1 /*
2  * The authors of this software are Rob Pike and Ken Thompson.
3  *              Copyright (c) 2002 by Lucent Technologies.
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose without fee is hereby granted, provided that this entire notice
6  * is included in all copies of any software which is or includes a copy
7  * or modification of this software and in all copies of the supporting
8  * documentation for such software.
9  * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED
10  * WARRANTY.  IN PARTICULAR, NEITHER THE AUTHORS NOR LUCENT TECHNOLOGIES MAKE
11  * ANY REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY
12  * OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
13  */
14 #include <stdio.h>
15 #include <math.h>
16 #include <float.h>
17 #include <string.h>
18 #include <stdlib.h>
19 #include <errno.h>
20 #include <stdarg.h>
21 #include <ctype.h>
22 #include <fmt.h>
23 #include "plan9.h"
24 #include "fmt.h"
25 #include "fmtdef.h"
26 
27 enum
28 {
29 	FDIGIT	= 30,
30 	FDEFLT	= 6,
31 	NSIGNIF	= 17
32 };
33 
34 /*
35  * first few powers of 10, enough for about 1/2 of the
36  * total space for doubles.
37  */
38 static double pows10[] =
39 {
40 	  1e0,   1e1,   1e2,   1e3,   1e4,   1e5,   1e6,   1e7,   1e8,   1e9,  
41 	 1e10,  1e11,  1e12,  1e13,  1e14,  1e15,  1e16,  1e17,  1e18,  1e19,  
42 	 1e20,  1e21,  1e22,  1e23,  1e24,  1e25,  1e26,  1e27,  1e28,  1e29,  
43 	 1e30,  1e31,  1e32,  1e33,  1e34,  1e35,  1e36,  1e37,  1e38,  1e39,  
44 	 1e40,  1e41,  1e42,  1e43,  1e44,  1e45,  1e46,  1e47,  1e48,  1e49,  
45 	 1e50,  1e51,  1e52,  1e53,  1e54,  1e55,  1e56,  1e57,  1e58,  1e59,  
46 	 1e60,  1e61,  1e62,  1e63,  1e64,  1e65,  1e66,  1e67,  1e68,  1e69,  
47 	 1e70,  1e71,  1e72,  1e73,  1e74,  1e75,  1e76,  1e77,  1e78,  1e79,  
48 	 1e80,  1e81,  1e82,  1e83,  1e84,  1e85,  1e86,  1e87,  1e88,  1e89,  
49 	 1e90,  1e91,  1e92,  1e93,  1e94,  1e95,  1e96,  1e97,  1e98,  1e99,  
50 	1e100, 1e101, 1e102, 1e103, 1e104, 1e105, 1e106, 1e107, 1e108, 1e109, 
51 	1e110, 1e111, 1e112, 1e113, 1e114, 1e115, 1e116, 1e117, 1e118, 1e119, 
52 	1e120, 1e121, 1e122, 1e123, 1e124, 1e125, 1e126, 1e127, 1e128, 1e129, 
53 	1e130, 1e131, 1e132, 1e133, 1e134, 1e135, 1e136, 1e137, 1e138, 1e139, 
54 	1e140, 1e141, 1e142, 1e143, 1e144, 1e145, 1e146, 1e147, 1e148, 1e149, 
55 	1e150, 1e151, 1e152, 1e153, 1e154, 1e155, 1e156, 1e157, 1e158, 1e159, 
56 };
57 
58 #define  pow10(x)  fmtpow10(x)
59 
60 static double
61 pow10(int n)
62 {
63 	double d;
64 	int neg;
65 
66 	neg = 0;
67 	if(n < 0){
68 		if(n < DBL_MIN_10_EXP){
69 			return 0.;
70 		}
71 		neg = 1;
72 		n = -n;
73 	}else if(n > DBL_MAX_10_EXP){
74 		return HUGE_VAL;
75 	}
76 	if(n < (int)(sizeof(pows10)/sizeof(pows10[0])))
77 		d = pows10[n];
78 	else{
79 		d = pows10[sizeof(pows10)/sizeof(pows10[0]) - 1];
80 		for(;;){
81 			n -= sizeof(pows10)/sizeof(pows10[0]) - 1;
82 			if(n < (int)(sizeof(pows10)/sizeof(pows10[0]))){
83 				d *= pows10[n];
84 				break;
85 			}
86 			d *= pows10[sizeof(pows10)/sizeof(pows10[0]) - 1];
87 		}
88 	}
89 	if(neg){
90 		return 1./d;
91 	}
92 	return d;
93 }
94 
95 static int
96 xadd(char *a, int n, int v)
97 {
98 	char *b;
99 	int c;
100 
101 	if(n < 0 || n >= NSIGNIF)
102 		return 0;
103 	for(b = a+n; b >= a; b--) {
104 		c = *b + v;
105 		if(c <= '9') {
106 			*b = c;
107 			return 0;
108 		}
109 		*b = '0';
110 		v = 1;
111 	}
112 	*a = '1';	/* overflow adding */
113 	return 1;
114 }
115 
116 static int
117 xsub(char *a, int n, int v)
118 {
119 	char *b;
120 	int c;
121 
122 	for(b = a+n; b >= a; b--) {
123 		c = *b - v;
124 		if(c >= '0') {
125 			*b = c;
126 			return 0;
127 		}
128 		*b = '9';
129 		v = 1;
130 	}
131 	*a = '9';	/* underflow subtracting */
132 	return 1;
133 }
134 
135 static void
136 xdtoa(Fmt *fmt, char *s2, double f)
137 {
138 	char s1[NSIGNIF+10];
139 	double g, h;
140 	int e, d, i, n;
141 	int c1, c2, c3, c4, ucase, sign, chr, prec;
142 
143 	prec = FDEFLT;
144 	if(fmt->flags & FmtPrec)
145 		prec = fmt->prec;
146 	if(prec > FDIGIT)
147 		prec = FDIGIT;
148 	if(__isNaN(f)) {
149 		strcpy(s2, "NaN");
150 		return;
151 	}
152 	if(__isInf(f, 1)) {
153 		strcpy(s2, "+Inf");
154 		return;
155 	}
156 	if(__isInf(f, -1)) {
157 		strcpy(s2, "-Inf");
158 		return;
159 	}
160 	sign = 0;
161 	if(f < 0) {
162 		f = -f;
163 		sign++;
164 	}
165 	ucase = 0;
166 	chr = fmt->r;
167 	if(isupper(chr)) {
168 		ucase = 1;
169 		chr = tolower(chr);
170 	}
171 
172 	e = 0;
173 	g = f;
174 	if(g != 0) {
175 		frexp(f, &e);
176 		e = e * .301029995664;
177 		if(e >= -150 && e <= +150) {
178 			d = 0;
179 			h = f;
180 		} else {
181 			d = e/2;
182 			h = f * pow10(-d);
183 		}
184 		g = h * pow10(d-e);
185 		while(g < 1) {
186 			e--;
187 			g = h * pow10(d-e);
188 		}
189 		while(g >= 10) {
190 			e++;
191 			g = h * pow10(d-e);
192 		}
193 	}
194 
195 	/*
196 	 * convert NSIGNIF digits and convert
197 	 * back to get accuracy.
198 	 */
199 	for(i=0; i<NSIGNIF; i++) {
200 		d = g;
201 		s1[i] = d + '0';
202 		g = (g - d) * 10;
203 	}
204 	s1[i] = 0;
205 
206 	/*
207 	 * try decimal rounding to eliminate 9s
208 	 */
209 	c2 = prec + 1;
210 	if(chr == 'f')
211 		c2 += e;
212 	if(c2 >= NSIGNIF-2) {
213 		strcpy(s2, s1);
214 		d = e;
215 		s1[NSIGNIF-2] = '0';
216 		s1[NSIGNIF-1] = '0';
217 		sprint(s1+NSIGNIF, "e%d", e-NSIGNIF+1);
218 		g = strtod(s1, nil);
219 		if(g == f)
220 			goto found;
221 		if(xadd(s1, NSIGNIF-3, 1)) {
222 			e++;
223 			sprint(s1+NSIGNIF, "e%d", e-NSIGNIF+1);
224 		}
225 		g = strtod(s1, nil);
226 		if(g == f)
227 			goto found;
228 		strcpy(s1, s2);
229 		e = d;
230 	}
231 
232 	/*
233 	 * convert back so s1 gets exact answer
234 	 */
235 	for(;;) {
236 		sprint(s1+NSIGNIF, "e%d", e-NSIGNIF+1);
237 		g = strtod(s1, nil);
238 		if(f > g) {
239 			if(xadd(s1, NSIGNIF-1, 1))
240 				e--;
241 			continue;
242 		}
243 		if(f < g) {
244 			if(xsub(s1, NSIGNIF-1, 1))
245 				e++;
246 			continue;
247 		}
248 		break;
249 	}
250 
251 found:
252 	/*
253 	 * sign
254 	 */
255 	d = 0;
256 	i = 0;
257 	if(sign)
258 		s2[d++] = '-';
259 	else if(fmt->flags & FmtSign)
260 		s2[d++] = '+';
261 	else if(fmt->flags & FmtSpace)
262 		s2[d++] = ' ';
263 
264 	/*
265 	 * copy into final place
266 	 * c1 digits of leading '0'
267 	 * c2 digits from conversion
268 	 * c3 digits of trailing '0'
269 	 * c4 digits after '.'
270 	 */
271 	c1 = 0;
272 	c2 = prec + 1;
273 	c3 = 0;
274 	c4 = prec;
275 	switch(chr) {
276 	default:
277 		if(xadd(s1, c2, 5))
278 			e++;
279 		break;
280 	case 'g':
281 		/*
282 		 * decide on 'e' of 'f' style convers
283 		 */
284 		if(xadd(s1, c2, 5))
285 			e++;
286 		if(e >= -5 && e <= prec) {
287 			c1 = -e - 1;
288 			c4 = prec - e;
289 			chr = 'h';	// flag for 'f' style
290 		}
291 		break;
292 	case 'f':
293 		if(xadd(s1, c2+e, 5))
294 			e++;
295 		c1 = -e;
296 		if(c1 > prec)
297 			c1 = c2;
298 		c2 += e;
299 		break;
300 	}
301 
302 	/*
303 	 * clean up c1 c2 and c3
304 	 */
305 	if(c1 < 0)
306 		c1 = 0;
307 	if(c2 < 0)
308 		c2 = 0;
309 	if(c2 > NSIGNIF) {
310 		c3 = c2-NSIGNIF;
311 		c2 = NSIGNIF;
312 	}
313 
314 	/*
315 	 * copy digits
316 	 */
317 	while(c1 > 0) {
318 		if(c1+c2+c3 == c4)
319 			s2[d++] = '.';
320 		s2[d++] = '0';
321 		c1--;
322 	}
323 	while(c2 > 0) {
324 		if(c2+c3 == c4)
325 			s2[d++] = '.';
326 		s2[d++] = s1[i++];
327 		c2--;
328 	}
329 	while(c3 > 0) {
330 		if(c3 == c4)
331 			s2[d++] = '.';
332 		s2[d++] = '0';
333 		c3--;
334 	}
335 
336 	/*
337 	 * strip trailing '0' on g conv
338 	 */
339 	if(fmt->flags & FmtSharp) {
340 		if(0 == c4)
341 			s2[d++] = '.';
342 	} else
343 	if(chr == 'g' || chr == 'h') {
344 		for(n=d-1; n>=0; n--)
345 			if(s2[n] != '0')
346 				break;
347 		for(i=n; i>=0; i--)
348 			if(s2[i] == '.') {
349 				d = n;
350 				if(i != n)
351 					d++;
352 				break;
353 			}
354 	}
355 	if(chr == 'e' || chr == 'g') {
356 		if(ucase)
357 			s2[d++] = 'E';
358 		else
359 			s2[d++] = 'e';
360 		c1 = e;
361 		if(c1 < 0) {
362 			s2[d++] = '-';
363 			c1 = -c1;
364 		} else
365 			s2[d++] = '+';
366 		if(c1 >= 100) {
367 			s2[d++] = c1/100 + '0';
368 			c1 = c1%100;
369 		}
370 		s2[d++] = c1/10 + '0';
371 		s2[d++] = c1%10 + '0';
372 	}
373 	s2[d] = 0;
374 }
375 
376 static int
377 floatfmt(Fmt *fmt, double f)
378 {
379 	char s[FDIGIT+10];
380 
381 	xdtoa(fmt, s, f);
382 	fmt->flags &= FmtWidth|FmtLeft;
383 	__fmtcpy(fmt, s, strlen(s), strlen(s));
384 	return 0;
385 }
386 
387 int
388 __efgfmt(Fmt *f)
389 {
390 	double d;
391 
392 	d = va_arg(f->args, double);
393 	return floatfmt(f, d);
394 }