VisualDSP++ Kernel (VDK) User's Guide
Contents
1. and may not be used by the user in any manner The following interrupts are reserved for use by the VDK on the ADSP 2192 Timer Bit 5 Priority 6 the timer interrupt Timer 2 generates the interrupts for system ticks and provides all VDK timing ser vices Disabling this timer will stop services such as sleeping round robin scheduling pending with timeout periodic semaphores etc This interrupt is reserved for use by the scheduler and may not be used by the user in any manner Reserved ISR the reschedule interrupt This interrupt is reserved for use by the scheduler and may not be used by the user in any man ner When using the VDK there are some restrictions placed on the ISRs associated with the AC 97 codec port Specifically your entire ISR at priority level 16 bit 15 must execute within a critical region VisualDSP Kernel VDK User s Guide A 5 VDK FOR ADSP 219x DSPs ADSP 2191and ADSP 2192 You should never enable interrupts while servicing an AC 97 Frame and a nested interrupt should never be allowed to occur once an AC 97 Frame ISR begins Software Mapped Interrupt Controller The ADSP 2191 allows interrupt levels five IRPTLE5 through fourteen IRPTL 14 to be mapped in software to the on chip peripherals IRPTL 4 and IRPTL 15 are reserved by VDK The IDDE generates source code templates with a single entry point per interrupt level rather than for each peripheral Therefore you are responsible2. for dispatching interrupts when more than one peripheral is used at the same level The technique used depends on the application but typically either chaining or a jump table is used When chaining a handler will check to see if the interrupt was caused by the specific peripheral it knows how to handle If not execution is passed to the next handler in the chain A jump table makes use of an ID or constant to index into a table of function pointers to find the appropriate interrupt handler The ADSP 2192 maps periph erals to specific interrupt levels in hardware so this initialization is not necessary A 6 VisualDSP Kernel VDK User s Guide Processor Specific Notes VDK FOR ADSP TS101 User and Supervisor Modes The TigerSHARC architecture makes a distinction between execution in user and supervisor modes VDK supports these modes and switches back and forth as necessary When writing applications using VDK you must be aware of the processor mode at the time the kernel calls the functions that you implement All thread functions execute in user mode including Run RunFunc tion and ErrorHandler ErrorFunction Conversely all interrupt service routines execute in supervisor mode The implementation function for device drivers their single entry point may be called by the kernel in either user mode or supervisor mode depending on the purpose of the call Specifically when the initialization routine is cal
3. regis ters for both the computation units and the DAGs VDK does not save and restore these alternate registers during context switches but instead employs them to accelerate entry to and exit from the scheduler interrupt by providing it with a dedicated C run time environment This means that the following alternate registers contain fixed values and must not be changed by user code Register Value Bay MTS 0 6 M14 1 AML 1 B6 B7 System stack base lO y LA System stack length L2 L5 L10 L15 0 A 12 VisualDSP Kernel VDK User s Guide Processor Specific Notes Since these are used at interrupt level which may be entered at any time it is not sufficient to save and restore these registers after use except within a critical region The following alternate registers are not used by VDK and are available for use by user code I0 MO BO LO Te MES Be ELA FQ MET BS EBs TIT M94 BOs LY Note that these registers do not form part of the thread context and hence are not context switched between threads Therefore their most appropriate use is in implementing fast I O interrupt handlers for devices where DMA is not available The remaining alternate registers RO R15 Leh TONS LS M2 M4 M10 M12 B2 B5 BTO BT5 are used by the Scheduler ISR and hence may change at any time unless inside a critical region If they are to be used in a user defined interrupt service routi
4. A PROCESSOR SPECIFIC NOTES VDK for BLACKfin DSPs ADSP 21535 User and Supervisor Modes The BLACKfin architecture makes a distinction between execution in user and supervisor modes VDK supports these modes and switches back and forth as necessary When writing applications using VDK you must be aware of the processor mode at the time the kernel calls the functions that you implement All thread functions execute in user mode including Run RunFunc tion and ErrorHandler ErrorFunction Conversely all Interrupt Service Routines execute in supervisor mode The implementation func tion for device drivers their single entry point may be called by the kernel in either user mode or supervisor mode depending on the purpose of the call Specifically when the initialization routine is called at system boot time kDD_Init when an ISR calls VDK_ISR_ACTIVATE_DEVICE_DRIVER_ kKDD_Activate or when a thread calls Devicel0Ct1 kDD_IO0Ct1 the function executes in supervisor mode and within a critical region For calls to OpenDevice kDD_Open CloseDevice kDD_Close SyncRead kDD_SyncRead and Syn cWrite kKDD_SyncWrite the function executes in user mode This limits somewhat the operations that can be performed in threads but enforces the intended architecture model System mode registers should be accessed at boot time by defining a device driver with the proper initializa tion steps and at run time through the De
5. TigerSHARC DSPs for more information on the use of stacks and the run time model maintained by C C compiler The VDK performs parallel addressing by using multiple heaps The default LDF file for VDK projects defines two heaps each 16K words These sections must appear with the names used in the default LDF file You may define additional heaps using the multiple heap API If you do so you must define the heaps in an object file or library that is listed on the line in the LDF file that defines the symbol LIBS after the library VDK CORE TS101 d1b and before the symbol BASE_LIBRARIES This ensures that the new heaps are not placed after the token that terminates the heap list See the VisualDSP 2 0 C C Compiler amp Library Manual for TigerSHARC DSPs for more information on using multiple heaps A 10 VisualDSP Kernel VDK User s Guide Processor Specific Notes VDK FOR ADSP 2106X and ADSP 2116X DSPs Analog Devices ADSP 2106x family includes ADSP 21060 ADSP 21061 ADSP 21062 and ADSP 21065L processors and ADSP 2116x family includes ADSP 21160 and ADSP 21161 processors Interrupts The following interrupts are reserved for use by the VDK on the ADSP 2106x devices e IRPTLE4 the high priority timer interrupt TMZHI The timer Timer0 on ADSP 21065L generates the interrupts for system ticks and provides all VDK timing services Disabling this timer stops ser vices such as sleeping round robin scheduling pendin
6. as defined in the API Reference chapter without REG_ only accepts constants as arguments Passing a register name will result in an assembler error Interrupts The following interrupts are reserved for use by the kernel on the ADSP TS101 e INT_TIMEROH ILAT bit 52 the high priority interrupt associated with timer 0 This timer generates the interrupts for system ticks and provides all VDK timing services Disabling this timer stops ser vices such as sleeping round robin scheduling pending with time out periodic semaphores etc e INT_TIMEROL ILAT bit 2 the low priority interrupt associated with timer 0 is reserved for use by the scheduler and may not be used by the user in any manner All other interrupts are available for user applications and should be installed by right clicking the Interrupts icon on the VDK tab of the Project Window VisualDSP Kernel VDK User s Guide A 9 VDK FOR ADSP TS101 Parallel Memory Accesses The ADSP TS101 takes advantage of the dual IALU architecture of Tiger SHARC and allocates two stacks per thread The number shown in the VDK tab of the Project Window specifies the number of 32 bit words per stack Since each thread has two stacks corresponding to the J and K IALUs multiply this number by two to compute the number of memory words used per thread or by eight for the number of bytes used per thread See the VisualDSP 2 0 C C Compiler amp Library Manual for
7. assembly syntax requires the use of separate API macros depending on whether the arguments are constants immediate values enumerations or data registers RO through R7 The arguments to the default APIs described in the reference chapter must be constants When A 2 VisualDSP Kernel VDK User s Guide Processor Specific Notes passing data registers as arguments append REG_ to the macro name as follows VDK_ISR_POST_SEMAPHORE_REG_ Semaphore_num_ VDK_ISR_ACTIVATE_DEVICE_REG_ dev_num_ VDK_ISR_SET_EVENTBIT_REG_ eventbit_num_ VDK_ISR_CLEAR_EVENTBIT_REG_Ceventbit_num_ VDK_ISR_LOG_HISTORY_REG_ Cenum_ value_ threadID_ The API macros as defined in the reference guide without REG_ only accept constants as arguments Passing a register name results in an assem bler error Interrupts The following hardware events interrupts are reserved for use by the VDK on the ADSP 21535 e EVT_EVSW a k a EVT_EVX the software exception handler User code handles software exceptions by modifying the source file cre ated by the IDDE called ExceptionHandler 21535 asm e EVT_TMR the interrupt associated with the timer integral to the processor core This timer generates the interrupts for system ticks and provides all VDK timing services Disabling this timer will stop services such as sleeping round robin scheduling pending with tim eout periodic semaphores etc e EVT_IVG15 general interrup
8. g with time out periodic semaphores etc This interrupt is reserved for use by the scheduler and may not be used by the user in any manner e IRPTLE31 user software interrupt 3 This interrupt is reserved for use by the scheduler and may not be used by the user in any man ner On ADSP 21065L Timer1 is available for use by user code but only the low priority timer interrupt TMZLI is available for servicing it as the high priority interrupt TMZHI is reserved by VDK for Timer0 By default VDK assigns Timer1 to the low priority timer interrupt IRPTL 23 so using it only requires an interrupt handler to be defined for TMZLI and for Timer1 to be initialized VisualDSP Kernel VDK User s Guide A 11 VDK FOR ADSP 2106X and ADSP 2116X DSPs The following interrupts are reserved for use by the VDK on the ADSP 2116x devices e IRPTLE4 the high priority timer interrupt TMZH1I The timer generates the interrupts for system ticks and provides all VDK tim ing services Disabling this timer stops services such as sleeping round robin scheduling pending with timeout periodic sema phores etc This interrupt is reserved for use by the scheduler and may not be used by the user in any manner e IRPTLE30 user software interrupt 3 This interrupt is reserved for use by the scheduler and may not be used by the user in any man ner Register Usage The ADSP 21x6x devices provide a set of alternate or background
9. led at system boot time kKDD_Init when an ISR calls VDK_ISR_ACTIVATE_DEVICE_DRIVER_ kKDD_Activate or when a thread calls DeviceI0Ct1 kDD_I0Ct1 the function executes in supervisor mode and within a critical region For calls from a thread to OpenDevice kDD_Open CloseDevice kKDD_Close SyncRead kKDD_SyncRead and SyncWrite kDD_SyncWrite the func tion executes in user mode This limits somewhat the operations that can be performed in threads but enforces the intended architecture model System mode registers should be initialized at boot time by defining a device driver with the proper initial ization steps in its kDD_Activate portion At runtime access system registers through the Devicel0Ct1 function or from an ISR This model separates the algorithm code maintained in threads from hardware depen dent details contained in device drivers and ISRs VisualDSP Kernel VDK User s Guide A 7 VDK FOR ADSP TS101 Critical and Unscheduled Regions In the TigerSHARC architecture interrupts may only be enabled or dis abled while in supervisor mode The API functions PushCriticalRegion and PopCriticalRegion handle this mode change in a manner transpar ent to threads however entering and exiting critical regions takes considerably longer than entering and exiting unscheduled regions because of the overhead of entering supervisor mode Exceptions The TigerSHARC architecture requires the use of a use
10. ne then their contents must be saved and restored before returning from the interrupt as for the primary registers Note that the background multiplier result register MRB is not considered to be an alternate register in the above discussion and that both MRB and MRF are context switched between threads VisualDSP Kernel VDK User s Guide A 13 VDK FOR ADSP 2106X and ADSP 2116X DSPs A 14 VisualDSP Kernel VDK User s Guide
11. r in which the timer is clocked The simulator dec rements the time once per instruction without taking into account the number of cycles required to dispatch the instruction Thus the period of a Tick will be a larger number of cycles than on the actual hardware This behavior differs from execution in hardware Memory By default the VDK LDF file places all user code and data into a single section called program Refer to the Linker and Utilities Manual for information on segmenting your code By default the scratch SRAM is not used or defined in the LDF file and is not configured to be used as level one cache If you choose to use the pro cessor in a L1 cache mode you should write an initialization device driver for configuration as described in Device Drivers on page 4 34 A 4 VisualDSP Kernel VDK User s Guide Processor Specific Notes VDK FOR ADSP 219x DSPs ADSP 2191and ADSP 2192 Interrupts The following interrupts are reserved for use by the VDK on the ADSP 2191 IRPTLE4 the timer interrupt Timer 2 generates the interrupts for system ticks and provides all VDK timing services Disabling this timer will stop services such as sleeping round robin schedul ing pending with timeout periodic semaphores etc This interrupt is reserved for use by the scheduler and may not be used by the user in any manner IRPTLL15 general interrupt 15 This interrupt is reserved for use by the scheduler
12. r software inter rupt a k a service exception trap to enter supervisor mode When you throw a software exception the TRAP opcode incorporates a 5 bit identi fier that is available as via a system status register SQSTAT 7 3 in the instruction handler VDK reserves exception ID 0 TRAP 0 for internal use Additionally the IDDE automatically generates a source file for all TigerSHARC VDK projects that define an entry point for any service or error exceptions you wish to trap When an exception occurs the VDK intercepts the excep tion and if it is not the VDK exception the user defined exception handler executes ISR APIs The TigerSHARC assembly syntax requires the use of separate API macros depending on whether the arguments are constants immediate values enumerations or compute block registers XRO through XR7 or YRO through YR7 Note that IALU registers may not be used directly as argu ments to ISR macros The arguments to the default APIs described in the A 8 VisualDSP Kernel VDK User s Guide Processor Specific Notes API Reference on page 6 1 must be constants When passing compute block registers as arguments append REG_ to the macro name as follows VDK_ISR_POST_SEMAPHORE_REG_ Ssemaphore_num_ VDK_ISR_ACTIVATE_DEVICE_REG_ dev_num_ VDK_ISR_SET_EVENTBIT_REG_ eventbit_num_ VDK_ISR_CLEAR_EVENTBIT_REG_ eventbit_num_ VDK_ISR_LOG_HISTORY_REG_ enum_ value_ threadID_ The API macros
13. t 15 This interrupt is reserved for use by the scheduler and may not be used by the user in any manner The ADSP 21535 designates hardware events seven 1VG7 through thir teen I1VG13 as general interrupts and each maps to more than one physical peripheral The IDDE generates source code templates with a sin gle entry point per interrupt level rather than for each peripheral Therefore you are responsible for dispatching interrupts when more than one is used peripheral at the same level The technique used depends on VisualDSP Kernel VDK User s Guide A 3 VDK for BLACKfin DSPs ADSP 21535 the application but typically either chaining or a jump table is used When chaining a handler will check to see if the interrupt was caused by the specific peripheral it knows how to handle If not execution is passed to the next handler in the chain A jump table makes use of an ID or con stant to index into a table of function pointers to find the appropriate interrupt handler Timer VDK Ticks are derived from the timer implemented in the inner processor core of the ADSP 21535 and are synchronized to the main core clock CCLK However this timer is disabled when the ADSP 21535 enters low power mode Thus all VDK timing services such as sleeping time outs and periodic semaphores do not operate while the core is in IDLE or low power mode The ADSP 21535 simulator shipped with VisualDSP 2 0 exhibits an anomaly in the manne
14. vicel0Ct1 function or from an VisualDSP Kernel VDK User s Guide A 1 VDK for BLACKfin DSPs ADSP 21535 ISR This model separates the algorithm code maintained in threads from hardware dependent details contained in device drivers and ISRs Critical and Unscheduled Regions Note that on the BLACKfin architecture interrupts may only be enabled or disabled while in supervisor mode The API functions PushCriticalRe gion and PopCriticalRegion handle this mode change in a manner transparent to threads however entering and exiting critical regions takes approximately four times longer than entering and exiting unscheduled regions because of this overhead Exceptions The BLACKfin architecture requires the use of service exceptions to enter supervisor mode Therefore VDK reserves service exception ID 0 EXCPT 0 for internal use Additionally the IDDE automatically gener ates a source file for all BLACKfin VDK projects that defines an entry point for any service or error exceptions you wish to trap When an excep tion occurs the VDK will intercept the exception and if it is not the VDK exception the user defined exception handler executes You should not manipulate the IMASK system register from within your exception handler If you need to mask or unmask an interrupt in response to an exception raise an interrupt and change the value of IMASK in the ISR after the exception handler ISR APIs The BLACKfin
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