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kender
Joined: 09 Aug 2004
Posts: 768
Location: Silicon Valley
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| struct with bit-array members |
 Posted: Sat Nov 29, 2008 4:24 am |
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Colleagues,
Could you look at the code below and see if there's anything obviously wrong with it?
| Code: | const int8 iN_ELECTRODES = 4;
const int8 iN_PRODUCTS = 2;
typedef struct
{
int1 bProductMap[iN_PRODUCTS][4 * iN_ELECTRODES];
int1 bSumMap[2 * iN_PRODUCTS];
}
structRecipe;
/* const */ structRecipe g_sRECIPE = { // ideally, this variable would sit in ROM, but RAM is ok too
{
{1,0,1,0,1,0,1,0,0,0,0,0,0,0,0,0},
{0,0,0,0,0,0,0,0,0,1,0,1,0,1,0,1}
},
{1,0,0,1}
}; |
g_sRECIPE.iSumMap[i] compiles, but it doesn't output the correct values of the array members. At the same time, g_sRECIPE.bProductMap[i][j] works fine for any i and j in range. I was expecting more problems with a 2-D array rather than 1-D. Even if I remove bProductMap from the struct, I can't access iSumMap.
I'd be happy to post more code if needed.
Thanks!
- Nick
EDIT: In response to FvM. Compiler v4.071. Target PIC18LF4525.
P.S. May be it will seem clearer in the morning.
_________________
Read the label, before opening a can of worms.
Last edited by kender on Sat Nov 29, 2008 4:51 am; edited 3 times in total |
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FvM
Joined: 27 Aug 2008
Posts: 2337
Location: Germany
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| Posted: Sat Nov 29, 2008 4:43 am |
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As a compiler specific bug must be assumed, it's important to know the compiler type and version. Otherwise, I just can say, the code looks O.K. Also a minimal example reproducing the error would be helpful.
Regards,
Frank |
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Ttelmah
Guest
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| Posted: Sat Nov 29, 2008 11:10 am |
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What type are you putting the result 'into'?.
There have been a number of posts in the past, about CCS, having real 'oddities' with int1 types, when moving them into other types. Tried compiling the code, and looked at the listing. Accessing g_SRECIPE.bSumMap[0], put all four bits into an int8 variable, rather than accessing just the bottom bit. The addressing was correct. Adding an int1 cast to the operation, made the code work. So:
temp = (int1)g_SRECIPE.bSumMap[0];
gave a working value, as did copying the value into another int1 variable. It appears to be a 'global' problem with int1 values, in some circumstances The two dimensional array, results in a correct bit test.
I'd suggest that anyone using int1, gets into the 'habit' of casting them when reading them, which seems to fix this problem.
Best Wishes |
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kender
Joined: 09 Aug 2004
Posts: 768
Location: Silicon Valley
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| Posted: Mon Dec 01, 2008 1:18 am |
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The only thing that ultimately helped was padding the bit array to 8 members. Without padding it didn't work, even with casting to int1. With padding it does work even without casting to int1.
Here are some peculiar results that I got in the process:
| Code: |
// g_sRECIPE.bSumMap = {1,0,0,1};
for (i = 0; i < iN_PRODUCTS * 2; ++i)
{
printf("%u", g_sRECIPE.bSumMap[i]); // 9999
printf("%u", (int1)g_sRECIPE.bSumMap[i]); // 1111
b = g_sRECIPE.bSumMap[i];
printf("%u", b); // 1111
b = (int1)g_sRECIPE.bSumMap[i];
printf("%u", b); // 1111
}
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Read the label, before opening a can of worms. |
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