More Flexible Handling Of Constant Data
There are a few ways of allowing pointers to constant data. First, pointers to constants:
/*
A simple example showing the assignment of a pointer to a constant with the address of a constant string:
*/
ROM char version[] = "PRODUCT ID V1.01";
ROM char *ptr;
ptr = &version[0];
A simple example showing the assignment of a pointer to a constant with the address of a constant string:
*/
ROM char version[] = "PRODUCT ID V1.01";
ROM char *ptr;
ptr = &version[0];
/*
A more complex example that creates an array of pointers to constant strings:
*/
ROM char *strings[] =
{
"HELLO",
"WORLD",
"CONST",
"STRINGS"
};
/*
Access the above const pointers
*/
ROM char *ptr;
while (i = 0; i < (sizeof(strings) / sizeof(const char *)); i++)
{
ptr = strings[i];
printf("%s", ptr);
}
A more complex example that creates an array of pointers to constant strings:
*/
ROM char *strings[] =
{
"HELLO",
"WORLD",
"CONST",
"STRINGS"
};
/*
Access the above const pointers
*/
ROM char *ptr;
while (i = 0; i < (sizeof(strings) / sizeof(const char *)); i++)
{
ptr = strings[i];
printf("%s", ptr);
}
In addition, constant strings can be passed to functions that are normally looking for pointers to characters:
/*
The following enables the ability for the compiler to copy constant strings into RAM when being passed as a parameter to a function:
*/
#device PASS_STRINGS=IN_RAM
/*
An example of using this new feature:
*/
if (stricmp(buffer,"ATDT\r")==0)
{
//do something
}
The following enables the ability for the compiler to copy constant strings into RAM when being passed as a parameter to a function:
*/
#device PASS_STRINGS=IN_RAM
/*
An example of using this new feature:
*/
if (stricmp(buffer,"ATDT\r")==0)
{
//do something
}
Note: The const qualifier in CCS always means that the data will be placed in program memory, and that the data is 'read-only'. It does not follow the ANSI definition which simply states that const is 'read-only'.
