#include <u.h>
#include <libc.h>
void
main(int argc, char *argv[]){
	double f, Δ, s, e, exp;
	vlong u, a, n;
	uchar *b = nil;
	switch(argc){
	default:
		sysfatal("usage: %s [startamp [endamp [exponent]]]", argv[0]);
	case 1:
		s = 1.0;
		e = 0.0;
		exp = 1.0;
		break;
	case 2:
		s = e = atof(argv[1]);
		exp = 1.0;
		break;
	case 3:
		s = atof(argv[1]);
		e = atof(argv[2]);
		exp = 1.0;
		break;
	case 4:
		s = atof(argv[1]);
		e = atof(argv[2]);
		exp = atof(argv[3]);
		break;
	}
	a = u = 0;
	while(9){
		if(a - u < 1024UL){
			b = realloc(b, a += 0x100000UL);
			if(b == nil)
				sysfatal("realloc: %r");
		}
		n = read(0, b + u, a - u);
		if(n < 1)
			break;
		u += n;
	}
	if(n)
		sysfatal("read: %r");
	if(u & 3)
		sysfatal("read not a multiple of four bytes");
	b = realloc(b, u);
	if(b == nil)
		sysfatal("realloc: %r");
	Δ = e - s;
	e = u;
	for(n = 0; n < u; n += 4){
		f = s + pow(n / e, exp) * Δ;
		a = (s16int)(b[n] | b[n | 1] << 8);
		a *= f;
		if(a < -0x8000)
			a = -0x8000;
		if(a > 0x7fff)
			a = 0x7fff;
		b[n] = a;
		b[n | 1] = a >> 8;
		a = (s16int)(b[n | 2] | b[n | 3] << 8);
		a *= f;
		if(a < -0x8000)
			a = -0x8000;
		if(a > 0x7fff)
			a = 0x7fff;
		b[n | 2] = a;
		b[n | 3] = a >> 8;
	}
	if(write(1, b, u) != u)
		sysfatal("write: %r");
	exits(nil);
}