PicC 9.50 dsPIC Manual.pdf

Macro AssemblerHI-TECH C Assembly Languagemaybe used, but the opening and closing quotes must be the same.4.3.5 IdentifiersAssembly identifiers are user-defined symbols representing memory locations or numbers. A symbolmay contain any number of characters drawn from the alphabetics, numerics and the specialcharacters dollar, $, question mark, ? and underscore, _.The first character of an identifier may not be numeric. The case of alphabetics is significant,e.g. Fred is not the same symbol as fred. Some examples of identifiers are shown here:An_identifieran_identifieran_identifier1$?$_123454.3.5.1 Significance of IdentifiersUsers of other assemblers that attempt to implement forms of data typing for identifiers should notethat this assembler attaches no significance to any symbol, and places no restrictions or expectationson the usage of a symbol.The names of psects (program sections) and ordinary symbols occupy separate, overlappingname spaces, but other than this, the assembler does not care whether a symbol is used to representbytes, words or sports cars. No special syntax is needed or provided to define the addresses of bitsor any other data type, nor will the assembler issue any warnings if a symbol is used in more thanone context. The instruction and addressing mode syntax provide all the information necessary forthe assembler to generate correct code.4.3.5.2 Assembler-Generated IdentifiersWhere a LOCAL directive is used in a macro block, the assembler will generate a unique symbol toreplace each specified identifier in each expansion of that macro. These unique symbols will havethe form ??nnnn where nnnn is a 4 digit number. The user should avoid defining symbols with thesame form.4.3.5.3 Location CounterThe current location within the active program section is accessible via the symbol $. This symbolexpands to the address of the currently executing instruction. Thus:71