1 #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
pow10(int n)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
xadd(char * a,int n,int v)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
xsub(char * a,int n,int v)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
xdtoa(Fmt * fmt,char * s2,double f)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
floatfmt(Fmt * fmt,double f)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
__efgfmt(Fmt * f)369 __efgfmt(Fmt *f)
370 {
371 double d;
372
373 d = va_arg(f->args, double);
374 return floatfmt(f, d);
375 }
376