atof.c

来自「mips架构的bootloader,99左右的版本 但源代码现在没人更新了」· C语言 代码 · 共 57 行

/*************************************************************
 * File: lib/atof.c
 * Purpose: Part of C runtime library
 * Author: Phil Bunce ([e-mail])
 * Revision History:
 *	970304	Start of revision history
 */

#include <defines.h>
/*
** should ignore leading white space, and give up on first bad char
*/
#ifdef FLOATINGPT
double atof(p)
char *p;
{
double d,t;
int len,val,sz,div,isneg;
char tmp[18];

if (*p == '-') {
	isneg = 1;
	p++;
	}
else isneg = 0;

sz = strcspn(p,".");
if (sz > 0) {
	strncpy(tmp,p,sz);
	tmp[sz] = 0;
	if (!atob(&val,tmp,10)) return(d);
	}
else val = 0;

d = (double) val;
p += sz;
if (*p) p++;
if (*p) {
	len = strlen(p);
	if (!atob(&val,p,10)) return(0);

	div = 1;
	for (;len>0;len--) div *= 10;

	t = (double)val;
	t /= div;

	d += t;
	}
if (isneg) d = 0-d;
return(d);
}
#else
atof() {return(0);}
#endif