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 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 } 376