cpik C compiler for PIC c -18 devices Version 0.7.1 - PiKdev, An IDE ...

9.3 Data structuration
9.3.1 Array
cpik currently supports arrays in any valid way.
9.3.2 Struct and Union
struct and union are supported since version 0.4, and this support is efficient. Unlike several other
well known compilers, cpik offers full support: structs can be passed to functions as parameters
and can be returned by functions.
structs are passed to function by value, as specified by the standard. Anonymous structs are
supported. structs are perfectly compatible with typedef. structs entities can be affected to
other entities of same type.
structs are guaranteed to be compact: as PIC-18 architecture does not impose any alignment
constraint, the size of a struct is the sum of the sizes of its members 8 .
structs cannot be larger than 128 bytes 9 , but I suppose it is not a terrible limitation for a 8 bit
microcontroller.
Members of structs can be signed or unsigned bit fields. As stated by the standard, a bit field
cannot cross an int boundary, so the size of a bit field can range from 1 to 8 bits. For example,
in the following code
struct XXX
{
unsigned a: 4 ,
b: 4 ;
} xxx ;
struct YYY
{
unsigned a: 5 ,
b: 4 ;
} yyy ;
the variable xxx is exactly 1 byte long, but the variable yyy is 2 bytes long because the second field
is one bit too long to be inserted in the first byte. Please note that unsigned bit fields are more
efficient than their signed couterpart because they don’t need to be sign extended when they are
converted to int.
Notice that bits are specified from low to high (so, in the above examples, a is the low nibble)
9.4 Symbolic constants
Symbolic integer constants can be defined with the traditionnal enum declarator.
enum numbers { one=1, two, three } ;
or
typedef enum { peugeot=1, renault=2, citroen=4, other } cars ;
8 However, this feature does no apply to structures composed of bit-fields, as explainded below.
9 This feature is due to hardware limitation
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