1
0
mirror of https://github.com/fadden/6502bench.git synced 2024-10-31 19:04:44 +00:00
6502bench/SourceGen/SymbolTable.cs
Andy McFadden 0d9814d993 Allow explicit widths in project/platform symbols, part 3
Implement multi-byte project/platform symbols by filling out a table
of addresses.  Each symbol is "painted" into the table, replacing
an existing entry if the new entry has higher priority.  This allows
us to handle overlapping entries, giving boosted priority to platform
symbols that are defined in .sym65 files loaded later.

The bounds on project/platform symbols are now rigidly defined.  If
the "nearby" feature is enabled, references to SYM-1 will be picked
up, but we won't go hunting for SYM+1 unless the symbol is at least
two bytes wide.

The cost of adding a symbol to the symbol table is about the same,
but we don't have a quick way to remove a symbol.

Previously, if two platform symbols had the same value, the symbol
with the alphabetically lowest label would win.  Now, the symbol
defined in the most-recently-loaded file wins.  (If you define two
symbols with the same value in the same file, it's still resolved
alphabetically.)  This allows the user to pick the winner by
arranging the load order of the platform symbol files.

Platform symbols now keep a reference to the file ident of the
symbol file that defined them, so we can show the symbols's source
in the Info panel.

These changes altered the behavior of test 2008-address-changes,
which includes some tests on external addresses that are close to
labeled internal addresses.  The previous behavior essentially
treated user labels as being 3 bytes wide and extending outside the
file bounds, which was mildly convenient on occasion but felt a
little skanky.  (We could do with a way to define external symbols
relative to internal symbols, for things like the source address of
code that gets relocated.)

Also, re-enabled some unit tests.

Also, added a bit of identifying stuff to CrashLog.txt.
2019-10-02 16:50:15 -07:00

287 lines
11 KiB
C#

/*
* Copyright 2019 faddenSoft
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
namespace SourceGen {
/// <summary>
/// List of all symbols, arranged primarily by label, but also accessible by value. All
/// symbols have a unique label.
/// </summary>
public class SymbolTable : IEnumerable<Symbol> {
/// <summary>
/// Primary storage. Provides fast lookup by label. The StringComparer we choose
/// determines how case sensitivity and Culture is handled.
private SortedList<string, Symbol> mSymbols =
new SortedList<string, Symbol>(Asm65.Label.LABEL_COMPARER);
/// <summary>
/// By-address lookup table. Because symbols can span more than one byte, there may
/// be more than one entry per symbol here. If two symbols cover the same address,
/// only the highest-priority symbol is kept, so not all symbols are represented here.
///
/// This does not contain constants or local variables.
/// </summary>
/// <remarks>
/// For efficiency on larger data files, we may want to break this up by bank. That
/// way we can do a partial update.
/// </remarks>
private Dictionary<int, Symbol> mSymbolsByAddress =
new Dictionary<int, Symbol>();
/// <summary>
/// This is incremented whenever the contents of the symbol table change. External
/// code can compare this against a previous value to see if anything has changed
/// since the last visit.
///
/// We could theoretically miss something at the 2^32 rollover. Not worried.
/// </summary>
//public int ChangeSerial { get; private set; }
public SymbolTable() { }
// IEnumerable
public IEnumerator<Symbol> GetEnumerator() {
// .Values is documented as O(1)
return mSymbols.Values.GetEnumerator();
}
// IEnumerable
IEnumerator IEnumerable.GetEnumerator() {
return mSymbols.Values.GetEnumerator();
}
/// <summary>
/// Clears the symbol table.
/// </summary>
public void Clear() {
mSymbols.Clear();
mSymbolsByAddress.Clear();
//ChangeSerial++;
}
/// <summary>
/// Returns the number of symbols in the table.
/// </summary>
public int Count() {
return mSymbols.Count;
}
/// <summary>
/// Adds the specified symbol to the list. Throws an exception if the symbol is
/// already present.
/// </summary>
public void Add(Symbol sym) {
// If Symbol with matching label is in list, this will throw an exception,
// and the by-value add won't happen.
mSymbols.Add(sym.Label, sym);
AddAddressTableEntry(sym);
//ChangeSerial++;
}
/// <summary>
/// get: Finds the specified symbol by label. Throws an exception if it's not found.
///
/// set: Adds the specified symbol to the list, or replaces it if it's already present.
/// </summary>
public Symbol this[string key] {
get {
return mSymbols[key];
}
set {
mSymbols.TryGetValue(key, out Symbol oldValue);
mSymbols[key] = value;
if (oldValue != null) {
ReplaceAddressTableEntry(oldValue, value);
} else {
AddAddressTableEntry(value);
}
//ChangeSerial++;
}
}
/// <summary>
/// Gets the value associated with the key.
/// </summary>
/// <param name="key">Label to look up.</param>
/// <param name="sym">Symbol, or null if not found.</param>
/// <returns>True if the key is present, false otherwise.</returns>
public bool TryGetValue(string key, out Symbol sym) {
return mSymbols.TryGetValue(key, out sym);
}
/// <summary>
/// Gets the value associated with the key, unless it's a variable.
/// </summary>
/// <param name="key">Label to look up.</param>
/// <param name="sym">Symbol, or null if not found, or found but it's a variable.</param>
/// <returns>True if the key is present, false otherwise.</returns>
public bool TryGetNonVariableValue(string key, out Symbol sym) {
bool found = mSymbols.TryGetValue(key, out sym);
if (found && sym.IsVariable) {
sym = null;
found = false;
}
return found;
}
/// <summary>
/// Removes the specified symbol.
/// </summary>
public void Remove(Symbol sym) {
mSymbols.Remove(sym.Label);
RemoveAddressTableEntry(sym);
//ChangeSerial++;
}
/// <summary>
/// Adds a symbol to the address table. All affected addresses are updated. If an
/// existing symbol is already present at an address, the new or old symbol will be
/// selected in priority order.
/// </summary>
/// <param name="sym">Symbol to add.</param>
private void AddAddressTableEntry(Symbol sym) {
if (sym.SymbolType == Symbol.Type.Constant) {
return;
}
if (sym.SymbolSource == Symbol.Source.Variable) {
return;
}
int width = 1;
if (sym is DefSymbol) {
width = ((DefSymbol)sym).DataDescriptor.Length;
}
// we could restore some older behavior by giving user labels a width of 3, but
// we'd have to make sure that they didn't win for addresses outside the file
for (int i = 0; i < width; i++) {
// see if there's already something here
mSymbolsByAddress.TryGetValue(sym.Value + i, out Symbol curSym);
mSymbolsByAddress[sym.Value + i] = (curSym == null) ? sym :
HighestPriority(sym, curSym);
}
}
private Symbol HighestPriority(Symbol sym1, Symbol sym2) {
// First determinant is symbol source. User labels have highest priority, then
// project symbols, then platform symbols, then auto labels.
if ((int)sym1.SymbolSource < (int)sym2.SymbolSource) {
return sym1;
} else if ((int)sym1.SymbolSource > (int)sym2.SymbolSource) {
return sym2;
}
// Same source. Are they platform symbols?
if (sym1.SymbolSource == Symbol.Source.Platform) {
// Sort by file load order. Symbols from files loaded later, which will have
// a higher ordinal, have priority.
int lo1 = ((DefSymbol)sym1).LoadOrdinal;
int lo2 = ((DefSymbol)sym2).LoadOrdinal;
if (lo1 > lo2) {
return sym1;
} else if (lo1 < lo2) {
return sym2;
}
}
// Same source, so this is e.g. two project symbol definitions that overlap. We
// handle this by selecting whichever one was defined closer to the target address,
// i.e. whichever one has the higher value.
if (sym1.Value > sym2.Value) {
return sym1;
} else if (sym1.Value < sym2.Value) {
return sym2;
}
// In the absence of anything better, we select them alphabetically. (If they have
// the same name, value, and source, there's not much to distinguish them anyway.)
if (Asm65.Label.LABEL_COMPARER.Compare(sym1.Label, sym2.Label) < 0) {
return sym1;
} else {
return sym2;
}
}
/// <summary>
/// Replaces an entry in the address table. Must be called AFTER the by-label list
/// has been updated.
/// </summary>
/// <param name="oldSym">Symbol being replaced.</param>
/// <param name="newSym">New symbol.</param>
private void ReplaceAddressTableEntry(Symbol oldSym, Symbol newSym) {
RemoveAddressTableEntry(oldSym);
AddAddressTableEntry(newSym);
}
/// <summary>
/// Removes an entry from the address table. Must be called AFTER the by-label list
/// has been updated.
/// </summary>
/// <param name="sym">Symbol to remove.</param>
private void RemoveAddressTableEntry(Symbol sym) {
// Easiest thing to do is just regenerate the table. Since we don't track
// constants or variables, we can just ignore those.
if (sym.SymbolType == Symbol.Type.Constant) {
return;
}
if (sym.SymbolSource == Symbol.Source.Variable) {
return;
}
if (sym.SymbolSource == Symbol.Source.User || sym.SymbolSource == Symbol.Source.Auto) {
// These have a width of 1 and can't overlap with anything meaningful... even
// if there's a project symbol for the address, it won't be used, because it's
// an in-file address. So we can just remove the entry.
mSymbolsByAddress.Remove(sym.Value);
}
RegenerateAddressTable();
}
/// <summary>
/// Regenerates the entire by-address table, from the contents of the by-label list.
/// </summary>
/// <remarks>
/// This is a little painful, but if a symbol gets removed we don't have a way to
/// restore lower-priority items. If this becomes a performance issue we can create
/// an ordered list of symbols at each address, but with a few hundred symbols this
/// should take very little time.
/// </remarks>
private void RegenerateAddressTable() {
Debug.WriteLine("SymbolTable: regenerating address table");
mSymbolsByAddress.Clear();
foreach (KeyValuePair<string, Symbol> kvp in mSymbols) {
AddAddressTableEntry(kvp.Value);
}
}
/// <summary>
/// Searches the table for symbols with matching address values. Ignores constants and
/// variables.
/// </summary>
/// <param name="addr">Address to find.</param>
/// <returns>First matching symbol found, or null if nothing matched.</returns>
public Symbol FindNonVariableByAddress(int addr) {
mSymbolsByAddress.TryGetValue(addr, out Symbol sym);
return sym;
}
}
}