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6502bench/SourceGen/RuntimeData/Atari/VisDVG.cs
Andy McFadden e622afd929 Tweak DVG visualizer
Adopted the naming conventions from the "Hitch-Hacker's Guide" doc.
Updated some comments.  No change in behavior.
2021-11-03 08:58:17 -07:00

358 lines
15 KiB
C#

/*
* Copyright 2021 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.ObjectModel;
using PluginCommon;
namespace RuntimeData.Atari {
/// <summary>
/// Visualizer for Atari Digital Vector Generator commands (Asteroids, etc).
///
/// Currently ignores beam brightness, except as on/off.
///
/// References:
/// https://wiki.philpem.me.uk/_media/elec/vecgen/vecgen.pdf
///
/// https://github.com/mamedev/mame/blob/master/src/mame/video/avgdvg.cpp is the
/// definitive description, but it's harder to parse than the above (it's emulating
/// the hardware at a lower level).
/// </summary>
public class VisDVG : MarshalByRefObject, IPlugin, IPlugin_Visualizer_v2 {
private readonly bool VERBOSE = false;
// IPlugin
public string Identifier {
get { return "Atari DVG Visualizer"; }
}
private IApplication mAppRef;
private byte[] mFileData;
private AddressTranslate mAddrTrans;
// Visualization identifiers; DO NOT change or projects that use them will break.
private const string VIS_GEN_DVG = "atari-dvg";
private const string P_OFFSET = "offset";
private const string P_BASE_ADDR = "baseAddr";
private const string P_IGNORE_LABS = "ignoreLabs";
// Visualization descriptors.
private VisDescr[] mDescriptors = new VisDescr[] {
new VisDescr(VIS_GEN_DVG, "Atari DVG Commands", VisDescr.VisType.Wireframe,
new VisParamDescr[] {
new VisParamDescr("File offset (hex)",
P_OFFSET, typeof(int), 0, 0x00ffffff, VisParamDescr.SpecialMode.Offset, 0),
new VisParamDescr("Base address",
P_BASE_ADDR, typeof(int), 0x0000, 0xffff, 0, 0x4000),
new VisParamDescr("Ignore LABS move",
P_IGNORE_LABS, typeof(bool), false, true, 0, false),
VisWireframe.Param_IsRecentered("Centered", true),
}),
};
// IPlugin
public void Prepare(IApplication appRef, byte[] fileData, AddressTranslate addrTrans) {
mAppRef = appRef;
mFileData = fileData;
mAddrTrans = addrTrans;
}
// IPlugin
public void Unprepare() {
mAppRef = null;
mFileData = null;
mAddrTrans = null;
}
// IPlugin_Visualizer
public VisDescr[] GetVisGenDescrs() {
if (mFileData == null) {
return null;
}
return mDescriptors;
}
// IPlugin_Visualizer
public IVisualization2d Generate2d(VisDescr descr,
ReadOnlyDictionary<string, object> parms) {
mAppRef.ReportError("2d not supported");
return null;
}
// IPlugin_Visualizer_v2
public IVisualizationWireframe GenerateWireframe(VisDescr descr,
ReadOnlyDictionary<string, object> parms) {
switch (descr.Ident) {
case VIS_GEN_DVG:
return GenerateWireframe(parms);
default:
mAppRef.ReportError("Unknown ident " + descr.Ident);
return null;
}
}
private enum Opcode {
Unknown = 0, VCTR, LABS, HALT, JSRL, RTSL, JMPL, SVEC
}
private IVisualizationWireframe GenerateWireframe(ReadOnlyDictionary<string, object> parms) {
int offset = Util.GetFromObjDict(parms, P_OFFSET, 0);
int baseAddr = Util.GetFromObjDict(parms, P_BASE_ADDR, 0);
bool ignoreLabs = Util.GetFromObjDict(parms, P_IGNORE_LABS, false);
if (offset < 0 || offset >= mFileData.Length) {
// should be caught by editor
mAppRef.ReportError("Invalid parameter");
return null;
}
VisWireframe vw = new VisWireframe();
vw.Is2d = true;
try {
int[] stack = new int[4];
int stackPtr = 0;
double beamX = 0;
double beamY = 0;
int scaleFactor = 0; // tiny
bool done = false;
int centerVertex = vw.AddVertex(0, 0, 0);
int curVertex = centerVertex;
while (!done && offset < mFileData.Length) {
ushort code0 = (ushort)Util.GetWord(mFileData, offset, 2, false);
offset += 2;
Opcode opc = GetOpcode(code0);
switch (opc) {
case Opcode.VCTR: { // SSSS -mYY YYYY YYYY | BBBB -mXX XXXX XXXX
ushort code1 = (ushort)Util.GetWord(mFileData, offset, 2, false);
offset += 2;
int yval = sign11(code0 & 0x07ff);
int xval = sign11(code1 & 0x07ff);
int localsc = code0 >> 12; // local scale
int bb = code1 >> 12; // brightness
double scale = CalcScaleMult(scaleFactor + localsc);
double dx = xval * scale;
double dy = yval * scale;
beamX += dx;
beamY += dy;
if (bb == 0) {
// move only
curVertex = vw.AddVertex((float)beamX, (float)beamY, 0);
} else if (xval == 0 && yval == 0) {
// plot point
vw.AddPoint(curVertex);
//mAppRef.DebugLog("PLOT v" + curVertex + ": "
// + beamX + "," + beamY);
} else {
// draw line from previous vertex
int newVertex = vw.AddVertex((float)beamX, (float)beamY, 0);
vw.AddEdge(curVertex, newVertex);
curVertex = newVertex;
}
if (VERBOSE) {
mAppRef.DebugLog("VCTR scale=" + localsc + " x=" + dx +
" y=" + dy + " b=" + bb + " --> dx=" + dx +
" dy=" + dy);
}
}
break;
case Opcode.LABS: { // 1010 00yy yyyy yyyy | SSSS 00xx xxxx xxxx
ushort code1 = (ushort)Util.GetWord(mFileData, offset, 2, false);
offset += 2;
int yc = code0 & 0x07ff;
int xc = code1 & 0x07ff;
int scale = code1 >> 12;
if (!ignoreLabs) {
// Some things do a big screen movement before they start
// drawing, which throws off the auto-scaling. The output
// looks better if we ignore the initial movement.
beamX = xc;
beamY = yc;
}
// Sign-extend the scale factor. (It's usually 0 or 1 in ROM.)
byte left = (byte)(scale << 4);
scaleFactor = (sbyte)left >> 4;
if (VERBOSE) {
mAppRef.DebugLog("LABS scale=" + scale + " x=" + xc +
" y=" + yc);
}
}
break;
case Opcode.HALT: // 1011 0000 0000 0000
if (stackPtr != 0) {
mAppRef.DebugLog("NOTE: encountered HALT with nonzero stack");
}
done = true;
break;
case Opcode.JSRL: { // 1100 aaaa aaaa aaaa
int vaddr = code0 & 0x0fff;
if (stackPtr == stack.Length) {
mAppRef.ReportError("Stack overflow at +" +
offset.ToString("x6"));
return null;
}
stack[stackPtr++] = offset;
if (!Branch(vaddr, baseAddr, ref offset)) {
return null;
}
}
break;
case Opcode.JMPL: { // 1110 aaaa aaaa aaaa
int vaddr = code0 & 0x0fff;
if (!Branch(vaddr, baseAddr, ref offset)) {
return null;
}
}
break;
case Opcode.RTSL: // 1101 0000 0000 0000
if (stackPtr == 0) {
done = true;
} else {
offset = stack[--stackPtr];
}
break;
case Opcode.SVEC: { // 1111 smYY BBBB SmXX
int yval = sign3((code0 >> 8) & 0x07);
int xval = sign3(code0 & 0x07);
int localsc = ((code0 >> 11) & 0x01) | ((code0 >> 2) & 0x02);
// SVEC scale is VEC scale + 2
double scale = CalcScaleMult(scaleFactor + localsc + 2);
int bb = (code0 >> 4) & 0x0f;
// The dx/dy values need to be x256 to make them work right.
// This is not mentioned in any document I've found, but it's
// required if e.g. you want the hexagon to match up with the 'C'
// in the Asteroids copyright message.
double dx = (xval << 8) * scale;
double dy = (yval << 8) * scale;
beamX += dx;
beamY += dy;
if (bb == 0) {
// move only
curVertex = vw.AddVertex((float)beamX, (float)beamY, 0);
} else if (xval == 0 && yval == 0) {
// plot point
vw.AddPoint(curVertex);
//mAppRef.DebugLog("SPLOT v" + curVertex + ": "
// + beamX + "," + beamY);
} else {
// draw line from previous vertex
int newVertex = vw.AddVertex((float)beamX, (float)beamY, 0);
vw.AddEdge(curVertex, newVertex);
curVertex = newVertex;
}
if (VERBOSE) {
mAppRef.DebugLog("SVEC scale=" + localsc + " x=" + dx +
" y=" + dy + " b=" + bb + " --> dx=" + dx +
" dy=" + dy);
}
}
break;
default:
mAppRef.ReportError("Unhandled code $" + code0.ToString("x4"));
return null;
}
}
} catch (IndexOutOfRangeException) {
// assume it was our file data access that caused the failure
mAppRef.ReportError("Ran off end of file");
return null;
}
string msg;
if (!vw.Validate(out msg)) {
mAppRef.ReportError("Data error: " + msg);
return null;
}
return vw;
}
private static Opcode GetOpcode(ushort code) {
switch (code & 0xf000) {
case 0xa000: return Opcode.LABS;
case 0xb000: return Opcode.HALT;
case 0xc000: return Opcode.JSRL;
case 0xd000: return Opcode.RTSL;
case 0xe000: return Opcode.JMPL;
case 0xf000: return Opcode.SVEC;
default: return Opcode.VCTR; // 0x0nnn - 0x9nnn
}
}
// Convert scale factor (0-9) to a multiplier.
private static double CalcScaleMult(int scaleFactor) {
// 0 is N/512, 9 is N/1.
if (scaleFactor < 0) {
scaleFactor = 0;
} else if (scaleFactor > 9) {
scaleFactor = 9;
}
return 1.0 / (1 << (9 - scaleFactor));
}
// Set the sign for a 2-bit value with a sign flag in the 3rd bit.
private static int sign3(int val) {
if ((val & 0x0004) == 0) {
return val;
} else {
return -(val & 0x03);
}
}
// Set the sign for a 10-bit value with a sign flag in the 11th bit.
private static int sign11(int val) {
if ((val & 0x0400) == 0) {
return val;
} else {
return -(val & 0x03ff);
}
}
/// <summary>
/// Converts a JSRL/JMPL operand to a file offset.
/// </summary>
/// <param name="vaddr">DVG address operand.</param>
/// <param name="baseAddr">Base address of vector memory.</param>
/// <param name="offset">File offset of instruction.</param>
/// <returns>False if the target address is outside the file bounds.</returns>
private bool Branch(int vaddr, int baseAddr, ref int offset) {
int fileAddr = baseAddr + vaddr * 2;
int fileOffset = mAddrTrans.AddressToOffset(offset, fileAddr);
if (fileOffset < 0) {
mAppRef.ReportError("JMPL/JSRL to " + vaddr.ToString("x4") + " invalid");
return false;
}
offset = fileOffset;
return true;
}
}
}