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Diffstat (limited to 'src/midifile.c')
| -rw-r--r-- | src/midifile.c | 287 |
1 files changed, 287 insertions, 0 deletions
diff --git a/src/midifile.c b/src/midifile.c new file mode 100644 index 00000000..e74cf17f --- /dev/null +++ b/src/midifile.c @@ -0,0 +1,287 @@ +// Emacs style mode select -*- C++ -*- +//----------------------------------------------------------------------------- +// +// Copyright(C) 2009 Simon Howard +// +// This program is free software; you can redistribute it and/or +// modify it under the terms of the GNU General Public License +// as published by the Free Software Foundation; either version 2 +// of the License, or (at your option) any later version. +// +// This program is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +// GNU General Public License for more details. +// +// You should have received a copy of the GNU General Public License +// along with this program; if not, write to the Free Software +// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA +// 02111-1307, USA. +// +// DESCRIPTION: +// Reading of MIDI files. +// +//----------------------------------------------------------------------------- + +#include <stdio.h> +#include <stdlib.h> +#include <string.h> + +#include "doomtype.h" +#include "i_swap.h" +#include "midifile.h" + +#define HEADER_CHUNK_ID "MThd" +#define TRACK_CHUNK_ID "MTrk" + +typedef struct +{ + byte chunk_id[4]; + unsigned int chunk_size; +} chunk_header_t; + +typedef struct +{ + chunk_header_t chunk_header; + unsigned short format_type; + unsigned short num_tracks; + unsigned int time_division; +} midi_header_t; + +struct midi_file_s +{ + FILE *stream; + midi_header_t header; + unsigned int data_len; +}; + +static boolean CheckChunkHeader(chunk_header_t *chunk, + char *expected_id) +{ + boolean result; + + result = (strcmp((char *) chunk->chunk_id, expected_id) == 0); + + if (!result) + { + fprintf(stderr, "CheckChunkHeader: Expected '%s' chunk header!\n", + expected_id); + } + + return result; +} + +// Read and check the header chunk. + +static boolean ReadHeaderChunk(midi_file_t *file) +{ + size_t bytes_read; + + bytes_read = fread(&file->header, sizeof(midi_header_t), 1, file->stream); + + if (bytes_read < sizeof(midi_header_t)) + { + return false; + } + + if (!CheckChunkHeader(&file->header.chunk_header, HEADER_CHUNK_ID) + || LONG(file->header.chunk_header.chunk_size) != 6) + { + fprintf(stderr, "ReadHeaderChunk: Invalid MIDI chunk header!\n"); + return false; + } + + if (SHORT(file->header.format_type) != 0 + || SHORT(file->header.num_tracks) != 1) + { + fprintf(stderr, "ReadHeaderChunk: Only single track, " + "type 0 MIDI files supported!\n"); + return false; + } + + return true; +} + +// Read and check the track chunk header + +static boolean ReadTrackChunk(midi_file_t *file) +{ + size_t bytes_read; + chunk_header_t chunk_header; + + bytes_read = fread(&chunk_header, sizeof(chunk_header_t), 1, file->stream); + + if (bytes_read < sizeof(chunk_header)) + { + return false; + } + + if (!CheckChunkHeader(&chunk_header, TRACK_CHUNK_ID)) + { + return false; + } + + file->data_len = LONG(chunk_header.chunk_size); + + return true; +} + +midi_file_t *MIDI_OpenFile(char *filename) +{ + midi_file_t *file; + + file = malloc(sizeof(midi_file_t)); + + if (file == NULL) + { + return NULL; + } + + // Open file + + file->stream = fopen(filename, "rb"); + + if (file->stream == NULL) + { + fprintf(stderr, "Failed to open '%s'\n", filename); + free(file); + return NULL; + } + + // Read MIDI file header + + if (!ReadHeaderChunk(file)) + { + fclose(file->stream); + free(file); + return NULL; + } + + // Read track header + + if (!ReadTrackChunk(file)) + { + fclose(file->stream); + free(file); + return NULL; + } + + return file; +} + +void MIDI_CloseFile(midi_file_t *file) +{ + fclose(file->stream); + free(file); +} + +// Read a MIDI channel event. +// two_param indicates that the event type takes two parameters +// (three byte) otherwise it is single parameter (two byte) + +static boolean ReadChannelEvent(midi_file_t *file, midi_event_t *event, + int event_type, boolean two_param) +{ + int c; + + // Set basics: + + event->event_type = event_type >> 4; + event->data.channel.channel = event_type & 0xf; + + // Read parameters: + + c = fgetc(file->stream); + + if (c == EOF) + { + return false; + } + + event->data.channel.param1 = c; + + // Second parameter: + + if (two_param) + { + c = fgetc(file->stream); + + if (c == EOF) + { + return false; + } + + event->data.channel.param2 = c; + } + + return true; +} + +// Read sysex event: + +static boolean ReadSysExEvent(midi_file_t *file, midi_event_t *event, + int event_type) +{ + // TODO + return false; +} + +// Read meta event: + +static boolean ReadMetaEvent(midi_file_t *file, midi_event_t *event) +{ + // TODO + return false; +} + +boolean MIDI_ReadEvent(midi_file_t *file, midi_event_t *event) +{ + int event_type; + + event_type = fgetc(file->stream); + + if (event_type == EOF) + { + return false; + } + + // Check event type: + + switch (event_type >> 4) + { + // Two parameter channel events: + + case MIDI_EVENT_NOTE_OFF: + case MIDI_EVENT_NOTE_ON: + case MIDI_EVENT_AFTERTOUCH: + case MIDI_EVENT_CONTROLLER: + case MIDI_EVENT_PITCH_BEND: + return ReadChannelEvent(file, event, event_type, true); + + // Single parameter channel events: + + case MIDI_EVENT_PROGRAM_CHANGE: + case MIDI_EVENT_CHAN_AFTERTOUCH: + return ReadChannelEvent(file, event, event_type, false); + + // Other event types: + + case 0xf: + if (event_type == MIDI_EVENT_SYSEX + || event_type == MIDI_EVENT_SYSEX_SPLIT) + { + return ReadSysExEvent(file, event, event_type); + } + else if (event_type == MIDI_EVENT_META) + { + return ReadMetaEvent(file, event); + } + + // Fall-through deliberate - + + default: + fprintf(stderr, "Unknown MIDI event type: 0x%x\n", event_type); + return false; + } +} + |