First partial working attempt at sound. Producing output, but very distorted

7 files changed, 194 insertions, 10 deletions

diff --git a/src/Makefile b/src/Makefile
index 15db934..37e1d26 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -85,7 +85,7 @@ clean:
 
 main.o: z80.h spec.h gfx.h gui.h memmenu.h config.h kbbmp.h exit.h tape.h audio.h
 main.o: util.h
-spec.o: spec.h z80.h snap.h gfx.h gui.h config.h exit.h tape.h util.h
+spec.o: spec.h z80.h snap.h gfx.h gui.h config.h exit.h tape.h util.h audio.h
 snap.o: snap.h z80.h util.h
 config.o: exit.h config.h
 gfx.o: gfx.h exit.h config.h util.h font.h
@@ -99,4 +99,4 @@ symtochar.o: symtochar.h
 font.o: font.h
 z80.o: z80.h z80_private.h
 z80_decode.o: z80.h z80_private.h
-audio.o: audio.c audio.h
+audio.o: audio.c audio.h util.h
diff --git a/src/audio.c b/src/audio.c
index b5ce1df..7eef433 100644
--- a/src/audio.c
+++ b/src/audio.c
@@ -27,17 +27,41 @@
 #include <SDL.h>
 
 #include "audio.h"
+#include "util.h"
 
-/* ---------------------------------------- INTERFACES
+/* ---------------------------------------- INTERNAL DATA
 */
+static SDL_AudioSpec		actual;
+static SDL_AudioDeviceID	device;
+
 
+/* ---------------------------------------- INTERFACES
+*/
 int AUDIOInit(void)
 {
-    return 0;
+    SDL_AudioSpec spec = {0};
+
+    spec.freq = SAMPLE_RATE;
+    spec.format = AUDIO_S8;
+    spec.channels = 1;
+    spec.samples = 4096;
+
+    device = SDL_OpenAudioDevice(NULL, 0, &spec, &actual, 0);
+
+    if (device != 0)
+    {
+    	SDL_PauseAudioDevice(device, 0);
+    }
+
+    return device != 0;
 }
 
-void AUDIOQueue(char *buffer, size_t len)
+void AUDIOQueue(Uint8 *buffer, size_t len)
 {
+    if (device != 0)
+    {
+	SDL_QueueAudio(device, buffer, len);
+    }
 }
 
 
diff --git a/src/audio.h b/src/audio.h
index 83980e4..b799abd 100644
--- a/src/audio.h
+++ b/src/audio.h
@@ -28,6 +28,11 @@
 #define ESPEC_AUDIO_H
 
 #include <stdlib.h>
+#include <SDL.h>
+
+/* The sample rate
+*/
+#define SAMPLE_RATE 48000
 
 /* ---------------------------------------- INTERFACES
 */
@@ -39,10 +44,11 @@
 int		AUDIOInit(void);
 
 
-/* Add the passed buffer to the sound queue.  It is a signed 8-bit mono
+/* Add the passed buffer to the sound queue.  It is an unsigned 8-bit mono
    sample which will be converted as appropriate by the audio interface.
+   Well turns out SDL does that for you.
 */
-void		AUDIOQueue(char *buffer, size_t len);
+void		AUDIOQueue(Uint8 *buffer, size_t len);
 
 
 #endif
diff --git a/src/spec.c b/src/spec.c
index 2ddf661..6393ef2 100644
--- a/src/spec.c
+++ b/src/spec.c
@@ -26,6 +26,7 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
+#include <SDL.h>
 #include "spec.h"
 #include "snap.h"
 #include "gfx.h"
@@ -33,6 +34,7 @@
 #include "config.h"
 #include "exit.h"
 #include "tape.h"
+#include "audio.h"
 #include "util.h"
 
 #ifndef TRUE
@@ -77,7 +79,9 @@ static Z80Byte		mem[0x10000];
 
 /* Number of cycles per scan lines and scan line control
 */
-static Z80Val		SCAN_CYCLES=224;
+#define SCAN_CYCLES	224
+#define FRAME_CYCLES	69888
+
 static int		scanline=0;
 static int		enable_screen=TRUE;
 
@@ -202,6 +206,22 @@ static const MatrixMap keymap[]=
     {SDLK_UNKNOWN,	0,0,0,0},
 };
 
+static size_t		sample_buff_sz;
+static double		cycles_per_sample;
+
+typedef struct SoundRecord
+{
+    Z80Val		cycle;
+    Uint8		level;
+    struct SoundRecord	*next;
+} SoundRecord;
+
+static struct
+{
+    SoundRecord	*head;
+    SoundRecord	*tail;
+    Uint8	last_level;
+} sound;
 
 /* ---------------------------------------- DEBUG FUNCTIONS
 */
@@ -251,6 +271,39 @@ static void ClearKeys(void)
     }
 }
 
+static void AddSoundRecord(Z80Val cycle, Uint8 level)
+{
+    SoundRecord *new = Malloc(sizeof *new);
+
+    new->cycle = cycle;
+    new->level = level;
+    new->next = NULL;
+
+    if (sound.tail)
+    {
+    	sound.tail->next = new;
+	sound.tail = new;
+    }
+    else
+    {
+    	sound.head = new;
+    	sound.tail = new;
+    }
+}
+
+static void ClearSoundRecord(void)
+{
+    while(sound.head)
+    {
+    	SoundRecord *next = sound.head->next;
+	free(sound.head);
+	sound.head = next;
+    }
+
+    sound.tail = NULL;
+}
+
+
 static void DrawScanlineAt(int y, int sline)
 {
     int aline;
@@ -485,6 +538,55 @@ static int CheckTimers(Z80 *z80, Z80Val val)
             {
                 selected_out_tape--;
             }
+
+	    if (IConfig(CONF_SOUND))
+	    {
+		Uint8 *sample = Malloc(sample_buff_sz);
+		SoundRecord *current = sound.head;
+		int offset = 0;
+
+		memset(sample, 0, sample_buff_sz);
+
+		if (current)
+		{
+		    int f;
+		    int first_offset = (int)(current->cycle / cycles_per_sample);
+
+		    for(f = 0; f < first_offset; f++)
+		    {
+			sample[f] = sound.last_level;
+		    }
+
+		    while(current)
+		    {
+			int next_offset;
+
+			if (current->next)
+			{
+			    next_offset = (int)(current->cycle / cycles_per_sample);
+			}
+			else
+			{
+			    next_offset = sample_buff_sz;
+			}
+
+			for(f = offset; f < next_offset; f++)
+			{
+			    sample[f] = current->level;
+			}
+
+			offset = next_offset;
+			sound.last_level = current->level;
+			current = current->next;
+		    }
+		}
+
+		AUDIOQueue(sample, sample_buff_sz);
+
+		free(sample);
+		ClearSoundRecord();
+	    }
+
 	}
 
 	/* Draw scanline
@@ -494,7 +596,7 @@ static int CheckTimers(Z80 *z80, Z80Val val)
 	if (y>=0 && y<GFX_HEIGHT && enable_screen)
 	    DrawScanline(y);
 
-	/* TODO: Process sound emulation */
+	Z80SetTimer(z80, eZ80_Timer_1, 0);
     }
 
     return TRUE;
@@ -532,6 +634,14 @@ void SPECInit(Z80 *z80)
     Z80LodgeCallback(z80,eZ80_EDHook,EDCallback);
     Z80LodgeCallback(z80,eZ80_Instruction,CheckTimers);
 
+    /* Calculate the audio buffer sizes
+    */
+    if (IConfig(CONF_SOUND))
+    {
+    	sample_buff_sz = SAMPLE_RATE / IConfig(CONF_FRAMES_PER_SEC);
+	cycles_per_sample = (double)FRAME_CYCLES / (double)SAMPLE_RATE;
+    }
+
     SPECReset(z80);
 }
 
@@ -622,6 +732,7 @@ void SPECWritePort(Z80 *z80, Z80Word port, Z80Byte val)
     {
 	case 0xfe:	/* ULA */
 	    border=val&0x07;
+	    AddSoundRecord(Z80GetTimer(z80, eZ80_Timer_1), val & 0x10 ? 64 : 0);
 	    break;
 
 	case 0xfb:	/* TODO: ZX Printer */
diff --git a/src/z80.c b/src/z80.c
index deccb8c..5935d5d 100644
--- a/src/z80.c
+++ b/src/z80.c
@@ -149,9 +149,15 @@ Z80	*Z80Init(Z80ReadMemory read_memory,
 
 void Z80Reset(Z80 *cpu)
 {
+    int f;
+
     cpu->cycle=0;
     cpu->PC=0;
 
+    cpu->timer[eZ80_Timer_1] = 0;
+    cpu->timer[eZ80_Timer_2] = 0;
+    cpu->timer[eZ80_Timer_3] = 0;
+
     cpu->AF.w=0xffff;
     cpu->BC.w=0xffff;
     cpu->DE.w=0xffff;
@@ -362,4 +368,17 @@ const char *Z80Disassemble(Z80 *cpu, Z80Word *pc)
 #endif
 }
 
+
+Z80Val Z80GetTimer(Z80 *cpu, Z80Timer timer)
+{
+    return cpu->timer[timer];
+}
+
+
+void Z80SetTimer(Z80 *cpu, Z80Timer timer, Z80Val value)
+{
+    cpu->timer[timer] = value;
+}
+
+
 /* END OF FILE */
diff --git a/src/z80.h b/src/z80.h
index 66385e7..601127d 100644
--- a/src/z80.h
+++ b/src/z80.h
@@ -151,6 +151,16 @@ typedef struct
 } Z80Label;
 
 
+/* The Z80 provides a number of cycle timers
+*/
+typedef enum
+{
+    eZ80_Timer_1,
+    eZ80_Timer_2,
+    eZ80_Timer_3
+} Z80Timer;
+
+
 /* ---------------------------------------- INTERFACES
 */
 
@@ -230,6 +240,12 @@ void	Z80GetState(Z80 *cpu, Z80State *state);
 void	Z80SetState(Z80 *cpu, const Z80State *state);
 
 
+/* Timers that count in cycle counts
+*/
+Z80Val  Z80GetTimer(Z80 *cpu, Z80Timer timer);
+void    Z80SetTimer(Z80 *cpu, Z80Timer timer, Z80Val cycles);
+
+
 /* Set address to label mappings for the disassembler
 */
 void	Z80SetLabels(Z80Label labels[]);
diff --git a/src/z80_private.h b/src/z80_private.h
index 628e23d..b015d6f 100644
--- a/src/z80_private.h
+++ b/src/z80_private.h
@@ -96,6 +96,8 @@ struct Z80
     Z80Callback		callback[eZ80_NO_CALLBACK][MAX_PER_CALLBACK];
 
     int			last_cb;
+
+    Z80Val		timer[3];
 };
 
 
@@ -159,7 +161,13 @@ struct Z80
 #define IS_IX_IY		(cpu->shift==0xdd || cpu->shift==0xfd)
 #define OFFSET(off)		off=(IS_IX_IY ? (Z80Relative)FETCH_BYTE:0)
 
-#define TSTATE(n)		cpu->cycle+=n
+#define TSTATE(n)		do					\
+				{					\
+				    cpu->cycle+=n;			\
+				    cpu->timer[eZ80_Timer_1]+=n;	\
+				    cpu->timer[eZ80_Timer_2]+=n;	\
+				    cpu->timer[eZ80_Timer_3]+=n;	\
+				} while(0)
 
 #define ADD_R(v)		cpu->R=((cpu->R&0x80)|((cpu->R+(v))&0x7f))
 #define INC_R			ADD_R(1)