Abstract:
A processor system, comprising: a plurality of arithmetic units capable of performing arithmetic processings in parallel; a storage which stores data that said plurality of arithmetic units use for arithmetic processings; a plurality of DMA controllers which perform data transfer between said plurality of arithmetic units, and between said plurality of arithmetic units and said storage in parallel with processings of a host processor; and a DMA control circuit which controls start-up of said plurality of arithmetic units and said plurality of DMA controllers in parallel with processings of said host processor.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims benefit of priority under 35USC§ 119 to Japanese Patent Application No. 2004-9351, filed on Jan. 16, 2004, the entire contents of which are incorporated by reference herein.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a processor system which can perform a data transfer process by DMA (Direct Memory Access), a DMA control circuit, a DMA control method, a control method for DMA controller, a graphic processing method, and a graphic processing circuit.  
         [0004]     2. Related Background Art  
         [0005]     In conventional DMA transfer, data transfer is performed in parallel with an operation of a host processor to reduce processing load on the host processor. While the DMA transfer is performed, the host processor can perform another process. For this reason, the DMA transfer is suitably applied to a case in which a large amount of data such as image data is transferred.  
         [0006]     A DMA transfer is generally performed under the control of a DMA controller. A host processor sets transfer control information representing time when a DMA transfer is performed, a position from which the DMA transfer is performed, and a position to which the DMA transfer is performed in the DMA controller in advance. According to the setting information, the DMA controller performs the DMA transfer.  
         [0007]     On the other hand, as a method of increasing the speed of a process in a processor system, there is known a method in which a plurality of arithmetic units are arranged and operated in parallel to each other. In this case, calculation process results of the plurality of arithmetic units are desirably transferred in parallel to each other, and a plurality of DMA controller may be arranged.  
         [0008]     However, when the plurality of DMA controllers are arranged to make it possible to perform data transfer processes in parallel to each other, the host processor must set pieces of transfer control information for the DMA controllers, processing load on the host processor increases. The processing load increases in proportion to the number of DMA controllers.  
       SUMMARY OF THE INVENTION  
       [0009]     A processor system according to one embodiment of the present invention, comprising: 
        a plurality of arithmetic units capable of performing is arithmetic processings in parallel;     a storage which stores data that said plurality of arithmetic units use for arithmetic processings;     a plurality of DMA controllers which perform data transfer between said plurality of arithmetic units, and between said plurality of arithmetic units and said storage in parallel with processings of a host processor; and     a DMA control circuit which controls start-up of said plurality of arithmetic units and said plurality of DMA controllers in parallel with processings of said host processor.        
 
         [0014]     A DMA control circuit according to one embodiment of the present invention, comprising: 
        a plurality of instruction storages which store information relating to a plurality of instructions instructed from a host processor, respectively; and     a scheduler which performs data transfer between a plurality of arithmetic units each being capable of performing arithmetic processings in parallel, data transfer between a storage which stores data that said plurality of arithmetic units use for arithmetic processings and said plurality of arithmetic units, and starting control of said plurality of arithmetic units, based information stored in said plurality of instruction storages, in parallel with processings of said host processor.        
 
         [0017]     A method of controlling a DMA controller according to one embodiment of the present invention, comprising: 
        storing data that arithmetic units capable of performing arithmetic processing in parallel use for arithmetic processings into a storage;     performing data transfer by using a plurality of DMA controllers in parallel with processings of a host processor, between said plurality of arithmetic units, and between said plurality of arithmetic units and said storage;     transmitting data transfer completion information expressing completion of data transfer, by monitoring said plurality of DMA controllers and said plurality of arithmetic processing units;     determining whether or not other data transfer is possible, based on the data transfer completion information; and     performing data transfer by using at least one of said plurality of DMA controllers when determined that data transfer is possible.        
 
         [0023]     A graphic processing method according to one embodiment of the present invention, comprising: 
        converting vertex information into pixel information;     generating image by a plurality of arithmetic units based on the pixel information;     storing data that said arithmetic units capable of performing the arithmetic processings in parallel use for the arithmetic processings, into a storage;     performing data transfer by using a plurality of DMA controllers between said plurality of arithmetic units, and between said plurality of arithmetic units and said storage;     transmitting data transfer completion information expressing that data transfer has been completed, by monitoring said plurality of DMA controllers and said plurality of arithmetic units;     determining whether or not other data transfer is possible, based on the data transfer completion information; and     performing data transfer by at least one of said plurality of DMA controllers when determined that the other data transfer is possible.        
 
         [0031]     A graphic processing circuit according to one embodiment of the present invention, comprising: 
        a pixel information converter which converts vertex information into pixel information;     a plurality of arithmetic units capable of performing arithmetic processings in parallel based on the pixel information;     a plurality of DMA controllers which perform data transfer between said plurality of arithmetic units, and data transfer between a storage which stores data used by said plurality of arithmetic units and said arithmetic units;     an instruction information storage which stores instruction information relating to a plurality of DMA transfers; and     a control circuit which determines whether DMA transfer by said plurality of DMA controllers is possible, based on instruction information stored in said instruction information storage.       
 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0037]      FIG. 1  is a block diagram showing a schematic configuration of a processor system according to the first embodiment of the present invention.  
         [0038]      FIG. 2  is a block diagram showing the details of the internal configuration of the graphic processing processor  2  shown in  FIG. 1 .  
         [0039]      FIG. 3  is a block diagram showing an example of the internal configuration of the controller  21 .  
         [0040]      FIG. 4  is a block diagram showing an example of the internal configuration of the dedicated circuit  32  in  FIG. 3 .  
         [0041]      FIG. 5  is a flow chart showing an example of procedures performed by the controller  21  in  FIG. 1 .  
         [0042]      FIGS. 6A and 6B  are diagrams showing an example of tasks executed by the dedicated circuit  32 .  
         [0043]      FIG. 7A  is a diagram showing a first operation of a conventional DMAC  31 ,  FIG. 7B  is a diagram showing a second operation of the conventional DMAC  31 , and  FIG. 7C  is a diagram showing an operation of the DMAC  31  according to this embodiment.  
         [0044]      FIG. 8  is a timing chart corresponding to  FIG. 7A .  
         [0045]      FIG. 9  is a timing chart corresponding to  FIG. 7B .  
         [0046]      FIG. 10  is a timing chart corresponding to  FIG. 7C .  
         [0047]      FIG. 11  is a diagram showing one example of how to use the sync register.  
         [0048]      FIG. 12  is a diagram showing another example of how to use the sync register.  
         [0049]      FIG. 13  is a diagram showing another example of how to use the sync register.  
         [0050]      FIG. 14  is a diagram showing a method of processing two instruction strings.  
         [0051]      FIG. 15  is a data flow chart showing an example of procedures of the controller  21 .  
         [0052]      FIG. 16  is a diagram showing one example of a program of the host processor  1 .  
         [0053]      FIG. 17  is a block diagram showing the internal configuration of the controller  21  according to the second embodiment.  
         [0054]      FIG. 18  is a block diagram showing an example of the internal configuration of the dedicated circuit  32 a in  FIG. 17 .  
         [0055]      FIG. 19  is a flow chart showing an example of a procedure performed by the controller  21  in  FIG. 17 .  
         [0056]      FIG. 20  is a block diagram showing a case in which the processor system according to this application is built in a digital television set.  
         [0057]      FIG. 21  is a block diagram showing an example in which the processor system according to this embodiment is built in a video recorder/player.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0058]     A processor system, a DMA control circuit, a DMA control method, a control method for a DMA controller, a graphic processing method, and a graphic processing circuit according to an embodiment of the present invention will be described below with reference to the accompanying drawings.  
       FIRST EMBODIMENT  
       [0059]      FIG. 1  is a block diagram showing a schematic configuration of a processor system according to the first embodiment of the present invention. The processor system shown in  FIG. 1  includes a host processor  1 , a graphic processing processor  2 , a main memory  3 , and an I/O processor  4 .  
         [0060]     The host processor  1  includes a main processor  11 , a plurality of digital signal processors (DSP)  12 , and I/O units  13 ,  14 , and  15  which controls input/output operations with an external circuit. The I/O unit  13  controls input/output operations with the main memory  3 , the I/O unit  14  controls the input/output operations with the graphic processing processor  2 , and the I/O unit  15  controls the input/output operations with the I/O processor  4 .  
         [0061]     The graphic processing processor  2  includes a controller  21  serving as a characteristic part of this embodiment, an I/O unit  22  which performs data exchange with the host processor  1 , various universal buses such as a PCI bus, an I/O unit  23  which controls input/output operations of video data, audio data, or the like, and a graphic processing unit  24  which performs graphic processing calculation.  
         [0062]     The graphic processing unit  24  includes a pixel converters  26  which converts the vertex information of a polygon into pixel data and a plurality of arithmetic units (DSP)  27  which process the pixel data.  
         [0063]     The I/O processor  4  controls connection to a universal bus, a peripheral devices such as an HDD and a DVD or the like, and a network.  
         [0064]      FIG. 2  is a block diagram showing the details of the internal configuration of the graphic processing processor  2  shown in  FIG. 1 . Each of the plurality of arithmetic units  27  includes a processor cluster  28  constituted by a plurality of processors and a memory  29  which stores a processing results of the processor cluster  28 . The plurality of processors in the processor cluster  28  can execute independent processes in parallel to each other, and can execute one process such that the plurality of processor cluster  28  share the process. The memory  29  stores an execution result of the processor cluster  28 . The controller  21 , the pixel converters  26 , the I/O units  22  and  23 , and the memory  29  which are shown in  FIG. 2  are connected to a common bus  30 .  
         [0065]      FIG. 3  is a block diagram showing an example of the internal configuration of the controller  21 . The controller  21  shown in  FIG. 3  includes a plurality of DMA controllers (DMAC)  31 , a dedicated circuit  32 , a control processor  33  constituted by general-purpose processors, a timer  34 , an interruption unit  35  and a memory  36 .  
         [0066]     The DMA controllers  31  perform data transfer between the plurality of arithmetic units  27  and between the plurality of arithmetic units  27  and the memory  36 . The dedicated circuit  32  is a circuit which is dedicated to this system, and performs start-up control for the DMA controllers  31  and the arithmetic units  27 . The control processor  33  controls the dedicated circuit  32  according to a program code stored in the memory  36  or an instruction from the host processor  1 . The timer  34  performs time management and instructs the interruption unit  35  to perform interruption as needed. The interruption unit  35  receives a signal from the timer  34  or a completion signal from the DMA controllers  31  or the arithmetic units  27  to perform interruption to the control processor  33 .  
         [0067]     The dedicated circuit  32 , the timer  34 , the interruption unit  35 , and the memory  36  shown in  FIG. 3  are connected to a local network  37 . The host processor  1  is also connected to the local network  37  through the I/O unit  22 . The memory  36  is, for example, consisted of an embedded DRAM. The DMA controllers are, for example, provided more than 30 pieces.  
         [0068]      FIG. 4  is a block diagram showing an example of the internal configuration of the dedicated circuit  32  in  FIG. 3 . This block diagram shows a configuration in which the dedicated circuit  32  is connected as a co-processor of the control processor  33 . The dedicated circuit  32  in  FIG. 4  includes a control processor I/O unit  41 , a plurality of DMA registers  42 , a DMA issuance unit  43 , a plurality of sync registers  44 , and a sync register control units  45 .  
         [0069]     The control processor I/O unit  41  exchanges data with the control processor  33 . The DMA registers  42  stores various pieces of information required for the operations of the DMACs  31 . The DMA issuance unit  43  performs a process of transferring the pieces of information in the DMA registers  42  to the DMACs  31 . A specific DMA register from which the information is transferred and a specific DMAC  31  to which the information is transferred are determined by the control processor  33 . The DMA issuance unit  43  is notified of the specific DMA register and the specific DMAC  31  through the control processor I/O unit  41 . The sync registers  44  stores the operation states of the DMACs  31  and the arithmetic units  27 . The sync register control units  45  controls updating of the sync registers  44 .  
         [0070]      FIG. 5  is a flow chart showing an example of procedures performed by the controller  21  in  FIG. 1 . This flow chart shows procedures performed when data prepared in the host processor  1  is DMA-transferred to the memory  36  in the graphic processing processor  2 .  
         [0071]     When data to be processed by the graphic processing processor  2  is prepared by the host processor  1 , the host processor  1  transmits a preparation completion signal to the local network  37  in  FIG. 3 . This signal is received by the sync register control unit  45  in  FIG. 4  (step S 1 ).  
         [0072]     The sync register control unit  45  updates the value of the sync register  44  (step S 2 ). More specifically, the sync register  44  is set at a value representing that preparation for data transfer of the host processor  1  is completed.  
         [0073]     The control processor  33  reads the value of the sync register  44  through the control processor I/O unit  41  according to a dedicated instruction to confirm that the preparation for the host processor  1  is completed (step S 3 ). Here, the dedicated instruction expresses a task. An instruction string including the dedicated instruction (task) executed by the control processor  33  and the dedicated circuit  32  expresses a task string.  
         [0074]     The control processor  33  transfers the setting information of the DMAC  31  to the DMA register  42  through the control processor I/O unit  41  (step S 4 ).  
         [0075]     The control processor  33  starts the DMA issuance unit  43  through the control processor I/O unit  41  based on a dedicated instruction, and instructs the DMA issuance unit  43  to set the setting information of the DMAC  31  stored in the DMA registers  42  in each DMAC  31  (step S 5 ).  
         [0076]     Thereafter, the DMAC  31  performs a DMA transfer. Upon completion of the DMA transfer, the DMAC  31  notifies the sync register control units  45  that the DMA transfer is completed (step S 6 ). The sync register control units  45  updates the sync register  44  (step S 7 ).  
         [0077]     The control processor  33  reads the value of the sync resister through the control processor I/O unit  41  based on a dedicated instruction, and confirms that the DMA transfer is completed (step S 8 ). Thereafter, the control processor  33  starts the arithmetic unit  27  through the control processor I/O unit  41 , and processes data transferred from the host processor  1  to the memory in the graphic processing processor  2  (step S 9 ).  
         [0078]     As described above, the sync register control unit  45  in  FIG. 4  monitors the value of the sync registers  44 . Periodical monitoring is generally called “polling”. The sync register control unit  45  according to this embodiment can monitor the operations of the DMAC  31 , the arithmetic unit  27 , and the host processor  1  by the polling.  
         [0079]     In place of the monitoring of the sync register  44  by the sync register control unit  45 , the control processor  33  may monitor the sync register  44  through the control processor I/O unit  41 .  
         [0080]     In this case, a command for controlling the DMAC  31  is called an instruction, and each command is constituted of, e.g., 256-bit data. The sync register control unit  45  and the sync register  44  in the dedicated circuit  32  serve as a task scheduler.  
         [0081]     More specifically, the task includes a command related to data transfer control of the DMAC  31  and a command related to start-up control of the arithmetic units  27  and an initial setting for the arithmetic units  27 , and a command related to an interruption notice for the host processor  1 .  
         [0082]     The dedicated circuit  32  according to this embodiment continuously execute tasks until a special task called a block task is executed. The block task is a task which waits for execution completion of a task (DMA execution or a process of a processor cluster) issued before the block task. When the block task is executed, the dedicated circuit  32  waits until the execution of the set tasks is completed.  
         [0083]      FIG. 6A  is a diagram showing an example of tasks executed by the dedicated circuit  32 , and shows an example in which tasks A, B, C, D, E, F, and G are executed. The tasks in  FIG. 6A  are written as a data flow chart as shown in  FIG. 6B . The dedicated circuit  32  executes task A and waits for execution completion of task A as a block task. Upon completion of the execution of task A, the dedicated circuit  32  executes tasks F and B in parallel. The dedicated circuit  32  waits execution completion of the tasks F and B as block tasks. Upon completion of the execution of the tasks F and B, the dedicated circuit  32  executes tasks C and D in parallel. The dedicated circuit  32  waits for execution completion of the tasks C and D as block tasks. Upon completion of the execution of tasks C and D, the dedicated circuit  32  executes task E. The dedicated circuit  32  waits execution completion of task E as a block task. Upon completion of the execution of task E, the dedicated circuit  32  executes task G.  
         [0084]     In this manner, a block task in  FIG. 6B  can synchronize a plurality of DMA transfers.  
         [0085]     The dedicated circuit  32  of this embodiment can start the following DMA transfer by an event except for a notice of completion of a DMA transfer. The event mentioned here is, e.g., completion of a calculation process of the arithmetic units  27  or a notice from the host processor  1 .  
         [0086]      FIG. 7A  is a diagram showing a first operation of a conventional DMAC  31 ,  FIG. 7B  is a diagram showing a second operation of the conventional DMAC  31 , and  FIG. 7C  is a diagram showing an operation of the DMAC  31  according to this embodiment.  FIG. 8  is a timing chart corresponding to  FIG. 7A ,  FIG. 9  is a timing chart corresponding to  FIG. 7B , and  FIG. 10  is a timing chart corresponding to  FIG. 7C .  
         [0087]      FIGS. 7A and 8  show most popular DMA transfers. After a certain DMA transfer is completed, the next DMA transfer is performed. In this case, as shown in  FIG. 8 , the host processor  1  (CPU) performs designation (t 1 ) of DMA, register setting (t 2 ) of the arithmetic unit  27 , and designation of execution (t 3 ) of the arithmetic unit  27 . The DMAC  31  executes a DMA command designated by the host processor  1 .  
         [0088]     In the examples shown in  FIGS. 7A and 8 , various settings and designation related to a DMA transfer and the designation of execution of the arithmetic unit  27  are performed by the host processor  1 . For this reason, load on the host processor  1  is excessively large. Therefore, a period (t 4 ) in which the host processor  1  performs another process becomes short so that the performance of the host processor  1  is deteriorated.  
         [0089]     In examples shown in  FIGS. 7B and 9 , a plurality of DMA transfers can be performed in parallel to each other. However, as shown in  FIG. 9 , the host processor  1  performs the register setting and the designation of start of the arithmetic unit  27  (period t 5 ). According to the designation, the DMAC  31  transfers the register setting and the designation of start of the arithmetic unit  27  (period t 6 ). In this example, since the register setting can be performed to the plurality of DMACs  31  in parallel, when the number of registers to be resister-set is large, processing load on the host processor  1  can be reduced. However, when only some registers are reset, as in the cases in  FIGS. 7A and 8 , the processing load on the host processor  1  increases.  
         [0090]     On the other hand, in this embodiment shown in  FIGS. 7C and 10 , not only the next DMA transfer is performed by using only the end of a DMA transfer as a trigger, but also the next DMA transfer is performed by using a notice from the arithmetic unit  27  or the host processor  1  as a trigger. The DMAC  31  can perform register setting of the arithmetic unit  27  and designation of execution of the arithmetic unit  27 . More specifically, as shown in  FIG. 10 , when the host processor  1  designates the DMAC  31  to perform a DMA transfer (period t 7 ), in response to this designation, the DMAC  31  performs register setting (period t 8 ) of the arithmetic unit  27 , a DMA transfer (period t 9 ), and designation of execution (period t 10 ) of the arithmetic unit  27 . Upon completion of the calculation process, the arithmetic unit  27  notifies the DMAC  31  of the end of the calculation process.  
         [0091]     As shown in  FIG. 10 , since the DMAC  31  controls a DMA transfer and controls execution of the arithmetic unit  27 , the host processor  1  can allocate long time to other processes. Therefore, the performance of the host processor  1  can be enhanced.  
         [0092]     The operations of the host processor  1  and the controller  21  in the graphic processing processor  2  will be described in further detail. The host processor  1  reads a task string stored in the main memory  3  to transfer the task string to a memory in the graphic processing processor  2 . This transfer process may be directly written in the memory by a store task of the host processor  1 , or a DMA transfer may be performed as one of tasks.  
         [0093]     The sync register control units  45  in the controller  21  sets pointer information or the like of a task string in the DMA register  42  of the DMAC  31 . According to the contents of the DMA registers  42 , the DMA issue device performs various settings to each DMAC  31 .  
         [0094]     The controller  21  can perform not only start-up control of the DMAC  31  but also start-up control of the arithmetic unit  27 . As tasks used when the controller  21  controls the arithmetic unit  27 , tasks of two types, i.e., a set task and a kick task are known. The set task is a task for performing various settings to the arithmetic unit  27 . More specifically, various settings are performed to display a three-dimensional image such as a texture or a vertex. The kick task is a task for designating the start of execution of the arithmetic unit  27 .  
         [0095]     As described above, in the sync register  44 , the operation states of the DMAC  31 , the arithmetic unit  27 , and the like are stored. The host processor  1  can read the value of the sync registers  44  through the sync register control units  45 . Several methods may be used as methods of using the sync register  44 . Typical one of these methods is shown in  FIGS. 11, 12 , and  13 .  
         [0096]     In  FIG. 11 , some process is performed by the controller  21  (step S 11 ). The process result is written in the sync register  44  by a write task (step S 12 ). The controller  21  interrupts the execution of the task until the controller  21  receives a notice for block cancellation from the host processor  1  (step S 13 ). When the host processor  1  periodically performs polling of the sync register  44  (step S 13 ) to acquire the values written in the sync register  44  in the write task, the host processor  1  notifies the controller  21  of block cancellation (step S 15 ).  
         [0097]     In  FIG. 12 , the controller  21  starts the arithmetic unit  27  by a kick task (step S 16 ), and interrupts the execution of the tasks until the process in the arithmetic unit  27  is ended (step S 17 ). The arithmetic unit  27  started by the kick task executes some process (step S 18 ). Upon completion of the process, the arithmetic unit  27  transmits a completion notice to the controller  21  and writes a return value in the sync register  44  (step S 19 ). The controller  21  which receives the completion notice performs branching with reference to a value of a general-purpose register (step S 20 ).  
         [0098]     In  FIG. 13 , some process is performed by the controller  21  (step S 21 ). Upon completion of the process, the execution of the task is interrupted until the controller  21  receives a notice of block cancellation from the host processor  1  (step S 22 ). The host processor  1  dynamically sets time when the execution of the task is restarted by the controller  21  (step S 23 ). At that time, the host processor  1  cancels the block of the controller  21  and writes the return value in the sync register  44  (step S 24 ). The controller  21  performs branching with reference to the value of the sync register  44  (step S 25 ).  
         [0099]     As described above, the controller  21  can simultaneously execute a plurality of task strings. As an example of the execution, a program which is executed such that data is transferred from the main memory  3  to a memory and the pointer of the data is set in the arithmetic unit  27  will be described below. In this case, the controller  21  simultaneously executes two task strings and synchronizes the task strings. This synchronization is performed by designation from the host processor  1 .  
         [0100]     It is assumed that, as shown in  FIG. 14 , the memory is divided into four regions (to be referred to as FIFO  0  to  3  hereinafter). In one (to be referred to as Task String  1  hereinafter) of the two task strings, the main memory  3  transfers data to FIFO  0  to  3 . In the other task string (to be referred to as Task String  2 ), data is transferred from FIFO  0  to  3  to the arithmetic unit  27 .  
         [0101]     Task String  2  actually performs an initial setting to the arithmetic unit  27  by a set task. The arithmetic unit  27  reads the data from the memory.  
         [0102]      FIG. 15  is a data flow chart showing an example of procedures of the controller  21  which executes two Task Strings  1  and  2  described above. Task String  1  and Task String  2  in  FIG. 15  are executed in parallel to each other. In Task String  1 , data is sequentially transferred from the main memory  3  to FIFO  0  to  3 . Thereafter the controller  21  returns to the top of Task String  1  (step S 31  to S 39 ). Each time the data transfer process to FIFO  0  to  3  is finished, the process is interrupted. When the controller  21  receives a notice of block cancellation from the host processor  1 , the controller  21  performs the next data transfer process.  
         [0103]     On the other hand, in Task String  2 , the addresses of FIFO  0  to  3  are set in the arithmetic units  27 , processes for designating the arithmetic units  27  to start are sequentially repeated, and the controller  21  returns to the top of Task String  2  (step S 41  to S 54 ). After the addresses of FIFO  0  to  3  are set in the arithmetic units  27 , the process is interrupted. When the host processor  1  cancels the block, the next process is performed.  
         [0104]     An example of a program of the host processor  1  for realizing the processes in  FIG. 15  is as shown in  FIG. 16 .  
         [0105]     In this manner, in the first embodiment, the graphic processing processor  2  having the controller  21  for performing start-up control of the plurality of DMACs  31  and the plurality of arithmetic units  27  is arranged independently of the host processor  1 , so that control of the DMACs  31  and start designation of the arithmetic units  27  can be performed by the controller  21  in parallel to the processes performed in the host processor  1 . For this reason, processing load on the host processor  1  can be reduced.  
         [0106]     The start designation of the DMACs  31  and the arithmetic units  27  can also be performed by an event except for a notice of the end of DMA transfer. For this reason, task processes having higher degrees of freedom can be performed.  
       SECOND EMBODIMENT  
       [0107]     In the first embodiment described above, the example in which the start-up of the DMACs  31  and the arithmetic units  27  is controlled by the control processor  33  and the dedicated circuit  32  has been explained. However, the start-up control of the DMACs  31  and the arithmetic units  27  can be performed by only the dedicated circuit  32 .  
         [0108]      FIG. 17  is a block diagram showing the internal configuration of the controller  21  according to the second embodiment. The same reference numerals as in  FIG. 3  denote the same parts in  FIG. 17 . Different points between  FIG. 3  and  FIG. 17  will be mainly described below. In the controller  21  in  FIG. 17 , the control processor  33  and the dedicated circuit  32  in  FIG. 3  are integrated into one dedicated circuit  32   a.    
         [0109]     The dedicated circuit  32   a  in  FIG. 17  controls the DMACs  31  and the arithmetic units  27  according to a program code stored in the memory  36 .  
         [0110]      FIG. 18  is a block diagram showing an example of the internal configuration of the dedicated circuit  32   a  in  FIG. 17 . The dedicated circuit  32   a  in  FIG. 18  includes a task fetch decoder  51 , a sync management unit  52 , a DMA issuance unit  43 , a plurality of sync registers  44 , and a sync register control units  45 .  
         [0111]     The task fetch decoder  51  interprets a program code stored in a memory  36 . The sync management unit  52  executes a task interpreted by the task fetch decoder  51  and reads values of the sync registers  44  to control the arithmetic units  27  and the DMA issuance unit  43 .  
         [0112]      FIG. 19  is a flow chart showing an example of a procedure performed by the controller  21  in  FIG. 17 . Different processes between the flow chart in  FIG. 19  and the flow chart in  FIG. 5  will be mainly described below. After the sync register control units  45  updates the value of the sync register  44  (step S 62 ), the sync management unit  52  reads the value of the sync register  44  according to a task decoded by the task fetch decoder  51  (step S 63 ). In this manner, it is confirmed that preparation for data transfer in the preparation of the host processor  1  is completed.  
         [0113]     The sync management unit  52  sets various pieces of information to the DMACs  31  to transfer pieces of information (in this case, data prepared in the host processor  1 ) to be set in the DMACs  31  to the memory in the graphic processing processor  2  (step S 64 ).  
         [0114]     When the DMAC  31  ends the DMA transfer after the DMAC  31  is started, a completion signal is transmitted to the sync register control units  45  (step S 65 ). The sync register control units  45  updates the sync registers  44  (step S 66 ).  
         [0115]     According to the task decoded by the task fetch decoder  51 , the sync management unit  52  reads the value of the sync register  44  (step S 67 ) to confirm the completion of the DMAC  31 .  
         [0116]     According to the task decoded by the task fetch decoder  51 , the sync management unit  52  starts the arithmetic unit  27  to start processing of the data transferred from the host processor  1  to the memory in the graphic processing processor  2  (step S 68 ).  
         [0117]     As described above, in the second embodiment, start-up control of the DMAC  31  and the arithmetic unit  27  is realized by only the dedicated circuit  32   a.  For this reason, a circuit scale which is smaller than a circuit scale obtained by using a general-purpose processor can be achieved, and a low power consumption can also be achieved.  
         [0118]     Each of the above embodiments exemplifies the case in which the controller  21  is arranged in the graphic processing processor  2 . However, the controller  21  may be arranged outside the graphic processing processor  2 .  
         [0119]     Each of the above embodiments exemplifies the case in which the host processor  1  and the graphic processing processor  2  are formed as different chips. However, the host processor  1  and the graphic processing processor  2  can also be formed as a macro core on the same chip. In this case, the controller  21  is desirably arranged in the graphic processing processor  2 . However, the controller  21  may be arranged outside the graphic processing processor  2 .  
         [0120]     Each of the above embodiments exemplifies the case in which the controller  21  is dedicated to data processing performed by the graphic processing processor  2 . However, the controller  21  can also control another DMAC, i.e., a DMAC in the host processor  1 . In this case, another controller may be arranged in the host processor  1  independently of the controller  21 . The DMAC in the host processor  1  and the DMAC in the graphic processing processor  2  can also be controlled by a common controller.  
         [0121]     The same function as described above can also be processed by an OS (Operating System) in place of the controller  21 .  
         [0122]     The processor system according to the present invention can be built in a game machine, a home server, a television set, a portable information device, or the like.  
         [0123]      FIG. 20  is a block diagram showing a case in which the processor system according to this application is built in a digital television set. The digital television set serving as an example of the configuration includes a digital board  55  for controlling communication information. The digital board  55  includes a processor system  56  for realizing the same function as that in  FIG. 1  in which image information is controlled. More specifically, the processor system  56  includes a transceiver circuit (DEMUX)  57  for transmitting/receiving video and communication information, a decoder circuit  58 , a processor (CPU)  59 , a graphic processing circuit (graphic engine)  60 , and a digital format converter  61 .  
         [0124]      FIG. 21  is a block diagram showing an example in which the processor system according to this embodiment is built in a video recorder/player. As an example of the configuration, this video recorder/player includes an image information control circuit  62  which realizes the same function as shown in  FIG. 1  and which controls image information. More specifically, the image information control circuit  62  includes a processor (CPU)  63 , a digital signal processor (DSP)  64 , a processor  65  for processing video (image) data, and a processor  66  for processing audio data.