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119 lines
5.2 KiB
HTML
119 lines
5.2 KiB
HTML
15 years ago
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<HTML>
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<HEAD>
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<TITLE>Watch Window Help</TITLE>
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</HEAD>
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<BODY>
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<H1>The Watch Window</H1>
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<H3>Overview</H3>
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<P>The Watch Window may be used to inspect any collected expression, including
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global variables, static variables, local variables, function arguments,
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and registers.</P>
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<P>Watch Window topics:
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<UL>
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<LI><UL><A HREF="#menus">Watch Menu</A>
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<LI><A HREF="#menus_fmt">Format</A>
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<LI><A HREF="#menus_remove">Remove</A>
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</UL>
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<LI><UL><A HREF="#new">Adding Watch Expressions</A>
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<LI><A HREF="#new_ent">In the Watch Window</A>
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<LI><A HREF="#new_src">In the Source Window</A>
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<LI><A HREF="#new_cast">Casting Pointers</A>
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</UL>
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<LI><UL><A HREF="#display">Watch Display</A>
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<LI><A HREF="#display_deref">Dereferencing Pointers</A>
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<LI><A HREF="#display_struct">Viewing a Structure or Class</A>
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<LI><A HREF="#display_popup">Watch Pop-up Menu</A>
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</UL>
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</UL></P>
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<H3><A NAME="menus">Watch Menu</A></H3>
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The Watch Menu gives on-screen access to the funtions of the Watch Window.
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To use any of these functions, first use the left mouse button to select an
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expression from the display. Then select:
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<DL>
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<DT><A NAME="menus_fmt">Format</A>
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<DD>Change the display format of the expression
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<DT><A NAME="menus_remove">Remove</A>
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<DD>Remove the expression from the Watch Window
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</DL>
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<H3><A NAME="new">Adding Watch Expressions</A></H3>
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<A NAME="new_ent">To add an expression to the Watch Window</A>, simply enter
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the expression into the entry at the bottom of the window and press return
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or click the "Add Watch" button. The expression is validated and added to the
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Watch Window Display.
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<P><A NAME="new_src">To add an expression to the Watch Window from the
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<A HREF="source.html">Source Window</A></A>, use the
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"<A HREF="source.html#add_to_watch">Add to Watch</A>" option of the
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<A HREF="source.html#display_popup">Source Window Pop-up Menu</A>.</P>
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<P>Any legal expression may be added to the Watch Window, which will
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evaluate each of its expressions everytime the program runs. Be cautious
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adding expressions which cause assignments, such as "<CODE>i++</CODE>".</P>
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<P>Adding a register to the Watch Window can be advantages when debugging
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via a slow serial line. In this case, keeping the entire Register Window open
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may be inefficient. Consider adding the register to the Watch Window. Simply
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enter the name of the register preceded with a dollar sign ($) into the
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Entry. For example, to watch the PC register, enter "<CODE>$pc</CODE>" into
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the Watch Window Entry. The program counter is added to the Display.</P>
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<P><A NAME="new_cast">To cast pointers</A>, simply enter the cast into the
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Watch Window Entry at the bottom of the window. Use the same syntax for the
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cast that the source file uses. If the source file uses C, the a simple
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cast of "<CODE>ptr</CODE>" of type "<CODE>void *</CODE>" can be cast to type
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"<CODE>my_struct</CODE>" by entering "<CODE>(my_struct *) ptr</CODE>" into
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the Entry.</P>
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<H3><A NAME="display">Watch Display</A></H3>
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The Watch Window Display consists of a scrolled listbox which contains all
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watch expressions, one per line. To use any of the functions of the Watch
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Window, use the left mouse button to select any element from the Display.
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<P>Pointers, structures, and classes appear in the display with a small
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exapansion box before their names. To <A NAME="display_deref">dereference
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pointers</A> or <A NAME="display_struct">view the members of classes or
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structures</A>, click the closed expansion box (which appears as a small
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plus sign, "+") to "expand" the listing. The expansion box changes to a
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minus sign, "-", indicating that the display is now open. Pointers,
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structures and classes may be expanded recursively to allow multiple pointer
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dereferences and embedded structure viewing.
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<P>The Locals Display updates as the trace buffer is navigated, highlighting
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in blue those variables whose values have changed.</P>
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<P>The Watch Window will, by default, display all pointers in hexadecimal and all
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other variables in decimal. To change the default display of variables, use the
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"set output-radix" command in the console window. (Type "help set output-radix" in the
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console window for help. To make this change permanent, it must be added to the user's
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init file -- .gdbinit.) To change the display
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format for a variable, select the Format option from either the Variable Menu or the
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<A HREF="#display_popup">Watch Pop-up Menu</A>.
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<BR>
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<H4><A NAME="display_popup">Watch Pop-up Menu</A></H4>
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The Watch Pop-up Menu provides quick access to the functions of the Watch Window.
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To use the Locals Pop-up Menu, first select an expression from the Display (by
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clicking the left mouse button on it) and click the right mouse button, choosing
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from the pop-up:
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<DL>
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<DT>Format
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<DD>Change the display format of the expression. The expression may be
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displayed as:
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<DL>
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<DT>Hex
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<DD>hexadecimal (base 16)
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<DT>Decimal
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<DD>decimal (base 10)
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<DT>Binary
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<DD>binary (base 2)
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<DT>Octal
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<DD>octal (base 8)
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</DL>
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</DL>
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</BODY>
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</HTML>
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