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Ralf
Joined: 21 Feb 2007
Posts: 3
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| Error in memset |
 Posted: Tue Feb 27, 2007 4:47 am |
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i have a struct gMenue with a size of 0x128 bytes.
When i compile it, i get the following:
memset(&gMenue, 0, sizeof (T_MENUE));
*
018FC: MOVLW 01
018FE: MOVWF 02
01900: MOVLW 28
01902: MOVWF 01
01904: MOVLW 01
01906: MOVWF FEA
01908: MOVLW C4
0190A: MOVWF FE9
0190C: CLRF FEE
0190E: DECFSZ 01,F
01910: BRA 190C
01912: DECFSZ 02,F
01914: BRA 190C
BUT, only the first 0x28 bytes where cleared (Seeing in the debugger). I think the second "decfsz 02,f" is wrong. The register 02 must be loaded with 02 and not with 01.
Is this correct?
Thanks for your help |
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ckielstra
Joined: 18 Mar 2004
Posts: 3680
Location: The Netherlands
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| Posted: Tue Feb 27, 2007 6:40 am |
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From the Jan-2007 PICC manual: | Quote: | MEMSET( )
Syntax: memset (destination, value, n)
Parameters: destination is a pointer to memory, value is a 8 bit int, n is a 8 bit int.
Returns: undefined |
Note that the size n parameter is only 8 bit, clearing an area of 0x128 bytes doesn't fit.
Studying the generated assembly code it looks like CCS did partially implement the support for a 16-bit size parameter, except for the 'small' off by 1 error.
Which compiler version are you using?
I guess it is a v4.0xx version as v3.249 generates slightly different code for only an 8 bit variable.
Suggested actions:
1) Report this to CCS as a request for enhancement.
2) Create your own large memset routine until CCS releases the new feature.
| Code: | void large_memset(char *destination, int8 value, signed int16 size)
{
while (size > 0)
{
memset(destination, value, (int8)size);
size -= 256;
}
} |
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Ralf
Joined: 21 Feb 2007
Posts: 3
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| Posted: Tue Feb 27, 2007 6:56 am |
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| Thanks for your help. I reported this to CCS. |
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