1 /*
2 ** midisource_mids.cpp
3 ** Code to let ZMusic play MIDS MIDI music through the MIDI streaming API.
4 **
5 **---------------------------------------------------------------------------
6 ** Copyright 2020 Cacodemon345
7 ** All rights reserved.
8 **
9 ** Redistribution and use in source and binary forms, with or without
10 ** modification, are permitted provided that the following conditions
11 ** are met:
12 **
13 ** 1. Redistributions of source code must retain the above copyright
14 ** notice, this list of conditions and the following disclaimer.
15 ** 2. Redistributions in binary form must reproduce the above copyright
16 ** notice, this list of conditions and the following disclaimer in the
17 ** documentation and/or other materials provided with the distribution.
18 ** 3. The name of the author may not be used to endorse or promote products
19 ** derived from this software without specific prior written permission.
20 **
21 ** THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
22 ** IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
23 ** OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
24 ** IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
25 ** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
26 ** NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27 ** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28 ** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29 ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
30 ** THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 **---------------------------------------------------------------------------
32 **
33 */
34
35 // HEADER FILES ------------------------------------------------------------
36
37 #include <algorithm>
38 #include "midisource.h"
39 #include "zmusic/m_swap.h"
40
41 // MACROS ------------------------------------------------------------------
42
43 // TYPES -------------------------------------------------------------------
44
45 // EXTERNAL FUNCTION PROTOTYPES --------------------------------------------
46
47 // PUBLIC FUNCTION PROTOTYPES ----------------------------------------------
48
49 // PRIVATE FUNCTION PROTOTYPES ---------------------------------------------
50
51 // EXTERNAL DATA DECLARATIONS ----------------------------------------------
52
53 // PRIVATE DATA DEFINITIONS ------------------------------------------------
54
55 // PUBLIC DATA DEFINITIONS -------------------------------------------------
56
57 // CODE --------------------------------------------------------------------
58
59 //==========================================================================
60 //
61 // MIDSSong constructor
62 //
63 // Reads the buffers from the file and validates the MIDS header
64 //
65 //==========================================================================
66
MIDSSong(const uint8_t * data,size_t len)67 MIDSSong::MIDSSong(const uint8_t* data, size_t len)
68 {
69 if (len <= 52)
70 return;
71
72 if ((len % 4) != 0)
73 return;
74
75 // Validate the header first.
76 if (data[12] != 'f' || data[13] != 'm' || data[14] != 't' || data[15] != ' ')
77 {
78 return;
79 }
80 int headerSize = LittleLong(GetInt(&data[16]));
81 if (headerSize != 12) return;
82 Division = LittleLong(GetInt(&data[20]));
83 FormatFlags = LittleLong(GetInt(&data[28]));
84 // Validate the data chunk.
85 if (data[32] != 'd' || data[33] != 'a' || data[34] != 't' || data[35] != 'a')
86 {
87 return;
88 }
89 int NumBlocks = LittleLong(GetInt(&data[40]));
90 const uint32_t* midiData = (const uint32_t*)&data[44];
91 uint32_t tkStart = 0;
92 uint32_t cbBuffer = 0;
93 while (NumBlocks-- > 0)
94 {
95 tkStart = LittleLong(*midiData);
96 cbBuffer = LittleLong(*(midiData + 1));
97 midiData += 2;
98 if ((cbBuffer % (FormatFlags ? 8 : 12)) != 0) return;
99 MidsBuffer.insert(MidsBuffer.end(), midiData, midiData + (cbBuffer / 4));
100 midiData += cbBuffer / 4;
101 }
102 MidsP = 0;
103 MaxMidsP = MidsBuffer.size() - 1;
104 for (auto& curMidiData : MidsBuffer)
105 {
106 curMidiData = LittleLong(curMidiData);
107 }
108 }
109
110 //==========================================================================
111 //
112 // MIDSSong :: DoInitialSetup
113 //
114 // Sets the starting channel volumes.
115 //
116 //==========================================================================
117
DoInitialSetup()118 void MIDSSong::DoInitialSetup()
119 {
120 for (int i = 0; i < 16; ++i)
121 {
122 ChannelVolumes[i] = 100;
123 }
124 }
125
126 //==========================================================================
127 //
128 // MIDSSong :: CheckDone
129 //
130 //==========================================================================
131
CheckDone()132 bool MIDSSong::CheckDone()
133 {
134 return MidsP >= MaxMidsP;
135 }
136
137 //==========================================================================
138 //
139 // MIDSSong :: DoRestart()
140 //
141 // Rewinds the song
142 //
143 //==========================================================================
144
DoRestart()145 void MIDSSong::DoRestart()
146 {
147 MidsP = 0;
148 ProcessInitialTempoEvents();
149 }
150
151 //==========================================================================
152 //
153 // MIDSSong :: ProcessInitialTempoEvents()
154 //
155 // Process initial tempo events at the start of the song.
156 //
157 //==========================================================================
158
ProcessInitialTempoEvents()159 void MIDSSong::ProcessInitialTempoEvents()
160 {
161 if (MEVENT_EVENTTYPE(MidsBuffer[FormatFlags ? 1 : 2]) == MEVENT_TEMPO)
162 {
163 SetTempo(MEVENT_EVENTPARM(MidsBuffer[FormatFlags ? 1 : 2]));
164 }
165 }
166
167 //==========================================================================
168 //
169 // MUSSong2 :: MakeEvents
170 //
171 // Puts MIDS events into a MIDI stream
172 // buffer. Returns the new position in the buffer.
173 //
174 //==========================================================================
175
MakeEvents(uint32_t * events,uint32_t * max_event_p,uint32_t max_time)176 uint32_t* MIDSSong::MakeEvents(uint32_t* events, uint32_t* max_event_p, uint32_t max_time)
177 {
178 uint32_t time = 0;
179 uint32_t tot_time = 0;
180
181 max_time = max_time * Division / Tempo;
182 while (events < max_event_p && tot_time <= max_time)
183 {
184 events[0] = time = MidsBuffer[MidsP++];
185 events[1] = FormatFlags ? 0 : MidsBuffer[MidsP++];
186 events[2] = MidsBuffer[MidsP++];
187 events += 3;
188 tot_time += time;
189 if (MidsP >= MaxMidsP) break;
190 }
191 return events;
192 }
193