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alan
Joined: 12 Nov 2012
Posts: 357
Location: South Africa
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| char not evaluating properly? |
 Posted: Mon Dec 10, 2012 1:55 am |
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If I replace the int16 with char it is an endless loop as the for loop with i does not quit at 0x80 as expected but just keep on incrementing until rollover. Am I missing something regarding types or maybe compiler error. I know this code not optimised but busy with it to write to GLCD with driver not on forum yet.
Using version 4.140
| Code: |
void glcd_DispClr() {
int16 i,j,t;
for(j=0;j<8;j++){
t=j*8;
for(i=0; i<128; i++) { // 16 bytes per line 64 lines
glcd_SetRowCol(t,i);
glcd_WriteData(0,1); // write empty byte
}
}
}
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Thanks Alan |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19506
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| Posted: Mon Dec 10, 2012 2:24 am |
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What chip?.
If you are using a PIC24, then the default type is 'signed', not unsigned. A signed char, can only support 0..127.
Best Wishes |
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ckielstra
Joined: 18 Mar 2004
Posts: 3680
Location: The Netherlands
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| Posted: Mon Dec 10, 2012 3:40 am |
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| In general it is bad practice to use the char type for counters, use a type that better represents it's purpose like int8, int16, etc. It is possible that at a lower level these types do map onto a basic compiler type like char, but then at least from your code it is more clear what your intentions are. |
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alan
Joined: 12 Nov 2012
Posts: 357
Location: South Africa
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| Posted: Mon Dec 10, 2012 3:47 am |
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Sorry forgot. PIC24.
According to CCS docs char are unsigned, but obviously I missed the part where it states that char are signed for PIC24.
Have already changed it to unsigned int8 which as expected works.
Thanks for your replies. |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19506
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| Posted: Mon Dec 10, 2012 8:07 am |
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Yes. They do not explicitly 'say', but default to all the integer types being 'signed'. Being explicit is always much safer....
Best Wishes |
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