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 <u.h> 15 #include <libc.h> 16 #include <float.h> 17 #include <ctype.h> 18 #include "fmtdef.h" 19 20 enum 21 { 22 FDIGIT = 30, 23 FDEFLT = 6, 24 NSIGNIF = 17 25 }; 26 27 /* 28 * first few powers of 10, enough for about 1/2 of the 29 * total space for doubles. 30 */ 31 static double pows10[] = 32 { 33 1e0, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6, 1e7, 1e8, 1e9, 34 1e10, 1e11, 1e12, 1e13, 1e14, 1e15, 1e16, 1e17, 1e18, 1e19, 35 1e20, 1e21, 1e22, 1e23, 1e24, 1e25, 1e26, 1e27, 1e28, 1e29, 36 1e30, 1e31, 1e32, 1e33, 1e34, 1e35, 1e36, 1e37, 1e38, 1e39, 37 1e40, 1e41, 1e42, 1e43, 1e44, 1e45, 1e46, 1e47, 1e48, 1e49, 38 1e50, 1e51, 1e52, 1e53, 1e54, 1e55, 1e56, 1e57, 1e58, 1e59, 39 1e60, 1e61, 1e62, 1e63, 1e64, 1e65, 1e66, 1e67, 1e68, 1e69, 40 1e70, 1e71, 1e72, 1e73, 1e74, 1e75, 1e76, 1e77, 1e78, 1e79, 41 1e80, 1e81, 1e82, 1e83, 1e84, 1e85, 1e86, 1e87, 1e88, 1e89, 42 1e90, 1e91, 1e92, 1e93, 1e94, 1e95, 1e96, 1e97, 1e98, 1e99, 43 1e100, 1e101, 1e102, 1e103, 1e104, 1e105, 1e106, 1e107, 1e108, 1e109, 44 1e110, 1e111, 1e112, 1e113, 1e114, 1e115, 1e116, 1e117, 1e118, 1e119, 45 1e120, 1e121, 1e122, 1e123, 1e124, 1e125, 1e126, 1e127, 1e128, 1e129, 46 1e130, 1e131, 1e132, 1e133, 1e134, 1e135, 1e136, 1e137, 1e138, 1e139, 47 1e140, 1e141, 1e142, 1e143, 1e144, 1e145, 1e146, 1e147, 1e148, 1e149, 48 1e150, 1e151, 1e152, 1e153, 1e154, 1e155, 1e156, 1e157, 1e158, 1e159, 49 }; 50 51 #undef pow10 52 #define pow10(x) fmtpow10(x) 53 54 static double 55 pow10(int n) 56 { 57 double d; 58 int neg; 59 60 neg = 0; 61 if(n < 0){ 62 if(n < DBL_MIN_10_EXP){ 63 return 0.; 64 } 65 neg = 1; 66 n = -n; 67 }else if(n > DBL_MAX_10_EXP){ 68 return HUGE_VAL; 69 } 70 if(n < (int)(sizeof(pows10)/sizeof(pows10[0]))) 71 d = pows10[n]; 72 else{ 73 d = pows10[sizeof(pows10)/sizeof(pows10[0]) - 1]; 74 for(;;){ 75 n -= sizeof(pows10)/sizeof(pows10[0]) - 1; 76 if(n < (int)(sizeof(pows10)/sizeof(pows10[0]))){ 77 d *= pows10[n]; 78 break; 79 } 80 d *= pows10[sizeof(pows10)/sizeof(pows10[0]) - 1]; 81 } 82 } 83 if(neg){ 84 return 1./d; 85 } 86 return d; 87 } 88 89 static int 90 xadd(char *a, int n, int v) 91 { 92 char *b; 93 int c; 94 95 if(n < 0 || n >= NSIGNIF) 96 return 0; 97 for(b = a+n; b >= a; b--) { 98 c = *b + v; 99 if(c <= '9') { 100 *b = c; 101 return 0; 102 } 103 *b = '0'; 104 v = 1; 105 } 106 *a = '1'; /* overflow adding */ 107 return 1; 108 } 109 110 static int 111 xsub(char *a, int n, int v) 112 { 113 char *b; 114 int c; 115 116 for(b = a+n; b >= a; b--) { 117 c = *b - v; 118 if(c >= '0') { 119 *b = c; 120 return 0; 121 } 122 *b = '9'; 123 v = 1; 124 } 125 *a = '9'; /* underflow subtracting */ 126 return 1; 127 } 128 129 static void 130 xdtoa(Fmt *fmt, char *s2, double f) 131 { 132 char s1[NSIGNIF+10]; 133 double g, h; 134 int e, d, i, n; 135 int c1, c2, c3, c4, ucase, sign, chr, prec; 136 137 prec = FDEFLT; 138 if(fmt->flags & FmtPrec) 139 prec = fmt->prec; 140 if(prec > FDIGIT) 141 prec = FDIGIT; 142 if(__isNaN(f)) { 143 strcpy(s2, "NaN"); 144 return; 145 } 146 if(__isInf(f, 1)) { 147 strcpy(s2, "+Inf"); 148 return; 149 } 150 if(__isInf(f, -1)) { 151 strcpy(s2, "-Inf"); 152 return; 153 } 154 sign = 0; 155 if(f < 0) { 156 f = -f; 157 sign++; 158 } 159 ucase = 0; 160 chr = fmt->r; 161 if(isupper(chr)) { 162 ucase = 1; 163 chr = tolower(chr); 164 } 165 166 e = 0; 167 g = f; 168 if(g != 0) { 169 frexp(f, &e); 170 e = e * .301029995664; 171 if(e >= -150 && e <= +150) { 172 d = 0; 173 h = f; 174 } else { 175 d = e/2; 176 h = f * pow10(-d); 177 } 178 g = h * pow10(d-e); 179 while(g < 1) { 180 e--; 181 g = h * pow10(d-e); 182 } 183 while(g >= 10) { 184 e++; 185 g = h * pow10(d-e); 186 } 187 } 188 189 /* 190 * convert NSIGNIF digits and convert 191 * back to get accuracy. 192 */ 193 for(i=0; i<NSIGNIF; i++) { 194 d = g; 195 s1[i] = d + '0'; 196 g = (g - d) * 10; 197 } 198 s1[i] = 0; 199 200 /* 201 * try decimal rounding to eliminate 9s 202 */ 203 c2 = prec + 1; 204 if(chr == 'f') 205 c2 += e; 206 if(c2 >= NSIGNIF-2) { 207 strcpy(s2, s1); 208 d = e; 209 s1[NSIGNIF-2] = '0'; 210 s1[NSIGNIF-1] = '0'; 211 sprint(s1+NSIGNIF, "e%d", e-NSIGNIF+1); 212 g = strtod(s1, nil); 213 if(g == f) 214 goto found; 215 if(xadd(s1, NSIGNIF-3, 1)) { 216 e++; 217 sprint(s1+NSIGNIF, "e%d", e-NSIGNIF+1); 218 } 219 g = strtod(s1, nil); 220 if(g == f) 221 goto found; 222 strcpy(s1, s2); 223 e = d; 224 } 225 226 /* 227 * convert back so s1 gets exact answer 228 */ 229 for(;;) { 230 sprint(s1+NSIGNIF, "e%d", e-NSIGNIF+1); 231 g = strtod(s1, nil); 232 if(f > g) { 233 if(xadd(s1, NSIGNIF-1, 1)) 234 e--; 235 continue; 236 } 237 if(f < g) { 238 if(xsub(s1, NSIGNIF-1, 1)) 239 e++; 240 continue; 241 } 242 break; 243 } 244 245 found: 246 /* 247 * sign 248 */ 249 d = 0; 250 i = 0; 251 if(sign) 252 s2[d++] = '-'; 253 else if(fmt->flags & FmtSign) 254 s2[d++] = '+'; 255 else if(fmt->flags & FmtSpace) 256 s2[d++] = ' '; 257 258 /* 259 * copy into final place 260 * c1 digits of leading '0' 261 * c2 digits from conversion 262 * c3 digits of trailing '0' 263 * c4 digits after '.' 264 */ 265 c1 = 0; 266 c2 = prec + 1; 267 c3 = 0; 268 c4 = prec; 269 switch(chr) { 270 default: 271 if(xadd(s1, c2, 5)) 272 e++; 273 break; 274 case 'g': 275 /* 276 * decide on 'e' of 'f' style convers 277 */ 278 if(xadd(s1, c2, 5)) 279 e++; 280 if(e >= -5 && e <= prec) { 281 c1 = -e - 1; 282 c4 = prec - e; 283 chr = 'h'; // flag for 'f' style 284 } 285 break; 286 case 'f': 287 if(xadd(s1, c2+e, 5)) 288 e++; 289 c1 = -e; 290 if(c1 > prec) 291 c1 = c2; 292 c2 += e; 293 break; 294 } 295 296 /* 297 * clean up c1 c2 and c3 298 */ 299 if(c1 < 0) 300 c1 = 0; 301 if(c2 < 0) 302 c2 = 0; 303 if(c2 > NSIGNIF) { 304 c3 = c2-NSIGNIF; 305 c2 = NSIGNIF; 306 } 307 308 /* 309 * copy digits 310 */ 311 while(c1 > 0) { 312 if(c1+c2+c3 == c4) 313 s2[d++] = '.'; 314 s2[d++] = '0'; 315 c1--; 316 } 317 while(c2 > 0) { 318 if(c2+c3 == c4) 319 s2[d++] = '.'; 320 s2[d++] = s1[i++]; 321 c2--; 322 } 323 while(c3 > 0) { 324 if(c3 == c4) 325 s2[d++] = '.'; 326 s2[d++] = '0'; 327 c3--; 328 } 329 330 /* 331 * strip trailing '0' on g conv 332 */ 333 if(fmt->flags & FmtSharp) { 334 if(0 == c4) 335 s2[d++] = '.'; 336 } else 337 if(chr == 'g' || chr == 'h') { 338 for(n=d-1; n>=0; n--) 339 if(s2[n] != '0') 340 break; 341 for(i=n; i>=0; i--) 342 if(s2[i] == '.') { 343 d = n; 344 if(i != n) 345 d++; 346 break; 347 } 348 } 349 if(chr == 'e' || chr == 'g') { 350 if(ucase) 351 s2[d++] = 'E'; 352 else 353 s2[d++] = 'e'; 354 c1 = e; 355 if(c1 < 0) { 356 s2[d++] = '-'; 357 c1 = -c1; 358 } else 359 s2[d++] = '+'; 360 if(c1 >= 100) { 361 s2[d++] = c1/100 + '0'; 362 c1 = c1%100; 363 } 364 s2[d++] = c1/10 + '0'; 365 s2[d++] = c1%10 + '0'; 366 } 367 s2[d] = 0; 368 } 369 370 static int 371 floatfmt(Fmt *fmt, double f) 372 { 373 char s[341]; /* precision+exponent+sign+'.'+null */ 374 375 xdtoa(fmt, s, f); 376 fmt->flags &= FmtWidth|FmtLeft; 377 __fmtcpy(fmt, s, strlen(s), strlen(s)); 378 return 0; 379 } 380 381 int 382 __efgfmt(Fmt *f) 383 { 384 double d; 385 386 d = va_arg(f->args, double); 387 return floatfmt(f, d); 388 } 389