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 ANY
11  * 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 static double
59 pow10(int n)
60 {
61 	double d;
62 	int neg;
63 
64 	neg = 0;
65 	if(n < 0){
66 		if(n < DBL_MIN_10_EXP){
67 			return 0.;
68 		}
69 		neg = 1;
70 		n = -n;
71 	}else if(n > DBL_MAX_10_EXP){
72 		return HUGE_VAL;
73 	}
74 	if(n < (int)(sizeof(pows10)/sizeof(pows10[0])))
75 		d = pows10[n];
76 	else{
77 		d = pows10[sizeof(pows10)/sizeof(pows10[0]) - 1];
78 		for(;;){
79 			n -= sizeof(pows10)/sizeof(pows10[0]) - 1;
80 			if(n < (int)(sizeof(pows10)/sizeof(pows10[0]))){
81 				d *= pows10[n];
82 				break;
83 			}
84 			d *= pows10[sizeof(pows10)/sizeof(pows10[0]) - 1];
85 		}
86 	}
87 	if(neg){
88 		return 1./d;
89 	}
90 	return d;
91 }
92 
93 static int
94 xadd(char *a, int n, int v)
95 {
96 	char *b;
97 	int c;
98 
99 	if(n < 0 || n >= NSIGNIF)
100 		return 0;
101 	for(b = a+n; b >= a; b--) {
102 		c = *b + v;
103 		if(c <= '9') {
104 			*b = c;
105 			return 0;
106 		}
107 		*b = '0';
108 		v = 1;
109 	}
110 	*a = '1';	/* overflow adding */
111 	return 1;
112 }
113 
114 static int
115 xsub(char *a, int n, int v)
116 {
117 	char *b;
118 	int c;
119 
120 	for(b = a+n; b >= a; b--) {
121 		c = *b - v;
122 		if(c >= '0') {
123 			*b = c;
124 			return 0;
125 		}
126 		*b = '9';
127 		v = 1;
128 	}
129 	*a = '9';	/* underflow subtracting */
130 	return 1;
131 }
132 
133 static void
134 xdtoa(Fmt *fmt, char *s2, double f)
135 {
136 	char s1[NSIGNIF+10];
137 	double g, h;
138 	int e, d, i, n;
139 	int c1, c2, c3, c4, ucase, sign, chr, prec;
140 
141 	prec = FDEFLT;
142 	if(fmt->flags & FmtPrec)
143 		prec = fmt->prec;
144 	if(prec > FDIGIT)
145 		prec = FDIGIT;
146 	if(__isNaN(f)) {
147 		strcpy(s2, "NaN");
148 		return;
149 	}
150 	if(__isInf(f, 1)) {
151 		strcpy(s2, "+Inf");
152 		return;
153 	}
154 	if(__isInf(f, -1)) {
155 		strcpy(s2, "-Inf");
156 		return;
157 	}
158 	sign = 0;
159 	if(f < 0) {
160 		f = -f;
161 		sign++;
162 	}
163 	ucase = 0;
164 	chr = fmt->r;
165 	if(isupper(chr)) {
166 		ucase = 1;
167 		chr = tolower(chr);
168 	}
169 
170 	e = 0;
171 	g = f;
172 	if(g != 0) {
173 		frexp(f, &e);
174 		e = e * .301029995664;
175 		if(e >= -150 && e <= +150) {
176 			d = 0;
177 			h = f;
178 		} else {
179 			d = e/2;
180 			h = f * pow10(-d);
181 		}
182 		g = h * pow10(d-e);
183 		while(g < 1) {
184 			e--;
185 			g = h * pow10(d-e);
186 		}
187 		while(g >= 10) {
188 			e++;
189 			g = h * pow10(d-e);
190 		}
191 	}
192 
193 	/*
194 	 * convert NSIGNIF digits and convert
195 	 * back to get accuracy.
196 	 */
197 	for(i=0; i<NSIGNIF; i++) {
198 		d = g;
199 		s1[i] = d + '0';
200 		g = (g - d) * 10;
201 	}
202 	s1[i] = 0;
203 
204 	/*
205 	 * try decimal rounding to eliminate 9s
206 	 */
207 	c2 = prec + 1;
208 	if(chr == 'f')
209 		c2 += e;
210 	if(c2 >= NSIGNIF-2) {
211 		strcpy(s2, s1);
212 		d = e;
213 		s1[NSIGNIF-2] = '0';
214 		s1[NSIGNIF-1] = '0';
215 		sprint(s1+NSIGNIF, "e%d", e-NSIGNIF+1);
216 		g = strtod(s1, nil);
217 		if(g == f)
218 			goto found;
219 		if(xadd(s1, NSIGNIF-3, 1)) {
220 			e++;
221 			sprint(s1+NSIGNIF, "e%d", e-NSIGNIF+1);
222 		}
223 		g = strtod(s1, nil);
224 		if(g == f)
225 			goto found;
226 		strcpy(s1, s2);
227 		e = d;
228 	}
229 
230 	/*
231 	 * convert back so s1 gets exact answer
232 	 */
233 	for(;;) {
234 		sprint(s1+NSIGNIF, "e%d", e-NSIGNIF+1);
235 		g = strtod(s1, nil);
236 		if(f > g) {
237 			if(xadd(s1, NSIGNIF-1, 1))
238 				e--;
239 			continue;
240 		}
241 		if(f < g) {
242 			if(xsub(s1, NSIGNIF-1, 1))
243 				e++;
244 			continue;
245 		}
246 		break;
247 	}
248 
249 found:
250 	/*
251 	 * sign
252 	 */
253 	d = 0;
254 	i = 0;
255 	if(sign)
256 		s2[d++] = '-';
257 	else if(fmt->flags & FmtSign)
258 		s2[d++] = '+';
259 	else if(fmt->flags & FmtSpace)
260 		s2[d++] = ' ';
261 
262 	/*
263 	 * copy into final place
264 	 * c1 digits of leading '0'
265 	 * c2 digits from conversion
266 	 * c3 digits of trailing '0'
267 	 * c4 digits after '.'
268 	 */
269 	c1 = 0;
270 	c2 = prec + 1;
271 	c3 = 0;
272 	c4 = prec;
273 	switch(chr) {
274 	default:
275 		if(xadd(s1, c2, 5))
276 			e++;
277 		break;
278 	case 'g':
279 		/*
280 		 * decide on 'e' of 'f' style convers
281 		 */
282 		if(xadd(s1, c2, 5))
283 			e++;
284 		if(e >= -5 && e <= prec) {
285 			c1 = -e - 1;
286 			c4 = prec - e;
287 			chr = 'h';	// flag for 'f' style
288 		}
289 		break;
290 	case 'f':
291 		if(xadd(s1, c2+e, 5))
292 			e++;
293 		c1 = -e;
294 		if(c1 > prec)
295 			c1 = c2;
296 		c2 += e;
297 		break;
298 	}
299 
300 	/*
301 	 * clean up c1 c2 and c3
302 	 */
303 	if(c1 < 0)
304 		c1 = 0;
305 	if(c2 < 0)
306 		c2 = 0;
307 	if(c2 > NSIGNIF) {
308 		c3 = c2-NSIGNIF;
309 		c2 = NSIGNIF;
310 	}
311 
312 	/*
313 	 * copy digits
314 	 */
315 	while(c1 > 0) {
316 		if(c1+c2+c3 == c4)
317 			s2[d++] = '.';
318 		s2[d++] = '0';
319 		c1--;
320 	}
321 	while(c2 > 0) {
322 		if(c2+c3 == c4)
323 			s2[d++] = '.';
324 		s2[d++] = s1[i++];
325 		c2--;
326 	}
327 	while(c3 > 0) {
328 		if(c3 == c4)
329 			s2[d++] = '.';
330 		s2[d++] = '0';
331 		c3--;
332 	}
333 
334 	/*
335 	 * strip trailing '0' on g conv
336 	 */
337 	if(fmt->flags & FmtSharp) {
338 		if(0 == c4)
339 			s2[d++] = '.';
340 	} else
341 	if(chr == 'g' || chr == 'h') {
342 		for(n=d-1; n>=0; n--)
343 			if(s2[n] != '0')
344 				break;
345 		for(i=n; i>=0; i--)
346 			if(s2[i] == '.') {
347 				d = n;
348 				if(i != n)
349 					d++;
350 				break;
351 			}
352 	}
353 	if(chr == 'e' || chr == 'g') {
354 		if(ucase)
355 			s2[d++] = 'E';
356 		else
357 			s2[d++] = 'e';
358 		c1 = e;
359 		if(c1 < 0) {
360 			s2[d++] = '-';
361 			c1 = -c1;
362 		} else
363 			s2[d++] = '+';
364 		if(c1 >= 100) {
365 			s2[d++] = c1/100 + '0';
366 			c1 = c1%100;
367 		}
368 		s2[d++] = c1/10 + '0';
369 		s2[d++] = c1%10 + '0';
370 	}
371 	s2[d] = 0;
372 }
373 
374 static int
375 floatfmt(Fmt *fmt, double f)
376 {
377 	char s[FDIGIT+10];
378 
379 	xdtoa(fmt, s, f);
380 	fmt->flags &= FmtWidth|FmtLeft;
381 	__fmtcpy(fmt, s, strlen(s), strlen(s));
382 	return 0;
383 }
384 
385 int
386 __efgfmt(Fmt *f)
387 {
388 	double d;
389 
390 	d = va_arg(f->args, double);
391 	return floatfmt(f, d);
392 }