CCS C Compiler Manual PCB / PCM / PCH

In this case the first i8 is converted to 16 bit, then the add is a 16 bit add and the second i8 is
forced to 16 bit.
A common C programming error is to do something like:
i16 = i8 * 100;
When the intent was:
i16 = (long) i8 * 100;
Remember that with unsigned ints (the default for this compiler) the values are never
negative. For example 2-4 is 254 (in 8 bit). This means the following is an endless loop since i
is never less than 0:
int i;
for( i=100; i>=0; i--)
How can a constant data table be placed in ROM?
The compiler has support for placing any data structure into the device ROM as a constant
read-only element. Since the ROM and RAM data paths are separate in the PIC® , there are
restrictions on how the data is accessed. For example, to place a 10 element BYTE array in
ROM use:
BYTE CONST TABLE [10]= {9,8,7,6,5,4,3,2,1,0};
and to access the table use:
x = TABLE [i];
OR
x = TABLE [5];
BUT NOT
ptr = &TABLE [i];
In this case, a pointer to the table cannot be constructed.
Similar constructs using CONST may be used with any data type including structures, longs and
floats.
Note that in the implementation of the above table, a function call is made when a table is
accessed with a subscript that cannot be evaluated at compile time.
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