ref: 2b64dfc84981dbbd9de1a0d9cb11995bf0ba9379
parent: b96cdbe82fa6cb51ac91072ad86e084d739fd9be
author: Simon Howard <fraggle@gmail.com>
date: Sun Mar 29 18:39:25 EDT 2009
Parse SysEx, meta events Subversion-branch: /branches/opl-branch Subversion-revision: 1490
--- a/src/midifile.c
+++ b/src/midifile.c
@@ -53,6 +53,10 @@
FILE *stream;
midi_header_t header;
unsigned int data_len;
+
+ // Data buffer used to store data read for SysEx or meta events:
+ byte *buffer;
+ unsigned int buffer_size;
};
static boolean CheckChunkHeader(chunk_header_t *chunk,
@@ -137,6 +141,9 @@
return NULL;
}
+ file->buffer = NULL;
+ file->buffer_size = 0;
+
// Open file
file->stream = fopen(filename, "rb");
@@ -172,9 +179,116 @@
void MIDI_CloseFile(midi_file_t *file)
{fclose(file->stream);
+ free(file->buffer);
free(file);
}
+// Read a single byte. Returns false on error.
+
+static boolean ReadByte(midi_file_t *file, byte *result)
+{+ int c;
+
+ c = fgetc(file->stream);
+
+ if (c == EOF)
+ {+ return false;
+ }
+ else
+ {+ *result = (byte) c;
+
+ return true;
+ }
+}
+
+// Read a variable-length value.
+
+static boolean ReadVariableLength(midi_file_t *file, unsigned int *result)
+{+ int i;
+ byte b;
+
+ *result = 0;
+
+ for (i=0; i<4; ++i)
+ {+ if (!ReadByte(file, &b))
+ {+ fprintf(stderr, "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, "Variable-length value too long: maximum of four bytes!\n");;
+ return false;
+}
+
+// Expand the size of the buffer used for SysEx/Meta events:
+
+static boolean ExpandBuffer(midi_file_t *file, unsigned int new_size)
+{+ byte *new_buffer;
+
+ if (file->buffer_size < new_size)
+ {+ // Reallocate to a larger size:
+
+ new_buffer = realloc(file->buffer, new_size);
+
+ if (new_buffer == NULL)
+ {+ fprintf(stderr, "ExpandBuffer: Failed to expand buffer to %u "
+ "bytes\n", new_size);
+ return false;
+ }
+
+ file->buffer = new_buffer;
+ file->buffer_size = new_size;
+ }
+
+ return true;
+}
+
+// Read a byte sequence into the data buffer.
+
+static boolean ReadByteSequence(midi_file_t *file, unsigned int num_bytes)
+{+ unsigned int i;
+
+ // Check that we have enough space:
+
+ if (!ExpandBuffer(file, num_bytes))
+ {+ return false;
+ }
+
+ for (i=0; i<num_bytes; ++i)
+ {+ if (!ReadByte(file, &file->buffer[i]))
+ {+ fprintf(stderr, "ReadByteSequence: Error while reading byte %u\n",
+ i);
+ return false;
+ }
+ }
+
+ return true;
+}
+
// Read a MIDI channel event.
// two_param indicates that the event type takes two parameters
// (three byte) otherwise it is single parameter (two byte)
@@ -182,7 +296,7 @@
static boolean ReadChannelEvent(midi_file_t *file, midi_event_t *event,
int event_type, boolean two_param)
{- int c;
+ byte b;
// Set basics:
@@ -191,27 +305,23 @@
// Read parameters:
- c = fgetc(file->stream);
-
- if (c == EOF)
+ if (!ReadByte(file, &b))
{return false;
}
- event->data.channel.param1 = c;
+ event->data.channel.param1 = b;
// Second parameter:
if (two_param)
{- c = fgetc(file->stream);
-
- if (c == EOF)
+ if (!ReadByte(file, &b))
{return false;
}
- event->data.channel.param2 = c;
+ event->data.channel.param2 = b;
}
return true;
@@ -222,8 +332,26 @@
static boolean ReadSysExEvent(midi_file_t *file, midi_event_t *event,
int event_type)
{- // TODO
- return false;
+ event->event_type = event_type;
+
+ if (!ReadVariableLength(file, &event->data.sysex.length))
+ {+ fprintf(stderr, "ReadSysExEvent: Failed to read length of "
+ "SysEx block\n");
+ return false;
+ }
+
+ // Read the byte sequence:
+
+ if (!ReadByteSequence(file, event->data.sysex.length))
+ {+ fprintf(stderr, "ReadSysExEvent: Failed while reading SysEx event\n");
+ return false;
+ }
+
+ event->data.sysex.data = file->buffer;
+
+ return true;
}
// Read meta event:
@@ -230,18 +358,53 @@
static boolean ReadMetaEvent(midi_file_t *file, midi_event_t *event)
{- // TODO
+ byte b;
+
+ // Read meta event type:
+
+ if (!ReadByte(file, &b))
+ {+ 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(file, &event->data.meta.length))
+ {+ fprintf(stderr, "ReadSysExEvent: Failed to read length of "
+ "SysEx block\n");
+ return false;
+ }
+
+ // Read the byte sequence:
+
+ if (!ReadByteSequence(file, event->data.meta.length))
+ {+ fprintf(stderr, "ReadSysExEvent: Failed while reading SysEx event\n");
+ return false;
+ }
+
+ event->data.meta.data = file->buffer;
+
return false;
}
boolean MIDI_ReadEvent(midi_file_t *file, midi_event_t *event)
{- int event_type;
+ byte event_type;
- event_type = fgetc(file->stream);
+ if (!ReadVariableLength(file, &event->delta_time))
+ {+ fprintf(stderr, "MIDI_ReadEvent: Failed to read event timestamp\n");
+ return false;
+ }
- if (event_type == EOF)
+ if (!ReadByte(file, &event_type))
{+ fprintf(stderr, "MIDI_ReadEvent: Failed to read event type\n");
return false;
}
@@ -277,7 +440,8 @@
return ReadMetaEvent(file, event);
}
- // Fall-through deliberate -
+ // --- Fall-through deliberate ---
+ // Other 0xfx event types are unknown
default:
fprintf(stderr, "Unknown MIDI event type: 0x%x\n", event_type);