musix 0.3.5

Music player library for esoteric audio formats (music from C64,Amiga etc)
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157

/*
	SCSP LFO handling

	Part of the SCSP (YMF292-F) emulator package.
	(not compiled directly, #included from scsp.c)

	By ElSemi
	MAME/M1 conversion and cleanup by R. Belmont
*/

#define LFO_SHIFT 	8

struct _LFO
{
    unsigned short phase;
    UINT32 phase_step;
    int *table;
    int *scale;
};

#define LFIX(v)	((unsigned int) ((float) (1<<LFO_SHIFT)*(v)))

//Convert DB to multiply amplitude
#define DB(v) 	LFIX(pow(10.0,v/20.0))

//Convert cents to step increment
#define CENTS(v) LFIX(pow(2.0,v/1200.0))

static int PLFO_TRI[256],PLFO_SQR[256],PLFO_SAW[256],PLFO_NOI[256];
static int ALFO_TRI[256],ALFO_SQR[256],ALFO_SAW[256],ALFO_NOI[256];
static float LFOFreq[32]={0.17,0.19,0.23,0.27,0.34,0.39,0.45,0.55,0.68,0.78,0.92,1.10,1.39,1.60,1.87,2.27,
			  2.87,3.31,3.92,4.79,6.15,7.18,8.60,10.8,14.4,17.2,21.5,28.7,43.1,57.4,86.1,172.3};
static float ASCALE[8]={0.0,0.4,0.8,1.5,3.0,6.0,12.0,24.0};
static float PSCALE[8]={0.0,7.0,13.5,27.0,55.0,112.0,230.0,494};
static int PSCALES[8][256];
static int ASCALES[8][256];

void LFO_Init(void)
{
    int i,s;
    for(i=0;i<256;++i)
    {
		int a,p;
//		float TL;
		//Saw
		a=255-i;
		if(i<128)
			p=i;
		else
			p=i-256;    
		ALFO_SAW[i]=a;
		PLFO_SAW[i]=p;
	
		//Square
		if(i<128)
		{
			a=255;
			p=127;
		}
		else
		{
			a=0;
			p=-128;
		}
		ALFO_SQR[i]=a;
		PLFO_SQR[i]=p;
	
		//Tri
		if(i<128)
			a=255-(i*2);
		else
			a=(i*2)-256;
		if(i<64)
			p=i*2;
		else if(i<128)
			p=255-i*2;
		else if(i<192)
			p=256-i*2;
		else
			p=i*2-511;
		ALFO_TRI[i]=a;
		PLFO_TRI[i]=p;
	
		//noise
		//a=lfo_noise[i];
		a=rand()&0xff;
		p=128-a;
		ALFO_NOI[i]=a;
		PLFO_NOI[i]=p;
    }

	for(s=0;s<8;++s)
	{
		float limit=PSCALE[s];
		for(i=-128;i<128;++i)
		{
			PSCALES[s][i+128]=CENTS(((limit*(float) i)/128.0));
		}
		limit=-ASCALE[s];
		for(i=0;i<256;++i)
		{
			ASCALES[s][i]=DB(((limit*(float) i)/256.0));
		}
	}
}

signed int INLINE PLFO_Step(struct _LFO *LFO)
{
	int p;
    LFO->phase+=LFO->phase_step;    
#if LFO_SHIFT!=8    
    LFO->phase&=(1<<(LFO_SHIFT+8))-1;
#endif    
    p=LFO->table[LFO->phase>>LFO_SHIFT];
	p=LFO->scale[p+128];
	return p<<(SHIFT-LFO_SHIFT);
}

signed int INLINE ALFO_Step(struct _LFO *LFO)
{
	int p;
    LFO->phase+=LFO->phase_step;    
#if LFO_SHIFT!=8    
    LFO->phase&=(1<<(LFO_SHIFT+8))-1;
#endif    
    p=LFO->table[LFO->phase>>LFO_SHIFT];
	p=LFO->scale[p];
	return p<<(SHIFT-LFO_SHIFT);
}

void LFO_ComputeStep(struct _LFO *LFO,UINT32 LFOF,UINT32 LFOWS,UINT32 LFOS,int ALFO)
{
    float step=(float) LFOFreq[LFOF]*256.0/(float)44100.0;
    LFO->phase_step=(unsigned int) ((float) (1<<LFO_SHIFT)*step);
    if(ALFO)
    {
		switch(LFOWS)
		{
			case 0: LFO->table=ALFO_SAW; break;
			case 1: LFO->table=ALFO_SQR; break;
			case 2: LFO->table=ALFO_TRI; break;
			case 3: LFO->table=ALFO_NOI; break;
		}
		LFO->scale=ASCALES[LFOS];
	}
	else
	{
		switch(LFOWS)
		{
		    case 0: LFO->table=PLFO_SAW; break;
		    case 1: LFO->table=PLFO_SQR; break;
			case 2: LFO->table=PLFO_TRI; break;
		    case 3: LFO->table=PLFO_NOI; break;
		}
		LFO->scale=PSCALES[LFOS];
	}
}