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Intel
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IXP42X Product Line of Network Processors and IXC1100 Control Plane Processor
September 2006 DM
Order Number: 252480-006US 143
Intel XScale
®
Processor—Intel
®
IXP42X product line and IXC1100 control plane processors
Counter overflow can be dealt with in the IRQ interrupt service routine as shown below:
As an example, assume the following values in CCNT, PMN0, PMN1 and PMNC:
Example 14. Configuring the Performance Monitor
; Configure the performance monitor with the following values:
; EVTSEL.evtCount0 = 7, EVTSEL.evtCount1 = 0 instruction cache efficiency
; INTEN.inten = 0x7 set all counters to trigger an interrupt on overflow
; PMNC.C = 1 reset CCNT register
; PMNC.P = 1 reset PMN0 and PMN1 registers
; PMNC.E = 1 enable counting
MOV R0,#0x700
MCR P14,0,R0,C8,c1,0 ; setup EVTSEL
MOV R0,#0x7
MCR P14,0,R0,C4,c1,0 ; setup INTEN
MCR P14,0,R0,C0,c1,0 ; setup PMNC, reset counters & enable
; Counting begins
Example 15. Interrupt Handling
IRQ_INTERRUPT_SERVICE_ROUTINE:
; Assume that performance counting interrupts are the only IRQ in the system
MRC P14,0,R1,C0,c1,0 ; read the PMNC register
BIC R2,R1,#1 ; clear the enable bit, preserve other bits in PMNC
MCR P14,0,R2,C0,c1,0 ; disable counting
MRC P14,0,R3,C1,c1,0 ; read CCNT register
MRC P14,0,R4,C0,c2,0 ; read PMN0 register
MRC P14,0,R5,C1,c2,0 ; read PMN1 register
<process the results>
SUBS PC,R14,#4 ; return from interrupt