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cfernandez
Joined: 18 Oct 2003
Posts: 145
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| ROM or CONST Pointer |
 Posted: Sat May 12, 2012 8:20 am |
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Is possible use memcpy with a ROM POINTER ?
For example:
| Code: | rom unsigned char matrix[4] = {1,2,3,4};
rom char *pointer;
char aux[2];
pointer = &matrix;
memcpy( aux, &pointer[ 2 ], 2 );
printf( %02X %02X\n\r", aux[ 0 ], aux[ 1 ] ); |
I test this and dont work.
I use the last version of compiler.
Best Regards, |
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bkamen
Joined: 07 Jan 2004
Posts: 1615
Location: Central Illinois, USA
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| Posted: Sat May 12, 2012 6:09 pm |
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ROM CONST is used in C18.
To understand how CCS deals with ROM based information, look at the CCS help .CHM file and the section Titled: Using Program Memory for Data.
Cheers,
-Ben
_________________
Dazed and confused? I don't think so. Just "plain lost" will do. :D |
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FvM
Joined: 27 Aug 2008
Posts: 2337
Location: Germany
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| Posted: Sun May 13, 2012 4:47 am |
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With PIC16 and PIC18, rom pointers need to be emulated by the compiler, this works only with specific settings. With PIC24 and newer PCD versions, PSV (program storage visibility) allows a direct pointer access to ROM.
Your syntax is wrong however. You are writing
| Code: | pointer = &matrix;
memcpy( aux, &pointer[ 2 ], 2 ); |
Should be changed to
| Code: | pointer = matrix; // or &matrix[0], &matrix is usually understood too
memcpy( aux, pointer[ 2 ], 2 ); // you want to load the pointer value rather than it's address |
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