#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <getopt.h>
#include <err.h>

#define CHUNK_DEFAULT (0x1000)

#define MIN(a, b) (a < b? a : b)
#define MAX(a, b) (a > b? a : b)

int
usage(const char* progname)
{
	fprintf(stderr, "usage: %s [-c chunk] [-m mul] [-s start] [-e end]\n", progname);
	return 1;
}

int
main(int argc, char** argv)
{
	int optch;
	int cflag = 0;
	const char* carg = NULL;
	int mflag = 0;
	const char* marg = NULL;
	int sflag = 0;
	const char* sarg = NULL;
	int eflag = 0;
	const char* earg = NULL;

	while ((optch = getopt(argc, argv, "c:m:s:e:h")) != -1) {
		switch (optch) {
		case 'c':
			cflag = 1;
			carg = optarg;
			break;
		case 'm':
			mflag = 1;
			marg = optarg;
			break;
		case 's':
			sflag = 1;
			sarg = optarg;
			break;
		case 'e':
			eflag = 1;
			earg = optarg;
			break;
		case 'h':
		default:
			return usage(*argv);
		}
	}

	size_t chunk = cflag? strtoull(carg, NULL, 10) : CHUNK_DEFAULT;
	float mul = mflag? strtof(marg, NULL) : 1.0f;
	size_t start = sflag? strtoull(sarg, NULL, 10) : 0;
	size_t end = eflag? strtoull(earg, NULL, 10) : chunk;
	
	float* buffer = aligned_alloc(0x40, chunk * sizeof(float));
	size_t rd;

	if (buffer == NULL)
		err(1, "malloc()");

	while ((rd = fread(buffer, sizeof(float), chunk, stdin))) {
		float min = buffer[start];
		float max = buffer[start];

		for (size_t i = start; i < MIN(rd, end); ++i) {
			min = MIN(min, buffer[i]);
			max = MAX(max, buffer[i]);
		}

		for (size_t i = start; i < MIN(rd, end); ++i) {
			buffer[i] = mul * (buffer[i] - min) / (max - min);
		}

		fwrite(buffer, sizeof(float), rd, stdout);
	}

	return 0;
}