[森のタクト] アニメーションを再生速度に合わせて変化させる

#include <alsa/asoundlib.h>

static snd_seq_t *seq_handle[6];
static snd_seq_event_t ev[6];
float ref_value[11];

void note_on(unsigned char num, unsigned char ch, unsigned char note, unsigned char velocity){
    //省略
}

void note_off(unsigned char num, unsigned char ch, unsigned char note, unsigned char velocity){
    //省略
}

unsigned char find_nearest_idx(float coeff){
    //ref_value[]の中身とcoeffを比較してもっとも近いインデックスのものを返す（コード省略）

    return nearest_idx;
}

void speed_msg(unsigned char num, unsigned char speed){
    static unsigned char dataptr[3] = {0xf0, 0x00, 0xf7};
    dataptr[1] = speed;
    snd_seq_ev_set_sysex(&ev[num], (unsigned int)sizeof(dataptr), dataptr);
    send_event(num, 1);
}


void calc_speed(){
    //途中省略

    //基本のテンポ周期からどれだけズレているか係数を計算
    coeff = (float) dur / (BASE_PERIOD * 1000000)
    //速度係数から11段階の速度インデックスに変換
    unsigned char idx = find_nearest_idx(coeff);
    //サーバーへ送信
    for(i = 0; i < NUM_SERVER; i++){
        speed_msg(i, idx);
    }
}

int main(){

    //速度係数coeffと１１段階の速度を対応付けるための配列を予め作成
    for (i = 0; i < 11 ; i++){
        ref_value[i] = (float) pow(2.0, -1+0.2*i);
    }

    //曲の再生
    for(p = datahead->next; p != NULL; p = p->next){
        //省略
    }

    return 0;
}

//新しく追加
static void set_gpio(snd_seq_event_t *ev){
	static unsigned char *dataptr;

	switch (ev->type) {
		case SND_SEQ_EVENT_SYSEX:
				dataptr = (unsigned char*)ev->data.ext.ptr;
                //ここでデータの受け取り
				speed_idx = dataptr[1];
				printf("Sys EX, datalen:%d, data:%d \n", ev->data.ext.len, speed_idx);
				break;

		case SND_SEQ_EVENT_NOTEON:
			if(ev->data.note.velocity == 0){
					//Note off

			}else{
					//Note on
			}

			break;
		case SND_SEQ_EVENT_NOTEOFF:
			//Note off
			break;
	}
}


//この部分を改変
static int copy_remote_to_local(int fd)
{
	int count;
	char *buf;
	snd_seq_event_t *ev;

	count = read(fd, readbuf, MAX_BUF_EVENTS * sizeof(snd_seq_event_t));
	buf = readbuf;

	if (count == 0) {
		if (verbose)
			fprintf(stderr, _("disconnected\n"));
		return 1;
	}

	while (count > 0) {
		ev = (snd_seq_event_t*)buf;
		buf += EVENT_PACKET_SIZE;
		count -= EVENT_PACKET_SIZE;
		if (snd_seq_ev_is_variable(ev) && ev->data.ext.len > 0) {
			ev->data.ext.ptr = buf;
			buf += ev->data.ext.len;
			count -= ev->data.ext.len;
		}


		snd_seq_ev_set_direct(ev);
		snd_seq_ev_set_source(ev, seq_port);
		snd_seq_ev_set_subs(ev);
		if (info)
			print_event(ev);
		snd_seq_event_output(handle, ev);

		//ここに追加
		set_gpio(ev);
	}

	snd_seq_drain_output(handle);
	return 0;
}