Remove the need for a separate channel-mapping loop

The channel mapping is now handled inline by the mixer in
a generic and minimal way (without adding new logic or
loops).  This eliminates the need for a separate loop in
the CD handling code, as well as eliminating the same
volume and channel mapping loop in the Windows CDROM code.
There's also no longer a need for the image player class
to carry around a TCtrl object and the associated ctrlUsed
boolean.

include/mixer.h

@@ -46,9 +46,11 @@ extern Bit8u MixTemp[MIXER_BUFSIZE];
 
 class MixerChannel {
 public:
+	MixerChannel(MIXER_Handler _handler, Bitu _freq, const char * _name);
 	void SetVolume(float _left,float _right);
-	void SetScale( float f );
-	void SetScale( float _left, float _right_);
+	void SetScale(float f );
+	void SetScale(float _left, float _right);
+	void MapChannels(Bit8u _left, Bit8u _right);
 	void UpdateVolume(void);
 	void SetFreq(Bitu _freq);
 	void Mix(Bitu _needed);
@@ -78,24 +80,25 @@ class MixerChannel {
 
 	void FillUp(void);
 	void Enable(bool _yesno);
-	MIXER_Handler handler;
-	float volmain[2];
-	float scale[2];
-	Bit32s volmul[2];
-
-	//This gets added the frequency counter each mixer step
-	Bitu freq_add;
-	//When this flows over a new sample needs to be read from the device
-	Bitu freq_counter;
-	//Timing on how many samples have been done and were needed by th emixer
-	Bitu done, needed;
-	//Previous and next samples
-	Bits prevSample[2];
-	Bits nextSample[2];
-	const char * name;
-	bool interpolate;
-	bool enabled;
-	MixerChannel * next;
+
+	float          volmain[2];
+	MixerChannel*  next;
+	const char*    name;
+	Bitu           done;           //Timing on how many samples have been done by the mixer
+	bool           enabled;
+
+private:
+	MixerChannel();
+	MIXER_Handler  handler;
+	Bitu           freq_add;       //This gets added the frequency counter each mixer step
+	Bitu           freq_counter;   //When this flows over a new sample needs to be read from the device
+	Bitu           needed; 	       //Timing on how many samples were needed by the mixer
+	Bits           prev_sample[2]; //Previous and next samples
+	Bits           next_sample[2];
+	Bit32s         volmul[2];
+	float          scale[2];
+	Bit8u          channel_map[2]; //Output channel mapping
+	bool           interpolate;
 };
 
 MixerChannel * MIXER_AddChannel(MIXER_Handler handler,Bitu freq,const char * name);

src/dos/cdrom.h

@@ -51,8 +51,8 @@ typedef struct SMSF {
 } TMSF;
 
 typedef struct SCtrl {
-	Bit8u	out[4];			// output channel
-	Bit8u	vol[4];			// channel volume
+	Bit8u	out[4];			// output channel mapping
+	Bit8u	vol[4];			// channel volume (0 to 255)
 } TCtrl;
 
 // Conversion function from frames to Minutes/Second/Frames
@@ -238,7 +238,6 @@ static	void	CDAudioCallBack(Bitu desired_frames);
 
 static  struct imagePlayer {
 		Bit16s                buffer[MIXER_BUFSIZE * 2]; // 2 channels (max)
-		TCtrl                 ctrlData;
 		TrackFile             *trackFile;
 		MixerChannel          *channel;
 		CDROM_Interface_Image *cd;
@@ -249,7 +248,6 @@ static  struct imagePlayer {
 		Bit32u                totalTrackFrames;
 		bool                  isPlaying;
 		bool                  isPaused;
-		bool                  ctrlUsed;
 	} player;
 
 	void  ClearTracks();

src/dos/cdrom_image.cpp

@@ -27,21 +27,21 @@
 #include <fstream>
 #include <iostream>
 #include <limits>
-#include <limits.h> //GCC 2.95
 #include <sstream>
 #include <vector>
 #include <sys/stat.h>
-#include "cdrom.h"
-#include "drives.h"
-#include "support.h"
-#include "setup.h"
 
 #if !defined(WIN32)
 #include <libgen.h>
 #else
 #include <string.h>
 #endif
 
+#include "cdrom.h"
+#include "drives.h"
+#include "support.h"
+#include "setup.h"
+
 using namespace std;
 
 #define MAX_LINE_LENGTH 512
@@ -208,7 +208,6 @@ int CDROM_Interface_Image::refCount = 0;
 CDROM_Interface_Image* CDROM_Interface_Image::images[26] = {};
 CDROM_Interface_Image::imagePlayer CDROM_Interface_Image::player = {
 	{0},        // buffer[]
-	{{0}, {0}}, // TCtrl struct
 	nullptr,    // TrackFile*
 	nullptr,    // MixerChannel*
 	nullptr,    // CDROM_Interface_Image*
@@ -218,8 +217,7 @@ CDROM_Interface_Image::imagePlayer CDROM_Interface_Image::player = {
 	0,          // playedTrackFrames
 	0,          // totalTrackFrames
 	false,      // isPlaying
-	false,      // isPaused
-	false       // ctrlUsed
+	false       // isPaused
 };
 
 CDROM_Interface_Image::CDROM_Interface_Image(Bit8u subUnit)
@@ -432,7 +430,7 @@ bool CDROM_Interface_Image::PlayAudioSector(unsigned long start, unsigned long l
 
 	// We can't play audio from a data track (as it would result in garbage/static)
 	else if (track >= 0 && tracks[track].attr == 0x40)
-		LOG(LOG_MISC,LOG_WARN)("Game tries to play the data track. Not doing this");
+		LOG(LOG_MISC,LOG_WARN)("Game tried to play the data track. Not doing this");
 
 	// Checks passed, setup the audio stream
 	else {
@@ -469,19 +467,15 @@ bool CDROM_Interface_Image::PlayAudioSector(unsigned long start, unsigned long l
 			player.playedTrackFrames = 0;
 
 #ifdef DEBUG
-			LOG_MSG("%s CDROM: Playing track %d at %d Hz "
-			        "%d-channel at start sector %lu (%.1f minute-mark), seek %u ms from track start, "
-			        "(skip=%d,dstart=%d,secsize=%d), for %u Redbook frames (%.1f seconds)",
+			LOG_MSG("%s CDROM: Playing track %d (%d Hz "
+			        "%d-channel) at starting sector %lu (%.1f minute-mark) "
+			        "for %u Redbook frames (%.1f seconds)",
 			        get_time(),
 			        track,
 			        track_rate,
 			        track_channels,
 			        start,
 			        static_cast<float>(start) / (REDBOOK_FRAMES_PER_SECOND * 60),
-			        offset,
-			        tracks[track].skip,
-			        tracks[track].start,
-			        tracks[track].sectorSize,
 			        player.totalRedbookFrames,
 			        static_cast<float>(player.totalRedbookFrames) / REDBOOK_FRAMES_PER_SECOND);
 #endif
@@ -529,19 +523,14 @@ bool CDROM_Interface_Image::StopAudio(void)
 
 void CDROM_Interface_Image::ChannelControl(TCtrl ctrl)
 {
-	player.ctrlUsed = (ctrl.out[0]!=0 || ctrl.out[1]!=1 || ctrl.vol[0]<0xfe || ctrl.vol[1]<0xfe);
-	player.ctrlData = ctrl;
-
-	// Apply the volume to our Mixer Channel
-	if (player.ctrlUsed && player.channel != NULL) {
-		const float leftVolumePercent = static_cast<float>(player.ctrlData.vol[0] / 255.0);
-		const float rightVolumePercent = static_cast<float>(player.ctrlData.vol[1] / 255.0);
-		player.channel->SetScale(leftVolumePercent, rightVolumePercent);
-#ifdef DEBUG
-		LOG_MSG("%s CDROM: Game set the left and right volume to %3.0f%% and %3.0f%%, respectively",
-		        get_time(), leftVolumePercent * 100, rightVolumePercent * 100);
-#endif
-	}
+	if (player.channel == NULL) return;
+
+	// Scale our mixer channel's volume as defined by the application
+	player.channel->SetScale(static_cast<float>(ctrl.vol[0]/255.0),
+	                         static_cast<float>(ctrl.vol[1]/255.0));
+
+	// Map our mixer channel's as defined by the application
+	player.channel->MapChannels(ctrl.out[0], ctrl.out[1]);
 }
 
 bool CDROM_Interface_Image::ReadSectors(PhysPt buffer, bool raw, unsigned long sector, unsigned long num)
@@ -597,6 +586,7 @@ bool CDROM_Interface_Image::ReadSector(Bit8u *buffer, bool raw, unsigned long se
 	if (tracks[track].sectorSize == RAW_SECTOR_SIZE && !tracks[track].mode2 && !raw) seek += 16;
 	if (tracks[track].mode2 && !raw) seek += 24;
 
+#if 0 // Excessively verbose.. only enable if needed
 #ifdef DEBUG
 	LOG_MSG("%s CDROM: ReadSector track=%d, desired raw=%s, sector=%ld, length=%d",
 	        get_time(),
@@ -605,6 +595,8 @@ bool CDROM_Interface_Image::ReadSector(Bit8u *buffer, bool raw, unsigned long se
 	        sector,
 	        length);
 #endif
+#endif
+
 	return tracks[track].file->read(buffer, seek, length);
 }
 

src/dos/cdrom_ioctl_win32.cpp

@@ -470,8 +470,14 @@ bool CDROM_Interface_Ioctl::StopAudio(void) {
 
 void CDROM_Interface_Ioctl::ChannelControl(TCtrl ctrl)
 {
-	player.ctrlUsed = (ctrl.out[0]!=0 || ctrl.out[1]!=1 || ctrl.vol[0]<0xfe || ctrl.vol[1]<0xfe);
-	player.ctrlData = ctrl;
+	if (player.channel == NULL) return;
+
+	// Scale our mixer channel's volume as defined by the application
+	player.channel->SetScale(static_cast<float>(ctrl.vol[0]/255.0),
+	                         static_cast<float>(ctrl.vol[1]/255.0));
+
+	// Map our mixer channel's as defined by the application
+	player.channel->MapChannels(ctrl.out[0], ctrl.out[1]);
 }
 
 bool CDROM_Interface_Ioctl::LoadUnloadMedia(bool unload) {
@@ -565,16 +571,6 @@ void CDROM_Interface_Ioctl::dx_CDAudioCallBack(Bitu len) {
 		}
 	}
 	SDL_mutexV(player.mutex);
-	if (player.ctrlUsed) {
-		Bit16s sample0,sample1;
-		Bit16s * samples=(Bit16s *)&player.buffer;
-		for (Bitu pos=0;pos<len/4;pos++) {
-			sample0=samples[pos*2+player.ctrlData.out[0]];
-			sample1=samples[pos*2+player.ctrlData.out[1]];
-			samples[pos*2+0]=(Bit16s)(sample0*player.ctrlData.vol[0]/255.0);
-			samples[pos*2+1]=(Bit16s)(sample1*player.ctrlData.vol[1]/255.0);
-		}
-	}
 	player.channel->AddSamples_s16(len/4,(Bit16s *)player.buffer);
 	memmove(player.buffer, &player.buffer[len], player.bufLen - len);
 	player.bufLen -= len;