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/*
MIDI File Input/Output Utilities
*/
#include <stdio.h>
#include <stdlib.h>
#include "types.h"
#include "midifile.h"
#include "midio.h"
/* Low level input functions. */
/* READLONG -- Read long from a file (byte-order independent) */
long readlong(FILE *fp)
{
unsigned char c[4];
fread((char *) c, 1, sizeof c, fp);
return (long) ((c[0] << 24) | (c[1] << 16) | (c[2] << 8) | c[3]);
}
/* READSHORT -- Read short from a file (byte-order independent) */
short readshort(FILE *fp)
{
unsigned char c[2];
fread((char *) c, 1, sizeof c, fp);
return (short) ((c[0] << 8) | c[1]);
}
/* READVARLEN -- Parse variable length value from MIDI file */
vlint readVarLen(FILE *fp)
{
long value;
int ch;
if ((value = getc(fp)) & 0x80) {
value &= 0x7F;
do {
value = (value << 7) | ((ch = getc(fp)) & 0x7F);
} while (ch & 0x80);
}
return value;
}
/* High level input functions. */
/* READMIDIFILEHEADER -- Read file header structure. */
void readMidiFileHeader(FILE *fp, struct mhead *h)
{
fread(h->chunktype, sizeof h->chunktype, 1, fp);
h->length = readlong(fp);
h->format = readshort(fp);
h->ntrks = readshort(fp);
h->division = readshort(fp);
}
/* READMIDITRACKHEADER -- Read track header structure. */
void readMidiTrackHeader(FILE *fp, struct mtrack *t)
{
fread(t->chunktype, sizeof t->chunktype, 1, fp);
t->length = readlong(fp);
}
/* Low level output functions. */
/* WRITELONG -- Write a long to a file in big-endian order */
void writelong(FILE *fp, const long l)
{
putc((l >> 24) & 0xFF, fp);
putc((l >> 16) & 0xFF, fp);
putc((l >> 8) & 0xFF, fp);
putc(l & 0xFF, fp);
}
/* WRITESHORT -- Write a short to a file in big-endian order */
void writeshort(FILE *fp, const short s)
{
putc((s >> 8) & 0xFF, fp);
putc(s & 0xFF, fp);
}
/* WRITEVARLEN -- Write variable length value to MIDI file */
void writeVarLen(FILE *fp, const vlint v)
{
vlint value = v;
long buffer;
buffer = value & 0x7F;
while ((value >>= 7) > 0) {
buffer <<= 8;
buffer |= 0x80;
buffer += (value & 0x7F);
}
while (1) {
putc((int) (buffer & 0xFF), fp);
if (buffer & 0x80) {
buffer >>= 8;
} else {
break;
}
}
}
/* High level output functions. */
/* WRITEMIDIFILEHEADER -- Write file header structure. */
void writeMidiFileHeader(FILE *fp, struct mhead *h)
{
fwrite(h->chunktype, sizeof h->chunktype, 1, fp);
writelong(fp, h->length);
writeshort(fp, h->format);
writeshort(fp, h->ntrks);
writeshort(fp, h->division);
}
/* WRITEMIDITRACKHEADER -- Write track header structure. */
void writeMidiTrackHeader(FILE *fp, struct mtrack *t)
{
fwrite(t->chunktype, sizeof t->chunktype, 1, fp);
writelong(fp, t->length);
}
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