Make sure to set the magic value in vector table :

<code>
#include <stdint.h>

__attribute__((interrupt_handler))
__attribute__((section(".smallfunc")))
void doNothing(void) { /*asm volatile ("nop");*/ }

__attribute__((noreturn))
__attribute__((interrupt_handler))
__attribute__((section(".smallfunc")))
void halt(void) { while(1); }
#define RESERVED halt

// Vector table laid out according to SH7021 datasheet tables 4.2, 5.3.
__attribute__((section (".vectors"), used))
void (* const vector_table[])(void) = {
/* Reset vectors */
/* Never used, BIOS has its own at address 0 */
    // Power-on reset
    RESERVED, RESERVED,
    // Manual reset
    RESERVED, RESERVED,
/* CPU interrupts */
/* Always active, except User Break masked at level 15 */
    // General illegal instruction
    halt,
    // (Reserved for system use)
    RESERVED,
    // Illegal slot instruction
    halt,
    // (Reserved for system use)
    RESERVED, RESERVED,
    // CPU address error
    halt,
    // DMA address error
    halt,
    // NMI
    doNothing,
    // User Break
    doNothing,
    // (Reserved for system use)
    RESERVED, RESERVED, RESERVED, RESERVED,
    RESERVED, RESERVED, RESERVED, RESERVED,
    RESERVED, RESERVED, RESERVED, RESERVED,
    RESERVED, RESERVED, RESERVED, RESERVED,
    RESERVED, RESERVED, RESERVED,
    // Trap instruction (user vectors)
    doNothing, doNothing, doNothing, doNothing,
    doNothing, doNothing, doNothing, doNothing,
    doNothing, doNothing, doNothing, doNothing,
    doNothing, doNothing, doNothing, doNothing,
    doNothing, doNothing, doNothing, doNothing,
    doNothing, doNothing, doNothing, doNothing,
    doNothing, doNothing, doNothing, doNothing,
    doNothing, doNothing, doNothing, doNothing,
/* IRQ and on-chip module interrupts */
/* Set nonzero, nonmasked priority in IPRA-IPRB to enable */
    // IRQ0..IRQ7
    doNothing, doNothing, doNothing, doNothing,
    doNothing, doNothing, doNothing, doNothing,
    // DMAC0..DMAC3 (DEI, Reserved)
    doNothing, RESERVED,
    doNothing, RESERVED,
    doNothing, RESERVED,
    doNothing, RESERVED,
    // ITU0..ITU4 (IMIA, IMIB, OVI, Reserved)
    ((const void (*)(void))0x648C), doNothing, doNothing, RESERVED,
    doNothing, doNothing, doNothing, RESERVED,
    doNothing, doNothing, doNothing, RESERVED,
    doNothing, doNothing, doNothing, RESERVED,
    doNothing, doNothing, doNothing, RESERVED,
    // SCI0..SCI1 (ERI, RxI, TxI, TEI)
    serial_ERI0, serial_RxI0, doNothing, doNothing,
    doNothing, doNothing, doNothing, doNothing,
    // PRT PEI
    doNothing,
    // Reserved
    RESERVED, RESERVED, RESERVED,
    // WDT
    halt,
    // REF CMI
    halt,
    // Reserved
    RESERVED, RESERVED
};
</code>

Code for playing music
<code>
#include <stdint.h>
#include "loopy.h"
#include "tracksong2.h"

volatile void (*BiosVsync)(void) = (void (*)(void))0x6A5A;

uint16_t soundState[128];

void **biosSoundState = (void **) 0x0900003C;

void (*const BiosSoundDemo)(void) = (void (*)())0x6B86;

void (*const BiosInitSoundTransmission)() = (void (*)())0x613C;
void (*const BiosSoundChannels)(int) = (void (*)(int))0x6AC0;
void (*const BiosSoundVolume)(int, int) = (void (*)(int, int))0x6B50;
void (*const BiosPlayBGM)(void*, int, int, void**) = (void (*)(void*, int, int, void**))0x61A0;

const void *trackList[] = {
(const void*)_track_song2
};

int main() 
{
*biosSoundState = &soundState[0];

DMAOR = 0x0001;
IPRC = (IPRC & 0xFF0F) | 0x0080; // Enable Timer Interrupt
maskInterrupts(0);

BiosSoundChannels(2);
BiosSoundVolume(0, 2);
BiosSoundVolume(1, 2);
BiosInitSoundTransmission();
BiosPlayBGM((void *)soundState, 0xFF, 0, (void **)trackList);

VDP_BMn_SCROLLX[0] = 0xEA;
VDP_BMn_SCROLLX[0] = 0xAE;

    while(1)
    {
        BiosVsync();
    }
    return 0;
}
</code>

Example song 
<code>
#ifndef TRACK_SONG2_H
#define TRACK_SONG2_H

#include <stdint.h>

// Example boot logo track data (bytes given in hex)
const uint8_t _track_song2[] = {
    0x87, 0xA2,       // Timer rate 144 BPM
    0x08, 0xA0,       // Control value (ch2/3 high volume, ch4 mid volume)

    0x00,             // Delay 0
    0x0F,             // MidiData 15 bytes
    0xC0, 0x60,       // ProgramChange Channel=1 Instrument=60h
    0x90, 0x38, 0x40, // NoteOn Channel=1 Note=38h Velocity=40h
    0xC1, 0x5C,       // ProgramChange Channel=2 Instrument=5Ch
    0x91, 0x38, 0x40, // NoteOn Channel=2 Note=38h Velocity=40h
    0xC3, 0x50,       // ProgramChange Channel=4 Instrument=50h
    0x93, 0x38, 0x40, // NoteOn Channel=4 Note=38h Velocity=40h

    0x04,             // Delay 4
    0x03,             // MidiData 3 bytes
    0x90, 0x38, 0x00, // NoteOn Channel=1 Note=38h Velocity=OFF

    0x07,             // Delay 7
    0x03,             // MidiData 3 bytes
    0x91, 0x38, 0x00, // NoteOn Channel=2 Note=38h Velocity=OFF

    0x01,             // Delay 1
    0x06,             // MidiData 6 bytes
    0x90, 0x3C, 0x40, // NoteOn Channel=1 Note=3Ch Velocity=40h
    0x91, 0x3C, 0x40, // NoteOn Channel=2 Note=3Ch Velocity=40h

    0x04,             // Delay 4
    0x03,             // MidiData 3 bytes
    0x90, 0x3C, 0x00, // NoteOn Channel=1 Note=3Ch Velocity=OFF

    0x05,             // Delay 5
    0x03,             // MidiData 3 bytes
    0x91, 0x3C, 0x00, // NoteOn Channel=2 Note=3Ch Velocity=OFF

    0x03,             // Delay 3
    0x06,             // MidiData 6 bytes
    0x90, 0x3F, 0x40, // NoteOn Channel=1 Note=3Fh Velocity=40h
    0x91, 0x3F, 0x40, // NoteOn Channel=2 Note=3Fh Velocity=40h

    0x04,             // Delay 4
    0x03,             // MidiData 3 bytes
    0x90, 0x3F, 0x00, // NoteOn Channel=1 Note=3Fh Velocity=OFF

    0x02,             // Delay 2
    0x03,             // MidiData 3 bytes
    0x91, 0x3F, 0x00, // NoteOn Channel=2 Note=3Fh Velocity=OFF

    0x06,             // Delay 6
    0x06,             // MidiData 6 bytes
    0x90, 0x46, 0x40, // NoteOn Channel=1 Note=46h Velocity=40h
    0x91, 0x46, 0x40, // NoteOn Channel=2 Note=46h Velocity=40h

    0x04,             // Delay 4
    0x03,             // MidiData 3 bytes
    0x90, 0x46, 0x00, // NoteOn Channel=1 Note=46h Velocity=OFF

    0x04,             // Delay 4
    0x03,             // MidiData 3 bytes
    0x91, 0x46, 0x00, // NoteOn Channel=2 Note=46h Velocity=OFF

    0x04,             // Delay 4
    0x0C,             // MidiData 12 bytes
    0x90, 0x4B, 0x40, // NoteOn Channel=1 Note=4Bh Velocity=40h
    0x91, 0x4B, 0x40, // NoteOn Channel=2 Note=4Bh Velocity=40h
    0x93, 0x38, 0x00, // NoteOn Channel=4 Note=38h Velocity=OFF
    0x93, 0x3A, 0x40, // NoteOn Channel=4 Note=3Ah Velocity=40h

    0x04,             // Delay 4
    0x03,             // MidiData 3 bytes
    0x90, 0x4B, 0x00, // NoteOn Channel=1 Note=4Bh Velocity=OFF

    0x04,             // Delay 4
    0x03,             // MidiData 3 bytes
    0x91, 0x4B, 0x00, // NoteOn Channel=2 Note=4Bh Velocity=OFF

    0x05,             // Delay 5
    0x06,             // MidiData 6 bytes
    0x90, 0x4F, 0x40, // NoteOn Channel=1 Note=4Fh Velocity=40h
    0x91, 0x4F, 0x40, // NoteOn Channel=2 Note=4Fh Velocity=40h

    0x04,             // Delay 4
    0x03,             // MidiData 3 bytes
    0x90, 0x4F, 0x00, // NoteOn Channel=1 Note=4Fh Velocity=OFF

    0x04,             // Delay 4
    0x03,             // MidiData 3 bytes
    0x91, 0x4F, 0x00, // NoteOn Channel=2 Note=4Fh Velocity=OFF

    0x8D,             // Delay 141
    0x03,             // MidiData 3 bytes
    0x93, 0x3A, 0x00, // NoteOn Channel=4 Note=3Ah Velocity=OFF

    0x00,             // Delay 0
    0xFE, 0xFF, 0xFF  // TrackChange, Index=STOP
};

#endif // TRACK_SONG2_H
</code>