aml/aml_cvt.c

/*
 * Copyright (c) 2021-2022 Amlogic, Inc. All rights reserved.
 *
 * SPDX-License-Identifier: MIT
 */

#include "aml_cvt.h"

#include <math.h>
#define CVTBUFSIZE 80
static char CVTBUF[CVTBUFSIZE];

static char *cvt(double arg, int ndigits, int *decpt, int *sign, char *buf, int eflag)
{
	int r2;
	double fi, fj;
	char *p, *p1;

	if (ndigits < 0)
		ndigits = 0;
	if (ndigits >= CVTBUFSIZE - 1)
		ndigits = CVTBUFSIZE - 2;
	r2 = 0;
	*sign = 0;
	p = &buf[0];
	if (arg < 0) {
		*sign = 1;
		arg = -arg;
	}
	arg = modf(arg, &fi);
	p1 = &buf[CVTBUFSIZE];

	if (fi != 0) {
		p1 = &buf[CVTBUFSIZE];
		while (fi != 0) {
			fj = modf(fi / 10, &fi);
			*--p1 = (int)((fj + .03) * 10) + '0';
			r2++;
		}
		while (p1 < &buf[CVTBUFSIZE])
			*p++ = *p1++;
	} else if (arg > 0) {
		while ((fj = arg * 10) < 1) {
			arg = fj;
			r2--;
		}
	}
	p1 = &buf[ndigits];
	if (eflag == 0)
		p1 += r2;
	*decpt = r2;
	if (p1 < &buf[0]) {
		buf[0] = '\0';
		return buf;
	}
	while (p <= p1 && p < &buf[CVTBUFSIZE]) {
		arg *= 10;
		arg = modf(arg, &fj);
		*p++ = (int)fj + '0';
	}
	if (p1 >= &buf[CVTBUFSIZE]) {
		buf[CVTBUFSIZE - 1] = '\0';
		return buf;
	}
	p = p1;
	*p1 += 5;
	while (*p1 > '9') {
		*p1 = '0';
		if (p1 > buf)
			++*--p1;
		else {
			*p1 = '1';
			(*decpt)++;
			if (eflag == 0) {
				if (p > buf)
					*p = '0';
				p++;
			}
		}
	}
	*p = '\0';
	return buf;
}

char *ecvt(double arg, int ndigits, int *decpt, int *sign)
{
	return cvt(arg, ndigits, decpt, sign, CVTBUF, 1);
}

char *ecvtbuf(double arg, int ndigits, int *decpt, int *sign, char *buf)
{
	return cvt(arg, ndigits, decpt, sign, buf, 1);
}

char *my_fcvt(double arg, int ndigits, int *decpt, int *sign)
{
	return cvt(arg, ndigits, decpt, sign, CVTBUF, 0);
}

char *fcvtbuf(double arg, int ndigits, int *decpt, int *sign, char *buf)
{
	return cvt(arg, ndigits, decpt, sign, buf, 0);
}