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#include <u.h>
2 
#include <libc.h>
3 
#include <float.h>
4 
#include <ctype.h>
5 
#include "fmtdef.h"
6 
 
7 
enum
8 
{
9 
	FDIGIT	= 30,
10 
	FDEFLT	= 6,
11 
	NSIGNIF	= 17
12 
};
13 
 
14 
/*
15 
 * first few powers of 10, enough for about 1/2 of the
16 
 * total space for doubles.
17 
 */
18 
static double pows10[] =
19 
{
20 
	  1e0,   1e1,   1e2,   1e3,   1e4,   1e5,   1e6,   1e7,   1e8,   1e9,
21 
	 1e10,  1e11,  1e12,  1e13,  1e14,  1e15,  1e16,  1e17,  1e18,  1e19,
22 
	 1e20,  1e21,  1e22,  1e23,  1e24,  1e25,  1e26,  1e27,  1e28,  1e29,
23 
	 1e30,  1e31,  1e32,  1e33,  1e34,  1e35,  1e36,  1e37,  1e38,  1e39,
24 
	 1e40,  1e41,  1e42,  1e43,  1e44,  1e45,  1e46,  1e47,  1e48,  1e49,
25 
	 1e50,  1e51,  1e52,  1e53,  1e54,  1e55,  1e56,  1e57,  1e58,  1e59,
26 
	 1e60,  1e61,  1e62,  1e63,  1e64,  1e65,  1e66,  1e67,  1e68,  1e69,
27 
	 1e70,  1e71,  1e72,  1e73,  1e74,  1e75,  1e76,  1e77,  1e78,  1e79,
28 
	 1e80,  1e81,  1e82,  1e83,  1e84,  1e85,  1e86,  1e87,  1e88,  1e89,
29 
	 1e90,  1e91,  1e92,  1e93,  1e94,  1e95,  1e96,  1e97,  1e98,  1e99,
30 
	1e100, 1e101, 1e102, 1e103, 1e104, 1e105, 1e106, 1e107, 1e108, 1e109,
31 
	1e110, 1e111, 1e112, 1e113, 1e114, 1e115, 1e116, 1e117, 1e118, 1e119,
32 
	1e120, 1e121, 1e122, 1e123, 1e124, 1e125, 1e126, 1e127, 1e128, 1e129,
33 
	1e130, 1e131, 1e132, 1e133, 1e134, 1e135, 1e136, 1e137, 1e138, 1e139,
34 
	1e140, 1e141, 1e142, 1e143, 1e144, 1e145, 1e146, 1e147, 1e148, 1e149,
35 
	1e150, 1e151, 1e152, 1e153, 1e154, 1e155, 1e156, 1e157, 1e158, 1e159,
36 
};
37 
 
38 
#undef pow10
39 
#define  pow10(x)  fmtpow10(x)
40 
 
41 
static double
42 
pow10(int n)
43 
{
44 
	double d;
45 
	int neg;
46 
 
47 
	neg = 0;
48 
	if(n < 0){
49 
		if(n < DBL_MIN_10_EXP){
50 
			return 0.;
51 
		}
52 
		neg = 1;
53 
		n = -n;
54 
	}else if(n > DBL_MAX_10_EXP){
55 
		return HUGE_VAL;
56 
	}
57 
	if(n < (int)(sizeof(pows10)/sizeof(pows10[0])))
58 
		d = pows10[n];
59 
	else{
60 
		d = pows10[sizeof(pows10)/sizeof(pows10[0]) - 1];
61 
		for(;;){
62 
			n -= sizeof(pows10)/sizeof(pows10[0]) - 1;
63 
			if(n < (int)(sizeof(pows10)/sizeof(pows10[0]))){
64 
				d *= pows10[n];
65 
				break;
66 
			}
67 
			d *= pows10[sizeof(pows10)/sizeof(pows10[0]) - 1];
68 
		}
69 
	}
70 
	if(neg){
71 
		return 1./d;
72 
	}
73 
	return d;
74 
}
75 
 
76 
static int
77 
xadd(char *a, int n, int v)
78 
{
79 
	char *b;
80 
	int c;
81 
 
82 
	if(n < 0 || n >= NSIGNIF)
83 
		return 0;
84 
	for(b = a+n; b >= a; b--) {
85 
		c = *b + v;
86 
		if(c <= '9') {
87 
			*b = c;
88 
			return 0;
89 
		}
90 
		*b = '0';
91 
		v = 1;
92 
	}
93 
	*a = '1';	/* overflow adding */
94 
	return 1;
95 
}
96 
 
97 
static int
98 
xsub(char *a, int n, int v)
99 
{
100 
	char *b;
101 
	int c;
102 
 
103 
	for(b = a+n; b >= a; b--) {
104 
		c = *b - v;
105 
		if(c >= '0') {
106 
			*b = c;
107 
			return 0;
108 
		}
109 
		*b = '9';
110 
		v = 1;
111 
	}
112 
	*a = '9';	/* underflow subtracting */
113 
	return 1;
114 
}
115 
 
116 
static void
117 
xdtoa(Fmt *fmt, char *s2, double f)
118 
{
119 
	char s1[NSIGNIF+10];
120 
	double g, h;
121 
	int e, d, i, n;
122 
	int c1, c2, c3, c4, ucase, sign, chr, prec;
123 
 
124 
	prec = FDEFLT;
125 
	if(fmt->flags & FmtPrec)
126 
		prec = fmt->prec;
127 
	if(prec > FDIGIT)
128 
		prec = FDIGIT;
129 
	if(__isNaN(f)) {
130 
		strcpy(s2, "NaN");
131 
		return;
132 
	}
133 
	if(__isInf(f, 1)) {
134 
		strcpy(s2, "+Inf");
135 
		return;
136 
	}
137 
	if(__isInf(f, -1)) {
138 
		strcpy(s2, "-Inf");
139 
		return;
140 
	}
141 
	sign = 0;
142 
	if(f < 0) {
143 
		f = -f;
144 
		sign++;
145 
	}
146 
	ucase = 0;
147 
	chr = fmt->r;
148 
	if(isupper(chr)) {
149 
		ucase = 1;
150 
		chr = tolower(chr);
151 
	}
152 
 
153 
	e = 0;
154 
	g = f;
155 
	if(g != 0) {
156 
		frexp(f, &e);
157 
		e = e * .301029995664;
158 
		if(e >= -150 && e <= +150) {
159 
			d = 0;
160 
			h = f;
161 
		} else {
162 
			d = e/2;
163 
			h = f * pow10(-d);
164 
		}
165 
		g = h * pow10(d-e);
166 
		while(g < 1) {
167 
			e--;
168 
			g = h * pow10(d-e);
169 
		}
170 
		while(g >= 10) {
171 
			e++;
172 
			g = h * pow10(d-e);
173 
		}
174 
	}
175 
 
176 
	/*
177 
	 * convert NSIGNIF digits and convert
178 
	 * back to get accuracy.
179 
	 */
180 
	for(i=0; i<NSIGNIF; i++) {
181 
		d = g;
182 
		s1[i] = d + '0';
183 
		g = (g - d) * 10;
184 
	}
185 
	s1[i] = 0;
186 
 
187 
	/*
188 
	 * try decimal rounding to eliminate 9s
189 
	 */
190 
	c2 = prec + 1;
191 
	if(chr == 'f')
192 
		c2 += e;
193 
	if(c2 >= NSIGNIF-2) {
194 
		strcpy(s2, s1);
195 
		d = e;
196 
		s1[NSIGNIF-2] = '0';
197 
		s1[NSIGNIF-1] = '0';
198 
		sprint(s1+NSIGNIF, "e%d", e-NSIGNIF+1);
199 
		g = strtod(s1, nil);
200 
		if(g == f)
201 
			goto found;
202 
		if(xadd(s1, NSIGNIF-3, 1)) {
203 
			e++;
204 
			sprint(s1+NSIGNIF, "e%d", e-NSIGNIF+1);
205 
		}
206 
		g = strtod(s1, nil);
207 
		if(g == f)
208 
			goto found;
209 
		strcpy(s1, s2);
210 
		e = d;
211 
	}
212 
 
213 
	/*
214 
	 * convert back so s1 gets exact answer
215 
	 */
216 
	for(;;) {
217 
		sprint(s1+NSIGNIF, "e%d", e-NSIGNIF+1);
218 
		g = strtod(s1, nil);
219 
		if(f > g) {
220 
			if(xadd(s1, NSIGNIF-1, 1))
221 
				e--;
222 
			continue;
223 
		}
224 
		if(f < g) {
225 
			if(xsub(s1, NSIGNIF-1, 1))
226 
				e++;
227 
			continue;
228 
		}
229 
		break;
230 
	}
231 
 
232 
found:
233 
	/*
234 
	 * sign
235 
	 */
236 
	d = 0;
237 
	i = 0;
238 
	if(sign)
239 
		s2[d++] = '-';
240 
	else if(fmt->flags & FmtSign)
241 
		s2[d++] = '+';
242 
	else if(fmt->flags & FmtSpace)
243 
		s2[d++] = ' ';
244 
 
245 
	/*
246 
	 * copy into final place
247 
	 * c1 digits of leading '0'
248 
	 * c2 digits from conversion
249 
	 * c3 digits of trailing '0'
250 
	 * c4 digits after '.'
251 
	 */
252 
	c1 = 0;
253 
	c2 = prec + 1;
254 
	c3 = 0;
255 
	c4 = prec;
256 
	switch(chr) {
257 
	default:
258 
		if(xadd(s1, c2, 5))
259 
			e++;
260 
		break;
261 
	case 'g':
262 
		/*
263 
		 * decide on 'e' of 'f' style convers
264 
		 */
265 
		if(xadd(s1, c2, 5))
266 
			e++;
267 
		if(e >= -5 && e <= prec) {
268 
			c1 = -e - 1;
269 
			c4 = prec - e;
270 
			chr = 'h';	// flag for 'f' style
271 
		}
272 
		break;
273 
	case 'f':
274 
		if(xadd(s1, c2+e, 5))
275 
			e++;
276 
		c1 = -e;
277 
		if(c1 > prec)
278 
			c1 = c2;
279 
		c2 += e;
280 
		break;
281 
	}
282 
 
283 
	/*
284 
	 * clean up c1 c2 and c3
285 
	 */
286 
	if(c1 < 0)
287 
		c1 = 0;
288 
	if(c2 < 0)
289 
		c2 = 0;
290 
	if(c2 > NSIGNIF) {
291 
		c3 = c2-NSIGNIF;
292 
		c2 = NSIGNIF;
293 
	}
294 
 
295 
	/*
296 
	 * copy digits
297 
	 */
298 
	while(c1 > 0) {
299 
		if(c1+c2+c3 == c4)
300 
			s2[d++] = '.';
301 
		s2[d++] = '0';
302 
		c1--;
303 
	}
304 
	while(c2 > 0) {
305 
		if(c2+c3 == c4)
306 
			s2[d++] = '.';
307 
		s2[d++] = s1[i++];
308 
		c2--;
309 
	}
310 
	while(c3 > 0) {
311 
		if(c3 == c4)
312 
			s2[d++] = '.';
313 
		s2[d++] = '0';
314 
		c3--;
315 
	}
316 
 
317 
	/*
318 
	 * strip trailing '0' on g conv
319 
	 */
320 
	if(fmt->flags & FmtSharp) {
321 
		if(0 == c4)
322 
			s2[d++] = '.';
323 
	} else
324 
	if(chr == 'g' || chr == 'h') {
325 
		for(n=d-1; n>=0; n--)
326 
			if(s2[n] != '0')
327 
				break;
328 
		for(i=n; i>=0; i--)
329 
			if(s2[i] == '.') {
330 
				d = n;
331 
				if(i != n)
332 
					d++;
333 
				break;
334 
			}
335 
	}
336 
	if(chr == 'e' || chr == 'g') {
337 
		if(ucase)
338 
			s2[d++] = 'E';
339 
		else
340 
			s2[d++] = 'e';
341 
		c1 = e;
342 
		if(c1 < 0) {
343 
			s2[d++] = '-';
344 
			c1 = -c1;
345 
		} else
346 
			s2[d++] = '+';
347 
		if(c1 >= 100) {
348 
			s2[d++] = c1/100 + '0';
349 
			c1 = c1%100;
350 
		}
351 
		s2[d++] = c1/10 + '0';
352 
		s2[d++] = c1%10 + '0';
353 
	}
354 
	s2[d] = 0;
355 
}
356 
 
357 
static int
358 
floatfmt(Fmt *fmt, double f)
359 
{
360 
	char s[341];		/* precision+exponent+sign+'.'+null */
361 
 
362 
	xdtoa(fmt, s, f);
363 
	fmt->flags &= FmtWidth|FmtLeft;
364 
	__fmtcpy(fmt, s, strlen(s), strlen(s));
365 
	return 0;
366 
}
367 
 
368 
int
369 
__efgfmt(Fmt *f)
370 
{
371 
	double d;
372 
 
373 
	d = va_arg(f->args, double);
374 
	return floatfmt(f, d);
375 
}