From: John Tsiombikas <nuclear@member.fsf.org>
Date: Fri, 17 Jun 2022 00:18:32 +0000 (+0300)
Subject: - running status detection
X-Git-Url: http://git.mutantstargoat.com/user/nuclear/?a=commitdiff_plain;h=HEAD;p=midifile

- running status detection
- ignore unknown MIDI messages
- implement non-UNIX fallback for map_file/unmap_file
---

diff --git a/src/midi.c b/src/midi.c
index 60613d6..f6fc49e 100644
--- a/src/midi.c
+++ b/src/midi.c
@@ -3,13 +3,10 @@
 #include <string.h>
 #include <errno.h>
 #include <inttypes.h>
-#include <unistd.h>
-#include <fcntl.h>
-#include <sys/mman.h>
-#include <sys/stat.h>
-#include <arpa/inet.h>
 #include "midi.h"
 
+#define USE_MMAP
+
 #define FMT_SINGLE		0
 #define FMT_MULTI_TRACK	1
 #define FMT_MULTI_SEQ	2
@@ -31,28 +28,6 @@
 #define META_KEYSIG		89
 #define META_SPECIFIC	127
 
-struct midi {
-	int bpm;
-
-	int num_tracks;
-	struct midi_track *tracks;
-};
-
-struct midi_track {
-	char *name;
-	struct midi_event *head, *tail;
-	int num_ev;
-};
-
-struct midi_event {
-	long dt;
-	int type;
-	int channel;
-	int arg[2];
-
-	struct midi_event *next;
-};
-
 #define CHUNK_HDR_SIZE	8
 struct chunk_hdr {
 	char id[4];
@@ -185,6 +160,8 @@ static int read_track(struct midi *midi, struct chunk_hdr *chunk)
 	unsigned char *ptr;
 	struct midi_track trk = {0, 0, 0, 0};
 	unsigned char prev_stat = 0;
+	int type;
+	struct midi_event *ev;
 
 	if(!ischunk(chunk, "MTrk")) {
 		return -1;
@@ -195,7 +172,6 @@ static int read_track(struct midi *midi, struct chunk_hdr *chunk)
 		long dt;
 		unsigned char stat;
 
-		/* TODO also convert dt to some standard unit */
 		dt = read_vardata(&ptr);
 		stat = *ptr++;
 
@@ -204,7 +180,20 @@ static int read_track(struct midi *midi, struct chunk_hdr *chunk)
 		} else if(stat == 0xf0) {
 			read_sysex_event(midi, &ptr);
 		} else {
-			struct midi_event *ev = malloc(sizeof *ev);
+			if(!(stat & 0x80)) {
+				/* not a status byte, assume running status */
+				stat = prev_stat;
+				ptr--;
+			}
+			type = (stat >> 4) & 0xf;
+
+			if(!IS_VALID_EVTYPE(type) || !(ev = malloc(sizeof *ev))) {
+				/* unkwown message, skip all data bytes */
+				while(ptr < chunk->data + chunk->size && !(*ptr & 0x80)) {
+					ptr++;
+				}
+				continue;
+			}
 
 			if(trk.head) {
 				trk.tail->next = ev;
@@ -215,18 +204,8 @@ static int read_track(struct midi *midi, struct chunk_hdr *chunk)
 			ev->next = 0;
 			trk.num_ev++;
 
-			if(!(stat & 0x80)) {
-				/* not a status byte, assume running status */
-				stat = prev_stat;
-				ptr--;
-			}
-
 			ev->dt = dt;
-			ev->type = (stat >> 4) & 0xf;
-			if(!IS_VALID_EVTYPE(ev->type)) {
-				fprintf(stderr, "warning, skipping track with unknown event %d\n", ev->type);
-				return -1;
-			}
+			ev->type = type;
 			ev->channel = stat & 0xf;
 
 			ev->arg[0] = *ptr++;
@@ -234,6 +213,10 @@ static int read_track(struct midi *midi, struct chunk_hdr *chunk)
 				ev->arg[1] = *ptr++;
 			}
 
+			if(ev->type == MIDI_NOTE_ON && ev->arg[1] == 0) {
+				ev->type = MIDI_NOTE_OFF;
+			}
+
 			prev_stat = stat;
 		}
 	}
@@ -328,13 +311,24 @@ static struct midi_hdr *mkmidi(void *ptr)
 
 static void bigend(void *ptr, int sz)
 {
+	static unsigned char test[] = {0x12, 0x34};
+	uint32_t val32;
+	uint16_t val16;
+
+	if(sz < 2 || *(uint16_t*)test == 0x1234) {
+		return;
+	}
+
 	switch(sz) {
 	case 4:
-		*((uint32_t*)ptr) = ntohl(*(uint32_t*)ptr);
+		val32 = *(uint32_t*)ptr;
+		*(uint32_t*)ptr = (val32 << 24) | (val32 >> 24) | ((val32 & 0xff00) << 8) |
+			((val32 & 0xff0000) >> 8);
 		break;
 
 	case 2:
-		*(uint16_t*)ptr = ntohs(*(uint16_t*)ptr);
+		val16 = *(uint16_t*)ptr;
+		*(uint16_t*)ptr = (val16 >> 8) | (val16 << 8);
 		break;
 
 	case 1:
@@ -343,6 +337,12 @@ static void bigend(void *ptr, int sz)
 	}
 }
 
+#if defined(__unix__) && defined(USE_MMAP)
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+
 static void *map_file(const char *fname, int *size)
 {
 	int fd;
@@ -370,3 +370,40 @@ static void unmap_file(void *mem, int size)
 {
 	munmap(mem, size);
 }
+#else
+static void *map_file(const char *fname, int *size)
+{
+	FILE *fp;
+	long sz;
+	void *buf;
+
+	if(!(fp = fopen(fname, "rb"))) {
+		fprintf(stderr, "failed to open midi file: %s: %s\n", fname, strerror(errno));
+		return 0;
+	}
+	fseek(fp, 0, SEEK_END);
+	sz = ftell(fp);
+	rewind(fp);
+
+	if(!(buf = malloc(sz))) {
+		fprintf(stderr, "failed to allocate space for %s in memory (%ld bytes)\n", fname, sz);
+		fclose(fp);
+		return 0;
+	}
+	if(fread(buf, 1, sz, fp) != sz) {
+		fprintf(stderr, "failed to load midi file: %s: %s\n", fname, strerror(errno));
+		free(buf);
+		fclose(fp);
+		return 0;
+	}
+	fclose(fp);
+
+	*size = sz;
+	return buf;
+}
+
+static void unmap_file(void *mem, int size)
+{
+	free(mem);
+}
+#endif
diff --git a/src/midi.h b/src/midi.h
index 4ad08a4..96fefa8 100644
--- a/src/midi.h
+++ b/src/midi.h
@@ -3,9 +3,27 @@
 
 #include <stdio.h>
 
-struct midi;
-struct midi_track;
-struct midi_event;
+struct midi {
+	int bpm;
+
+	int num_tracks;
+	struct midi_track *tracks;
+};
+
+struct midi_track {
+	char *name;
+	struct midi_event *head, *tail;
+	int num_ev;
+};
+
+struct midi_event {
+	long dt;
+	int type;
+	int channel;
+	int arg[2];
+
+	struct midi_event *next;
+};
 
 #define MIDI_NOTE_OFF			8
 #define MIDI_NOTE_ON			9
@@ -15,6 +33,9 @@ struct midi_event;
 #define MIDI_CHAN_AFTERTOUCH	13
 #define MIDI_PITCH_BEND			14
 
+#define MIDI_NOTE_NUM(ev)	((ev)->arg[0])
+#define MIDI_NOTE_VEL(ev)	((ev)->arg[1])
+
 #ifdef __cplusplus
 extern "C" {
 #endif