[wip:20230104] my_fcvt(), my_gcvt() test

/*	$OpenBSD: gcvt_test.c,v 1.5 2019/01/25 00:19:26 millert Exp $	*/

/*
 * Public domain, 2010, Todd C. Miller <millert@openbsd.org>
 *
 * Modified for my_fcvt() and my_gcvt()
 * by SASANO Takayoshi <uaa@cvs.openbsd.org>
 */

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

static struct test_vector {
	double d;
	int ndig;
} test_vectors[] = {
	/* adapted from perl's Configure test */
	{ 0.1, 8, },
	{ 0.01, 8, },
	{ 0.001, 8, },
	{ 0.0001, 8, },
	{ 0.00009, 8, },
	{ 1.0, 8, },
	{ 1.1, 8, },
	{ 1.01, 8, },
	{ 1.001, 8, },
	{ 1.0001, 8, },
	{ 1.00001, 8, },
	{ 1.0, 8, },
	{ 0.0, 8, },
	{ -1.0, 8, },
	{ 100000, 8, },
	{ -100000, 8, },
	{ 123.456, 8, },
	{ 1e34, 8, },
	/* adapted from emx */
	{ 0.0, -1, },
	{ 0.0, 0, },
	{ 0.0, 1, },
	{ 0.0, 2, },
	{ 1.0, -1, },
	{ 1.0, 0, },
	{ 1.0, 2, },
	{ 1.0, 10, },
	{ 1.236, -1, },
	{ 1.236, 0, },
	{ 1.236, 1, },
	{ 1.236, 2, },
	{ 1.236, 3, },
	{ 1.236, 4, },
	{ 1.236, 5, },
	{ 1.236, 6, },
	{ 12.36, -1, },
	{ 12.36, 0, },
	{ 12.36, 1, },
	{ 12.36, 2, },
	{ 12.36, 3, },
	{ 12.36, 4, },
	{ 12.36, 5, },
	{ 12.36, 6, },
	{ 123.6, -1, },
	{ 123.6, 0, },
	{ 123.6, 1, },
	{ 123.6, 2, },
	{ 123.6, 3, },
	{ 123.6, 4, },
	{ 123.6, 5, },
	{ 123.6, 6, },
	{ 1236, -1, },
	{ 1236.0, 0, },
	{ 1236.0, 1, },
	{ 1236.0, 2, },
	{ 1236.0, 3, },
	{ 1236.0, 4, },
	{ 1236.0, 5, },
	{ 1236.0, 6, },
	{ 1e100, 10, },
	{ 1e100, 20, },
	{ 0.01236, -1, },
	{ 0.01236, 0, },
	{ 0.01236, 1, },
	{ 0.01236, 2, },
	{ 0.01236, 3, },
	{ 0.01236, 4, },
	{ 1e-100, 20, },
	{ 1e-100, -1, },
	{ -1.2, 5, },
	{ -0.03, 5, },
	{ 0.1, 1, },
	{ 0.1, 0, },
	{ 0.099999, 10, },
	{ 0.99999, 10, },
};

#define NTESTVEC (sizeof(test_vectors) / sizeof(test_vectors[0]))

char *my_gcvt(double value, int ndigit, char *buf)
{
	sprintf(buf, "%.*g", ndigit, value);
	return buf;
}

char *my_fcvt(double value, int ndigit, int *decpt, int *sign)
{
#define FCVT_BUFFER_SIZE 512

	int m, n, s;
	static char buf[FCVT_BUFFER_SIZE];
	char tmp[FCVT_BUFFER_SIZE], *p = tmp, *q;

	s = m = n = 0;

	if (ndigit == 0) {
		*p = '\0';

	} else if (ndigit > 0) {
		snprintf(tmp, sizeof(tmp), "%#+.*f", ndigit, value);
		s = (*p == '-');
		p++;

		if (value == 0.0f) {
			p += 2;
		} else if (*p == '0') {
			p += 2;
			for (n = 0; *p == '0'; p++, n--);
		} else {
			q = strchr(p, '.');
			m = q - p;
			memcpy(buf, p, m);
			p += m + 1;
		}

	} else {
		// XXX ndigit < 0 not supported
		return NULL;

	}

	if (sign != NULL) *sign = s;
	if (decpt != NULL) *decpt = m + n;

	strcpy(buf + m, p);
	return buf;
}

static int
dotest_gcvt(struct test_vector *tv)
{
	char buf0[256], buf1[256];

	gcvt(tv->d, tv->ndig, buf0);
	my_gcvt(tv->d, tv->ndig, buf1);
	if (strcmp(buf0, buf1)) {
		fprintf(stderr, "%g @ %d: expected %s got %s\n",
			tv->d, tv->ndig, buf0, buf1);
		return 1;
	}
	return 0;
}

static int
dotest_fcvt(struct test_vector *tv)
{
	char *p, buf0[256], buf1[256];
	int decpt0, decpt1, sign0, sign1;

	decpt0 = sign0 = 0;
	memset(buf0, 0, sizeof(buf0));
	p = fcvt(tv->d, tv->ndig, &decpt0, &sign0);
	if (p != NULL)
		strcpy(buf0, p);

	decpt1 = sign1 = 0;
	memset(buf1, 0, sizeof(buf1));
	p = my_fcvt(tv->d, tv->ndig, &decpt1, &sign1);
	if (p != NULL)
		strcpy(buf1, p);

	if (strcmp(buf0, buf1) || decpt0 != decpt1 || sign0 != sign1) {
		fprintf(stderr, "%g @ %d: expected %s %d %d got %s %d %d\n",
			tv->d, tv->ndig,
			buf0, decpt0, sign0, buf1, decpt1, sign1);
		return 1;
	}

	return 0;
}

int
main(int argc, char *argv[])
{
	int i, failures = 0;

	for (i = 0; i < NTESTVEC; i++) {
		failures += dotest_gcvt(&test_vectors[i]);
	}

	for (i = 0; i < NTESTVEC; i++) {
		failures += dotest_fcvt(&test_vectors[i]);
	}

	return failures;
}