HP 68000 Series, User Manual

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Symbols
A symbol (also called an identifier) is a name that identifies a location in
memory. It consists of a sequence of characters that identify program and
debugger variables, macros, keywords,registers, memory addresses, and line
numbers.
Symbols may be up to 40 characters in length. The first character in a symbol
must be alphabetic, an underscore (_), or an at sign (@). The characters
allowed in a symbol include upper and lower case alphabetic characters,
numeric characters, dollar signs ($), at signs (@), or underscores (_). No
other characters may be used in symbols. The debugger differentiates between
upper case and lower case characters in a symbol.
The following sections describe the different categories of symbols used by the
debugger.
Program Symbols
Program symbols are identifiers associated with a source program. They
consist of symbolic variable data names and function names that the
programmer defined when writing the source program. All symbols that were
defined in the source program can be passed to the debugger and referenced
during a debugging session. Note that preprocessor names are not symbols.
The compiler includes all program symbol information in the resulting output
object module file by default. When you load an executable file for debugging,
the debugger places all program symbols into the debugger symbol table by
default. The debugger preserves symbol types and treats the symbols
according to their type.
The debugger may be instructed to load only global symbols at load time,
loading local symbols as they are referenced. This behavior is known as
symbols on demand. R efer to the description of the Debugger Option General
Demand_Load command in the “Debugger Commands” chapter for more
information on symbols on demand.
Normally, the compiler prefixes a leading underscore to all global program
symbols. This is done to distinguish program symbols from reserved assembler
names. If the debugger has loaded all symbols, two symbols will be available;
the high-level symbol (for example, main), and its low-level
Chapter 10: Expressions and Symbols in Debugger Commands
Symbols
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