SW500010 Microchip Technology, SW500010 Datasheet - Page 88

• Manufacturer Part Number: SW500010
• Description: HI-TECH C PRO FOR PIC10/12/16
• Manufacturer: Microchip Technology
• Type: Compilerr
• Series: PIC10/12/16r

Specifications of SW500010

• Supported Families: PIC10, PIC12, PIC16
• Core Architecture: PIC
• Software Edition: Professional
• Kit Contents: Software And Docs
• Mcu Supported Families: PIC10/12/16
• Tool Type: Compiler
• Lead Free Status / RoHS Status: Not applicable / Not applicable
• For Use With/related Products: PIC10, PIC12, PIC14, PIC16, PIC16E
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 019P; 778-1006; 778-1006

Storage Class and Object Placement
3.4 Storage Class and Object Placement
Objects are positioned in different memory areas dependant on their storage class and declaration.
This is discussed in the following sections.
3.4.1 Local Variables
A local variable is one which only has scope within the block in which it was defined. That is, it
may only be referenced within that block. C supports two classes of local variables in functions:
auto variables which are normally allocated in the function’s stack frame, and static variables
which are always given a fixed memory location and have permanent duration.
3.4.1.1 Auto Variables
Auto (short for automatic) variables are the default type of local variable. Unless explicitly declared
to be static a local variable will be made auto, however the auto keyword may be used if desired.
Auto variables are allocated in the auto-variable block and referenced by indexing off the symbol
that represents that block. The variables will not necessarily be allocated in the order declared - in
contrast to parameters which are always in lexical order. Note that most type qualifiers cannot be
used with auto variables, since there is no control over the storage location. The exceptions are
const and volatile.
be used with objects of type auto.
are never called at the same time.
with a_function plus some offset, where function is the name of the function in which the object
is defined. For example, if the int object test is the first object placed in main’s auto-variable
block it will be accessed using the addresses ??_main and ??_main+1 since an int is two bytes
long.
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All auto variables are allocated memory wholly within one bank. The bank qualifiers cannot
The auto-variable blocks for a number of functions are overlapped by the linker if those functions
Auto objects are referenced with a symbol that consists of a question mark, ?, concatenated
Note that standard version compilers use the prefix ?a instead of ?? However the
allocation and access of auto variables is otherwise the same.
C Language Features