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unitcsw.pas
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unitcsw.pas
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unit UnitCSW;
// Copyright 2022-2024 Zoran Vučenović
// SPDX-License-Identifier: Apache-2.0
{$mode ObjFPC}{$H+}
{$i zxinc.inc}
// CSW (compressed square wave) format
// The CSW specification:
// [archived on 2022-02-20, as the original link is not available now (2024-03-24)]
// https://web.archive.org/web/20220220082010/http://ramsoft.bbk.org.omegahg.com/csw.html
interface
uses
Classes, SysUtils, UnitTapePlayer, UnitSpectrum, UnitStreamCompression;
type
TCswBlock = class (TTapeBlock)
public
type
TCswCompressionType = (cctRle, cctZRle);
TCswPlayState = (cpsStart, cpsPlaying, cpsFinished);
strict private
FState: TCswPlayState;
MS: TMemoryStream;
P: PByte;
PEnd: PByte;
FSampleRate: Int64;
FHalfSampleRate: Int64;
FTotalNumOfPulses: Integer;
FCountedNumOfPulses: Integer;
FCompressionType: TCswCompressionType;
FCswDataLength: Integer;
TicksNeeded: Int64;
FProcTicksPerSec: Int64;
procedure SetSampleRate(AValue: Int64);
function LoadCswData(const Stream: TStream; const L: Integer): Boolean;
public
constructor Create(ATapePlayer: TTapePlayer); override;
destructor Destroy; override;
function GetBlockLength: Integer; override;
class function GetBlockDescription: String; override;
function LoadBlock(const Stream: TStream): Boolean; override;
class function GetBlockId: DWord; override;
class function GetBlockIdAsString: String; override;
procedure Start; override;
function GetNextPulse: Boolean; override;
procedure Details(out S: String); override;
property State: TCswPlayState read FState;
property SampleRate: Int64 read FSampleRate write SetSampleRate;
property TotalNumOfPulses: Integer read FTotalNumOfPulses write FTotalNumOfPulses;
property CompressionType: TCswCompressionType read FCompressionType write FCompressionType;
property CswDataLength: Integer read FCswDataLength write FCswDataLength;
property CountedNumOfPulses: Integer read FCountedNumOfPulses;
end;
implementation
type
TCswBlock1 = class(TCswBlock)
strict private
FLen: Integer;
FEncodingApplicationDescription: AnsiString;
FCswMajorRevisionNumber: Byte;
FCswMinorRevisionNumber: Byte;
public
constructor Create(ATapePlayer: TTapePlayer); override;
function LoadBlock(const Stream: TStream): Boolean; override;
function GetBlockLength: Integer; override;
procedure Details(out S: String); override;
end;
TCswPlayer = class(TTapePlayer)
protected
procedure CheckNextBlock(); override;
class function CheckHeader(const Stream: TStream): Boolean; override;
class function GetNextBlockClass(const {%H-}Stream: TStream): TTapeBlockClass;
override;
class function GetTapeType: TTapeType; override;
class function CheckIsMyClass(const Stream: TStream): Boolean; override;
private
class procedure Init;
end;
{ TCswBlock1 }
constructor TCswBlock1.Create(ATapePlayer: TTapePlayer);
begin
inherited Create(ATapePlayer);
FLen := 0;
end;
function TCswBlock1.LoadBlock(const Stream: TStream): Boolean;
type
TCswBlockHeader1 = packed record
SampleRate: Word;
CompressionType: Byte; // 1: RLE
Flags: Byte; // bit 0 -- initial polarity, 1 - high, 0 - low
Reserved: packed array[0..2] of Byte;
end;
TCswBlockHeader2 = packed record
SampleRate: DWord;
TotalNumOfPulses: DWord; // total number of pulses (after decompression)
CompressionType: Byte; // 1: RLE, 2: Z-RLE
Flags: Byte; // bit 0 -- initial polarity, 1 - high, 0 - low
HDR: Byte; // Header extension length in bytes - for future expansions only, must be zero in version 2
EncodingApplicationDescription: array [0..15] of AnsiChar;
end;
var
Header1: TCswBlockHeader1;
Header2: TCswBlockHeader2;
VMajor, VMinor: Byte;
L: Integer;
N: Integer;
Okay: Boolean;
begin
Result := False;
L := Stream.Size - Stream.Position;
if L >= 2 then begin
if (Stream.Read(VMajor{%H-}, 1) = 1) and (Stream.Read(VMinor{%H-}, 1) = 1) then begin
FEncodingApplicationDescription := '';
case VMajor of
1:
begin
Okay := (Stream.Size - Stream.Position >= SizeOf(Header1))
and (Stream.Read(Header1{%H-}, SizeOf(Header1)) = SizeOf(Header1));
if Okay then begin
Header1.SampleRate := LEtoN(Header1.SampleRate);
SampleRate := Header1.SampleRate;
TotalNumOfPulses := 0;
CompressionType := cctRle;
end;
end;
otherwise
Okay := (Stream.Size - Stream.Position >= SizeOf(Header2))
and (Stream.Read(Header2{%H-}, SizeOf(Header2)) = SizeOf(Header2))
and ((Header2.HDR = 0) or (Stream.Size - Stream.Position >= Header2.HDR));
if Okay then begin
if Header2.HDR > 0 then begin
Stream.Seek(Int64(Header2.HDR), TSeekOrigin.soCurrent);
end;
Header2.SampleRate := LEtoN(Header2.SampleRate);
Header2.TotalNumOfPulses := LEtoN(Header2.TotalNumOfPulses);
SampleRate := Header2.SampleRate;
TotalNumOfPulses := Header2.TotalNumOfPulses;
if Header2.CompressionType = 2 then
CompressionType := cctZRle
else
CompressionType := cctRle;
N := 0;
while (N <= 15) and (Header2.EncodingApplicationDescription[N] <> #0) do begin
Inc(N);
end;
if N > 0 then begin
SetLength(FEncodingApplicationDescription, N);
Move(Header2.EncodingApplicationDescription[0], FEncodingApplicationDescription[1], N);
FEncodingApplicationDescription := Trim(FEncodingApplicationDescription);
end;
end;
end;
if Okay then begin
FCswMajorRevisionNumber := VMajor;
FCswMinorRevisionNumber := VMinor;
CswDataLength := Stream.Size - Stream.Position;
if inherited LoadBlock(Stream) then begin
if FCswMajorRevisionNumber = 1 then
TotalNumOfPulses := CountedNumOfPulses;
FLen := L;
Result := True;
end;
end;
end;
end;
end;
function TCswBlock1.GetBlockLength: Integer;
begin
Result := FLen;
end;
procedure TCswBlock1.Details(out S: String);
begin
inherited Details(S);
S := Format('CSW ver. %d.%d', [FCswMajorRevisionNumber, FCswMinorRevisionNumber])
+ #13 + S;
if FEncodingApplicationDescription <> '' then
S := S + #13 + 'Encoding application description: ' + FEncodingApplicationDescription;
end;
{ TCswBlock }
constructor TCswBlock.Create(ATapePlayer: TTapePlayer);
begin
inherited Create(ATapePlayer);
FCountedNumOfPulses := 0;
MS := nil;
P := nil;
PEnd := nil;
FState := cpsFinished;
SampleRate := 0;
FTotalNumOfPulses := 0;
FCompressionType := cctRle;
end;
destructor TCswBlock.Destroy;
begin
MS.Free;
inherited Destroy;
end;
function TCswBlock.LoadCswData(const Stream: TStream; const L: Integer
): Boolean;
var
S1, S2: TMemoryStream;
begin
FreeAndNil(MS);
if (FSampleRate > 0) and (L > 0) and (Stream.Size - Stream.Position >= L) then begin
S2 := TMemoryStream.Create;
try
S2.Size := L;
if Stream.Read(S2.Memory^, L) = L then begin
if FCompressionType = TCswCompressionType.cctZRle then begin
S1 := TMemoryStream.Create;
try
if DecompressStream(S2, S1) then begin
MS := S1;
S1 := nil;
Result := True;
end;
finally
S1.Free;
end;
end else begin
MS := S2;
S2 := nil;
Result := True;
end;
if Result then begin
if MS.Size > 0 then
MS.Position := 0
else begin
Result := False;
FreeAndNil(MS);
end;
end;
end;
finally
S2.Free;
end;
end;
end;
procedure TCswBlock.SetSampleRate(AValue: Int64);
begin
FSampleRate := AValue;
FHalfSampleRate := AValue div 2;
end;
function TCswBlock.GetBlockLength: Integer;
begin
Result := 0;
end;
class function TCswBlock.GetBlockDescription: String;
begin
Result := 'CSW';
end;
function TCswBlock.LoadBlock(const Stream: TStream): Boolean;
function CountPulses(): Boolean;
var
N: Integer;
P0: PByte;
P1: PByte;
Pdw0: PDWord absolute P0;
begin
Result := False;
FCountedNumOfPulses := 0;
if Assigned(MS) and (MS.Size > 0) then begin
P0 := PByte(MS.Memory);
PEnd := P0 + MS.Size;
N := 0;
repeat
if P0 >= PEnd then begin
if P0 = PEnd then begin
FCountedNumOfPulses := N;
Result := N > 0;
end;
Break;
end;
if P0^ > 0 then begin
Inc(N);
Inc(P0);
end else begin
Inc(P0);
P1 := P0 + 4;
if P1 <= PEnd then begin
Inc(N);
Pdw0^ := LEtoN(Pdw0^);
P0 := P1;
end else
PEnd := P0;
end;
until False;
end;
end;
begin
Result := LoadCswData(Stream, FCswDataLength)
and CountPulses();
end;
class function TCswBlock.GetBlockId: DWord;
begin
Result := 0;
end;
class function TCswBlock.GetBlockIdAsString: String;
begin
Result := '';
end;
procedure TCswBlock.Start;
begin
inherited Start;
if Assigned(MS) and (FSampleRate > 0) then begin
if FTapePlayer.GetSpectrum.Is128KModel then
FProcTicksPerSec := 3546900
else
FProcTicksPerSec := 3500000;
FState := TCswPlayState.cpsStart;
TicksNeeded := TicksNeeded.MinValue;
P := PByte(MS.Memory);
end else begin
FState := TCswPlayState.cpsFinished;
P := nil;
end;
end;
function TCswBlock.GetNextPulse: Boolean;
var
ProcTicks: Int64;
TicksNeeded0: Int64;
begin
if State = TCswPlayState.cpsFinished then
Exit(False);
ProcTicks := GetCurrentTotalSpectrumTicks;
if ProcTicks >= TicksNeeded then begin
if FState <> TCswPlayState.cpsStart then
FTapePlayer.ActiveBit := FTapePlayer.ActiveBit xor %01000000;
if P < PEnd then begin
TicksNeeded0 := P^;
Inc(P);
if TicksNeeded0 = 0 then begin
TicksNeeded0 := PDWord(P)^;
Inc(P, 4);
end;
TicksNeeded0 := (TicksNeeded0 * FProcTicksPerSec + FHalfSampleRate) div FSampleRate;
TicksNeeded := ProcTicks + TicksNeeded0;
FState := TCswPlayState.cpsPlaying;
end else begin
FState := TCswPlayState.cpsFinished;
end;
end;
Result := True;
end;
procedure TCswBlock.Details(out S: String);
begin
//inherited Details(S);
case CompressionType of
TCswCompressionType.cctRle:
S := 'RLE';
otherwise
S := 'Z-RLE';
end;
S := 'Sample rate: ' + SampleRate.ToString
+ #13 + 'Total number of pulses: ' + TotalNumOfPulses.ToString
+ #13 + 'Compression type: ' + S
;
end;
{ TCswPlayer }
procedure TCswPlayer.CheckNextBlock();
begin
StopPlaying;
end;
class function TCswPlayer.CheckHeader(const Stream: TStream): Boolean;
type
TCswSignature = packed array[0..22] of AnsiChar;
const
CCswSignature: RawByteString = 'Compressed Square Wave';
var
S: RawByteString;
CswSignature: TCswSignature; // "Compressed Square Wave" signature plus terminator code 0x1A
begin
Result := False;
if Stream.Size - Stream.Position >= SizeOf(CswSignature) then begin
if Stream.Read(CswSignature{%H-}, SizeOf(CswSignature)) = SizeOf(CswSignature) then begin
if CswSignature[22] = #$1A then begin
SetLength(S{%H-}, 22);
Move(CswSignature[0], S[1], 22);
Result := CompareText(S, CCswSignature) = 0;
end;
end;
end;
end;
class function TCswPlayer.GetNextBlockClass(const Stream: TStream
): TTapeBlockClass;
begin
Result := TCswBlock1;
end;
class function TCswPlayer.GetTapeType: TTapeType;
begin
Result := ttCsw;
end;
class function TCswPlayer.CheckIsMyClass(const Stream: TStream): Boolean;
var
P: Int64;
begin
P := Stream.Position;
Result := CheckHeader(Stream);
Result := (Stream.Seek(P - Stream.Position, TSeekOrigin.soCurrent) = P) and Result;
end;
class procedure TCswPlayer.Init;
begin
RegisterTapePlayerClass(Self);
end;
initialization
TCswPlayer.Init;
end.