Hi,
I've been tracking a wierd problem, 100% repeatable although the
failures vary.
I'm using:
/Users/nyholku/sdcc-3.4.0/bin/sdcc -v
SDCC :
mcs51/z80/z180/r2k/r3ka/gbz80/tlcs90/ds390/pic16/pic14/TININative/ds400/hc0
8/s08/stm8 3.4.0 #8981 (Apr 5 2014) (Mac OS X i386)
published under GNU General Public License (GPL)
with PIC18F4550
I've tracked the problem down to these four innocent looking statements
in my interrupt routine:
steppers[0].probePosition = steppers[0].position;
steppers[1].probePosition = steppers[1].position;
steppers[2].probePosition = steppers[2].position;
steppers[3].probePosition = steppers[3].position;
If I comment these out, then all the weird symptoms I've been having
disappear.
The '.probePosition' and '.position' are both 32 bit ints.
Looking at the generated code I see that the compiler generates code:
00438 ; .line 86; stepperirq.c
steppers[0].probePosition = steppers[0].position;
000086 C??? F??? 00439 MOVFF (_steppers + 7), r0x00
00008A C??? F??? 00440 MOVFF (_steppers + 8), r0x01
00008E C??? F??? 00441 MOVFF (_steppers + 9), r0x02
000092 C??? F??? 00442 MOVFF (_steppers + 10), r0x03
000096 50?? 00443 MOVF r0x00, W
000098 ???? 00444 BANKSEL (_steppers + 24)
00009A 6F?? 00445 MOVWF (_steppers + 24), B
00009C 50?? 00446 MOVF r0x01, W
00447 ; removed redundant BANKSEL
00009E 6F?? 00448 MOVWF (_steppers + 25), B
0000A0 50?? 00449 MOVF r0x02, W
00450 ; removed redundant BANKSEL
0000A2 6F?? 00451 MOVWF (_steppers + 26), B
0000A4 50?? 00452 MOVF r0x03, W
00453 ; removed redundant BANKSEL
0000A6 6F?? 00454 MOVWF (_steppers + 27), B
which uses the r0x00 etc variables which the compiler defines like:
00320 .registers udata_ovr 0x0000
000000 00321 r0x00 res 1
000001 00322 r0x01 res 1
000002 00323 r0x02 res 1
000003 00324 r0x03 res 1
Somewhere in the back of my mind I seem to recall that 'udata_ovr'
may cause problems if used both in main program and interrupt code.
My interrupt is defined as:
#pragma save
#pragma nojtbound
#pragma nooverlay
void stepperirq() __interrupt(1) {
in order to avoid overlaying.
So could this (use of overlaid compiler generated temp variables in
interrupt
and main program be a problem)???
br Kusti
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