ref: e7ae385752f8b9f601a44257d661c7ec25d266a5
dir: /src/midifile.c/
// 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 <assert.h> #include "doomtype.h" #include "i_swap.h" #include "midifile.h" #define HEADER_CHUNK_ID "MThd" #define TRACK_CHUNK_ID "MTrk" #define MAX_BUFFER_SIZE 0x10000 // haleyjd 09/09/10: packing required #ifdef _MSC_VER #pragma pack(push, 1) #endif typedef struct { byte chunk_id[4]; unsigned int chunk_size; } PACKEDATTR chunk_header_t; typedef struct { chunk_header_t chunk_header; unsigned short format_type; unsigned short num_tracks; unsigned short time_division; } PACKEDATTR midi_header_t; // haleyjd 09/09/10: packing off. #ifdef _MSC_VER #pragma pack(pop) #endif typedef struct { // Length in bytes: unsigned int data_len; // Events in this track: midi_event_t *events; int num_events; } midi_track_t; struct midi_track_iter_s { midi_track_t *track; unsigned int position; }; struct midi_file_s { midi_header_t header; // All tracks in this file: midi_track_t *tracks; unsigned int num_tracks; // Data buffer used to store data read for SysEx or meta events: byte *buffer; unsigned int buffer_size; }; // Check the header of a chunk: static boolean CheckChunkHeader(chunk_header_t *chunk, char *expected_id) { boolean result; result = (memcmp((char *) chunk->chunk_id, expected_id, 4) == 0); if (!result) { fprintf(stderr, "CheckChunkHeader: Expected '%s' chunk header, " "got '%c%c%c%c'\n", expected_id, chunk->chunk_id[0], chunk->chunk_id[1], chunk->chunk_id[2], chunk->chunk_id[3]); } return result; } // Read a single byte. Returns false on error. static boolean ReadByte(byte *result, FILE *stream) { int c; c = fgetc(stream); if (c == EOF) { fprintf(stderr, "ReadByte: Unexpected end of file\n"); return false; } else { *result = (byte) c; return true; } } // Read a variable-length value. static boolean ReadVariableLength(unsigned int *result, FILE *stream) { int i; byte b; *result = 0; for (i=0; i<4; ++i) { if (!ReadByte(&b, stream)) { fprintf(stderr, "ReadVariableLength: Error while reading " "variable-length value\n"); return false; } // Insert the bottom seven bits from this byte. *result <<= 7; *result |= b & 0x7f; // If the top bit is not set, this is the end. if ((b & 0x80) == 0) { return true; } } fprintf(stderr, "ReadVariableLength: Variable-length value too " "long: maximum of four bytes\n"); return false; } // Read a byte sequence into the data buffer. static void *ReadByteSequence(unsigned int num_bytes, FILE *stream) { unsigned int i; byte *result; // Allocate a buffer: result = malloc(num_bytes); if (result == NULL) { fprintf(stderr, "ReadByteSequence: Failed to allocate buffer\n"); return NULL; } // Read the data: for (i=0; i<num_bytes; ++i) { if (!ReadByte(&result[i], stream)) { fprintf(stderr, "ReadByteSequence: Error while reading byte %u\n", i); free(result); return NULL; } } return result; } // 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_event_t *event, byte event_type, boolean two_param, FILE *stream) { byte b; // Set basics: event->event_type = event_type & 0xf0; event->data.channel.channel = event_type & 0x0f; // Read parameters: if (!ReadByte(&b, stream)) { fprintf(stderr, "ReadChannelEvent: Error while reading channel " "event parameters\n"); return false; } event->data.channel.param1 = b; // Second parameter: if (two_param) { if (!ReadByte(&b, stream)) { fprintf(stderr, "ReadChannelEvent: Error while reading channel " "event parameters\n"); return false; } event->data.channel.param2 = b; } return true; } // Read sysex event: static boolean ReadSysExEvent(midi_event_t *event, int event_type, FILE *stream) { event->event_type = event_type; if (!ReadVariableLength(&event->data.sysex.length, stream)) { fprintf(stderr, "ReadSysExEvent: Failed to read length of " "SysEx block\n"); return false; } // Read the byte sequence: event->data.sysex.data = ReadByteSequence(event->data.sysex.length, stream); if (event->data.sysex.data == NULL) { fprintf(stderr, "ReadSysExEvent: Failed while reading SysEx event\n"); return false; } return true; } // Read meta event: static boolean ReadMetaEvent(midi_event_t *event, FILE *stream) { byte b; event->event_type = MIDI_EVENT_META; // Read meta event type: if (!ReadByte(&b, stream)) { fprintf(stderr, "ReadMetaEvent: Failed to read meta event type\n"); return false; } event->data.meta.type = b; // Read length of meta event data: if (!ReadVariableLength(&event->data.meta.length, stream)) { fprintf(stderr, "ReadSysExEvent: Failed to read length of " "SysEx block\n"); return false; } // Read the byte sequence: event->data.meta.data = ReadByteSequence(event->data.meta.length, stream); if (event->data.meta.data == NULL) { fprintf(stderr, "ReadSysExEvent: Failed while reading SysEx event\n"); return false; } return true; } static boolean ReadEvent(midi_event_t *event, unsigned int *last_event_type, FILE *stream) { byte event_type; if (!ReadVariableLength(&event->delta_time, stream)) { fprintf(stderr, "ReadEvent: Failed to read event timestamp\n"); return false; } if (!ReadByte(&event_type, stream)) { fprintf(stderr, "ReadEvent: Failed to read event type\n"); return false; } // All event types have their top bit set. Therefore, if // the top bit is not set, it is because we are using the "same // as previous event type" shortcut to save a byte. Skip back // a byte so that we read this byte again. if ((event_type & 0x80) == 0) { event_type = *last_event_type; if (fseek(stream, -1, SEEK_CUR) < 0) { fprintf(stderr, "ReadEvent: Unable to seek in stream\n"); return false; } } else { *last_event_type = event_type; } // Check event type: switch (event_type & 0xf0) { // 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(event, event_type, true, stream); // Single parameter channel events: case MIDI_EVENT_PROGRAM_CHANGE: case MIDI_EVENT_CHAN_AFTERTOUCH: return ReadChannelEvent(event, event_type, false, stream); default: break; } // Specific value? switch (event_type) { case MIDI_EVENT_SYSEX: case MIDI_EVENT_SYSEX_SPLIT: return ReadSysExEvent(event, event_type, stream); case MIDI_EVENT_META: return ReadMetaEvent(event, stream); default: break; } fprintf(stderr, "ReadEvent: Unknown MIDI event type: 0x%x\n", event_type); return false; } // Free an event: static void FreeEvent(midi_event_t *event) { // Some event types have dynamically allocated buffers assigned // to them that must be freed. switch (event->event_type) { case MIDI_EVENT_SYSEX: case MIDI_EVENT_SYSEX_SPLIT: free(event->data.sysex.data); break; case MIDI_EVENT_META: free(event->data.meta.data); break; default: // Nothing to do. break; } } // Read and check the track chunk header static boolean ReadTrackHeader(midi_track_t *track, FILE *stream) { size_t records_read; chunk_header_t chunk_header; records_read = fread(&chunk_header, sizeof(chunk_header_t), 1, stream); if (records_read < 1) { return false; } if (!CheckChunkHeader(&chunk_header, TRACK_CHUNK_ID)) { return false; } track->data_len = SDL_SwapBE32(chunk_header.chunk_size); return true; } static boolean ReadTrack(midi_track_t *track, FILE *stream) { midi_event_t *new_events; midi_event_t *event; unsigned int last_event_type; track->num_events = 0; track->events = NULL; // Read the header: if (!ReadTrackHeader(track, stream)) { return false; } // Then the events: last_event_type = 0; for (;;) { // Resize the track slightly larger to hold another event: new_events = realloc(track->events, sizeof(midi_event_t) * (track->num_events + 1)); if (new_events == NULL) { return false; } track->events = new_events; // Read the next event: event = &track->events[track->num_events]; if (!ReadEvent(event, &last_event_type, stream)) { return false; } ++track->num_events; // End of track? if (event->event_type == MIDI_EVENT_META && event->data.meta.type == MIDI_META_END_OF_TRACK) { break; } } return true; } // Free a track: static void FreeTrack(midi_track_t *track) { unsigned int i; for (i=0; i<track->num_events; ++i) { FreeEvent(&track->events[i]); } free(track->events); } static boolean ReadAllTracks(midi_file_t *file, FILE *stream) { unsigned int i; // Allocate list of tracks and read each track: file->tracks = malloc(sizeof(midi_track_t) * file->num_tracks); if (file->tracks == NULL) { return false; } memset(file->tracks, 0, sizeof(midi_track_t) * file->num_tracks); // Read each track: for (i=0; i<file->num_tracks; ++i) { if (!ReadTrack(&file->tracks[i], stream)) { return false; } } return true; } // Read and check the header chunk. static boolean ReadFileHeader(midi_file_t *file, FILE *stream) { size_t records_read; unsigned int format_type; records_read = fread(&file->header, sizeof(midi_header_t), 1, stream); if (records_read < 1) { return false; } if (!CheckChunkHeader(&file->header.chunk_header, HEADER_CHUNK_ID) || SDL_SwapBE32(file->header.chunk_header.chunk_size) != 6) { fprintf(stderr, "ReadFileHeader: Invalid MIDI chunk header! " "chunk_size=%i\n", SDL_SwapBE32(file->header.chunk_header.chunk_size)); return false; } format_type = SDL_SwapBE16(file->header.format_type); file->num_tracks = SDL_SwapBE16(file->header.num_tracks); if ((format_type != 0 && format_type != 1) || file->num_tracks < 1) { fprintf(stderr, "ReadFileHeader: Only type 0/1 " "MIDI files supported!\n"); return false; } return true; } void MIDI_FreeFile(midi_file_t *file) { int i; if (file->tracks != NULL) { for (i=0; i<file->num_tracks; ++i) { FreeTrack(&file->tracks[i]); } free(file->tracks); } free(file); } midi_file_t *MIDI_LoadFile(char *filename) { midi_file_t *file; FILE *stream; file = malloc(sizeof(midi_file_t)); if (file == NULL) { return NULL; } file->tracks = NULL; file->num_tracks = 0; file->buffer = NULL; file->buffer_size = 0; // Open file stream = fopen(filename, "rb"); if (stream == NULL) { fprintf(stderr, "MIDI_LoadFile: Failed to open '%s'\n", filename); MIDI_FreeFile(file); return NULL; } // Read MIDI file header if (!ReadFileHeader(file, stream)) { fclose(stream); MIDI_FreeFile(file); return NULL; } // Read all tracks: if (!ReadAllTracks(file, stream)) { fclose(stream); MIDI_FreeFile(file); return NULL; } fclose(stream); return file; } // Get the number of tracks in a MIDI file. unsigned int MIDI_NumTracks(midi_file_t *file) { return file->num_tracks; } // Start iterating over the events in a track. midi_track_iter_t *MIDI_IterateTrack(midi_file_t *file, unsigned int track) { midi_track_iter_t *iter; assert(track < file->num_tracks); iter = malloc(sizeof(*iter)); iter->track = &file->tracks[track]; iter->position = 0; return iter; } void MIDI_FreeIterator(midi_track_iter_t *iter) { free(iter); } // Get the time until the next MIDI event in a track. unsigned int MIDI_GetDeltaTime(midi_track_iter_t *iter) { if (iter->position < iter->track->num_events) { midi_event_t *next_event; next_event = &iter->track->events[iter->position]; return next_event->delta_time; } else { return 0; } } // Get a pointer to the next MIDI event. int MIDI_GetNextEvent(midi_track_iter_t *iter, midi_event_t **event) { if (iter->position < iter->track->num_events) { *event = &iter->track->events[iter->position]; ++iter->position; return 1; } else { return 0; } } unsigned int MIDI_GetFileTimeDivision(midi_file_t *file) { return file->header.time_division; } void MIDI_RestartIterator(midi_track_iter_t *iter) { iter->position = 0; } #ifdef TEST static char *MIDI_EventTypeToString(midi_event_type_t event_type) { switch (event_type) { case MIDI_EVENT_NOTE_OFF: return "MIDI_EVENT_NOTE_OFF"; case MIDI_EVENT_NOTE_ON: return "MIDI_EVENT_NOTE_ON"; case MIDI_EVENT_AFTERTOUCH: return "MIDI_EVENT_AFTERTOUCH"; case MIDI_EVENT_CONTROLLER: return "MIDI_EVENT_CONTROLLER"; case MIDI_EVENT_PROGRAM_CHANGE: return "MIDI_EVENT_PROGRAM_CHANGE"; case MIDI_EVENT_CHAN_AFTERTOUCH: return "MIDI_EVENT_CHAN_AFTERTOUCH"; case MIDI_EVENT_PITCH_BEND: return "MIDI_EVENT_PITCH_BEND"; case MIDI_EVENT_SYSEX: return "MIDI_EVENT_SYSEX"; case MIDI_EVENT_SYSEX_SPLIT: return "MIDI_EVENT_SYSEX_SPLIT"; case MIDI_EVENT_META: return "MIDI_EVENT_META"; default: return "(unknown)"; } } void PrintTrack(midi_track_t *track) { midi_event_t *event; unsigned int i; for (i=0; i<track->num_events; ++i) { event = &track->events[i]; if (event->delta_time > 0) { printf("Delay: %i ticks\n", event->delta_time); } printf("Event type: %s (%i)\n", MIDI_EventTypeToString(event->event_type), event->event_type); switch(event->event_type) { case MIDI_EVENT_NOTE_OFF: case MIDI_EVENT_NOTE_ON: case MIDI_EVENT_AFTERTOUCH: case MIDI_EVENT_CONTROLLER: case MIDI_EVENT_PROGRAM_CHANGE: case MIDI_EVENT_CHAN_AFTERTOUCH: case MIDI_EVENT_PITCH_BEND: printf("\tChannel: %i\n", event->data.channel.channel); printf("\tParameter 1: %i\n", event->data.channel.param1); printf("\tParameter 2: %i\n", event->data.channel.param2); break; case MIDI_EVENT_SYSEX: case MIDI_EVENT_SYSEX_SPLIT: printf("\tLength: %i\n", event->data.sysex.length); break; case MIDI_EVENT_META: printf("\tMeta type: %i\n", event->data.meta.type); printf("\tLength: %i\n", event->data.meta.length); break; } } } int main(int argc, char *argv[]) { midi_file_t *file; unsigned int i; if (argc < 2) { printf("Usage: %s <filename>\n", argv[0]); exit(1); } file = MIDI_LoadFile(argv[1]); if (file == NULL) { fprintf(stderr, "Failed to open %s\n", argv[1]); exit(1); } for (i=0; i<file->num_tracks; ++i) { printf("\n== Track %i ==\n\n", i); PrintTrack(&file->tracks[i]); } return 0; } #endif