read only data stream recalled memory. Streams are started by one of two types of stream start instructions. A stream start ordinary instruction specifies a register storing a stream start address and a register of storing a stream definition template which specifies stream parameters. A stream start short-cut instruction specifies a register storing a stream start address and an implied stream definition template. A functional unit is responsive to a stream operand instruction to receive at least one operand from a stream head register. The stream template supports plural nested loops with short-cut start instructions limited to a single loop. The stream template supports data element promotion to larger data element size with sign extension or zero extension. A set of allowed stream short-cut start instructions includes various data sizes and promotion factors.

Abstract: A streaming engine employed in a digital data processor specifies a fixed read only data stream defined by plural nested loops. An address generator produces address of data elements. A steam head register stores data elements next to be supplied to functional units for use as operands. Upon a stream break instruction specifying one of the nested loops, the stream engine ends a current iteration of the loop. If the specified loop was not the outermost loop, the streaming engine begins an iteration of a next outer loop. If the specified loop was the outermost nested loop, the streaming engine ends the stream. The streaming engine places a vector of data elements in order in lanes within a stream head register. A stream break instruction is operable upon a vector break.

Abstract: A streaming engine employed in a digital data processor specifies a fixed read only data stream. Once fetched data elements in the data stream are disposed in lanes in a stream head register in the fixed order. Some lanes may be invalid, for example when the number of remaining data elements are less than the number of lanes in the stream head register. The streaming engine automatically produces a valid data word stored in a stream valid register indicating lanes holding valid data. The data in the stream valid register may be automatically stored in a predicate register or otherwise made available. This data can be used to control vector SIMD operations or may be combined with other predicate register data.

Abstract: This invention addresses implements a range of interesting technologies into a single block. Each DSP CPU has a streaming engine. The streaming engines include: a SE to L2 interface that can request 512 bits/cycle from L2; a loose binding between SE and L2 interface, to allow a single stream to peak at 1024 bits/cycle; one-way coherence where the SE sees all earlier writes cached in system, but not writes that occur after stream opens; full protection against single-bit data errors within its internal storage via single-bit parity with semi-automatic restart on parity error.

Abstract: This invention is a streaming engine employed in a digital signal processor. A fixed data stream sequence is specified by a control register. The streaming engine fetches stream data ahead of use by a central processing unit and stores it in a stream buffer. Upon occurrence of a fault reading data from memory, the streaming engine identifies the data element triggering the fault preferably storing this address in a fault address register. The streaming engine defers signaling the fault to the central processing unit until this data element is used as an operand. If the data element is never used by the central processing unit, the streaming engine never signals the fault. The streaming engine preferably stores data identifying the fault in a fault source register. The fault address register and the fault source register are preferably extended control registers accessible only via a debugger.

Abstract: A multilayer butterfly network is shown that is operable to transform and align a plurality of fields from an input to an output data stream. Many transformations are possible with such a network which may include separate control of each multiplexer. This invention supports a limited set of multiplexer control signals, which enables a similarly limited set of data transformations. This limited capability is offset by the reduced complexity of the multiplexor control circuits. This invention used precalculated inputs and simple combinatorial logic to generate control signals for the butterfly network. Controls are independent for each layer and therefore are dependent only on the input and output patterns. Controls for the layers can be calculated in parallel.

Abstract: A multilayer butterfly network is shown that is operable to transform and align a plurality of fields from an input to an output data stream. Many transformations are possible with such a network which may include separate control of each multiplexer. This invention supports a limited set of multiplexer control signals, which enables a similarly limited set of data transformations. This limited capability is offset by the reduced complexity of the multiplexor control circuits. This invention used precalculated inputs and simple combinatorial logic to generate control signals for the butterfly network. Controls are independent for each layer and therefore are dependent only on the input and output patterns. Controls for the layers can be calculated in parallel.

Abstract: A streaming engine employed in a digital data processor specifies a fixed read only data stream defined by plural nested loops. An address generator produces address of data elements for the nested loops. A steam head register stores data elements next to be supplied to functional units for use as operands. A stream template register specifies a circular address mode for the loop, first and second block size numbers and a circular address block size selection. For a first circular address block size selection the block size corresponds to the first block size number. For a first circular address block size selection the block size corresponds to the first block size number. For a second circular address block size selection the block size corresponds to a sum of the first block size number and the second block size number.

Abstract: The number of registers required is reduced by overlapping scalar and vector registers. This allows increased compiler flexibility when mixing scalar and vector instructions. Local register read ports are reduced by restricting read access. Dedicated predicate registers reduce requirements for general registers, and allows reduction of critical timing paths by allowing the predicate registers to be placed next to the predicate unit.

Abstract: A streaming engine employed in a digital data processor specifies fixed first and second read only data streams. Corresponding stream address generator produces address of data elements of the two streams. Corresponding steam head registers stores data elements next to be supplied to functional units for use as operands. The two streams share two memory ports. A toggling preference of stream to port ensures fair allocation. The arbiters permit one stream to borrow the other's interface when the other interface is idle. Thus one stream may issue two memory requests, one from each memory port, if the other stream is idle. This spreads the bandwidth demand for each stream across both interfaces, ensuring neither interface becomes a bottleneck.

Abstract: This invention is a streaming engine employed in a digital signal processor. A fixed data stream sequence including plural nested loops is specified by a control register. The streaming engine includes an address generator producing addresses of data elements and a steam head register storing data elements next to be supplied as operands. The streaming engine fetches stream data ahead of use by the central processing unit core in a stream buffer. Parity bits are formed upon storage of data in the stream buffer which are stored with the corresponding data. Upon transfer to the stream head register a second parity is calculated and compared with the stored parity. The streaming engine signals a parity fault if the parities do not match. The streaming engine preferably restarts fetching the data stream at the data element generating a parity fault.

Abstract: A streaming engine employed in a digital data processor specifies a fixed read only data stream defined by plural nested loops. An address generator produces address of data elements. A steam head register stores data elements next to be supplied to functional units for use as operands. The streaming engine fetches stream data ahead of use by the central processing unit core in a stream buffer constructed like a cache. The stream buffer cache includes plural cache lines, each includes tag bits, at least one valid bit and data bits. Cache lines are allocated to store newly fetched stream data. Cache lines are deallocated upon consumption of the data by a central processing unit core functional unit. Instructions preferably include operand fields with a first subset of codings corresponding to registers, a stream read only operand coding and a stream read and advance operand coding.

Abstract: This invention is a streaming engine employed in a digital signal processor. A fixed data stream sequence is specified by a control register. The streaming engine fetches stream data ahead of use by a central processing unit and stores it in a stream buffer. Upon occurrence of a fault reading data from memory, the streaming engine identifies the data element triggering the fault preferably storing this address in a fault address register. The streaming engine defers signaling the fault to the central processing unit until this data element is used as an operand. If the data element is never used by the central processing unit, the streaming engine never signals the fault. The streaming engine preferably stores data identifying the fault in a fault source register. The fault address register and the fault source register are preferably extended control registers accessible only via a debugger.

Abstract: A streaming engine employed in a digital data processor specifies a fixed read only data stream defined by plural nested loops. An address generator produces address of data elements. A steam head register stores data elements next to be supplied to functional units for use as operands. An element duplication unit optionally duplicates data element an instruction specified number of times. A vector masking unit limits data elements received from the element duplication unit to least significant bits within an instruction specified vector length. If the vector length is less than a stream head register size, the vector masking unit stores all 0's in excess lanes of the stream head register (group duplication disabled) or stores duplicate copies of the least significant bits in excess lanes of the stream head register.

Abstract: The number of registers required is reduced by overlapping scalar and vector registers. This also allows increased compiler flexibility when mixing scalar and vector instructions. Local register read ports are minimized by restricting read access. Dedicated predicate registers reduces requirements for general registers, and allows reduction of critical timing paths by allowing the predicate registers to be placed next to the predicate unit.

Abstract: A streaming engine employed in a digital data processor specifies a fixed read only data stream defined by plural nested loops. An address generator produces address of data elements. A steam head register stores data elements next to be supplied to functional units for use as operands. The streaming engine stores an early address of next to be fetched data elements and a late address of a data element in the stream head register for each of the nested loops. The streaming engine stores an early loop counts of next to be fetched data elements and a late loop counts of a data element in the stream head register for each of the nested loops.

Abstract: A streaming engine employed in a digital data processor specifies a fixed read only data stream defined by plural nested loops. An address generator produces address of data elements for the nested loops. A steam head register stores data elements next to be supplied to functional units for use as operands. A stream template register independently specifies a linear address or a circular address mode for each of the nested loops.

Abstract: A streaming engine employed in a digital data processor specifies a fixed read only data stream defined by plural nested loops. An address generator produces address of data elements for the nested loops. A steam head register stores data elements next to be supplied to functional units for use as operands. A stream template specifies loop count and loop dimension for each nested loop. A format definition field in the stream template specifies the number of loops and the stream template bits devoted to the loop counts and loop dimensions. This permits the same bits of the stream template to be interpreted differently enabling trade off between the number of loops supported and the size of the loop counts and loop dimensions.

Abstract: A streaming engine employed in a digital data processor specifies a fixed read only data stream defined by plural nested loops. An address generator produces address of data elements for the nested loops. A steam head register stores data elements next to be supplied to functional units for use as operands. A stream template register specifies a circular address mode for the loop, first and second block size numbers and a circular address block size selection. For a first circular address block size selection the block size corresponds to the first block size number. For a first circular address block size selection the block size corresponds to the first block size number. For a second circular address block size selection the block size corresponds to a sum of the first block size number and the second block size number.

Abstract: This invention is a bus communication protocol. A master device stores bus credits. The master device may transmit a bus transaction only if it holds sufficient number and type of bus credits. Upon transmission, the master device decrements the number of stored bus credits. The bus credits correspond to resources on a slave device for receiving bus transactions. The slave device must receive the bus transaction if accompanied by the proper credits. The slave device services the transaction. The slave device then transmits a credit return. The master device adds the corresponding number and types of credits to the stored amount. The slave device is ready to accept another bus transaction and the master device is re-enabled to initiate the bus transaction. In many types of interactions a bus agent may act as both master and slave depending upon the state of the process.