Abstract:
Provided is a system and method for performing CRC analysis in a video test bench. An exemplary system includes a memory configured for storing a required number representative of the data fields to be analyzed. A module is coupled at least indirectly to the memory and configured for (i) receiving an input data stream, (ii) performing cyclic redundancy check (CRC) analysis of the received data stream, and (iii) producing an output representative of an actual number of received data fields analyzed. The input data stream includes synchronization markers defining boundaries of each of the received data fields. Next, a comparator is configured for (i) comparing the required number and the actual number and (ii) producing a disabling signal when the actual number matches the required number. A detector is coupled to the comparator and configured for (i) receiving the input data stream and sensing a presence of the synchronization markers, (ii) receiving the disabling signal, and (iii) disabling the CRC module when the disabling signal is received.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Provisional Application No. 60/495,122, filed Aug. 15, 2003, which is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates generally to CRC check sum analysis during video data testing procedures.  
         [0004]     2. Related Art  
         [0005]     CRC analysis is used, for example in analysis of video graphics data paths. The CRC analysis records check sums associated with video data fields transmitted in the form of video pixels. Video pixels include signal frame data, such as vertical synchronization pulses, which can be used as boundaries to distinguish one pixel data field from another pixel data field. In performing the check sum analysis, CRC modules are typically used to accumulate and analyze the associated CRC pixel check sums.  
         [0006]     Traditional bench test set-ups are unable to consistently distinguish one pixel data field from another pixel data field in the absence of complicated software. Therefore, during traditional bench testing, the CRC modules continuously record pixel checksums without strict regard for pixel data field boundaries. Such continuous recording, however, creates inconsistencies within the accumulated check sums because of the CRC module&#39;s inability to distinguish the individual data fields. Consequently, the CRC module is unable to associate the accumulated check sums with their respective data fields.  
         [0007]     Several well known software techniques can be used in more formal test settings to synchronize the timing of the CRC module&#39;s activation with the occurrence of pixel data field boundaries. In these more formal test settings, this synchronism facilitates association of individual check sums with their respective data fields based upon data field boundaries defined by, for example, the vertical synchronization pulses.  
         [0008]     During bench testing, however, the use of the conventional software routines to accomplish this synchronization may be impractical for several reasons. Among these reasons is overall cost, and test set-up complexity. Time also becomes a factor since loading of the conventional software routines is a time-consuming process.  
         [0009]     What is needed, therefore, is a technique that can be used during test bench debugging to facilitate synchronization between CRC module activation and the occurrence of synchronization markers. What is also needed is a technique that will enable a user to designate a particular number of data fields for CRC check sum analysis by the CRC module.  
       BRIEF SUMMARY OF THE INVENTION  
       [0010]     Consistent with the principles in the present invention as embodied and broadly described herein, an apparatus for conducting bench testing of data fields includes a memory configured for storing a required number representative of the data fields to be analyzed. Also included is a module, coupled at least indirectly to the memory and configured for (i) receiving an input data stream, (ii) performing cyclic redundancy check (CRC) analysis of the received data stream, and (iii) producing an output representative of an actual number of received data fields analyzed. The input data stream includes synchronization markers defining boundaries of each of the received data fields  
         [0011]     Next, a comparator is included and configured for (i) comparing the required number and the actual number of received data fields and (ii) producing a disabling signal when the actual number matches the required number. A detector is coupled to the comparator and configured for (i) receiving the input data stream and sensing a presence of the synchronization markers, (ii) receiving the disabling signal, and (iii) disabling the CRC module when the disabling signal is received.  
         [0012]     Further features and advantages of the present invention, as well as the structure and operation of various embodiments of the present invention are described in detail below with reference to the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS FIGURES  
       [0013]     The accompanying drawings, which are embodied in and constitute part of the specification, illustrate embodiments of the invention and, together with the general description given above and detail description of the embodiments given below, serve to explain the principles of the invention. In the invention:  
         [0014]      FIG. 1  is a flowchart of a software technique for CRC check sum analysis;  
         [0015]      FIG. 2  is an illustration of video data fields stored during CRC check sum analysis of  FIG. 1 ;  
         [0016]      FIG. 3  is a block diagram illustration of an exemplary CRC check sum analysis device constructed and arranged in accordance with an embodiment of the present invention;  
         [0017]      FIG. 4  is an illustration of video data fields stored within a memory of the check sum analysis device illustrated in  FIG. 3 ;  
         [0018]      FIG. 5  is a flow diagram of an exemplary method of practicing an embodiment of the present invention; and  
         [0019]      FIG. 6  is a block diagram of an exemplary computer system all of which the present invention can be practiced. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0020]     The following detailed description of the present invention refers to the accompanying drawings that illustrate exemplary embodiments consistent with this invention. Other embodiments are possible, and modifications may be made to the embodiments within the spirit and scope of the invention. Therefore, the following detailed description is not meant to limit the invention. Rather, the scope of the invention is defined by the impending claims.  
         [0021]     It would be apparent to one of skill in the art that the present invention, as described below, may be implemented in many different embodiments of hardware, software, firmware, and/or the entities illustrated in the figures. In the actual software code with the controlled hardware to implement the present invention is not limiting of the present invention. Thus the operation and behavior of the present invention will be described with the understanding that modifications and variations of the embodiments are possible, given the level of detail presented herein.  
         [0022]      FIG. 1  is a block diagram illustration of a software technique  100 , used for CRC check sum testing in formal test set-ups. The conventional software technique  100 , for example, can be used during regression testing of video systems. As illustrated in block  102  and during video scanning, for example, a CRC check sum module is enabled by using the software to set up an interrupt routine. As an initial matter, the software technique  100  must first wait for generation of an interrupt as indicated in block  104  using, for example, an interrupt service routine (ISR). Once the interrupt has been generated, the CRC module is enabled and can begin the accumulation of CRC check sums and to set up to receive its next interrupt, as indicated in block  106 .  
         [0023]     Use of the software routine  100  enables the CRC module to time the interrupts with occurrence of a synchronization marker at desired times or during specific events, such as video blanking. As noted above, synchronization markers, such as vertical synch, distinguish boundaries of one received data field from another received data field.  
         [0024]     Next, the software routine  100 , after enabling the CRC module to receive the first data field, waits for generation of another interrupt as illustrated in block  108 .  
         [0025]     Using the technique  100 , or similar techniques, a user can specify a particular number of data fields for collection analysis. The user can also synchronize the timing of the collection process. In the technique  100 , if a sufficient number of data fields has not been collected, the software routine  100  can again enable the CRC to receive and accumulate an additional data field as illustrated in block  110 . Once the desired field count has been reached, all of the accumulated CRCs are examined, as illustrated in block  112 .  
         [0026]     Software routines, such as the routine  100  of  FIG. 1 , enable a user to provide ISRs to the CRC module in synchronization with an occurrence of vertical synch pulses. The vertical synch pulses indicate the beginning and end of the associated data fields during CRC check sum testing. That is, the CRC module starts to collect data when active video pixels are coming in based upon the occurrence of the vertical synchronization pulse which define the pixel&#39;s boundaries.  
         [0027]     For example, an ISR can be generated to record any number of data fields and, at the same time, disable the CRC module after collection of the last data field for examination of the associated check sum values. Software routines, such as the routine  100 , facilitate a programmable number of data field counts such as 2, 3, 8 or any number, for use with CRC testing. For example, a particular number of data fields can be recorded within the CRC module. Afterwards, the field count can be checked. If the desired number has not been reached, the field count can be incremented by one, and the process is repeated until the desired number has been achieved. Further, these software routines permit specifying data collection not only in terms of field counts, but also in terms of periods of time. In this manner, the software provides the flexibility to record the check sum for any desirable increment during regression testing.  
         [0028]     During bench testing, however, software routines, such as the routine  100 , are impractical. Instead, during bench testing, testers typically use more flexible and dynamic testing methods, such as register access. Although conventional register access provides testers with a more convenient and more flexible testing technique, the associated check sum values are often inconsistent. The inconsistency results from an inability to precisely time the CRC module enablement with specific boundaries of the data fields. Additionally, register access techniques fail to provide testers with an ability to quickly change and specify the number of data fields to be recorded for the check sum analysis.  
         [0029]      FIG. 2  is an illustration of data fields stored within a memory of the CRC module during CRC check sum testing associated with the method of  FIG. 1 . In  FIG. 2 , the CRC module can include, for example, stored pixel data fields  200 . Within the data fields  200  are individual segments  202 ,  204 ,  206 , and  208  that are representative of data fields  1  through  4 .  
         [0030]     As shown in  FIG. 2 , data field segments  202  and  204  are separated by a synchronization marker  210 . The segments  204  and  206  are separated by a synchronization marker  212 . And the segments  206  and  208  are separated by a synchronization marker  214 . During bench testing, however, CRC module enablement can occur for example at a time  216 , as indicated in  FIG. 2 . CRC enablement at the time  216  occurs because the bench testing method does not always know when the synchronization markers occur.  
         [0031]     With enablement occurring at the time  216 , the first interrupt might subsequently occur, for example, at a time  218 . The time  218 , however, occurs during the video data field  202 . The next interrupt might occur at a time  220 , during video data field  204 . A final CRC module interrupt  222  is shown to occur within data field  206 . Since the CRC module interrupts  218 ,  220 , and  222  do not occur in synchronism with the synchronization markers  210 ,  212  and  214 , conventional bench test debugging will produce inconsistent check sum values because of the indistinguishable data fields  
         [0032]      FIG. 3  provides a block diagram illustration  300  of an exemplary CRC checksum system  300  constructed and arranged in accordance with an embodiment of the present invention. In particular, the CRC checksum system  300  enables bench testers to selectively program a desirable field count and provide synchronism between CRC module enablement and an occurrence of synchronization markers. This particular technique eliminates the problems noted above with regard to conventional bench testing.  
         [0033]     In  FIG. 3 , an external memory device  302 , such as a register, is added to a conventional video bench test set up. The register  302  is configured to receive as an input a desired numeric field count value  304 . The field count value  304  enables a user to specifically program the number of field counts desired to perform CRC check sum analysis. During CRC check sum analysis, the desirable field count value  304  is loaded into a comparator  306  for comparison with an actual field count value.  
         [0034]     A CRC module  308  is coupled to the comparator  306  and, at least indirectly, to the register  302 . The CRC module  308  receives as an input a video data stream  310  that includes, among other things, video pixel data and video synchronization markers. A detector  312  is coupled to the CRC module  308  and is structured to sense the video synchronization markers within the video data stream  310 . The detector  312  also receives as an input a CRC enablement bit  314 , which can be provided in real time by a user. During bench testing, when the user provides the CRC enablement bit  314 , an associated synchronization marker, such as the vertical synch pulse, is sensed from the video data stream  310  by the detector  312 . Consequently, an enablement command  316  is sent to the CRC module  308 . The enablement command  316  signals the CRC module  308  to begin accumulating associated CRC check sums.  
         [0035]     Among other things, the CRC module  308  provides a count of the accumulated data fields as an output along a data path  318  to the comparator  306 . The comparator  306  compares the data field count produced by the CRC module  308  with the desirable field count number  304  provided by the register  302 . When the field count number  304  matches the actual CRC field count from the data path  318 , a disablement command  320  is supplied to the detector  312  for detection of an end-point of the final collected data field. Once the required number of data fields have been accumulated within the CRC module  308 , the check sum values are recorded to another register  324 . This process is illustrated in  FIG. 4 .  
         [0036]     By way of the example illustrated in  FIG. 2 ,  FIG. 4  provides a depiction of operation of the exemplary embodiment of the present invention shown in  FIG. 3 . In  FIG. 4 , the data field segments  202  through  208  are loaded into the CRC module  308 . Here, for example, the user specifies a desirable number of field counts, such as two. That is, two data fields will be accumulated and examined for check sum analysis. In this example, the number “2” will be loaded in the register  302 . Next, the user provides the CRC enablement bit  314  of  FIG. 3  to initiate collection of checksums by the CRC module  308 .  
         [0037]     Next, the detector  312  senses a presence of the synchronization marker  210 , and nearly simultaneously, provides a CRC module interrupt  402  to enable the CRC module  308 . The synchronization marker  210  indicates a beginning of the first collected data segment  204 . After the two segments  204  and  206  have been received by the CRC module  308 , the CRC module disablement command  320  is sent to the detector  312 . The detector  312  then senses the synchronization marker  214 , indicating an end of the data field segment  214  and substantially simultaneously disables the CRC module  308 . The CRC module  308 , now having two complete data fields,  204  and  206  collected therein, will load their associated accumulated check sums into the register  324 .  
         [0038]     The system  300  provides bench testers with a technique to specify the number of data fields that will be examined for checksum analysis. It also provides the bench testers with a mechanism to ensure that the number of checksums that are analyzed are representative of complete data fields. The ability to specify the number of data fields and the ability to collect checksums from complete data fields produces more consistent and reliable bench testing results. This approach, due to its consistent results, can be used to automate the testing or software/hardware QA (Quality-Assurance) for video products, which traditionally require testers to perform visual inspection.  
         [0039]      FIG. 5  is a flow chart of an exemplary method  500  of practicing the present invention. In  FIG. 5 , the CRC analysis system  300  stores a desired number of fields requiring CRC analysis in the register  302 , as illustrated in block  502 . Next, video pixel data  310  is received in the CRC module  308 , as indicated in block  504 . The detector  312  senses the received video pixel data for a presence of synchronization markers, as shown in block  506 . When markers, such as the markers  210  through  214  are detected, the CRC module  308  is enabled in a manner indicated in block  508 . When the required number of video data fields has been collected, the CRC module  308  is disabled, as indicated in block  510 . Finally, the accumulated check sum values are recorded in the register  324  as indicated in block  512 .  
         [0040]     The present invention provides a function that enables a user to specify a programmable number of field counts for a CRC module to record the CRC check sum. It contains one register that specifies a number of fields to be recorded and a bit to enable the CRC analysis. Once CRC analysis has been enabled, the associated hardware will start performing CRC analysis at the next pixel start and continue to record the check sum until the specified number of fields has been recorded. It terminates check sum analysis at the end of that specified field count.  
         [0041]     In bench debugging, the present invention enables users to manually program a register to specify the number of fields requiring check sum testing. This technique prevents the need for complicated test software having sophisticated ISRs. It also provides a flexible dynamic mechanism for achieving consistent CRC results during bench test debugging.  
         [0042]      FIG. 6  provides an illustration of a general purpose computer system and is provided for completeness. As stated above, the present invention can be implemented in hardware, or as a combination of software and hardware. Consequently, the invention may be implemented in the environment of a computer system or other processing system. An example of such a computer system  600  is shown in  FIG. 6 .  
         [0043]     The computer system  600  includes one or more processors, such as a processor  604 . The processor  604  can be a special purpose or a general purpose digital signal processor and it&#39;s connected to a communication infrastructure  606  (for example, a bus or network). Various software implementations are described in terms of this exemplary computer system. after reading this description, it will become apparent to a person skilled in the relevant art how to implement the invention using other computer systems and/or computer architectures.  
         [0044]     The computer system  600  also includes a main memory  608 , preferably random access memory (RAM), and may also include a secondary memory  610 . The secondary memory  610  may include, for example, a hard disk drive  612  and/or a removable storage drive  614 , representing a floppy disk drive, a magnetic tape drive, an optical disk drive, etc. The removable storage drive  614  reads from and/or writes to a removable storage unit  618  in a well known manner. The removable storage unit  618 , represents a floppy disk, magnetic tape, optical disk, etc. which is read by and written to by removable storage drive  614 . As will be appreciated, the removable storage unit  618  includes a computer usable storage medium having stored therein computer software and/or data.  
         [0045]     In alternative implementations, the secondary memory  610  may include other similar means for allowing computer programs or other instructions to be loaded into the computer system  600 . Such means may include, for example, a removable storage unit  622  and an interface  620 .  
         [0046]     Examples of such means may include a program cartridge and cartridge interface (such as that found in video game devices), a removable memory chip (such as an EPROM, or PROM) and associated socket, and the other removable storage units  622  and the interfaces  620  which allow software and data to be transferred from the removable storage unit  622  to the computer system  600 .  
         [0047]     The computer system  600  may also include a communications interface  624 . The communications interface  624  allows software and data to be transferred between the computer system  600  and external devices. Examples of the communications interface  624  may include a modem, a network interface (such as an Ethernet card), a communications port, a PCMCIA slot and card, etc. Software and data transferred via the communications interface  624  are in the form of signals  628  which may be electronic, electromagnetic, optical or other signals capable of being received by the communications interface  624 . These signals  628  are provided to the communications interface  624  via a communications path  626 . The communications path  626  carries the signals  628  and may be implemented using wire or cable, fiber optics, a phone line, a cellular phone link, an RF link and other communications channels.  
         [0048]     In the present application, the terms “computer readable medium” and “computer usable medium” are used to generally refer to media such as the removable storage drive  614 , a hard disk installed in the hard disk drive  612 , and the signals  628 . These computer program products are means for providing software to the computer system  600 .  
         [0049]     Computer programs (also called computer control logic) are stored in the main memory  608  and/or the secondary memory  610 . Computer programs may also be received via the communications interface  624 . Such computer programs, when executed, enable the computer system  600  to implement the present invention as discussed herein.  
         [0050]     In particular, the computer programs, when executed, enable the processor  604  to implement the processes of the present invention. Accordingly, such computer programs represent controllers of the computer system  600 . By way of example, in the embodiments of the invention, the processes/methods performed by signal processing blocks of encoders and/or decoders can be performed by computer control logic. Where the invention is implemented using software, the software may be stored in a computer program product and loaded into the computer system  600  using the removable storage drive  614 , the hard drive  612  or the communications interface  624 .  
         [0051]     The present invention has been described above with the aid of functional building blocks illustrating the performance of specified functions and relationships thereof. The boundaries of these functional building blocks have been arbitrarily defined herein for the convenience of the description. Alternate boundaries can be defined so long as the specified functions and relationships thereof are appropriately performed.  
         [0052]     Any such alternate boundaries of thus within the scope and spirit of the claimed invention. One skilled in the art would recognize that these functional building blocks can be implemented by analog and/or digital circuits, discreet components, application specific integrated circuits, firmware, processors executing appropriate software and the like or any combination thereof. Thus, the breadth and scope of the present invention should not be limited by any way of the above described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.