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6502bench/SourceGen/DataAnalysis.cs
Andy McFadden 823aa072fb Update comments
2019-04-29 13:07:52 -07:00

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/*
* Copyright 2018 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.Diagnostics;
using Asm65;
using CommonUtil;
namespace SourceGen {
/// <summary>
/// Auto-detection of structured data.
///
/// This class doesn't really hold any state. It's just a convenient place to collect
/// the items needed by the analyzer methods.
/// </summary>
public class DataAnalysis {
// Minimum number of consecutive identical bytes for something to be called a "run".
private const int MIN_RUN_LENGTH = 5;
// Minimum length for treating data as a run if the byte is a valid ASCII value.
// (Alternatively, the maximum length of an ASCII string composed of single characters.)
// Anything shorter than this is handled with a string directive, anything this long or
// longer becomes FILL. This should be larger than the MinCharsForString parameter.
private const int MIN_RUN_LENGTH_ASCII = 62;
// Absolute minimum string length for auto-detection. This is used when generating the
// data tables.
public const int MIN_STRING_LENGTH = 3;
// Minimum length for an ASCII string. Anything shorter is just output as bytes.
// This is the default value; the actual value is configured as a project preference.
public const int DEFAULT_MIN_STRING_LENGTH = 4;
// Set min chars to this to disable string detection.
public const int MIN_CHARS_FOR_STRING_DISABLED = int.MaxValue;
/// <summary>
/// Project with which we are associated.
/// </summary>
private DisasmProject mProject;
/// <summary>
/// Reference to 65xx data.
/// </summary>
private byte[] mFileData;
/// <summary>
/// Attributes, one per byte in input file.
/// </summary>
private Anattrib[] mAnattribs;
/// <summary>
/// Configurable parameters.
/// </summary>
private ProjectProperties.AnalysisParameters mAnalysisParams;
/// <summary>
/// Debug trace log.
/// </summary>
private DebugLog mDebugLog = new DebugLog(DebugLog.Priority.Silent);
public DebugLog DebugLog {
set {
mDebugLog = value;
}
}
public DataAnalysis(DisasmProject proj, Anattrib[] anattribs) {
mProject = proj;
mAnattribs = anattribs;
mFileData = proj.FileData;
mAnalysisParams = proj.ProjectProps.AnalysisParams;
}
// Internal log functions. If we're concerned about performance overhead due to
// call-site string concatenation, we can #ifdef these to nothing in release builds,
// which should allow the compiler to elide the concat.
#if false
private void LogV(int offset, string msg) {
if (mDebugLog.IsLoggable(DebugLog.Priority.Verbose)) {
mDebugLog.LogV("+" + offset.ToString("x6") + " " + msg);
}
}
#else
private void LogV(int offset, string msg) { }
#endif
private void LogD(int offset, string msg) {
if (mDebugLog.IsLoggable(DebugLog.Priority.Debug)) {
mDebugLog.LogD("+" + offset.ToString("x6") + " " + msg);
}
}
private void LogI(int offset, string msg) {
if (mDebugLog.IsLoggable(DebugLog.Priority.Info)) {
mDebugLog.LogI("+" + offset.ToString("x6") + " " + msg);
}
}
private void LogW(int offset, string msg) {
if (mDebugLog.IsLoggable(DebugLog.Priority.Warning)) {
mDebugLog.LogW("+" + offset.ToString("x6") + " " + msg);
}
}
private void LogE(int offset, string msg) {
if (mDebugLog.IsLoggable(DebugLog.Priority.Error)) {
mDebugLog.LogE("+" + offset.ToString("x6") + " " + msg);
}
}
/// <summary>
/// Analyzes instruction operands and Address data descriptors to identify references
/// to offsets within the file.
///
/// Instructions with format descriptors are left alone. Instructions with
/// operand offsets but no descriptor will have a descriptor generated
/// using the label at the target offset; if the target offset is unlabeled,
/// a unique label will be generated. Data descriptors with type=Address are
/// handled the same way.
///
/// In some cases, such as a reference to the middle of an instruction, we will
/// label a nearby location instead.
///
/// This should be called after code analysis has run, user labels and format
/// descriptors have been applied, and platform/project symbols have been merged
/// into the symbol table.
/// </summary>
/// <returns>True on success.</returns>
public void AnalyzeDataTargets() {
mDebugLog.LogI("Analyzing data targets...");
for (int offset = 0; offset < mAnattribs.Length; offset++) {
Anattrib attr = mAnattribs[offset];
if (attr.IsInstructionStart) {
if (attr.DataDescriptor != null) {
// It's being shown as numeric, or as a reference to some other symbol.
// Either way there's nothing further for us to do. (Technically we
// would want to treat it like the no-descriptor case if the type was
// numeric/Address, but we don't allow that for instructions.)
Debug.Assert(attr.DataDescriptor.FormatSubType !=
FormatDescriptor.SubType.Address);
continue;
}
int operandOffset = attr.OperandOffset;
if (operandOffset >= 0) {
// This is an offset reference: a branch or data access instruction whose
// target is inside the file. Create a FormatDescriptor for it, and
// generate a label at the target if one is not already present.
SetDataTarget(offset, attr.Length, operandOffset);
}
// We advance by a single byte, rather than .Length, in case there's
// an instruction embedded inside another one.
} else if (attr.DataDescriptor != null) {
// We can't check IsDataStart / IsInlineDataStart because the bytes might
// still be uncategorized. If there's a user-specified format, check it
// to see if it's an address.
FormatDescriptor dfd = attr.DataDescriptor;
// Is this numeric/Address?
if ((dfd.FormatType == FormatDescriptor.Type.NumericLE ||
dfd.FormatType == FormatDescriptor.Type.NumericBE) &&
dfd.FormatSubType == FormatDescriptor.SubType.Address) {
// Treat like an absolute address. Convert the operand
// to an address, then resolve the file offset.
int address = RawData.GetWord(mFileData, offset, dfd.Length,
(dfd.FormatType == FormatDescriptor.Type.NumericBE));
if (dfd.Length < 3) {
// Bank not specified by data, add current program bank. Not always
// correct, but should be often enough. In most cases we'd just
// assume a correct data bank register, but here we need to find
// a file offset, so we have to assume data bank == program bank
// (unless we find a good way to track the data bank register).
address |= attr.Address & 0x7fff0000;
}
int operandOffset = mProject.AddrMap.AddressToOffset(offset, address);
if (operandOffset >= 0) {
SetDataTarget(offset, dfd.Length, operandOffset);
}
}
// For other formats, we don't need to do anything. Numeric/Address is
// the only one that represents an offset reference. Numeric/Symbol
// is a name reference. The others are just data.
// There shouldn't be any data items inside other data items, so we
// can just skip forward.
offset += mAnattribs[offset].DataDescriptor.Length - 1;
}
}
}
/// <summary>
/// Extracts the operand offset from a data item. Only useful for numeric/Address
/// and numeric/Symbol.
/// </summary>
/// <param name="proj">Project reference.</param>
/// <param name="offset">Offset of data item.</param>
/// <returns>Operand offset, or -1 if not applicable.</returns>
public static int GetDataOperandOffset(DisasmProject proj, int offset) {
Anattrib attr = proj.GetAnattrib(offset);
if (!attr.IsDataStart && !attr.IsInlineDataStart) {
return -1;
}
FormatDescriptor dfd = attr.DataDescriptor;
// Is this numeric/Address or numeric/Symbol?
if ((dfd.FormatType != FormatDescriptor.Type.NumericLE &&
dfd.FormatType != FormatDescriptor.Type.NumericBE) ||
(dfd.FormatSubType != FormatDescriptor.SubType.Address &&
dfd.FormatSubType != FormatDescriptor.SubType.Symbol)) {
return -1;
}
// Treat like an absolute address. Convert the operand
// to an address, then resolve the file offset.
int address = RawData.GetWord(proj.FileData, offset, dfd.Length,
(dfd.FormatType == FormatDescriptor.Type.NumericBE));
if (dfd.Length < 3) {
// Add the program bank where the data bank should go. Not perfect but
// we don't have anything better at the moment.
address |= attr.Address & 0x7fff0000;
}
int operandOffset = proj.AddrMap.AddressToOffset(offset, address);
return operandOffset;
}
/// <summary>
/// Returns the "base" operand offset. If the byte at the specified offset is not the
/// start of a code/data/inline-data item, walk backward until the start is found.
/// </summary>
/// <param name="proj">Project reference.</param>
/// <param name="offset">Start offset.</param>
/// <returns></returns>
public static int GetBaseOperandOffset(DisasmProject proj, int offset) {
Debug.Assert(offset >= 0 && offset < proj.FileDataLength);
while (!proj.GetAnattrib(offset).IsStart) {
offset--;
// Should not be possible to walk off the top of the list, since we're in
// the middle of something.
Debug.Assert(offset >= 0);
}
return offset;
}
/// <summary>
/// Creates a FormatDescriptor in the Anattrib array at srcOffset that links to
/// targetOffset, or a nearby label. If targetOffset doesn't have a useful label,
/// one will be generated.
///
/// This is used for both instruction and data operands.
/// </summary>
/// <param name="srcOffset">Offset of instruction or address data.</param>
/// <param name="srcLen">Length of instruction or data item.</param>
/// <param name="targetOffset">Offset of target.</param>
private void SetDataTarget(int srcOffset, int srcLen, int targetOffset) {
// NOTE: don't try to cache mAnattribs[targetOffset] -- we may be changing
// targetOffset and/or altering the Anattrib entry, so grabbing a copy of the
// struct may lead to problems.
// If the target offset has a symbol assigned, use it. Otherwise, try to
// find something nearby that might be more appropriate.
int origTargetOffset = targetOffset;
if (mAnattribs[targetOffset].Symbol == null) {
if (mAnalysisParams.SeekNearbyTargets) {
targetOffset = FindAlternateTarget(srcOffset, targetOffset);
}
// If we're not interested in seeking nearby targets, or we are but we failed
// to find something useful, we need to make sure that we're not pointing
// into the middle of the instruction. The assembler will only see labels on
// the opcode bytes, so if we're pointing at the middle we need to back up.
if (mAnattribs[targetOffset].IsInstruction &&
!mAnattribs[targetOffset].IsInstructionStart) {
while (!mAnattribs[--targetOffset].IsInstructionStart) {
// Should not be possible to move past the start of the file,
// since we know we're in the middle of an instruction.
Debug.Assert(targetOffset > 0);
}
} else if (!mAnattribs[targetOffset].IsInstruction &&
!mAnattribs[targetOffset].IsStart) {
// This is not part of an instruction, and is not the start of a formatted
// data area. However, it might be part of a formatted data area, in which
// case we need to avoid creating an auto label in the middle. So we seek
// backward, looking for the first offset with a descriptor. If that
// descriptor includes this offset, we set the target offset to that.
// (Note the uncategorized data pass hasn't run yet, so only instructions
// and offsets identified by users or scripts have been categorized.)
int scanOffset = targetOffset;
while (--scanOffset > 0) {
FormatDescriptor dfd = mAnattribs[scanOffset].DataDescriptor;
if (dfd != null && scanOffset + dfd.Length > targetOffset) {
// Descriptor encompasses target offset. Adjust target.
targetOffset = scanOffset;
break;
}
}
}
}
if (mAnattribs[targetOffset].Symbol == null) {
// No label at target offset, generate one.
//
// Generally speaking, the label we generate will be unique, because it
// incorporates the address. It's possible through various means to end
// up with a user or platform label that matches an auto label, so we
// need to do some renaming in that case. Shouldn't happen often.
Symbol sym = AutoLabel.GenerateUniqueForAddress(mAnattribs[targetOffset].Address,
mProject.SymbolTable, "L");
mAnattribs[targetOffset].Symbol = sym;
// This will throw if the symbol already exists. That is the desired
// behavior, as that would be a bug.
mProject.SymbolTable.Add(sym);
}
// Create a Numeric/Symbol descriptor that references the target label. If the
// source offset already had a descriptor (e.g. Numeric/Address data item),
// this will replace it in the Anattrib array. (The user-specified format
// is unaffected.)
//
// Doing this by target symbol, rather than offset in a Numeric/Address item,
// allows us to avoid carrying the adjustment stuff everywhere. OTOH we have
// to manually refactor label renames in the display list if we don't want to
// redo the data analysis.
bool isBigEndian = false;
if (mAnattribs[srcOffset].DataDescriptor != null) {
LogD(srcOffset, "Replacing " + mAnattribs[srcOffset].DataDescriptor +
" with reference to " + mAnattribs[targetOffset].Symbol.Label +
", adj=" + (origTargetOffset - targetOffset));
if (mAnattribs[srcOffset].DataDescriptor.FormatType ==
FormatDescriptor.Type.NumericBE) {
isBigEndian = true;
}
} else {
LogV(srcOffset, "Creating weak reference to label " +
mAnattribs[targetOffset].Symbol.Label +
", adj=" + (origTargetOffset - targetOffset));
}
mAnattribs[srcOffset].DataDescriptor = FormatDescriptor.Create(srcLen,
new WeakSymbolRef(mAnattribs[targetOffset].Symbol.Label, WeakSymbolRef.Part.Low),
isBigEndian);
}
/// <summary>
/// Given a reference from srcOffset to targetOffset, check to see if there's a
/// nearby location that we'd prefer to refer to. For example, if targetOffset points
/// into the middle of an instruction, we'd rather have it refer to the first byte.
/// </summary>
/// <param name="srcOffset">Reference source.</param>
/// <param name="targetOffset">Reference target.</param>
/// <returns>New value for targetOffset, or original value if nothing better was
/// found.</returns>
private int FindAlternateTarget(int srcOffset, int targetOffset) {
int origTargetOffset = targetOffset;
// Is the target outside the instruction stream? If it's just referencing data,
// do a simple check and move on.
if (!mAnattribs[targetOffset].IsInstruction) {
// We want to use user-defined labels whenever possible. If they're accessing
// memory within a few bytes, use that. We don't want to do this for
// code references, though, or our branches will get all weird.
// TODO(someday): make MAX user-configurable? Seek forward as well as backward?
const int MAX = 4;
for (int probeOffset = targetOffset - 1;
probeOffset >= 0 && probeOffset != targetOffset - MAX; probeOffset--) {
Symbol sym = mAnattribs[probeOffset].Symbol;
if (sym != null && sym.SymbolSource == Symbol.Source.User) {
// Found a nearby user label. Make sure it's actually nearby.
int addrDiff = mAnattribs[targetOffset].Address -
mAnattribs[probeOffset].Address;
if (addrDiff == targetOffset - probeOffset) {
targetOffset = probeOffset;
} else {
Debug.WriteLine("NOT probing past address boundary change");
}
break;
}
}
return targetOffset;
}
// Target is an instruction. Is the source an instruction or data element
// (e.g. ".dd2 <addr>").
if (!mAnattribs[srcOffset].IsInstructionStart) {
// Might be address-1 to set up an RTS. If the target address isn't
// an instruction start, check to see if the following byte is.
if (!mAnattribs[targetOffset].IsInstructionStart &&
targetOffset + 1 < mAnattribs.Length &&
mAnattribs[targetOffset + 1].IsInstructionStart) {
LogD(srcOffset, "Offsetting address reference");
targetOffset++;
}
return targetOffset;
}
// Source is an instruction, so we have an instruction referencing an instruction.
// Could be a branch, an address push, or self-modifying code.
OpDef op = mProject.CpuDef.GetOpDef(mProject.FileData[srcOffset]);
if (op.IsBranchOrSubCall) {
// Don't mess with jumps and branches -- always go directly to the
// target address.
} else if (op == OpDef.OpPEA_StackAbs || op == OpDef.OpPER_StackPCRelLong) {
// They might be pushing address-1 to set up an RTS. If the target address isn't
// an instruction start, check to see if the following byte is.
if (!mAnattribs[targetOffset].IsInstructionStart &&
targetOffset + 1 < mAnattribs.Length &&
mAnattribs[targetOffset + 1].IsInstructionStart) {
LogD(srcOffset, "Offsetting PEA/PER");
targetOffset++;
}
} else {
// Data operation (LDA, STA, etc). This could be self-modifying code, or
// an indexed access with an offset base address (LDA addr-1,Y) to an
// adjacent data area. Check to see if there's data right after this.
bool nearbyData = false;
for (int i = targetOffset + 1; i <= targetOffset + 2; i++) {
if (i < mAnattribs.Length && !mAnattribs[i].IsInstruction) {
targetOffset = i;
nearbyData = true;
break;
}
}
if (!nearbyData && !mAnattribs[targetOffset].IsInstructionStart) {
// There's no data nearby, and the target is not the start of the
// instruction, so this is probably self-modifying code. We want
// the label to be on the opcode, so back up to the instruction start.
while (!mAnattribs[--targetOffset].IsInstructionStart) {
// Should not be possible to move past the start of the file,
// since we know we're in the middle of an instruction.
Debug.Assert(targetOffset > 0);
}
}
}
if (targetOffset != origTargetOffset) {
LogV(srcOffset, "Creating instruction ref adj=" +
(origTargetOffset - targetOffset));
}
return targetOffset;
}
/// <summary>
/// Analyzes uncategorized regions of the file to see if they fit common patterns.
///
/// This is re-run after most changes to the project, so we don't want to do anything
/// crazily expensive.
/// </summary>
/// <returns>True on success.</returns>
public void AnalyzeUncategorized() {
FormatDescriptor oneByteDefault = FormatDescriptor.Create(1,
FormatDescriptor.Type.Default, FormatDescriptor.SubType.None);
FormatDescriptor.DebugPrefabBump(-1);
// If it hasn't been identified as code or data, set the "data" flag to
// give it a positive identification as data. (This should be the only
// place outside of CodeAnalysis that sets this flag.) This isn't strictly
// necessary, but it helps us assert things when pieces start moving around.
for (int offset = 0; offset < mAnattribs.Length; offset++) {
Anattrib attr = mAnattribs[offset];
if (attr.IsInlineData) {
// While we're here, add a default format descriptor for inline data
// that doesn't have one. We don't try to analyze it otherwise.
if (attr.DataDescriptor == null) {
mAnattribs[offset].DataDescriptor = oneByteDefault;
FormatDescriptor.DebugPrefabBump();
}
} else if (!attr.IsInstruction) {
mAnattribs[offset].IsData = true;
}
}
mDebugLog.LogI("Analyzing uncategorized data...");
int startOffset = -1;
for (int offset = 0; offset < mAnattribs.Length; ) {
// We want to find a contiguous series of offsets which are not known
// to hold code or data. We stop if we encounter a user-defined label
// or format descriptor.
Anattrib attr = mAnattribs[offset];
if (attr.IsInstruction || attr.IsInlineData || attr.IsDataStart) {
// Instruction, inline data, or formatted data known to be here. Analyze
// previous chunk, then advance past this.
if (startOffset >= 0) {
AnalyzeRange(startOffset, offset - 1);
startOffset = -1;
}
if (attr.IsInstruction) {
// Because of embedded instructions, we can't simply leap forward.
// [or can we?]
offset++;
} else {
Debug.Assert(attr.Length > 0);
offset += attr.Length;
}
} else if (attr.Symbol != null || mProject.HasCommentOrNote(offset)) {
// In an uncategorized area, but we want to break at this byte
// so the user or auto label doesn't get buried in the middle of
// a large chunk.
//
// This is similar to, but independent of, GroupedOffsetSetFromSelected()
// in ProjectView. This is for auto-detection, the other is for user
// selection. It's best if the two behave similarly though.
if (startOffset >= 0) {
AnalyzeRange(startOffset, offset - 1);
}
startOffset = offset;
offset++;
} else {
// This offset is uncategorized, keep gathering.
if (startOffset < 0) {
startOffset = offset;
}
offset++;
// Check to see if the address has changed from the previous entry.
if (offset < mAnattribs.Length &&
mAnattribs[offset-1].Address + 1 != mAnattribs[offset].Address) {
// Must be an ORG here. Scan previous region.
AnalyzeRange(startOffset, offset - 1);
startOffset = -1;
}
}
}
if (startOffset >= 0) {
AnalyzeRange(startOffset, mAnattribs.Length - 1);
}
}
/// <summary>
/// Analyzes a range of bytes, looking for opportunities to promote uncategorized
/// data to a more structured form.
/// </summary>
/// <param name="start">Offset of first byte in range.</param>
/// <param name="end">Offset of last byte in range.</param>
private void AnalyzeRange(int start, int end) {
// We want to identify runs of identical bytes, and runs of more than N human-
// readable characters (ASCII, high ASCII, PETSCII, whatever). There are a few
// ways to do this.
//
// The simple approach is to walk through the data from start to end, checking at
// each offset for runs of bytes matching the criteria. Because the data doesn't
// change, we can pre-analyze the data at project load time to speed things up.
//
// One approach is to put runs into TypedRangeSet (setting the type to the byte
// value so a run of 0x00 doesn't merge into an adjacent run of 0x01), and the
// various character encodings into individual RangeSets. Then, for any given
// byte address, you can query the length of a potential run directly. This could
// be made faster with a mergesort-like algorithm that walked through the various
// range sets, rather than iterating over every byte in the range. However, the
// ranges passed into this method tend to be small, so the initial setup time for
// each region can dominate the performance. (The optimized implementation of this
// approach is also fairly complicated.)
//
// A memory-hungry alternative is to create arrays of integers, one entry per byte
// in the file, and set each entry to the number of bytes in the run that would
// follow at that point. So if a run of 20 zeroes began at off set 5, you would
// set run[5]=20, run[6]=19, and so on. That avoids searching in the sets, at the
// cost of potentially several megabytes for a large 65816 file.
//
// It's even possible that Regex would handle this faster and more easily. This
// can be done fairly quickly with "unsafe" code, e.g.:
// https://stackoverflow.com/questions/3028768/net-regular-expressions-on-bytes-instead-of-chars
// https://stackoverflow.com/questions/1660694/regular-expression-to-match-any-character-being-repeated-more-than-10-times
//
// Ultimately we're just not spending that much time here. Setting
// AnalyzeUncategorizedData=false reveals that most of the time is spent in
// the caller, identifying the regions, so a significant improvement here won't
// have much impact on the user experience.
//
// Vague idea: figure out how to re-use the results from the previous analysis
// pass. At a superficial level we can cache the result of calling here with a
// particular (start, end) pair. At a higher level we may be able to avoid
// the search for uncategorized data, certainly at the bank level, possibly within
// a bank.
mDebugLog.LogI("Analyzing [+" + start.ToString("x6") + ",+" + end.ToString("x6") +"]");
FormatDescriptor oneByteDefault = FormatDescriptor.Create(1,
FormatDescriptor.Type.Default, FormatDescriptor.SubType.None);
FormatDescriptor.DebugPrefabBump(-1);
if (!mAnalysisParams.AnalyzeUncategorizedData) {
// Analysis is disabled, so just mark everything as single-byte data.
while (start <= end) {
mAnattribs[start].DataDescriptor = oneByteDefault;
FormatDescriptor.DebugPrefabBump();
start++;
}
return;
}
int minStringChars = mAnalysisParams.MinCharsForString;
#if false // this is actually slower (and uses more memory)
while (start <= end) {
// This is used to let us skip forward. It starts past the end of the block,
// and moves backward as we identify potential points of interest.
int minNextStart = end + 1;
bool found = mProject.RepeatedBytes.GetContainingOrSubsequentRange(start,
out TypedRangeSet.TypedRange tyRange);
if (found) {
if (tyRange.Low <= start) {
// found a matching range
Debug.Assert(tyRange.Low <= start && tyRange.High >= start);
int clampEnd = Math.Min(tyRange.High, end);
int repLen = clampEnd - start + 1;
if (repLen >= MIN_RUN_LENGTH) {
bool isAscii =
TextUtil.IsPrintableAscii((char)(mFileData[start] & 0x7f));
// IF the run isn't ASCII, OR it's so long that we don't want to
// encode it as a string, OR it's so short that we don't want to
// treat it as a string, THEN output it as a run. Otherwise, just
// let the ASCII-catcher handle it later.
if (!isAscii ||
repLen > MIN_RUN_LENGTH_ASCII || repLen < minStringChars) {
LogV(start, "Run of 0x" + mFileData[start].ToString("x2") + ": " +
repLen + " bytes");
mAnattribs[start].DataDescriptor = FormatDescriptor.Create(
repLen, FormatDescriptor.Type.Fill,
FormatDescriptor.SubType.None);
start += repLen;
continue;
}
}
// We didn't like this range. We probably won't like it for any other
// point within the range, so start again past it. Ideally we'd use
// Range.Low of the range that followed the one that was returned, but
// we don't have that handy.
minNextStart = Math.Min(minNextStart, tyRange.High + 1);
} else {
// no match; try to advance to the start of the next range.
Debug.Assert(tyRange.Low > start);
minNextStart = Math.Min(minNextStart, tyRange.Low);
}
}
found = mProject.StdAsciiBytes.GetContainingOrSubsequentRange(start,
out RangeSet.Range range);
if (found) {
if (range.Low <= start) {
// found a matching range
Debug.Assert(range.Low <= start && range.High >= start);
int clampEnd = Math.Min(range.High, end);
int repLen = clampEnd - start + 1;
if (repLen >= minStringChars) {
LogV(start, "Std ASCII string, len=" + repLen + " bytes");
mAnattribs[start].DataDescriptor = FormatDescriptor.Create(repLen,
FormatDescriptor.Type.String, FormatDescriptor.SubType.None);
start += repLen;
continue;
}
minNextStart = Math.Min(minNextStart, range.High + 1);
} else {
Debug.Assert(range.Low > start);
minNextStart = Math.Min(minNextStart, range.Low);
}
}
found = mProject.HighAsciiBytes.GetContainingOrSubsequentRange(start,
out range);
if (found) {
if (range.Low <= start) {
// found a matching range
Debug.Assert(range.Low <= start && range.High >= start);
int clampEnd = Math.Min(range.High, end);
int repLen = clampEnd - start + 1;
if (repLen >= minStringChars) {
LogV(start, "High ASCII string, len=" + repLen + " bytes");
mAnattribs[start].DataDescriptor = FormatDescriptor.Create(repLen,
FormatDescriptor.Type.String, FormatDescriptor.SubType.None);
start += repLen;
continue;
}
minNextStart = Math.Min(minNextStart, range.High + 1);
} else {
Debug.Assert(range.Low > start);
minNextStart = Math.Min(minNextStart, range.Low);
}
}
// Advance to the next possible run location.
int nextStart = minNextStart > 0 ? minNextStart : start + 1;
Debug.Assert(nextStart > start);
// No runs found, output as single bytes. This is the easiest form for users
// to edit.
while (start < nextStart) {
mAnattribs[start].DataDescriptor = oneByteDefault;
FormatDescriptor.DebugPrefabBump();
start++;
}
}
#else
while (start <= end) {
// Check for block of repeated values.
int runLen = RecognizeRun(mFileData, start, end);
bool isAscii = TextUtil.IsPrintableAscii((char)(mFileData[start] & 0x7f));
if (runLen >= MIN_RUN_LENGTH) {
// Output as run or ASCII string. Prefer ASCII if the string is short
// enough to fit on one line (e.g. 64 chars including delimiters) and
// meets the minimum string length threshold.
if (isAscii && runLen <= MIN_RUN_LENGTH_ASCII && runLen >= minStringChars) {
// String -- if we create the descriptor here, we save a little time,
// but strings like "*****hello" turn into two separate strings. So
// just fall through and let the ASCII recognizer handle it.
} else {
// run
LogV(start, "Run of 0x" + mFileData[start].ToString("x2") + ": " +
runLen + " bytes");
mAnattribs[start].DataDescriptor = FormatDescriptor.Create(
runLen, FormatDescriptor.Type.Fill,
FormatDescriptor.SubType.None);
start += runLen;
continue;
}
}
int asciiLen = RecognizeAscii(mFileData, start, end);
if (asciiLen >= minStringChars) {
LogV(start, "ASCII string, len=" + asciiLen + " bytes");
mAnattribs[start].DataDescriptor = FormatDescriptor.Create(asciiLen,
FormatDescriptor.Type.String, FormatDescriptor.SubType.None);
start += asciiLen;
continue;
}
// Nothing found, output as single byte. This is the easiest form for users
// to edit. If we found a run, but it was too short, we can go ahead and
// mark all bytes in the run because we know the later matches will also be
// too short.
Debug.Assert(runLen > 0);
while (runLen-- != 0) {
mAnattribs[start++].DataDescriptor = oneByteDefault;
FormatDescriptor.DebugPrefabBump();
}
}
#endif
}
#region Static analyzer methods
/// <summary>
/// Checks for a repeated run of the same byte.
/// </summary>
/// <param name="fileData">Raw data.</param>
/// <param name="start">Offset of first byte in range.</param>
/// <param name="end">Offset of last byte in range.</param>
/// <returns>Length of run.</returns>
public static int RecognizeRun(byte[] fileData, int start, int end) {
byte first = fileData[start];
int index = start;
while (++index <= end) {
if (fileData[index] != first) {
break;
}
}
return index - start;
}
/// <summary>
/// Checks for a run of ASCII values. Both high and low ASCII are recognized,
/// but the entire run must be one or the other.
/// </summary>
/// <param name="fileData">Raw data.</param>
/// <param name="start">Offset of first byte in range.</param>
/// <param name="end">Offset of last byte in range.</param>
/// <returns>Length of run.</returns>
public static int RecognizeAscii(byte[] fileData, int start, int end) {
// This won't find a mix of Apple II high/inverse/flashing text.
byte firstHi = (byte)(fileData[start] & 0x80);
int index;
for (index = start; index <= end; index++) {
char ch = (char)fileData[index];
if (!TextUtil.IsPrintableAscii((char)(ch & 0x7f)) || (ch & 0x80) != firstHi) {
break;
}
}
return index - start;
}
/// <summary>
/// Counts the number of low-ASCII, high-ASCII, and non-ASCII values in the
/// specified region.
/// </summary>
/// <param name="fileData">Raw data.</param>
/// <param name="start">Offset of first byte in range.</param>
/// <param name="end">Offset of last byte in range</param>
/// <param name="lowAscii">Set to the number of low-ASCII bytes found.</param>
/// <param name="highAscii">Set to the number of high-ASCII bytes found.</param>
/// <param name="nonAscii">Set to the number of non-ASCII bytes found.</param>
public static void CountAsciiBytes(byte[] fileData, int start, int end,
out int lowAscii, out int highAscii, out int nonAscii) {
lowAscii = highAscii = nonAscii = 0;
for (int i = start; i <= end; i++) {
byte val = fileData[i];
if (val < 0x20) {
nonAscii++;
} else if (val < 0x7f) {
lowAscii++;
} else if (val < 0xa0) {
nonAscii++;
} else if (val < 0xff) {
highAscii++;
} else {
nonAscii++;
}
}
}
/// <summary>
/// Counts the number of null-terminated strings in the buffer.
///
/// Zero-length strings are allowed but not included in the count.
///
/// Each string must be either high-ASCII or low-ASCII, not a mix.
///
/// If any bad data is found, the scan aborts and returns -1.
/// </summary>
/// <param name="fileData">Raw data.</param>
/// <param name="start">Offset of first byte in range.</param>
/// <param name="end">Offset of last byte in range.</param>
/// <returns>Number of strings found, or -1 if bad data identified.</returns>
public static int RecognizeNullTerminatedStrings(byte[] fileData, int start, int end) {
// Quick test.
if (fileData[end] != 0x00) {
return -1;
}
int stringCount = 0;
int expectedHiBit = -1;
int stringLen = 0;
for (int i = start; i <= end; i++) {
byte val = fileData[i];
if (val == 0x00) {
// End of string. Only update count if string wasn't empty.
if (stringLen != 0) {
stringCount++;
}
stringLen = 0;
expectedHiBit = -1;
} else {
if (expectedHiBit == -1) {
// First byte in string, set hi/lo expectation.
expectedHiBit = val & 0x80;
} else if ((val & 0x80) != expectedHiBit) {
// Mixed ASCII or non-ASCII, fail.
return -1;
}
val &= 0x7f;
if (val < 0x20 || val == 0x7f) {
// Non-ASCII, fail.
return -1;
}
stringLen++;
}
}
return stringCount;
}
/// <summary>
/// Counts strings prefixed with an 8-bit length.
///
/// Each string must be either high-ASCII or low-ASCII, not a mix.
///
/// Zero-length strings are allowed but not counted.
/// </summary>
/// <param name="fileData">Raw data.</param>
/// <param name="start">Offset of first byte in range.</param>
/// <param name="end">Offset of last byte in range.</param>
/// <returns>Number of strings found, or -1 if bad data identified.</returns>
public static int RecognizeLen8Strings(byte[] fileData, int start, int end) {
int posn = start;
int remaining = end - start + 1;
int stringCount = 0;
while (remaining > 0) {
int strLen = fileData[posn++];
if (strLen > --remaining) {
// Buffer doesn't hold entire string, fail.
return -1;
}
if (strLen == 0) {
continue;
}
stringCount++;
remaining -= strLen;
int expectedHiBit = fileData[posn] & 0x80;
while (strLen-- != 0) {
byte val = fileData[posn++];
if ((val & 0x80) != expectedHiBit) {
// Mixed ASCII, fail.
return -1;
}
val &= 0x7f;
if (val < 0x20 || val == 0x7f) {
// Non-ASCII, fail.
return -1;
}
}
}
return stringCount;
}
/// <summary>
/// Counts strings prefixed with a 16-bit length.
///
/// Each string must be either high-ASCII or low-ASCII, not a mix.
///
/// Zero-length strings are allowed but not counted.
/// </summary>
/// <param name="fileData">Raw data.</param>
/// <param name="start">Offset of first byte in range.</param>
/// <param name="end">Offset of last byte in range.</param>
/// <returns>Number of strings found, or -1 if bad data identified.</returns>
public static int RecognizeLen16Strings(byte[] fileData, int start, int end) {
int posn = start;
int remaining = end - start + 1;
int stringCount = 0;
while (remaining > 0) {
if (remaining < 2) {
// Not enough bytes for length, fail.
return -1;
}
int strLen = fileData[posn++];
strLen |= fileData[posn++] << 8;
remaining -= 2;
if (strLen > remaining) {
// Buffer doesn't hold entire string, fail.
return -1;
}
if (strLen == 0) {
continue;
}
stringCount++;
remaining -= strLen;
int expectedHiBit = fileData[posn] & 0x80;
while (strLen-- != 0) {
byte val = fileData[posn++];
if ((val & 0x80) != expectedHiBit) {
// Mixed ASCII, fail.
return -1;
}
val &= 0x7f;
if (val < 0x20 || val == 0x7f) {
// Non-ASCII, fail.
return -1;
}
}
}
return stringCount;
}
/// <summary>
/// Counts strings in Dextral Character Inverted format, meaning the high bit on the
/// last byte is the opposite of the preceding.
///
/// Each string must be at least two bytes. To reduce false-positives, we require
/// that all strings have the same hi/lo pattern.
/// </summary>
/// <param name="fileData">Raw data.</param>
/// <param name="start">Offset of first byte in range.</param>
/// <param name="end">Offset of last byte in range.</param>
/// <returns>Number of strings found, or -1 if bad data identified.</returns>
public static int RecognizeDciStrings(byte[] fileData, int start, int end) {
int expectedHiBit = fileData[start] & 0x80;
int stringCount = 0;
int stringLen = 0;
// Quick test on last byte.
if ((fileData[end] & 0x80) == expectedHiBit) {
return -1;
}
for (int i = start; i <= end; i++) {
byte val = fileData[i];
if ((val & 0x80) != expectedHiBit) {
// end of string
if (stringLen == 0) {
// Got two consecutive bytes with end-marker polarity... fail.
return -1;
}
stringCount++;
stringLen = 0;
} else {
stringLen++;
}
val &= 0x7f;
if (val < 0x20 || val == 0x7f) {
// Non-ASCII, fail.
return -1;
}
}
return stringCount;
}
/// <summary>
/// Counts strings in reverse Dextral Character Inverted format, meaning the string is
/// stored in reverse order in memory, and the high bit on the first (last) byte is
/// the opposite of the rest.
///
/// Each string must be at least two bytes. To reduce false-positives, we require
/// that all strings have the same hi/lo pattern.
/// </summary>
/// <param name="fileData">Raw data.</param>
/// <param name="start">Offset of first byte in range.</param>
/// <param name="end">Offset of last byte in range.</param>
/// <returns>Number of strings found, or -1 if bad data identified.</returns>
public static int RecognizeReverseDciStrings(byte[] fileData, int start, int end) {
int expectedHiBit = fileData[end] & 0x80;
int stringCount = 0;
int stringLen = 0;
// Quick test on last (first) byte.
if ((fileData[start] & 0x80) == expectedHiBit) {
return -1;
}
for (int i = end; i >= start; i--) {
byte val = fileData[i];
if ((val & 0x80) != expectedHiBit) {
// end of string
if (stringLen == 0) {
// Got two consecutive bytes with end-marker polarity... fail.
return -1;
}
stringCount++;
stringLen = 0;
} else {
stringLen++;
}
val &= 0x7f;
if (val < 0x20 || val == 0x7f) {
// Non-ASCII, fail.
return -1;
}
}
return stringCount;
}
#endregion // Static analyzers
}
}
#if false
/// <summary>
/// Iterator that generates a list of offsets which are not known to hold code or data.
///
/// Generates a set of integers in ascending order.
/// </summary>
private class UndeterminedValueIterator : IEnumerator {
/// <summary>
/// Index of current item, or -1 if we're not started yet.
/// </summary>
private int mCurIndex;
/// <summary>
/// Reference to Anattrib array we're iterating over.
/// </summary>
private Anattrib[] mAnattribs;
/// <summary>
/// Constructor.
/// </summary>
public UndeterminedValueIterator(Anattrib[] anattribs) {
mAnattribs = anattribs;
Reset();
}
// IEnumerator: current element
public object Current {
get {
if (mCurIndex < 0) {
// not started
return null;
}
return mCurIndex;
}
}
// IEnumerator: move to the next element, returning false if there isn't one
public bool MoveNext() {
while (++mCurIndex < mAnattribs.Length) {
Anattrib attr = mAnattribs[mCurIndex];
if (attr.IsInstructionStart) {
// skip past instruction
mCurIndex += attr.Length - 1;
} else if (attr.IsUncategorized) {
// got one
return true;
}
}
return false;
}
// IEnumerator: reset state
public void Reset() {
mCurIndex = -1;
}
}
#endif
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