Abstract: An indirect VLIW (iVLIW) architecture is described which contains a minimum of two instruction memories. The first instruction memory (SIM) contains short-instruction-words (SIWs) of a fixed length. The second instruction memory (VIM), contains very-long-instruction-words (VLIWs) which allow execution of multiple instructions in parallel. Each SIW may be fetched and executed as an independent instruction by one of the available execution units. A special class of SIW is used to reference the VIM indirectly to either execute or load a specified VLIW instruction (called an “XV” instruction for “eXecute VLIW”, or LV for “Load VLIW”). In these cases, the SIW instruction specifies how the location of the VLIW is to be accessed. Other aspects of this approach relate to the application of data memory addressing techniques for execution or loading of VLIWs that parallel the addressing modes used for data memory accesses.

Abstract: An improved manifold array (ManArray) architecture addresses the problem of configurable application-specific instruction set optimization and instruction memory reduction using an instruction abbreviation process thereby further optimizing the general ManArray architecture for application to high-volume and portable battery-powered type of products. In the ManArray abbreviation process a standard 32-bit ManArray instruction is reduced to a smaller length instruction format, such as 14-bits. An application is first programmed using the full ManArray instruction set using the native 32-bit instructions. After the application program is completed and verified, an instruction-abbreviation tool analyzes the 32-bit application program and generates the abbreviated program using the abbreviated instructions. This instruction abbreviation process allows different program-reduction optimizations tailored for each application program. This process develops an optimized instruction set for the intended application.

Abstract: A hierarchical instruction set architecture (ISA) provides pluggable instruction set capability and support of array processors. The term pluggable is from the programmer's viewpoint and relates to groups of instructions that can easily be added to a processor architecture for code density and performance enhancements. One specific aspect addressed herein is the unique compacted instruction set which allows the programmer the ability to dynamically create a set of compacted instructions on a task by task basis for the primary purpose of improving control and parallel code density. These compacted instructions are parallelizable in that they are not specifically restricted to control code application but can be executed in the processing elements (PEs) in an array processor. The ManArray family of processors is designed for this dynamic compacted instruction set capability and also supports a scalable array of from one to N PEs.

Abstract: An array processor includes processing elements arranged in clusters which are, in turn, combined in a rectangular array. Each cluster is formed of processing elements which preferably communicate with the processing elements of at least two other clusters. Additionally each inter-cluster communication path is mutually exclusive, that is, each path carries either north and west, south and east, north and east, or south and west communications. Due to the mutual exclusivity of the data paths, communications between the processing elements of each cluster may be combined in a single inter-cluster path. That is, communications from a cluster which communicates to the north and east with another cluster may be combined in one path, thus eliminating half the wiring required for the path. Additionally, the length of the longest communication path is not directly determined by the overall dimension of the array, as it is in conventional torus arrays.

Abstract: A very long instruction word (VLIW) processor typically requires a large number of register file ports due to the parallel execution of the sub-instructions comprising the VLIW. By splitting a general purpose register file into separate address and compute register files, the number of compute register file ports is significantly reduced. This reduction is particularly evident when multiple load and store execution units with indexed addressing modes are supported. The implication is that a faster register file and dedicated address registers are achieved in the programming model. The savings comes at the cost of providing support for data movement between the compute register file and the address register file. In addition, address arithmetic, table look-up, and store to table functions are desirable functions that cannot be obviously obtained when the address registers are separated from the compute registers.

Abstract: General purpose flags (ACFs) are defined and encoded utilizing a hierarchical one-, two- or three-bit encoding. Each added bit provides a superset of the previous functionality. With condition combination, a sequential series of conditional branches based on complex conditions may be avoided and complex conditions can then be used for conditional execution. ACF generation and use can be specified by the programmer. By varying the number of flags affected, conditional operation parallelism can be widely varied, for example, from mono-processing to octal-processing in VLIW execution, and across an array of processing elements (PE)s. Multiple PEs can generate condition information at the same time with the programmer being able to specify a conditional execution in one processor based upon a condition generated in a different processor using the communications interface between the processing elements to transfer the conditions.

Abstract: Processing element to processing element switch connection control is described using a receive model that precludes communication hazards from occurring in a synchronous MIMD mode of operation. Such control allows different communication topologies and various processing effects such as an array transpose, hypercomplement or the like to be efficiently achieved utilizing architectures, such as the manifold array processing architecture. An encoded instruction method reduces the amount of state information and setup burden on the programmer taking advantage of the recognition that the majority of algorithms will use only a small fraction of all possible mux settings available. Thus, by means of transforming the PE identification based upon a communication path specified by a PE communication instruction an efficient switch control mechanism can be used.

Abstract: An indirect VLIW (iVLIW) architecture is described which contains a minimum of two instruction memories. The first instruction memory (SIM) contains short-instruction-words (SIWs) of a fixed length. The second instruction memory (VIM), contains very-long-instruction-words (VLIWs) which allow execution of multiple instructions in parallel. Each SIW may be fetched and executed as an independent instruction by one of the available execution units. A special class of SIW is used to reference the VIM indirectly to either execute or load a specified VLIW instruction (called an “XV” instruction for “eXecute VLIW”, or LV for “Load VLIW”). In these cases, the SIW instruction specifies how the location of the VLIW is to be accessed. Other aspects of this approach relate to the application of data memory addressing techniques for execution or loading of VLIWs that parallel the addressing modes used for data memory accesses.

Abstract: Techniques and a set of heuristics are described to perform allocation of the special instruction memory where indirect very long instruction words (VLIW's) are stored for the ManArray family of multiprocessor digital signal processors (DSP). This approach substantially reduces the cost of pre-initializing the contents of VLIWs.

Abstract: A reconfigurable register file integrated in an instruction set architecture capable of extended precision operations, and also capable of parallel operation on lower precision data is described. A register file is composed of two separate files with each half containing half as many registers as the original. The halves are designated even or odd by virtue of the register addresses which they contain. Single width and double width operands are optimally supported without increasing the register file size and without increasing the number of register file ports. Separate extended registers are also employed to provide extended precision for operations such as multiply-accumulate operations.

Abstract: Low power architecture features and techniques are provided in a scalable array indirect VLIW processor. These features and techniques include power control of a reconfigurable register file, conditional power control of multi-cycle operations and indirect VLIW utilization, and power control of VLIW-based vector processing using the ManArray register file indexing mechanism. These techniques are applicable to all processing elements (PEs) and the array controller sequence processor (SP) to provide substantial power savings.

Abstract: An array processor includes processing elements arranged in clusters which are, in turn, combined in a rectangular array. Each cluster is formed of processing elements which preferably communicate with the processing elements of at least two other clusters. Additionally each inter-cluster communication path is mutually exclusive, that is, each path carries either north and west, south and east, north and east, or south and west communications. Due to the mutual exclusivity of the data paths, communications between the processing elements of each cluster may be combined in a single inter-cluster path. That is, communications from a cluster which communicates to the north and east with another cluster may be combined in one path, thus eliminating half the wiring required for the path. Additionally, the length of the longest communication path is not directly determined by the overall dimension of the array, as it is in conventional torus arrays.

Abstract: The ManArray processor is a scalable indirect VLIW array processor that defines two preferred architectures for indirect VLIW memories. One approach treats the VIM as one composite block of memory using one common address interface to access any VLIW stored in the VIM. The second approach treats the VIM as made up of multiple smaller VIMs each individually associated with the functional units and each individually addressable for loading and reading during XV execution. The VIM memories, contained in each processing element (PE), are accessible by the same type of LV and XV Short Instruction Words (SIWs) as in a single processor instantiation of the indirect VLIW architecture. In the ManArray architecture, the control processor, also called a sequence processor (SP), fetches the instructions from the SIW memory and dispatches them to itself and the PEs. By using the LV instruction, VLIWs can be loaded into VIMs in the SP and the PEs.

Abstract: Hardware and software techniques for interrupt detection and response in a scalable pipelined array processor environment are described. Utilizing these techniques, a sequential program execution model with interrupts can be maintained in a highly parallel scalable pipelined array processing containing multiple processing elements and distributed memories and register files. When an interrupt occurs, interface signals are provided to all PEs to support independent interrupt operations in each PE dependent upon the local PE instruction sequence prior to the interrupt. Processing/element exception interrupts are supported and low latency interrupt processing is also provided for embedded systems where real time signal processing is required. Further, a hierarchical interrupt structure is used allowing a generalized debug approach using debut interrupts and a dynamic debut monitor mechanism.

Abstract: A hierarchical instruction set architecture (ISA) provides pluggable instruction set capability and support of array processors. The term pluggable is from the programmer's viewpoint and relates to groups of instructions that can easily be added to a processor architecture for code density and performance enhancements. One specific aspect addressed herein is the unique compacted instruction set which allows the programmer the ability to dynamically create a set of compacted instructions on a task by task basis for the primary purpose of improving control and parallel code density. These compacted instructions are parallelizable in that they are not specifically restricted to control code application but can be executed in the processing elements (PEs) in an array processor. The ManArray family of processors is designed for this dynamic compacted instruction set capability and also supports a scalable array of from one to N PEs.

Abstract: A highly parallel data processing system includes an array of n processing elements (PEs) and a controller sequence processor (SP) wherein at least one PE is combined with the controller SP to create a Dynamic Merged Processor (DP) which supports two modes of operation. In its first mode of operation, the DP acts as one of the PEs in the array and participates in the execution of single-instruction-multiple-data (SIMD) instructions. In the second mode of operation, the DP acts as the controlling element for the array of PEs and executes non-array instructions. To support these two modes of operation, the DP includes a plurality of execution units and two general-purpose register files. The execution units are “shared” in that they can execute instructions in either mode of operation. With very long instruction word (VLIW) capability, both modes of operation can be in effect on a cycle by cycle basis for every VLIW executed.

Abstract: A reconfigurable register file integrated in an instruction set architecture capable of extended precision operations, and also capable of parallel operation on lower precision data is described. A register file is composed of two separate files with each half containing half as many registers as the original. The halves are designated even or odd by virtue of the register addresses which they contain. Single width and double width operands are optimally supported without increasing the register file size and without increasing the number of register file ports. Separate extended registers are also employed to provide extended precision for operations such as multiply-accumulate operations.

Abstract: A highly parallel data processing system includes an array of n processing elements (PEs) and a controller sequence processor (SP) wherein at least one PE is combined with the controller SP to create a Dynamic Merged Processor (DP) which supports two modes of operation. In its first mode of operation, the DP acts as one of the PEs in the array and participates in the execution of single-instruction-multiple-data (SIMD) instructions. In the second mode of operation, the DP acts as the controlling element for the array of PEs and executes non-array instructions. To support these two modes of operation, the DP includes a plurality of execution units and two general-purpose register files. The execution units are “shared” in that they can execute instructions in either mode of operation. With very long instruction word (VLIW) capability, both modes of operation can be in effect on a cycle by cycle basis for every VLIW executed.

Abstract: A ManArray processor pipeline design addresses an indirect VLIW memory access problem without increasing branch latency by providing a dynamically reconfigurable instruction pipeline for SIWs requiring a VLIW to be fetched. By introducing an additional cycle in the pipeline only when a VLIW fetch is required, the present invention solves the VLIW memory access problem. The pipeline stays in an expanded state, in general, until a branch type or load VLIW memory type operation is detected returning the pipeline to a compressed pipeline operation. By compressing the pipeline when a branch type operation is detected, the need for an additional cycle for the branch operation is avoided. Consequently, the shorter compressed pipeline provides more efficient performance for branch intensive control code as compared to a fixed pipeline with an expanded number of pipeline stages.

Abstract: A pipelined data processing unit includes an instruction sequencer and n functional units capable of executing n operations in parallel. The instruction sequencer includes a random access memory for storing very-long-instruction-words (VLIWs) used in operations involving the execution of two or more functional units in parallel. Each VLIW comprises a plurality of short-instruction-words (SIWs) where each SIW corresponds to a unique type of instruction associated with a unique functional unit. VLIWs are composed in the VLIW memory by loading and concatenating SIWs in each address, or entry. VLIWs are executed via the execute-VLIW (XV) instruction. The iVLIWs can be compressed at a VLIW memory address by use of a mask field contained within the XV1 instruction which specifics which functional units are enabled, or disabled, during the execution of the VLIW. The mask can be changed each time the XV1 instruction is executed, effectively modifying the VLIW every time it is executed.