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cd23580cc5
Sometimes there's a bunch of junk in the binary that isn't used for anything. Often it's there to make things line up at the start of a page boundary. This adds a ".junk" directive that tells the disassembler that it can safely disregard the contents of a region. If the region ends on a power-of-two boundary, an alignment value can be specified. The assembly source generators will output an alignment directive when possible, a .fill directive when appropriate, and a .dense directive when all else fails. Because we're required to regenerate the original data file, it's not always possible to avoid generating a hex dump.
361 lines
18 KiB
HTML
361 lines
18 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml">
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<head>
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<meta content="text/html; charset=utf-8" http-equiv="Content-Type" />
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<meta name="viewport" content="width=device-width, initial-scale=1" />
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<link href="main.css" rel="stylesheet" type="text/css" />
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<title>Editors - 6502bench SourceGen</title>
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</head>
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<body>
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<div id="content">
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<h1>6502bench SourceGen: Editors</h1>
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<p><a href="index.html">Back to index</a></p>
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<h2><a name="address">Edit Address</a></h2>
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<p>This adds a target address directive (".ORG") to the current offset.
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If you leave the text field blank, the directive will be removed.</p>
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<p>Addresses are always interpreted as hexadecimal. You can prefix
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it with a '$', but that's not required.
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24-bit addresses may be written with a bank separator, e.g. "12/3456"
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would resolve to address $123456.</p>
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<p>There will always be an address directive at the start of the file.
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Attempts to remove it will be ignored.</p>
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<h2><a name="flags">Edit Status Flag Override</a></h2>
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<p>The state of the processor status flags are tracked for every
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instruction. Each individual flag is recorded as zero, one, or
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"indeterminate", meaning it could hold either value at the start of
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that instruction. You can override the value of individual flags.</p>
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<p>The 65816 emulation bit, which is not part of the processor status
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register, may also be set in the editor.</p>
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<p>The M, X, and E flags will not be editable unless your CPU configuration
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is set to 65816.</p>
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<h2><a name="label">Edit Label</a></h2>
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<p>Sets or clears a label at the selected offset. The label must have
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the
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<a href="intro.html#about-symbols">proper form</a>, and not have the same
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name as another symbol. If you edit an auto-generated label you will
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be required to change the name.</p>
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<p>The label may be marked as local, global, or global and exported.
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Local labels may be modified by the assembly code generator to have a more
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convenient form, such as a local loop identifier. Global labels are
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always output as-is. Exported labels are added to a table that may
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be imported by other projects (see
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<a href="advanced.html#multi-bin">Working With Multiple Binaries</a>).</p>
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<h2><a name="instruction-operand">Edit Instruction Operand</a></h2>
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<p>Operands can be formatted explicitly, or you can let the disassembler
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select the format for you. By default, immediate constants and
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addresses with no matching symbol are formatted as hex. Symbols
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defined as address labels, platform/project symbols, and local
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variables will be identified and applied automatically.</p>
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<h3><a name="explicit-format">Explicit Formats</a></h3>
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<p>Operands can be displayed in a variety of numeric formats, or as a
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symbol. The character formats are only available for operands
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whose value falls into the proper range. The ASCII format handles
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both plain and high ASCII; the correct encoding is chosen based on
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the operand's value.</p>
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<p>Symbols may be used in their entirety, or, when used as constants,
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can be shifted and masked.
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The low / high / bank selector determines which byte is used as the
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low byte. For 16-bit operands, this acts as a shift rather than a byte
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select. If the symbol is wider than the operand field, e.g. you're
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referencing a 16-bit address in an 8-bit constant, a mask will be
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applied automatically.</p>
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<p>The editor will try to prevent you from using auto-generated
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labels and local variables in the symbol field. These types of symbols
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can be freely renamed by SourceGen, and thus cannot be reliably
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referenced by name.</p>
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<p>When you select a non-default format option, a "preview" of the
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formatted operand will be shown.</p>
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<p>The <code>MVN</code> and <code>MVP</code> instructions on the 65816
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are a bit peculiar, because they have two operands rather than one.
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SourceGen currently only allows you to set one format, which will be
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applied to both operands. If you specify a symbol, the symbol will
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be used twice, adjusted if necessary. (This limitation may be addressed
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in a future release.)</p>
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<p>The bottom part of the window has some shortcuts for working with
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address references and local variables. These are primarily used to
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change the way things work when "Default" is selected. The shortcuts
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don't cause any changes to the recorded format of the instruction
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being edited. All of the actions can be performed elsewhere, by
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editing the label at the target address, editing the project symbol
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set, or editing a local variable table.</p>
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<h3><a name="shortcut-nar">Numeric Address References</a></h3>
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<p>For operands that are 8-bit, 16-bit, or 24-bit addresses, you can
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define a symbol for the address as a label or
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<a href="intro.html#symbol-types">project symbol</a>.</p>
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<p>If the operand is an address inside the project, you can set a
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label at that address. If the address falls in the middle of an
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instruction or multi-byte data item, its position will be adjusted to
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the start. Labels may be created, modified, or (by erasing the label)
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deleted.</p>
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<p>The label finder does not do the optional search for "nearby" labels
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that the main analyzer does, so there will be times when an instruction
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that is shown with a symbol in the code list won't have a symbol
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in the editor.</p>
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<p>If the operand is an address outside the project, e.g. a ROM
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address or I/O location, you can define a project symbol. If a
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match was found in the configured platform definition files, it will be
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shown; it can't be edited, but it can be overridden by a project symbol.
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You can create or modify a project symbol by clicking on "Create Project
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Symbol" or "Edit Project Symbol". You can't delete project symbols
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from this editor (use Project Properties instead).</p>
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<p>It's possible to have more than one project symbol for the same
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address. For example, on the Apple II, reading from the memory-mapped
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I/O address $C000 returns the last key pressed, but writing to it
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changes the state of the 80-column display hardware, so it's useful to
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have two different names for it. If more than one project symbol has the
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same address, the first one found will be used, which may not be
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what is desired. In such situations, you should create the project
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symbol and then copy the symbol name into the operand. You can do this
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in one step by clicking the "Copy to Operand" button.
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(In most cases you don't want to do this, because if the project
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symbol is deleted or renamed, you'll have operands that refer to a
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nonexistent symbol. Unlike labels, project symbol renames do not
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refactor the rest of the project.)
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<h3><a name="shortcut-local-var">Local Variable References</a></h3>
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<p>For zero-page address operands and (65816-only) stack-relative
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constant operands, a local variable can be created or modified. This
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requires that a local variable table has been defined at or before
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the instruction being edited.</p>
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<p>If an existing entry is found, you will be able to edit the name
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and comment fields. If not, a new entry with a generic name and
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pre-filled value field will be created in the nearest table.</p>
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<h2><a name="data-operand">Edit Data Operand</a></h2>
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<p>This dialog offers a variety of choices, and can be used to apply a
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format to multiple lines. You must select all of the bytes you want
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to format. For example, to format two bytes as a 16-bit word, you must
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select both bytes in the editor. (If you click on the first item, then
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Shift+double-click on the operand field of the last item, you can do
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this very quickly.) The selection does not need to be contiguous: you
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can use Control+click to select scattered items.</p>
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<p>If the range is discontiguous, or crosses a visual boundary
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such as a change in address, a user-specified label, or a long comment
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or note, the selection will be split into smaller regions. A message at the
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top of the dialog indicates how many bytes have been selected, and how
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many regions they have been divided into.</p>
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<p>(End-of-line comments do <i>not</i> split a region, and will
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disappear if they end up inside a multi-byte data item.)</p>
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<p>The "Simple Data" items behave the same as their equivalents in the
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Edit Operand dialog. However, because the width is not determined by
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an instruction opcode, and multiple items can be selected, you will need
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to specify how wide each item is and what its byte order is. For data
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you also have the option of setting the format to "Address", which marks
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the selected bytes as a numeric reference.</p>
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<p>Consider a simple example: suppose you find a table of 16-bit
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addresses in the code. Click on
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the first byte, shift-click the last byte, then select the Edit Data menu
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item. The number of bytes selected should be even. Select
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"16-bit words, little-endian", then over to the right click on
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"Address". When you click OK, the selected data will be formatted as a
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series of 16-bit address values. If the addresses can be resolved inside
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the data file, each address will be assigned a label.</p>
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<p>The "Bulk Data" items can represent large chunks of data compactly.
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The "fill" option is only available if all selected bytes have the
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same value.
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If a region of bytes is irrelevant, perhaps used only as padding, you
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can mark it as "junk". If it appears to be adding bytes to reach a
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power-of-two address boundary, you can designate it as an alignment
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directive. If you have multiple regions selected, only options that
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work for all regions will be shown.</p>
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<p>The "String" items are enabled or disabled depending on whether the
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data you have selected is in the appropriate format. For example,
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"Null-terminated strings" is only enabled if the data regions are
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composed entirely of characters followed by $00. Zero-length strings
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are allowed, but only if some non-zero-length strings are present.
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DCI (Dextral Character Inverted) strings have the high bit on the last
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byte flipped; for PETSCII this will usually look like a series of
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lower-case letters followed by a capital letter, but may look odd if the
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last character is punctuation (e.g. '!' becomes $A1, which is a
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rectangle character that SourceGen will only display as hex).</p>
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<p>The character encoding can be selected, offering a choice between
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plain ASCII, low + high ASCII, C64 PETSCII, and C64 screen codes. When
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you change the encoding, your available options may change. The
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low + high ASCII setting will accept both, configuring the appropriate
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encoding based on the data values, but when identifying multiple strings
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it requires that each individual string be entirely one or the other.</p>
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<p>Due to fundamental limitations of the character set, C64 screen code
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strings cannot be null terminated ($00 is '@').</p>
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<p>To avoid burying a label in the middle of a data item, contiguous areas
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are split at labels. This can sometimes have unexpected effects. For
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example, this can be formatted as two 16-bit words or one 32-bit word:</p>
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<pre>
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.DD1 $01
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.DD1 $ef
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.DD1 $01
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.DD1 $f0
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</pre>
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<p>With a label in the middle, it be formatted as two 16-bit words, but
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not as a 32-bit word:</p>
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<pre>
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.DD1 $01
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.DD1 $ef
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LABEL .DD1 $01
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.DD1 $f0
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CODE LDA LABEL
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</pre>
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<p>If this is inconvenient, you can add a label at a 32-bit boundary, and
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reference that instead:</p>
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<pre>
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LABEL .DD1 $01
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.DD1 $ef
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.DD1 $01
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.DD1 $f0
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CODE LDA LABEL+2
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</pre>
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<p>With the label out of the way, the data can be formatted as desired.</p>
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<h2><a name="comment">Edit Comment</a></h2>
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<p>Enter an end-of-line (EOL) comment, or leave the text field blank to
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delete it. EOL comments may be placed on instruction and data lines, but
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not on assembler directives.</p>
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<p>It's wise to restrict comments to the ASCII character set, because
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not all assemblers can accept UTF-8 input. Code generators for such
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assemblers will convert non-ASCII characters to '?' or something similar.
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If this isn't a concern, you can enter any characters you like.</p>
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<p>There is no fixed limit on the number of characters, but you may
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want to limit the overall length if you're hoping to create 80-column
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output. Some retro assemblers may have hard line length limitations,
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which could result in the comment being truncated in generated sources.</p>
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<p>A semicolon (';') is placed at the start of the comment. If an assembler
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has different conventions, a different delimiter character may be used. You
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don't need to include a delimiter explicitly in the comment field.</p>
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<p>Comments on platform symbols are read from the platform symbol file, and
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cannot be edited from within SourceGen. Comments on project symbols are
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stored in the project file, and can be edited with the project symbol
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editor.</p>
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<h2><a name="long-comment">Edit Long Comment</a></h2>
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<p>Long comments can be arbitrarily long and span multiple lines. They
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will be word-wrapped at a line width of your choosing. They're always
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drawn with a fixed-width font, so you can create ASCII-art diagrams.
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Comment delimiters are added automatically at the start of each line.</p>
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<p>For a true retro look you can "box" the comment with asterisks. You
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can create a full-width row of asterisks by putting a '*' on a line by
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itself. (Assembly source generators are allowed to use a character
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other than '*' for the output, e.g. they might use a full set of
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box outline characters, though that's somewhat against the spirit of
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the thing. Regardless, a solo '*' results in a line.)</p>
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<p>The bottom window will update automatically as you type, showing what
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the output is expected to look like. The actual assembler source output
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will depend on features of the target assembler, such as comment
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delimiter choices and maximum line length limitations. For example,
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Merlin allows a leading '*' to indicate a comment, while cc65 does not,
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so cc65 code uses ";*' instead. Because the length limitation affects
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the length of the line, not just the comment text, an asterisk-boxed
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comment will have one fewer character per line in cc65 output.</p>
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<p>Clear the text field to delete the comment.</p>
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<p>You can use Ctrl+Enter as a keyboard shortcut for "OK".</p>
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<p>The long comment at the very top of the project is special, as it's
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not associated with a file offset. If you delete it, you can get it
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back by using Edit > Edit Header Comment.</p>
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<h2><a name="note">Edit Note</a></h2>
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<p>Notes are similar to long comments, in that they can be arbitrarily
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long and span multiple lines. However, because they're never included
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in generated output, options like line width formatting and boxing
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aren't relevant.</p>
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<p>Instead, you can select a highlight color for the note to make it
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stand out. You may want to assign certain colors to specific things,
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e.g. blue for "I don't know what this is" or green for "this is a
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bookmark for the really interesting stuff". The color will be applied
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to the note in the code list and in the "Notes" window.</p>
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<p>Clear the text field to delete the note.</p>
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<p>You can use Ctrl+Enter as a keyboard shortcut for "OK".</p>
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<h2><a name="project-symbol">Edit Project Symbol</a></h2>
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<p>This is used to edit the properties of a project symbol.</p>
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<p>Symbols marked as "address" will be applied automatically when an
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operand references an address outside the scope of the data file. They
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will not be applied to addresses inside the data file. Symbols
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marked as "constant" are not applied automatically, and must be
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explicitly specified as an operand.</p>
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<p>The label must meet the criteria for symbols (see
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<a href="intro.html#about-symbols">All About Symbols</a>), and must
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not have the same name as another project symbol. It can overlap
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with platform symbols and user labels.</p>
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<p>The value may be entered in decimal, hexadecimal, or binary. The numeric
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base you choose will be remembered, so that the value will be displayed
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the same way when used in a .EQ directive.</p>
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<p>You can optionally provide a width for address symbols. For example,
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if the address is of a two-byte pointer or a 64-byte buffer, you would
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set the width field to cause all references to any location in that range
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to be set to the symbol. Widths may be entered in hex or decimal. If
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the field is left blank, a width of 1 is assumed. Overlapping symbols
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are allowed. The width is ignored for constants.</p>
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<p>If you enter a comment, it will be placed at the end of the line of
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the .EQ directive.</p>
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<p>For address symbols that represent a memory-mapped I/O location, it
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can be useful to have different symbols for reads and writes. Use
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the Read/Write checkboxes to specify the desired behavior.</p>
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<h2><a name="lvtable">Create/Edit Local Variable Table</a></h2>
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<p><a href="intro.html#local-vars">Local variables</a> are arranged in
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tables, which are created at a specific file offset. They must be
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associated with a line of code, and are usually placed at the start of
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a subroutine.
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The "Create Local Variable Table" action creates a new table, and
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opens the editor. The "Edit Prior Local Variable Table" searches
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for the closest table that appears at or before the selected line,
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and edits that.</p>
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<p>The editor allows you to create, edit, and delete entries, as well
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as move and delete entire tables (though these last two options are not
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available when creating a new table). Empty tables are allowed. These
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can be useful if the "clear previous" flag is set. If you want to
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delete the table, click the "Delete Table" button.</p>
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<p>Use the buttons to add, edit, or remove individual variables. Each
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variable has a name, a value, a width, and an optional comment. The
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standard naming rules for symbols apply. Variables are only used for
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zero-page and stack-relative operands, so all values must fall in the
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range 0-255, with their width factored in. So the maximum address for
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a two-byte pointer is $fe.</p>
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<p>You can move a table to any offset that is the start of an instruction
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and doesn't already have a local variable table present. Click the
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"Move Table" button and enter the new offset in hex. You can also click
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on the up/down buttons to move to the next valid offset.</p>
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</div>
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<div id="footer">
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<p><a href="index.html">Back to index</a></p>
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