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Volume 2, Part 2: External Interrupt Architecture
The Interval Time Counter (ITC) gets updated at a fixed relation to the processor clock.
The ITM, Interval Timer Match, is used to determine when a interval timer interrupt is
generated. When the ITC matches the ITM and the timer is unmasked via ITV then an
interrupt will be generated.
//
// routine to reset the interval timer to zero..
//
ENTRY(em_timer_reinit)
mov ar.itc=r0
// reset itimer counter
br.ret.spnt.few rp
END(em_timer_reinit)
//
// routine to setup the interval timer.
//
// 1) setup the interval timer vector
// 2) initialize the time counter to zero
// 3) initialize the match register
//
// INPUTS: timermatch -- value to initialize ITM register with.
//
vector number -- vector to interrupt with
// OUTPUTS: none
//
ENTRY(enable_minterval)
alloc
r14=ar.pfs,0x2,0,0,0 // get ready for input parameters
mov
ar.itc=r0
// initialize counter to zero
;;
mov
cr.itm=r32
// set match register
;;
srlz.d
mov
cr.itv=r33
// set interval timer vector
;;
srlz.d
// make sure it goes through
br.ret.sptk.few rp
// return
.endp
Since the ITC gets updated at a fixed relation to the processor clock, in order to find out
the frequency at run time, one can use a firmware call to obtain the input frequency
information to the interval time. Using this frequency information the ITM can be set to
deliver an interrupt at a specific time interval (i.e. for operating system scheduling
purposes). Assuming the frequency information returned by the firmware is in ticks per
second, the programmer could use a time-out delta for delivering a timer interrupt
every 10 milliseconds as follows:
timeout_delta=ticks_per_second/100;
where
ticks_per_second
is the frequency value returned by the firmware and
timeout_delta
will be the value added to the ITC for setting the next ITM. Therefore, the
ITC is left free running, but the ITM must be updated upon every timer interrupt with its
next time out match value, i.e. ITM = ITC +
timeout_delta
.
The only issue with this setup is if the timer interrupt delivery is delayed beyond the
point of the original intended delivery time (i.e. ITC > ITM). This could happen if
interrupts were disabled or blocked by the operating system/device driver longer than
Содержание ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS VOLUME 3 REV 2.3
Страница 1: ......
Страница 11: ...x Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Страница 12: ...1 1 Intel Itanium Architecture Software Developer s Manual Rev 2 3 Part I Application Architecture Guide ...
Страница 13: ...1 2 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Страница 33: ...1 22 Volume 1 Part 1 Introduction to the Intel Itanium Architecture ...
Страница 57: ...1 46 Volume 1 Part 1 Execution Environment ...
Страница 147: ...1 136 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Страница 149: ...1 138 Volume 1 Part 2 About the Optimization Guide ...
Страница 191: ...1 180 Volume 1 Part 2 Predication Control Flow and Instruction Stream ...
Страница 230: ......
Страница 248: ...236 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Страница 249: ...2 1 Intel Itanium Architecture Software Developer s Manual Rev 2 3 Part I System Architecture Guide ...
Страница 250: ...2 2 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Страница 264: ...2 16 Volume 2 Part 1 Intel Itanium System Environment ...
Страница 380: ...2 132 Volume 2 Part 1 Interruptions ...
Страница 398: ...2 150 Volume 2 Part 1 Register Stack Engine ...
Страница 486: ...2 238 Volume 2 Part 1 IA 32 Interruption Vector Descriptions ...
Страница 749: ...2 501 Intel Itanium Architecture Software Developer s Manual Rev 2 3 Part II System Programmer s Guide ...
Страница 750: ...2 502 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Страница 754: ...2 506 Volume 2 Part 2 About the System Programmer s Guide ...
Страница 796: ...2 548 Volume 2 Part 2 Interruptions and Serialization ...
Страница 808: ...2 560 Volume 2 Part 2 Context Management ...
Страница 842: ...2 594 Volume 2 Part 2 Floating point System Software ...
Страница 850: ...2 602 Volume 2 Part 2 IA 32 Application Support ...
Страница 862: ...2 614 Volume 2 Part 2 External Interrupt Architecture ...
Страница 870: ...2 622 Volume 2 Part 2 Performance Monitoring Support ...
Страница 891: ......
Страница 941: ...3 42 Volume 3 Instruction Reference cmp illegal_operation_fault PR p1 0 PR p2 0 Interruptions Illegal Operation fault ...
Страница 1099: ...3 200 Volume 3 Instruction Reference padd Interruptions Illegal Operation fault ...
Страница 1191: ...3 292 Volume 3 Pseudo Code Functions Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Страница 1295: ...3 396 Volume 3 Resource and Dependency Semantics ...
Страница 1296: ......
Страница 1302: ...402 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Страница 1494: ...4 192 Volume 4 Base IA 32 Instruction Reference FWAIT Wait See entry for WAIT ...
Страница 1564: ...4 262 Volume 4 Base IA 32 Instruction Reference LES Load Full Pointer See entry for LDS LES LFS LGS LSS ...
Страница 1565: ...Volume 4 Base IA 32 Instruction Reference 4 263 LFS Load Full Pointer See entry for LDS LES LFS LGS LSS ...
Страница 1568: ...4 266 Volume 4 Base IA 32 Instruction Reference LGS Load Full Pointer See entry for LDS LES LFS LGS LSS ...
Страница 1583: ...Volume 4 Base IA 32 Instruction Reference 4 281 LSS Load Full Pointer See entry for LDS LES LFS LGS LSS ...
Страница 1647: ...Volume 4 Base IA 32 Instruction Reference 4 345 ROL ROR Rotate See entry for RCL RCR ROL ROR ...
Страница 1663: ...Volume 4 Base IA 32 Instruction Reference 4 361 SHL SHR Shift Instructions See entry for SAL SAR SHL SHR ...
Страница 1668: ...4 366 Volume 4 Base IA 32 Instruction Reference SIDT Store Interrupt Descriptor Table Register See entry for SGDT SIDT ...
Страница 1884: ...4 582 Volume 4 IA 32 SSE Instruction Reference ...
Страница 1885: ...Index Intel Itanium Architecture Software Developer s Manual Rev 2 3 Index ...
Страница 1886: ...Index Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Страница 1898: ...INDEX Index 12 Index for Volumes 1 2 3 and 4 ...