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Hi, Would someone explain the differences between them? (VisualDSP++ 1.0 SP1 for SHARC) |
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interrupt, interrupts, interruptf
Started by ●September 19, 2001
Reply by ●September 19, 20012001-09-19
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A Summary (from ADI's EE-134) * the regular interrupt() takes 128 cycles and saves and restores all regs. * The fast interruptf takes 60 cycles and saves and restores scratcg regs only * The superfast interrupts takes 30 cycles and saves and uses alternate reg set, with nothing saved. Interrupt nesting is disabled. See ADI's Engineer-to-Engineer Note 134 at http://www.analog.com/techsupt/application_notes/EE_notes/pdf_files/ee_134.p df. Also, ADI's site http://www.analog.com/publications/documentation/C_Library_Manual/Chapter_4. pdf has good definitions. > -----Original Message----- > From: [SMTP:] > Sent: Wednesday, September 19, 2001 2:02 AM > To: > Subject: [adsp] interrupt, interrupts, interruptf > > Hi, > > Would someone explain the differences between them? (VisualDSP++ 1.0 > SP1 for SHARC) > > _____________________________________ > Note: If you do a simple "reply" with your email client, only the author > of this message will receive your answer. You need to do a "reply all" if > you want your answer to be distributed to the entire group. > > _____________________________________ > About this discussion group: > > To Join: Send an email to > > To Post: Send an email to > > To Leave: Send an email to > > Archives: http://groups.yahoo.com/group/adsp > > Other Groups: http://www.dsprelated.com/groups.php3 > ">http://docs.yahoo.com/info/terms/ > |
Reply by ●September 19, 20012001-09-19
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It has been a long time since I dealt with the interrupt functions. Here
is what I know from working with them in the GNU based compiler (pre-VDSP). The functions provide different level of system state saving/restoring at the entry/exit of your interrupt service routines. interrupt() is the normal version and saves "everything" in the system. It is the safest, but also the slowest. If I remember correctly, it took about 125 clock cycles before execution made it to the actual ISR. interruptf() is the "fast" version. It saves most registers, but does not save the hardware loop stack, so you are limited to a total of 6 levels of hardware DO loops. Therefore the total of the number used in your ISR and the the maximum number used in the main code cannot exceed 6. I don't know if the C compiler actually uses the hardware DO loops, if not, then I this won't be a problem unless you write your own loops in assembly. This uses about 60 clock cycles. interrupts() is the "super fast" version. Like interruptf(), the loop stack is not saved. In addition the alternate register set is used which saves time. Interrupt nesting will not work using this version. Interrupt nesting works in the other 2 verisons. The uses about 30 clock cycles. Debugging problems in the interrupt dispatcher are painful. My recomendation is to use interrupt(). Then change to interruptf() or interrupts() if you find that your ISRs are not responding quickly enough. Hope that helps. Derek ----- Original Message ----- From: <> To: <> Sent: Wednesday, September 19, 2001 2:02 AM Subject: [adsp] interrupt, interrupts, interruptf > Hi, > > Would someone explain the differences between them? (VisualDSP++ 1.0 > SP1 for SHARC) > > _____________________________________ > Note: If you do a simple "reply" with your email client, only the author of this message will receive your answer. You need to do a "reply all" if you want your answer to be distributed to the entire group. > > _____________________________________ > About this discussion group: > > To Join: Send an email to > > To Post: Send an email to > > To Leave: Send an email to > > Archives: http://groups.yahoo.com/group/adsp > > Other Groups: http://www.dsprelated.com/groups.php3 > ">http://docs.yahoo.com/info/terms/ > |
Reply by ●September 19, 20012001-09-19
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wrote: > Would someone explain the differences between them? (VisualDSP++ 1.0 > SP1 for SHARC) You might take a look at ... - the C/C++ compiler & library manual p 3-10 (where signal.h is described) - the source code of libc.dlb (interrup.asm, signal.asm, int_cnXl.asm etc.) HTH Michael |
Reply by ●September 20, 20012001-09-20
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On Wed, 19 Sep 2001 06:02:04 -0000, wrote: > Would someone explain the differences between them? (VisualDSP++ 1.0 > SP1 for SHARC) See VisualDSP\Docs\cc21kpl\cc21k_03.pdf, page 3-10, on the file signal.h. In a nutshell, they save different amounts of state, so you tradeoff interrupt overhead vs. what it's safe to do in your handler. |
Reply by ●September 21, 20012001-09-21
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Hi, You can find a detailed description in the following document from AD (www.analog.com). Document: C/C++ Compiler and Library Manual for ADSP-21xxx Family DSPs This can be downloaded free of charge, as are all of ADs documents. Three interrupt functions let you disable interrupts and modify the processors MODE1 register from an interrupt handler. interrupt: Saves all scratch registers and the loop stack. Do loop and interrupt nesting is allowed because data is pushed onto the stack. Requires approximately 125 cycles for interrupt overhead. Preserves MODE1 register writes in an interrupt handler after the interrupt is serviced. Freezes the cache. interruptf: Does not save the loop stack; DO loop handling is restricted to six levels (specified in hardware). If the interrupt service routine (ISR) uses one level of nesting, your code cannot exceed five levels. Preserves MODE1 register writes in an interrupt handler after the interrupt is serviced. Interrupt nesting is not restricted (20 levels available). Does not send the interrupt number type to the ISR as a parameter. Requires approximately 60 cycles for interrupt overhead. interrupts: Does not save the loop stack, therefore do loop handling is restricted to six levels (specified in hardware). Interrupt nesting is disabled. This dispatcher does not send the interrupt number type to the ISR as a parameter. Uses the secondary register set. This dispatcher requires approximately 30 cycles for interrupt overhead. If you processor is not of the 21xxx family it may be worth checking in the compiler documentation for your processor to make sure that this is still true. -----Original Message----- From: [mailto:] Sent: Wednesday, September 19, 2001 7:02 AM To: Subject: [adsp] interrupt, interrupts, interruptf Hi, Would someone explain the differences between them? (VisualDSP++ 1.0 SP1 for SHARC) _____________________________________ Note: If you do a simple "reply" with your email client, only the author of this message will receive your answer. You need to do a "reply all" if you want your answer to be distributed to the entire group. _____________________________________ About this discussion group: To Join: Send an email to To Post: Send an email to To Leave: Send an email to Archives: http://groups.yahoo.com/group/adsp Other Groups: http://www.dsprelated.com/groups.php3 ">http://docs.yahoo.com/info/terms/ |
Reply by ●September 22, 20012001-09-22
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On Thu, 20 Sep 2001 14:15:07 -0500, Jaime Andrs Aranguren Cardona wrote: > But does it work all the same for the 2106x and the 21160? Check the library source code for the dispatchers and registration functions. I recall seeing conditionals in there. One obvious issue is that the 211xx has a second ALU that needs to be saved, so there's got to be extra code in the dispatcher for that case. Also, there's a display bug in the current debugger DLL for the secondary registers. The debugger fails to recognize when the alternate registers are active, so it still displays the primary registers when in a super-fast ISR, not the secondaries. As a workaround, view the "inactive" registers to see the correct set. And recognize that your locals window and expressions window will be wrong for any variables held in registers, as it will be evaluting the wrong register set. The mixed source view is extremely helpful here. |
