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JoeO
Joined: 22 Jun 2005
Posts: 1
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| while(TRUE) size limit |
 Posted: Wed Jun 22, 2005 7:27 am |
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Hello
I have a large while(TRUE) loop in my main routine. Above a certain size of code (in the while loop) the goto function that implements the while loop goto's some strange area, reduce the code and it goto's the correct place. Is there some fundamental limit within the compiler?
i.e (the dissassembly screen)
584: while(TRUE)
585: {
....lots of code
742: }
000ACD 285D GOTO 0x5d
which is obviously broken, whereas: remove some of the code in the while loop and
584: while(TRUE)
585: {
586: while(!kbhit())
587: {
000613 1A8C BTFSC 0xc, 0x5
000614 2E17 GOTO 0x617
.............
742: }
0007F9 2E13 GOTO 0x613
whis is OK. I am using a 16F628, CCS ver 3.226, mplab v7.00.
Whats going on? |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Wed Jun 22, 2005 1:20 pm |
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I tried to duplicate your problem but could not do so.
I compiled the program below with PCM vs. 3.226, and
it made a large loop that starts at address 0x28E:
| Code: |
0000 01624 .................... while(1)
0000 01625 .................... {
0000 01626 .................... a = 123.45678;
028E 30DF 01627 MOVLW DF
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It goes down to address 0x7B3 (near the end of ROM for the 16F628)
and jumps back up to 0x28E properly.
| Code: | 07B1 0877 02967 MOVF 77,W
07B2 00B1 02968 MOVWF 31
0000 02969 .................... }
07B3 2A8E 02970 GOTO 28E
0000 02971 ....................
0000 02972 .................... }
0000 02973 ....................
07B4 0063 2974 SLEEP |
I think you need to post a test program that demonstrates the
problem. My program below creates a large while() loop but
it doesn't show a problem.
| Code: | #include <16F628.H>
#fuses XT, NOWDT, NOPROTECT, BROWNOUT, PUT, NOLVP
#use delay(clock = 4000000)
#include <math.h>
//========================================
void main()
{
float a;
float b;
float c;
float d;
float result;
while(1)
{
a = 123.45678;
b = 456.78901;
c = 789.01234;
d = 246.13579;
result = a + b + c + d;
result = a - b - c - d;
result = a * b * c * d;
result = a / b / c / d;
result = a + b + c + d;
result = a - b - c - d;
result = a * b * c * d;
result = a / b / c / d;
result = a + b + c + d;
result = a - b - c - d;
result = a * b * c * d;
result = a / b / c / d;
result = a + b + c + d;
result = a - b - c - d;
result = a * b * c * d;
result = a / b / c / d;
result = a + b + c + d;
}
} |
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Guest
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| Posted: Wed Jun 22, 2005 3:11 pm |
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| I have thousands of lines in a do{ }while(true); loop. I don't think there's any limit beyond what the chip can physically hold. |
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treitmey
Joined: 23 Jan 2004
Posts: 1094
Location: Appleton,WI USA
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| Posted: Wed Jun 22, 2005 4:14 pm |
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Wow  |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Wed Jun 22, 2005 4:18 pm |
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Or, mark it down as 
Edited to add:
To be fair, he probably meant he has a couple thousand lines of
ASM code in his loop, which is possible. Treitmey and I thought
he meant 2000 lines of C source code. |
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