#include <u.h>
#include <libc.h>
#include <bio.h>

void
main(int argc, char *argv[])
{
	Biobuf in;
	Biobuf out;
	uchar b[2];
	int x[4], y;
	int t;

	if(argc != 2)
		exits("usage");
	Binit(&in, 0, OREAD);
	Binit(&out, 1, OWRITE);

	if(strcmp(argv[1], "nearest") == 0){
		t = 0;
		for(;;){
			if(Bread(&in, b, 2) < 2)
				break;
			t -= 1<<16;
			do{
				Bwrite(&out, b, 2);
				t += (32000<<16)/44100;
			}while(t < 0);
		}
	}else if(strcmp(argv[1], "linear") == 0){
		t = 1<<16;
		for(;;){
			if(Bread(&in, b, 2) < 2)
				break;
			x[0] = (s16int)(b[1] << 8 | b[0]);
			do{
				y = x[1] + ((x[0] - x[1]) * t >> 16);
				b[0] = y & 0xff;
				b[1] = y >> 8;
				Bwrite(&out, b, 2);
				t += (32000<<16)/44100;
			}while(t < 1<<16);
			t -= 1<<16;
			x[1] = x[0];
		}
	}else if(strcmp(argv[1], "hermite") == 0){
		t = 1<<15;
		for(;;){
			if(Bread(&in, b, 2) < 2)
				break;
			x[0] = (s16int)(b[1] << 8 | b[0]);
			do{
				y = (x[0] - x[3]) / 2 + (x[2] - x[1]) * 3 / 2;
				y = y * t >> 15;
				y += x[3] - x[2] * 5 / 2 + x[1] * 2 - x[0] / 2;
				y = y * t >> 15;
				y += (x[1] - x[3]) / 2;
				y = y * t >> 15;
				y += x[2];
				b[0] = y & 0xff;
				b[1] = y >> 8;
				Bwrite(&out, b, 2);
				t += (32000<<15)/44100;
			}while(t < 1<<15);
			t -= 1<<15;
			memmove(x + 1, x, sizeof(x) - sizeof(x[0]));
		}
	}
	exits(nil);
}