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fecd2382 RP |
1 | /* atof_generic.c - turn a string of digits into a Flonum |
2 | Copyright (C) 1987, 1990, 1991 Free Software Foundation, Inc. | |
3 | ||
4 | This file is part of GAS, the GNU Assembler. | |
5 | ||
6 | GAS is free software; you can redistribute it and/or modify | |
7 | it under the terms of the GNU General Public License as published by | |
8 | the Free Software Foundation; either version 1, or (at your option) | |
9 | any later version. | |
10 | ||
11 | GAS is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | GNU General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU General Public License | |
17 | along with GAS; see the file COPYING. If not, write to | |
18 | the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */ | |
19 | ||
20 | /* static const char rcsid[] = "$Id$"; */ | |
21 | ||
22 | #include <ctype.h> | |
23 | #include <string.h> | |
24 | ||
25 | #include "as.h" | |
26 | ||
27 | #ifdef __GNUC__ | |
28 | #define alloca __builtin_alloca | |
29 | #else | |
30 | #ifdef sparc | |
31 | #include <alloca.h> | |
32 | #endif | |
33 | #endif | |
34 | ||
35 | #ifdef USG | |
36 | #define bzero(s,n) memset(s,0,n) | |
37 | #endif | |
38 | ||
39 | /* #define FALSE (0) */ | |
40 | /* #define TRUE (1) */ | |
41 | ||
42 | /***********************************************************************\ | |
43 | * * | |
44 | * Given a string of decimal digits , with optional decimal * | |
45 | * mark and optional decimal exponent (place value) of the * | |
46 | * lowest_order decimal digit: produce a floating point * | |
47 | * number. The number is 'generic' floating point: our * | |
48 | * caller will encode it for a specific machine architecture. * | |
49 | * * | |
50 | * Assumptions * | |
51 | * uses base (radix) 2 * | |
52 | * this machine uses 2's complement binary integers * | |
53 | * target flonums use " " " " * | |
54 | * target flonums exponents fit in a long * | |
55 | * * | |
56 | \***********************************************************************/ | |
57 | ||
58 | /* | |
59 | ||
60 | Syntax: | |
61 | ||
62 | <flonum> ::= <optional-sign> <decimal-number> <optional-exponent> | |
63 | <optional-sign> ::= '+' | '-' | {empty} | |
64 | <decimal-number> ::= <integer> | |
65 | | <integer> <radix-character> | |
66 | | <integer> <radix-character> <integer> | |
67 | | <radix-character> <integer> | |
68 | <optional-exponent> ::= {empty} | <exponent-character> <optional-sign> <integer> | |
69 | <integer> ::= <digit> | <digit> <integer> | |
70 | <digit> ::= '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' | |
71 | <exponent-character> ::= {one character from "string_of_decimal_exponent_marks"} | |
72 | <radix-character> ::= {one character from "string_of_decimal_marks"} | |
73 | ||
74 | */ | |
75 | \f | |
76 | int /* 0 if OK */ | |
77 | atof_generic ( | |
78 | address_of_string_pointer, /* return pointer to just AFTER number we read. */ | |
79 | string_of_decimal_marks, /* At most one per number. */ | |
80 | string_of_decimal_exponent_marks, | |
81 | address_of_generic_floating_point_number) | |
82 | ||
83 | char * * address_of_string_pointer; | |
84 | const char * string_of_decimal_marks; | |
85 | const char * string_of_decimal_exponent_marks; | |
86 | FLONUM_TYPE * address_of_generic_floating_point_number; | |
87 | ||
88 | { | |
89 | ||
90 | int return_value; /* 0 means OK. */ | |
91 | char * first_digit; | |
92 | /* char * last_digit; JF unused */ | |
93 | int number_of_digits_before_decimal; | |
94 | int number_of_digits_after_decimal; | |
95 | long decimal_exponent; | |
96 | int number_of_digits_available; | |
97 | char digits_sign_char; | |
98 | \f | |
99 | { | |
100 | /* | |
101 | * Scan the input string, abstracting (1)digits (2)decimal mark (3) exponent. | |
102 | * It would be simpler to modify the string, but we don't; just to be nice | |
103 | * to caller. | |
104 | * We need to know how many digits we have, so we can allocate space for | |
105 | * the digits' value. | |
106 | */ | |
107 | ||
108 | char * p; | |
109 | char c; | |
110 | int seen_significant_digit; | |
111 | ||
112 | first_digit = * address_of_string_pointer; | |
113 | c= *first_digit; | |
114 | if (c=='-' || c=='+') | |
115 | { | |
116 | digits_sign_char = c; | |
117 | first_digit ++; | |
118 | } | |
119 | else | |
120 | digits_sign_char = '+'; | |
121 | ||
122 | if( (first_digit[0]=='n' || first_digit[0]=='N') | |
123 | && (first_digit[1]=='a' || first_digit[1]=='A') | |
124 | && (first_digit[2]=='n' || first_digit[2]=='N')) { | |
125 | address_of_generic_floating_point_number->sign=0; | |
126 | address_of_generic_floating_point_number->exponent=0; | |
127 | address_of_generic_floating_point_number->leader=address_of_generic_floating_point_number->low; | |
128 | (*address_of_string_pointer)=first_digit+3; | |
129 | return 0; | |
130 | } | |
131 | if( (first_digit[0]=='i' || first_digit[0]=='I') | |
132 | && (first_digit[1]=='n' || first_digit[1]=='N') | |
133 | && (first_digit[2]=='f' || first_digit[2]=='F')) { | |
134 | address_of_generic_floating_point_number->sign= digits_sign_char=='+' ? 'P' : 'N'; | |
135 | address_of_generic_floating_point_number->exponent=0; | |
136 | address_of_generic_floating_point_number->leader=address_of_generic_floating_point_number->low; | |
137 | if( (first_digit[3]=='i' || first_digit[3]=='I') | |
138 | && (first_digit[4]=='n' || first_digit[4]=='N') | |
139 | && (first_digit[5]=='i' || first_digit[5]=='I') | |
140 | && (first_digit[6]=='t' || first_digit[6]=='T') | |
141 | && (first_digit[7]=='y' || first_digit[7]=='Y')) | |
142 | (*address_of_string_pointer)=first_digit+8; | |
143 | else | |
144 | (*address_of_string_pointer)=first_digit+3; | |
145 | return 0; | |
146 | } | |
147 | ||
148 | number_of_digits_before_decimal = 0; | |
149 | number_of_digits_after_decimal = 0; | |
150 | decimal_exponent = 0; | |
151 | seen_significant_digit = 0; | |
152 | for (p = first_digit; | |
153 | ((c = * p) != '\0') | |
154 | && (!c || ! strchr (string_of_decimal_marks, c) ) | |
155 | && (!c || ! strchr (string_of_decimal_exponent_marks, c) ); | |
156 | p ++) | |
157 | { | |
158 | if (isdigit(c)) | |
159 | { | |
160 | if (seen_significant_digit || c > '0') | |
161 | { | |
162 | number_of_digits_before_decimal ++; | |
163 | seen_significant_digit = 1; | |
164 | } | |
165 | else | |
166 | { | |
167 | first_digit++; | |
168 | } | |
169 | } | |
170 | else | |
171 | { | |
172 | break; /* p -> char after pre-decimal digits. */ | |
173 | } | |
174 | } /* For each digit before decimal mark. */ | |
175 | ||
176 | #ifndef OLD_FLOAT_READS | |
177 | /* Ignore trailing 0's after the decimal point. The original code here | |
178 | * (ifdef'd out) does not do this, and numbers like | |
179 | * 4.29496729600000000000e+09 (2**31) | |
180 | * come out inexact for some reason related to length of the digit | |
181 | * string. | |
182 | */ | |
183 | if ( c && strchr(string_of_decimal_marks,c) ){ | |
184 | int zeros = 0; /* Length of current string of zeros */ | |
185 | ||
186 | for ( p++; (c = *p) && isdigit(c); p++ ){ | |
187 | if ( c == '0'){ | |
188 | zeros++; | |
189 | } else { | |
190 | number_of_digits_after_decimal += 1 + zeros; | |
191 | zeros = 0; | |
192 | } | |
193 | } | |
194 | } | |
195 | #else | |
196 | if (c && strchr (string_of_decimal_marks, c)) | |
197 | { | |
198 | for (p ++; | |
199 | ((c = * p) != '\0') | |
200 | && (!c || ! strchr (string_of_decimal_exponent_marks, c) ); | |
201 | p ++) | |
202 | { | |
203 | if (isdigit(c)) | |
204 | { | |
205 | number_of_digits_after_decimal ++; /* This may be retracted below. */ | |
206 | if (/* seen_significant_digit || */ c > '0') | |
207 | { | |
208 | seen_significant_digit = TRUE; | |
209 | } | |
210 | } | |
211 | else | |
212 | { | |
213 | if ( ! seen_significant_digit) | |
214 | { | |
215 | number_of_digits_after_decimal = 0; | |
216 | } | |
217 | break; | |
218 | } | |
219 | } /* For each digit after decimal mark. */ | |
220 | } | |
221 | while(number_of_digits_after_decimal && first_digit[number_of_digits_before_decimal+number_of_digits_after_decimal]=='0') | |
222 | --number_of_digits_after_decimal; | |
223 | /* last_digit = p; JF unused */ | |
224 | #endif | |
225 | ||
226 | if (c && strchr (string_of_decimal_exponent_marks, c) ) | |
227 | { | |
228 | char digits_exponent_sign_char; | |
229 | ||
230 | c = * ++ p; | |
231 | if (c && strchr ("+-",c)) | |
232 | { | |
233 | digits_exponent_sign_char = c; | |
234 | c = * ++ p; | |
235 | } | |
236 | else | |
237 | { | |
238 | digits_exponent_sign_char = '+'; | |
239 | } | |
240 | for (; | |
241 | (c); | |
242 | c = * ++ p) | |
243 | { | |
244 | if (isdigit(c)) | |
245 | { | |
246 | decimal_exponent = decimal_exponent * 10 + c - '0'; | |
247 | /* | |
248 | * BUG! If we overflow here, we lose! | |
249 | */ | |
250 | } | |
251 | else | |
252 | { | |
253 | break; | |
254 | } | |
255 | } | |
256 | if (digits_exponent_sign_char == '-') | |
257 | { | |
258 | decimal_exponent = - decimal_exponent; | |
259 | } | |
260 | } | |
261 | * address_of_string_pointer = p; | |
262 | } | |
263 | \f | |
264 | number_of_digits_available = | |
265 | number_of_digits_before_decimal | |
266 | + number_of_digits_after_decimal; | |
267 | return_value = 0; | |
268 | if (number_of_digits_available == 0) | |
269 | { | |
270 | address_of_generic_floating_point_number -> exponent = 0; /* Not strictly necessary */ | |
271 | address_of_generic_floating_point_number -> leader | |
272 | = -1 + address_of_generic_floating_point_number -> low; | |
273 | address_of_generic_floating_point_number -> sign = digits_sign_char; | |
274 | /* We have just concocted (+/-)0.0E0 */ | |
275 | } | |
276 | else | |
277 | { | |
278 | LITTLENUM_TYPE * digits_binary_low; | |
279 | int precision; | |
280 | int maximum_useful_digits; | |
281 | int number_of_digits_to_use; | |
282 | int more_than_enough_bits_for_digits; | |
283 | int more_than_enough_littlenums_for_digits; | |
284 | int size_of_digits_in_littlenums; | |
285 | int size_of_digits_in_chars; | |
286 | FLONUM_TYPE power_of_10_flonum; | |
287 | FLONUM_TYPE digits_flonum; | |
288 | ||
289 | ||
290 | precision = (address_of_generic_floating_point_number -> high | |
291 | - address_of_generic_floating_point_number -> low | |
292 | + 1 | |
293 | ); /* Number of destination littlenums. */ | |
294 | /* Includes guard bits (two littlenums worth) */ | |
295 | maximum_useful_digits = ( ((double) (precision - 2)) | |
296 | * ((double) (LITTLENUM_NUMBER_OF_BITS)) | |
297 | / (LOG_TO_BASE_2_OF_10) | |
298 | ) | |
299 | + 2; /* 2 :: guard digits. */ | |
300 | if (number_of_digits_available > maximum_useful_digits) | |
301 | { | |
302 | number_of_digits_to_use = maximum_useful_digits; | |
303 | } | |
304 | else | |
305 | { | |
306 | number_of_digits_to_use = number_of_digits_available; | |
307 | } | |
308 | decimal_exponent += number_of_digits_before_decimal - number_of_digits_to_use; | |
309 | ||
310 | more_than_enough_bits_for_digits | |
311 | = ((((double)number_of_digits_to_use) * LOG_TO_BASE_2_OF_10) + 1); | |
312 | more_than_enough_littlenums_for_digits | |
313 | = ( more_than_enough_bits_for_digits | |
314 | / LITTLENUM_NUMBER_OF_BITS | |
315 | ) | |
316 | + 2; | |
317 | ||
318 | /* | |
319 | * Compute (digits) part. In "12.34E56" this is the "1234" part. | |
320 | * Arithmetic is exact here. If no digits are supplied then | |
321 | * this part is a 0 valued binary integer. | |
322 | * Allocate room to build up the binary number as littlenums. | |
323 | * We want this memory to disappear when we leave this function. | |
324 | * Assume no alignment problems => (room for n objects) == | |
325 | * n * (room for 1 object). | |
326 | */ | |
327 | ||
328 | size_of_digits_in_littlenums = more_than_enough_littlenums_for_digits; | |
329 | size_of_digits_in_chars = size_of_digits_in_littlenums | |
330 | * sizeof( LITTLENUM_TYPE ); | |
331 | digits_binary_low = (LITTLENUM_TYPE *) | |
332 | alloca (size_of_digits_in_chars); | |
333 | bzero ((char *)digits_binary_low, size_of_digits_in_chars); | |
334 | ||
335 | /* Digits_binary_low[] is allocated and zeroed. */ | |
336 | ||
337 | { | |
338 | /* | |
339 | * Parse the decimal digits as if * digits_low was in the units position. | |
340 | * Emit a binary number into digits_binary_low[]. | |
341 | * | |
342 | * Use a large-precision version of: | |
343 | * (((1st-digit) * 10 + 2nd-digit) * 10 + 3rd-digit ...) * 10 + last-digit | |
344 | */ | |
345 | ||
346 | char * p; | |
347 | char c; | |
348 | int count; /* Number of useful digits left to scan. */ | |
349 | ||
350 | for (p = first_digit, count = number_of_digits_to_use; | |
351 | count; | |
352 | p ++, -- count) | |
353 | { | |
354 | c = * p; | |
355 | if (isdigit(c)) | |
356 | { | |
357 | /* | |
358 | * Multiply by 10. Assume can never overflow. | |
359 | * Add this digit to digits_binary_low[]. | |
360 | */ | |
361 | ||
362 | long carry; | |
363 | LITTLENUM_TYPE * littlenum_pointer; | |
364 | LITTLENUM_TYPE * littlenum_limit; | |
365 | ||
366 | littlenum_limit | |
367 | = digits_binary_low | |
368 | + more_than_enough_littlenums_for_digits | |
369 | - 1; | |
370 | carry = c - '0'; /* char -> binary */ | |
371 | for (littlenum_pointer = digits_binary_low; | |
372 | littlenum_pointer <= littlenum_limit; | |
373 | littlenum_pointer ++) | |
374 | { | |
375 | long work; | |
376 | ||
377 | work = carry + 10 * (long)(*littlenum_pointer); | |
378 | * littlenum_pointer = work & LITTLENUM_MASK; | |
379 | carry = work >> LITTLENUM_NUMBER_OF_BITS; | |
380 | } | |
381 | if (carry != 0) | |
382 | { | |
383 | /* | |
384 | * We have a GROSS internal error. | |
385 | * This should never happen. | |
386 | */ | |
387 | abort(); /* RMS prefers abort() to any message. */ | |
388 | } | |
389 | } | |
390 | else | |
391 | { | |
392 | ++ count; /* '.' doesn't alter digits used count. */ | |
393 | } /* if valid digit */ | |
394 | } /* for each digit */ | |
395 | } | |
396 | ||
397 | /* | |
398 | * Digits_binary_low[] properly encodes the value of the digits. | |
399 | * Forget about any high-order littlenums that are 0. | |
400 | */ | |
401 | while (digits_binary_low [size_of_digits_in_littlenums - 1] == 0 | |
402 | && size_of_digits_in_littlenums >= 2) | |
403 | size_of_digits_in_littlenums --; | |
404 | ||
405 | digits_flonum . low = digits_binary_low; | |
406 | digits_flonum . high = digits_binary_low + size_of_digits_in_littlenums - 1; | |
407 | digits_flonum . leader = digits_flonum . high; | |
408 | digits_flonum . exponent = 0; | |
409 | /* | |
410 | * The value of digits_flonum . sign should not be important. | |
411 | * We have already decided the output's sign. | |
412 | * We trust that the sign won't influence the other parts of the number! | |
413 | * So we give it a value for these reasons: | |
414 | * (1) courtesy to humans reading/debugging | |
415 | * these numbers so they don't get excited about strange values | |
416 | * (2) in future there may be more meaning attached to sign, | |
417 | * and what was | |
418 | * harmless noise may become disruptive, ill-conditioned (or worse) | |
419 | * input. | |
420 | */ | |
421 | digits_flonum . sign = '+'; | |
422 | ||
423 | { | |
424 | /* | |
425 | * Compute the mantssa (& exponent) of the power of 10. | |
426 | * If sucessful, then multiply the power of 10 by the digits | |
427 | * giving return_binary_mantissa and return_binary_exponent. | |
428 | */ | |
429 | ||
430 | LITTLENUM_TYPE *power_binary_low; | |
431 | int decimal_exponent_is_negative; | |
432 | /* This refers to the "-56" in "12.34E-56". */ | |
433 | /* FALSE: decimal_exponent is positive (or 0) */ | |
434 | /* TRUE: decimal_exponent is negative */ | |
435 | FLONUM_TYPE temporary_flonum; | |
436 | LITTLENUM_TYPE *temporary_binary_low; | |
437 | int size_of_power_in_littlenums; | |
438 | int size_of_power_in_chars; | |
439 | ||
440 | size_of_power_in_littlenums = precision; | |
441 | /* Precision has a built-in fudge factor so we get a few guard bits. */ | |
442 | ||
443 | ||
444 | decimal_exponent_is_negative = decimal_exponent < 0; | |
445 | if (decimal_exponent_is_negative) | |
446 | { | |
447 | decimal_exponent = - decimal_exponent; | |
448 | } | |
449 | /* From now on: the decimal exponent is > 0. Its sign is seperate. */ | |
450 | ||
451 | size_of_power_in_chars | |
452 | = size_of_power_in_littlenums | |
453 | * sizeof( LITTLENUM_TYPE ) + 2; | |
454 | power_binary_low = (LITTLENUM_TYPE *) alloca ( size_of_power_in_chars ); | |
455 | temporary_binary_low = (LITTLENUM_TYPE *) alloca ( size_of_power_in_chars ); | |
456 | bzero ((char *)power_binary_low, size_of_power_in_chars); | |
457 | * power_binary_low = 1; | |
458 | power_of_10_flonum . exponent = 0; | |
459 | power_of_10_flonum . low = power_binary_low; | |
460 | power_of_10_flonum . leader = power_binary_low; | |
461 | power_of_10_flonum . high = power_binary_low + size_of_power_in_littlenums - 1; | |
462 | power_of_10_flonum . sign = '+'; | |
463 | temporary_flonum . low = temporary_binary_low; | |
464 | temporary_flonum . high = temporary_binary_low + size_of_power_in_littlenums - 1; | |
465 | /* | |
466 | * (power) == 1. | |
467 | * Space for temporary_flonum allocated. | |
468 | */ | |
469 | ||
470 | /* | |
471 | * ... | |
472 | * | |
473 | * WHILE more bits | |
474 | * DO find next bit (with place value) | |
475 | * multiply into power mantissa | |
476 | * OD | |
477 | */ | |
478 | { | |
479 | int place_number_limit; | |
480 | /* Any 10^(2^n) whose "n" exceeds this */ | |
481 | /* value will fall off the end of */ | |
482 | /* flonum_XXXX_powers_of_ten[]. */ | |
483 | int place_number; | |
484 | const FLONUM_TYPE * multiplicand; /* -> 10^(2^n) */ | |
485 | ||
486 | place_number_limit = table_size_of_flonum_powers_of_ten; | |
487 | multiplicand | |
488 | = ( decimal_exponent_is_negative | |
489 | ? flonum_negative_powers_of_ten | |
490 | : flonum_positive_powers_of_ten); | |
491 | for (place_number = 1; /* Place value of this bit of exponent. */ | |
492 | decimal_exponent; /* Quit when no more 1 bits in exponent. */ | |
493 | decimal_exponent >>= 1 | |
494 | , place_number ++) | |
495 | { | |
496 | if (decimal_exponent & 1) | |
497 | { | |
498 | if (place_number > place_number_limit) | |
499 | { | |
500 | /* | |
501 | * The decimal exponent has a magnitude so great that | |
502 | * our tables can't help us fragment it. Although this | |
503 | * routine is in error because it can't imagine a | |
504 | * number that big, signal an error as if it is the | |
505 | * user's fault for presenting such a big number. | |
506 | */ | |
507 | return_value = ERROR_EXPONENT_OVERFLOW; | |
508 | /* | |
509 | * quit out of loop gracefully | |
510 | */ | |
511 | decimal_exponent = 0; | |
512 | } | |
513 | else | |
514 | { | |
515 | #ifdef TRACE | |
516 | printf("before multiply, place_number = %d., power_of_10_flonum:\n", place_number); | |
517 | flonum_print( & power_of_10_flonum ); | |
518 | (void)putchar('\n'); | |
519 | #endif | |
520 | flonum_multip(multiplicand + place_number, &power_of_10_flonum, &temporary_flonum); | |
521 | flonum_copy (& temporary_flonum, & power_of_10_flonum); | |
522 | } /* If this bit of decimal_exponent was computable.*/ | |
523 | } /* If this bit of decimal_exponent was set. */ | |
524 | } /* For each bit of binary representation of exponent */ | |
525 | #ifdef TRACE | |
526 | printf( " after computing power_of_10_flonum: " ); | |
527 | flonum_print( & power_of_10_flonum ); | |
528 | (void)putchar('\n'); | |
529 | #endif | |
530 | } | |
531 | ||
532 | } | |
533 | ||
534 | /* | |
535 | * power_of_10_flonum is power of ten in binary (mantissa) , (exponent). | |
536 | * It may be the number 1, in which case we don't NEED to multiply. | |
537 | * | |
538 | * Multiply (decimal digits) by power_of_10_flonum. | |
539 | */ | |
540 | ||
541 | flonum_multip (& power_of_10_flonum, & digits_flonum, address_of_generic_floating_point_number); | |
542 | /* Assert sign of the number we made is '+'. */ | |
543 | address_of_generic_floating_point_number -> sign = digits_sign_char; | |
544 | ||
545 | } /* If we had any significant digits. */ | |
546 | return (return_value); | |
547 | } /* atof_generic () */ | |
548 | ||
549 | /* end: atof_generic.c */ |