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kutkm_ti
Joined: 19 Jul 2007
Posts: 9
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| Convert search string that points to a constant into CCS |
 Posted: Mon Dec 26, 2011 1:42 am |
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Hi, below is AVR code, but I got problem to modify into CCS code.
The problem is this line, I don't know how to convert, can anyone help?
| Code: |
const unsigned char *searchStrings[4] = {OK, CMTI, READY, CR_LF}; //!< Initialize pointer
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| Code: |
//! Possible strings pointed to by searchStr
const unsigned char OK[] = "OK\r\n"; //!< "OK"
const unsigned char CMTI[] = "+CMTI: "; //!< New Message arrived
const unsigned char READY[] = "> "; //!< Phone ready to receive text message
const unsigned char CR_LF[] = "\r\n"; //!< Carrige Return Line Feed
const unsigned char *searchFor; //!< Flash pointer
const unsigned char *searchStrings[4] = {OK, CMTI, READY, CR_LF}; //!< Initialize pointer
void COM_setSearchString( unsigned char Response )
{
disable_interrupts(INT_RDA);//UCSR0B &= ~( 1 << RXCIE0 ); // Disable RX interrupt
searchFor = searchStrings[Response]; //Set desired search dtring
searchStr = Response; //Used in rx_isr
rx_i = 0;
}
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Ttelmah
Joined: 11 Mar 2010
Posts: 19346
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| Posted: Mon Dec 26, 2011 7:41 am |
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Several bits to this.
First 'const', on the AVR, has a different meaning to 'const' on the PIC. On the PIC, a 'const' is stored in ROM, (unless you select 'ANSI' mode). On the AVR (or the PIC if you select ANSI), a 'const' is just a variable that cannot be written.
Now the default 'const' constructor in CCS, doesn't support pointers (this is down to just how hard (imposssible...) pointers to ROM were on the earliest PICs. On latter PICs you can have pointers to ROM, using the 'ROM' constructor, rather than 'const'.
However in all cases, CCS does not support compile time initialisation.
So realistically, the easiest construction, is:
| Code: |
unsigned char *searchStrings[4];
//! Possible strings pointed to by searchStr
unsigned char OK[] = "OK\r\n"; //!< "OK"
unsigned char CMTI[] = "+CMTI: "; //!< New Message arrived
unsigned char READY[] = "> "; //!< Phone ready to receive text message
unsigned char CR_LF[] = "\r\n"; //!< Carrige Return Line Feed
unsigned char *searchFor; //!< Flash pointer
//Then at some point in your early code in the main:
searchStrings[0] = OK;
searchStrings[1] = CMTI;
searchStrings[2] = READY;
searchStrings[3] = CR_LF; //!< Initialize pointer
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It is also possible to use ROM for the actual string declarations, which will save RAM, but make the code a little larger.
Best Wishes |
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kutkm_ti
Joined: 19 Jul 2007
Posts: 9
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| Posted: Mon Dec 26, 2011 10:07 pm |
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| thank you very much, now i can compile my own code! |
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