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Start development on 386BSD 0.0
[unix-history] / .ref-BSD-4_3_Net_2 / usr / src / usr.bin / gas / expr.c
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ee3d3814
C		 1/* expr.c -operands, expressions-
2 Copyright (C) 1987 Free Software Foundation, Inc.
3
4This file is part of GAS, the GNU Assembler.
5
6GAS is free software; you can redistribute it and/or modify
7it under the terms of the GNU General Public License as published by
8the Free Software Foundation; either version 1, or (at your option)
9any later version.
10
11GAS is distributed in the hope that it will be useful,
12but WITHOUT ANY WARRANTY; without even the implied warranty of
13MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14GNU General Public License for more details.
15
16You should have received a copy of the GNU General Public License
17along with GAS; see the file COPYING. If not, write to
18the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
19
20/*
21 * This is really a branch office of as-read.c. I split it out to clearly
22 * distinguish the world of expressions from the world of statements.
23 * (It also gives smaller files to re-compile.)
24 * Here, "operand"s are of expressions, not instructions.
25 */
26
27#include <ctype.h>
28#include "as.h"
29#include "flonum.h"
30#include "read.h"
31#include "struc-symbol.h"
32#include "expr.h"
33#include "obstack.h"
34#include "symbols.h"
35
36static void clean_up_expression(); /* Internal. */
37extern const char EXP_CHARS[]; /* JF hide MD floating pt stuff all the same place */
38extern const char FLT_CHARS[];
39
40#ifdef SUN_ASM_SYNTAX
41extern int local_label_defined[];
42#endif
43
44/*
45 * Build any floating-point literal here.
46 * Also build any bignum literal here.
47 */
48
49/* LITTLENUM_TYPE generic_buffer [6]; /* JF this is a hack */
50/* Seems atof_machine can backscan through generic_bignum and hit whatever
51 happens to be loaded before it in memory. And its way too complicated
52 for me to fix right. Thus a hack. JF: Just make generic_bignum bigger,
53 and never write into the early words, thus they'll always be zero.
54 I hate Dean's floating-point code. Bleh.
55 */
56LITTLENUM_TYPE generic_bignum [SIZE_OF_LARGE_NUMBER+6];
57FLONUM_TYPE generic_floating_point_number =
58{
59 & generic_bignum [6], /* low (JF: Was 0) */
60 & generic_bignum [SIZE_OF_LARGE_NUMBER+6 - 1], /* high JF: (added +6) */
61 0, /* leader */
62 0, /* exponent */
63 0 /* sign */
64};
65/* If nonzero, we've been asked to assemble nan, +inf or -inf */
66int generic_floating_point_magic;
67\f
68/*
69 * Summary of operand().
70 *
71 * in: Input_line_pointer points to 1st char of operand, which may
72 * be a space.
73 *
74 * out: A expressionS. X_seg determines how to understand the rest of the
75 * expressionS.
76 * The operand may have been empty: in this case X_seg == SEG_NONE.
77 * Input_line_pointer -> (next non-blank) char after operand.
78 *
79 */
80\f
81static segT
82operand (expressionP)
83 register expressionS * expressionP;
84{
85 register char c;
86 register char *name; /* points to name of symbol */
87 register struct symbol * symbolP; /* Points to symbol */
88
89 extern char hex_value[]; /* In hex_value.c */
90 char *local_label_name();
91
92 SKIP_WHITESPACE(); /* Leading whitespace is part of operand. */
93 c = * input_line_pointer ++; /* Input_line_pointer -> past char in c. */
94 if (isdigit(c))
95 {
96 register valueT number; /* offset or (absolute) value */
97 register short int digit; /* value of next digit in current radix */
98 /* invented for humans only, hope */
99 /* optimising compiler flushes it! */
100 register short int radix; /* 8, 10 or 16 */
101 /* 0 means we saw start of a floating- */
102 /* point constant. */
103 register short int maxdig;/* Highest permitted digit value. */
104 register int too_many_digits; /* If we see >= this number of */
105 /* digits, assume it is a bignum. */
106 register char * digit_2; /* -> 2nd digit of number. */
107 int small; /* TRUE if fits in 32 bits. */
108
109 if (c=='0')
110 { /* non-decimal radix */
111 if ((c = * input_line_pointer ++)=='x' || c=='X')
112 {
113 c = * input_line_pointer ++; /* read past "0x" or "0X" */
114 maxdig = radix = 16;
115 too_many_digits = 9;
116 }
117 else
118 {
119 /* If it says '0f' and the line ends or it DOESN'T look like
120 a floating point #, its a local label ref. DTRT */
121 if(c=='f' && (! *input_line_pointer ||
122 (!index("+-.0123456789",*input_line_pointer) &&
123 !index(EXP_CHARS,*input_line_pointer))))
124 {
125 maxdig = radix = 10;
126 too_many_digits = 11;
127 c='0';
128 input_line_pointer-=2;
129 }
130 else if (c && index (FLT_CHARS,c))
131 {
132 radix = 0; /* Start of floating-point constant. */
133 /* input_line_pointer -> 1st char of number. */
134 expressionP -> X_add_number = - (isupper(c) ? tolower(c) : c);
135 }
136 else
137 { /* By elimination, assume octal radix. */
138 radix = 8;
139 maxdig = 10; /* Un*x sux. Compatibility. */
140 too_many_digits = 11;
141 }
142 }
143 /* c == char after "0" or "0x" or "0X" or "0e" etc.*/
144 }
145 else
146 {
147 maxdig = radix = 10;
148 too_many_digits = 11;
149 }
150 if (radix)
151 { /* Fixed-point integer constant. */
152 /* May be bignum, or may fit in 32 bits. */
153/*
154 * Most numbers fit into 32 bits, and we want this case to be fast.
155 * So we pretend it will fit into 32 bits. If, after making up a 32
156 * bit number, we realise that we have scanned more digits than
157 * comfortably fit into 32 bits, we re-scan the digits coding
158 * them into a bignum. For decimal and octal numbers we are conservative: some
159 * numbers may be assumed bignums when in fact they do fit into 32 bits.
160 * Numbers of any radix can have excess leading zeros: we strive
161 * to recognise this and cast them back into 32 bits.
162 * We must check that the bignum really is more than 32
163 * bits, and change it back to a 32-bit number if it fits.
164 * The number we are looking for is expected to be positive, but
165 * if it fits into 32 bits as an unsigned number, we let it be a 32-bit
166 * number. The cavalier approach is for speed in ordinary cases.
167 */
168 digit_2 = input_line_pointer;
169 for (number=0; (digit=hex_value[c])<maxdig; c = * input_line_pointer ++)
170 {
171 number = number * radix + digit;
172 }
173 /* C contains character after number. */
174 /* Input_line_pointer -> char after C. */
175 small = input_line_pointer - digit_2 < too_many_digits;
176 if ( ! small)
177 {
178 /*
179 * We saw a lot of digits. Manufacture a bignum the hard way.
180 */
181 LITTLENUM_TYPE * leader; /* -> high order littlenum of the bignum. */
182 LITTLENUM_TYPE * pointer; /* -> littlenum we are frobbing now. */
183 long int carry;
184
185 leader = generic_bignum;
186 generic_bignum [0] = 0;
187 generic_bignum [1] = 0;
188 /* We could just use digit_2, but lets be mnemonic. */
189 input_line_pointer = -- digit_2; /* -> 1st digit. */
190 c = *input_line_pointer ++;
191 for (; (carry = hex_value [c]) < maxdig; c = * input_line_pointer ++)
192 {
193 for (pointer = generic_bignum;
194 pointer <= leader;
195 pointer ++)
196 {
197 long int work;
198
199 work = carry + radix * * pointer;
200 * pointer = work & LITTLENUM_MASK;
201 carry = work >> LITTLENUM_NUMBER_OF_BITS;
202 }
203 if (carry)
204 {
205 if (leader < generic_bignum + SIZE_OF_LARGE_NUMBER - 1)
206 { /* Room to grow a longer bignum. */
207 * ++ leader = carry;
208 }
209 }
210 }
211 /* Again, C is char after number, */
212 /* input_line_pointer -> after C. */
213 know( BITS_PER_INT == 32 );
214 know( LITTLENUM_NUMBER_OF_BITS == 16 );
215 /* Hence the constant "2" in the next line. */
216 if (leader < generic_bignum + 2)
217 { /* Will fit into 32 bits. */
218 number =
219 ( (generic_bignum [1] & LITTLENUM_MASK) << LITTLENUM_NUMBER_OF_BITS )
220 | (generic_bignum [0] & LITTLENUM_MASK);
221 small = TRUE;
222 }
223 else
224 {
225 number = leader - generic_bignum + 1; /* Number of littlenums in the bignum. */
226 }
227 }
228 if (small)
229 {
230 /*
231 * Here with number, in correct radix. c is the next char.
232 * Note that unlike Un*x, we allow "011f" "0x9f" to
233 * both mean the same as the (conventional) "9f". This is simply easier
234 * than checking for strict canonical form. Syntax sux!
235 */
236 if (number<10)
237 {
238#ifdef SUN_ASM_SYNTAX
239 if (c=='b' || (c=='$' && local_label_defined[number]))
240#else
241 if (c=='b')
242#endif
243 {
244 /*
245 * Backward ref to local label.
246 * Because it is backward, expect it to be DEFINED.
247 */
248 /*
249 * Construct a local label.
250 */
251 name = local_label_name ((int)number, 0);
252 if ( (symbolP = symbol_table_lookup(name)) /* seen before */
253 && (symbolP -> sy_type & N_TYPE) != N_UNDF /* symbol is defined: OK */
254 )
255 { /* Expected path: symbol defined. */
256 /* Local labels are never absolute. Don't waste time checking absoluteness. */
257 know( (symbolP -> sy_type & N_TYPE) == N_DATA
258 || (symbolP -> sy_type & N_TYPE) == N_TEXT );
259 expressionP -> X_add_symbol = symbolP;
260 expressionP -> X_add_number = 0;
261 expressionP -> X_seg = N_TYPE_seg [symbolP -> sy_type];
262 }
263 else
264 { /* Either not seen or not defined. */
265 as_warn( "Backw. ref to unknown label \"%d:\", 0 assumed.",
266 number
267 );
268 expressionP -> X_add_number = 0;
269 expressionP -> X_seg = SEG_ABSOLUTE;
270 }
271 }
272 else
273 {
274#ifdef SUN_ASM_SYNTAX
275 if (c=='f' || (c=='$' && !local_label_defined[number]))
276#else
277 if (c=='f')
278#endif
279 {
280 /*
281 * Forward reference. Expect symbol to be undefined or
282 * unknown. Undefined: seen it before. Unknown: never seen
283 * it in this pass.
284 * Construct a local label name, then an undefined symbol.
285 * Don't create a XSEG frag for it: caller may do that.
286 * Just return it as never seen before.
287 */
288 name = local_label_name ((int)number, 1);
289 if ( symbolP = symbol_table_lookup( name ))
290 {
291 /* We have no need to check symbol properties. */
292 know( (symbolP -> sy_type & N_TYPE) == N_UNDF
293 || (symbolP -> sy_type & N_TYPE) == N_DATA
294 || (symbolP -> sy_type & N_TYPE) == N_TEXT);
295 }
296 else
297 {
298 symbolP = symbol_new (name, N_UNDF, 0,0,0, & zero_address_frag);
299 symbol_table_insert (symbolP);
300 }
301 expressionP -> X_add_symbol = symbolP;
302 expressionP -> X_seg = SEG_UNKNOWN;
303 expressionP -> X_subtract_symbol = NULL;
304 expressionP -> X_add_number = 0;
305 }
306 else
307 { /* Really a number, not a local label. */
308 expressionP -> X_add_number = number;
309 expressionP -> X_seg = SEG_ABSOLUTE;
310 input_line_pointer --; /* Restore following character. */
311 } /* if (c=='f') */
312 } /* if (c=='b') */
313 }
314 else
315 { /* Really a number. */
316 expressionP -> X_add_number = number;
317 expressionP -> X_seg = SEG_ABSOLUTE;
318 input_line_pointer --; /* Restore following character. */
319 } /* if (number<10) */
320 }
321 else
322 {
323 expressionP -> X_add_number = number;
324 expressionP -> X_seg = SEG_BIG;
325 input_line_pointer --; /* -> char following number. */
326 } /* if (small) */
327 } /* (If integer constant) */
328 else
329 { /* input_line_pointer -> */
330 /* floating-point constant. */
331 int error_code;
332
333 error_code = atof_generic
334 (& input_line_pointer, ".", EXP_CHARS,
335 & generic_floating_point_number);
336
337 if (error_code)
338 {
339 if (error_code == ERROR_EXPONENT_OVERFLOW)
340 {
341 as_warn( "Bad floating-point constant: exponent overflow, probably assembling junk" );
342 }
343 else
344 {
345 as_warn( "Bad floating-point constant: unknown error code=%d.", error_code);
346 }
347 }
348 expressionP -> X_seg = SEG_BIG;
349 /* input_line_pointer -> just after constant, */
350 /* which may point to whitespace. */
351 know( expressionP -> X_add_number < 0 ); /* < 0 means "floating point". */
352 } /* if (not floating-point constant) */
353 }
354 else if(c=='.' && !is_part_of_name(*input_line_pointer)) {
355 extern struct obstack frags;
356
357 /*
358 JF: '.' is pseudo symbol with value of current location in current
359 segment. . .
360 */
361 symbolP = symbol_new("L0\001",
362 (unsigned char)(seg_N_TYPE[(int)now_seg]),
363 0,
364 0,
365 (valueT)(obstack_next_free(&frags)-frag_now->fr_literal),
366 frag_now);
367 expressionP->X_add_number=0;
368 expressionP->X_add_symbol=symbolP;
369 expressionP->X_seg = now_seg;
370
371 } else if ( is_name_beginner(c) ) /* here if did not begin with a digit */
372 {
373 /*
374 * Identifier begins here.
375 * This is kludged for speed, so code is repeated.
376 */
377 name = -- input_line_pointer;
378 c = get_symbol_end();
379 symbolP = symbol_table_lookup(name);
380 if (symbolP)
381 {
382 /*
383 * If we have an absolute symbol, then we know it's value now.
384 */
385 register segT seg;
386
387 seg = N_TYPE_seg [(int) symbolP -> sy_type & N_TYPE];
388 if ((expressionP -> X_seg = seg) == SEG_ABSOLUTE )
389 {
390 expressionP -> X_add_number = symbolP -> sy_value;
391 }
392 else
393 {
394 expressionP -> X_add_number = 0;
395 expressionP -> X_add_symbol = symbolP;
396 }
397 }
398 else
399 {
400 expressionP -> X_add_symbol
401 = symbolP
402 = symbol_new (name, N_UNDF, 0,0,0, & zero_address_frag);
403
404 expressionP -> X_add_number = 0;
405 expressionP -> X_seg = SEG_UNKNOWN;
406 symbol_table_insert (symbolP);
407 }
408 * input_line_pointer = c;
409 expressionP -> X_subtract_symbol = NULL;
410 }
411 else if (c=='(')/* didn't begin with digit & not a name */
412 {
413 (void)expression( expressionP );
414 /* Expression() will pass trailing whitespace */
415 if ( * input_line_pointer ++ != ')' )
416 {
417 as_warn( "Missing ')' assumed");
418 input_line_pointer --;
419 }
420 /* here with input_line_pointer -> char after "(...)" */
421 }
422 else if ( c=='~' || c=='-' )
423 { /* unary operator: hope for SEG_ABSOLUTE */
424 switch(operand (expressionP)) {
425 case SEG_ABSOLUTE:
426 /* input_line_pointer -> char after operand */
427 if ( c=='-' )
428 {
429 expressionP -> X_add_number = - expressionP -> X_add_number;
430/*
431 * Notice: '-' may overflow: no warning is given. This is compatible
432 * with other people's assemblers. Sigh.
433 */
434 }
435 else
436 {
437 expressionP -> X_add_number = ~ expressionP -> X_add_number;
438 }
439 break;
440
441 case SEG_TEXT:
442 case SEG_DATA:
443 case SEG_BSS:
444 case SEG_PASS1:
445 case SEG_UNKNOWN:
446 if(c=='-') { /* JF I hope this hack works */
447 expressionP->X_subtract_symbol=expressionP->X_add_symbol;
448 expressionP->X_add_symbol=0;
449 expressionP->X_seg=SEG_DIFFERENCE;
450 break;
451 }
452 default: /* unary on non-absolute is unsuported */
453 as_warn("Unary operator %c ignored because bad operand follows", c);
454 break;
455 /* Expression undisturbed from operand(). */
456 }
457 }
458 else if (c=='\'')
459 {
460/*
461 * Warning: to conform to other people's assemblers NO ESCAPEMENT is permitted
462 * for a single quote. The next character, parity errors and all, is taken
463 * as the value of the operand. VERY KINKY.
464 */
465 expressionP -> X_add_number = * input_line_pointer ++;
466 expressionP -> X_seg = SEG_ABSOLUTE;
467 }
468 else
469 {
470 /* can't imagine any other kind of operand */
471 expressionP -> X_seg = SEG_NONE;
472 input_line_pointer --;
473 }
474/*
475 * It is more 'efficient' to clean up the expressions when they are created.
476 * Doing it here saves lines of code.
477 */
478 clean_up_expression (expressionP);
479 SKIP_WHITESPACE(); /* -> 1st char after operand. */
480 know( * input_line_pointer != ' ' );
481 return (expressionP -> X_seg);
482} /* operand */
483\f
484/* Internal. Simplify a struct expression for use by expr() */
485
486/*
487 * In: address of a expressionS.
488 * The X_seg field of the expressionS may only take certain values.
489 * Now, we permit SEG_PASS1 to make code smaller & faster.
490 * Elsewise we waste time special-case testing. Sigh. Ditto SEG_NONE.
491 * Out: expressionS may have been modified:
492 * 'foo-foo' symbol references cancelled to 0,
493 * which changes X_seg from SEG_DIFFERENCE to SEG_ABSOLUTE;
494 * Unused fields zeroed to help expr().
495 */
496
497static void
498clean_up_expression (expressionP)
499 register expressionS * expressionP;
500{
501 switch (expressionP -> X_seg)
502 {
503 case SEG_NONE:
504 case SEG_PASS1:
505 expressionP -> X_add_symbol = NULL;
506 expressionP -> X_subtract_symbol = NULL;
507 expressionP -> X_add_number = 0;
508 break;
509
510 case SEG_BIG:
511 case SEG_ABSOLUTE:
512 expressionP -> X_subtract_symbol = NULL;
513 expressionP -> X_add_symbol = NULL;
514 break;
515
516 case SEG_TEXT:
517 case SEG_DATA:
518 case SEG_BSS:
519 case SEG_UNKNOWN:
520 expressionP -> X_subtract_symbol = NULL;
521 break;
522
523 case SEG_DIFFERENCE:
524 /*
525 * It does not hurt to 'cancel' NULL==NULL
526 * when comparing symbols for 'eq'ness.
527 * It is faster to re-cancel them to NULL
528 * than to check for this special case.
529 */
530 if (expressionP -> X_subtract_symbol == expressionP -> X_add_symbol
531 || ( expressionP->X_subtract_symbol
532 && expressionP->X_add_symbol
533 && expressionP->X_subtract_symbol->sy_frag==expressionP->X_add_symbol->sy_frag
534 && expressionP->X_subtract_symbol->sy_value==expressionP->X_add_symbol->sy_value))
535 {
536 expressionP -> X_subtract_symbol = NULL;
537 expressionP -> X_add_symbol = NULL;
538 expressionP -> X_seg = SEG_ABSOLUTE;
539 }
540 break;
541
542 default:
543 BAD_CASE( expressionP -> X_seg);
544 break;
545 }
546}
547\f
548/*
549 * expr_part ()
550 *
551 * Internal. Made a function because this code is used in 2 places.
552 * Generate error or correct X_?????_symbol of expressionS.
553 */
554
555/*
556 * symbol_1 += symbol_2 ... well ... sort of.
557 */
558
559static segT
560expr_part (symbol_1_PP, symbol_2_P)
561 struct symbol ** symbol_1_PP;
562 struct symbol * symbol_2_P;
563{
564 segT return_value;
565
566 know( (* symbol_1_PP) == NULL
567 || ((* symbol_1_PP) -> sy_type & N_TYPE) == N_TEXT
568 || ((* symbol_1_PP) -> sy_type & N_TYPE) == N_DATA
569 || ((* symbol_1_PP) -> sy_type & N_TYPE) == N_BSS
570 || ((* symbol_1_PP) -> sy_type & N_TYPE) == N_UNDF
571 );
572 know( symbol_2_P == NULL
573 || (symbol_2_P -> sy_type & N_TYPE) == N_TEXT
574 || (symbol_2_P -> sy_type & N_TYPE) == N_DATA
575 || (symbol_2_P -> sy_type & N_TYPE) == N_BSS
576 || (symbol_2_P -> sy_type & N_TYPE) == N_UNDF
577 );
578 if (* symbol_1_PP)
579 {
580 if (((* symbol_1_PP) -> sy_type & N_TYPE) == N_UNDF)
581 {
582 if (symbol_2_P)
583 {
584 return_value = SEG_PASS1;
585 * symbol_1_PP = NULL;
586 }
587 else
588 {
589 know( ((* symbol_1_PP) -> sy_type & N_TYPE) == N_UNDF)
590 return_value = SEG_UNKNOWN;
591 }
592 }
593 else
594 {
595 if (symbol_2_P)
596 {
597 if ((symbol_2_P -> sy_type & N_TYPE) == N_UNDF)
598 {
599 * symbol_1_PP = NULL;
600 return_value = SEG_PASS1;
601 }
602 else
603 {
604 /* {seg1} - {seg2} */
605 as_warn( "Expression too complex, 2 symbols forgotten: \"%s\" \"%s\"",
606 (* symbol_1_PP) -> sy_name, symbol_2_P -> sy_name );
607 * symbol_1_PP = NULL;
608 return_value = SEG_ABSOLUTE;
609 }
610 }
611 else
612 {
613 return_value = N_TYPE_seg [(* symbol_1_PP) -> sy_type & N_TYPE];
614 }
615 }
616 }
617 else
618 { /* (* symbol_1_PP) == NULL */
619 if (symbol_2_P)
620 {
621 * symbol_1_PP = symbol_2_P;
622 return_value = N_TYPE_seg [(symbol_2_P) -> sy_type & N_TYPE];
623 }
624 else
625 {
626 * symbol_1_PP = NULL;
627 return_value = SEG_ABSOLUTE;
628 }
629 }
630 know( return_value == SEG_ABSOLUTE
631 || return_value == SEG_TEXT
632 || return_value == SEG_DATA
633 || return_value == SEG_BSS
634 || return_value == SEG_UNKNOWN
635 || return_value == SEG_PASS1
636 );
637 know( (* symbol_1_PP) == NULL
638 || ((* symbol_1_PP) -> sy_type & N_TYPE) == seg_N_TYPE [(int) return_value] );
639 return (return_value);
640} /* expr_part() */
641\f
642/* Expression parser. */
643
644/*
645 * We allow an empty expression, and just assume (absolute,0) silently.
646 * Unary operators and parenthetical expressions are treated as operands.
647 * As usual, Q==quantity==operand, O==operator, X==expression mnemonics.
648 *
649 * We used to do a aho/ullman shift-reduce parser, but the logic got so
650 * warped that I flushed it and wrote a recursive-descent parser instead.
651 * Now things are stable, would anybody like to write a fast parser?
652 * Most expressions are either register (which does not even reach here)
653 * or 1 symbol. Then "symbol+constant" and "symbol-symbol" are common.
654 * So I guess it doesn't really matter how inefficient more complex expressions
655 * are parsed.
656 *
657 * After expr(RANK,resultP) input_line_pointer -> operator of rank <= RANK.
658 * Also, we have consumed any leading or trailing spaces (operand does that)
659 * and done all intervening operators.
660 */
661
662typedef enum
663{
664O_illegal, /* (0) what we get for illegal op */
665
666O_multiply, /* (1) * */
667O_divide, /* (2) / */
668O_modulus, /* (3) % */
669O_left_shift, /* (4) < */
670O_right_shift, /* (5) > */
671O_bit_inclusive_or, /* (6) | */
672O_bit_or_not, /* (7) ! */
673O_bit_exclusive_or, /* (8) ^ */
674O_bit_and, /* (9) & */
675O_add, /* (10) + */
676O_subtract /* (11) - */
677}
678operatorT;
679
680#define __ O_illegal
681
682static const operatorT op_encoding [256] = { /* maps ASCII -> operators */
683
684__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
685__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
686
687__, O_bit_or_not, __, __, __, O_modulus, O_bit_and, __,
688__, __, O_multiply, O_add, __, O_subtract, __, O_divide,
689__, __, __, __, __, __, __, __,
690__, __, __, __, O_left_shift, __, O_right_shift, __,
691__, __, __, __, __, __, __, __,
692__, __, __, __, __, __, __, __,
693__, __, __, __, __, __, __, __,
694__, __, __, __, __, __, O_bit_exclusive_or, __,
695__, __, __, __, __, __, __, __,
696__, __, __, __, __, __, __, __,
697__, __, __, __, __, __, __, __,
698__, __, __, __, O_bit_inclusive_or, __, __, __,
699
700__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
701__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
702__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
703__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
704__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
705__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
706__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
707__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __
708};
709
710
711/*
712 * Rank Examples
713 * 0 operand, (expression)
714 * 1 + -
715 * 2 & ^ ! |
716 * 3 * / % < >
717 */
718typedef char operator_rankT;
719static const operator_rankT
720op_rank [] = { 0, 3, 3, 3, 3, 3, 2, 2, 2, 2, 1, 1 };
721\f
722segT /* Return resultP -> X_seg. */
723expr (rank, resultP)
724 register operator_rankT rank; /* Larger # is higher rank. */
725 register expressionS * resultP; /* Deliver result here. */
726{
727 expressionS right;
728 register operatorT op_left;
729 register char c_left; /* 1st operator character. */
730 register operatorT op_right;
731 register char c_right;
732
733 know( rank >= 0 );
734 (void)operand (resultP);
735 know( * input_line_pointer != ' ' ); /* Operand() gobbles spaces. */
736 c_left = * input_line_pointer; /* Potential operator character. */
737 op_left = op_encoding [c_left];
738 while (op_left != O_illegal && op_rank [(int) op_left] > rank)
739 {
740 input_line_pointer ++; /* -> after 1st character of operator. */
741 /* Operators "<<" and ">>" have 2 characters. */
742 if (* input_line_pointer == c_left && (c_left == '<' || c_left == '>') )
743 {
744 input_line_pointer ++;
745 } /* -> after operator. */
746 if (SEG_NONE == expr (op_rank[(int) op_left], &right))
747 {
748 as_warn("Missing operand value assumed absolute 0.");
749 resultP -> X_add_number = 0;
750 resultP -> X_subtract_symbol = NULL;
751 resultP -> X_add_symbol = NULL;
752 resultP -> X_seg = SEG_ABSOLUTE;
753 }
754 know( * input_line_pointer != ' ' );
755 c_right = * input_line_pointer;
756 op_right = op_encoding [c_right];
757 if (* input_line_pointer == c_right && (c_right == '<' || c_right == '>') )
758 {
759 input_line_pointer ++;
760 } /* -> after operator. */
761 know( (int) op_right == 0
762 || op_rank [(int) op_right] <= op_rank[(int) op_left] );
763 /* input_line_pointer -> after right-hand quantity. */
764 /* left-hand quantity in resultP */
765 /* right-hand quantity in right. */
766 /* operator in op_left. */
767 if ( resultP -> X_seg == SEG_PASS1 || right . X_seg == SEG_PASS1 )
768 {
769 resultP -> X_seg = SEG_PASS1;
770 }
771 else
772 {
773 if ( resultP -> X_seg == SEG_BIG )
774 {
775 as_warn( "Left operand of %c is a %s. Integer 0 assumed.",
776 c_left, resultP -> X_add_number > 0 ? "bignum" : "float");
777 resultP -> X_seg = SEG_ABSOLUTE;
778 resultP -> X_add_symbol = 0;
779 resultP -> X_subtract_symbol = 0;
780 resultP -> X_add_number = 0;
781 }
782 if ( right . X_seg == SEG_BIG )
783 {
784 as_warn( "Right operand of %c is a %s. Integer 0 assumed.",
785 c_left, right . X_add_number > 0 ? "bignum" : "float");
786 right . X_seg = SEG_ABSOLUTE;
787 right . X_add_symbol = 0;
788 right . X_subtract_symbol = 0;
789 right . X_add_number = 0;
790 }
791 if ( op_left == O_subtract )
792 {
793 /*
794 * Convert - into + by exchanging symbols and negating number.
795 * I know -infinity can't be negated in 2's complement:
796 * but then it can't be subtracted either. This trick
797 * does not cause any further inaccuracy.
798 */
799
800 register struct symbol * symbolP;
801
802 right . X_add_number = - right . X_add_number;
803 symbolP = right . X_add_symbol;
804 right . X_add_symbol = right . X_subtract_symbol;
805 right . X_subtract_symbol = symbolP;
806 if (symbolP)
807 {
808 right . X_seg = SEG_DIFFERENCE;
809 }
810 op_left = O_add;
811 }
812\f
813 if ( op_left == O_add )
814 {
815 segT seg1;
816 segT seg2;
817
818 know( resultP -> X_seg == SEG_DATA
819 || resultP -> X_seg == SEG_TEXT
820 || resultP -> X_seg == SEG_BSS
821 || resultP -> X_seg == SEG_UNKNOWN
822 || resultP -> X_seg == SEG_DIFFERENCE
823 || resultP -> X_seg == SEG_ABSOLUTE
824 || resultP -> X_seg == SEG_PASS1
825 );
826 know( right . X_seg == SEG_DATA
827 || right . X_seg == SEG_TEXT
828 || right . X_seg == SEG_BSS
829 || right . X_seg == SEG_UNKNOWN
830 || right . X_seg == SEG_DIFFERENCE
831 || right . X_seg == SEG_ABSOLUTE
832 || right . X_seg == SEG_PASS1
833 );
834
835 clean_up_expression (& right);
836 clean_up_expression (resultP);
837
838 seg1 = expr_part (& resultP -> X_add_symbol, right . X_add_symbol);
839 seg2 = expr_part (& resultP -> X_subtract_symbol, right . X_subtract_symbol);
840 if (seg1 == SEG_PASS1 || seg2 == SEG_PASS1) {
841 need_pass_2 = TRUE;
842 resultP -> X_seg = SEG_PASS1;
843 } else if (seg2 == SEG_ABSOLUTE)
844 resultP -> X_seg = seg1;
845 else if ( seg1 != SEG_UNKNOWN
846 && seg1 != SEG_ABSOLUTE
847 && seg2 != SEG_UNKNOWN
848 && seg1 != seg2) {
849 know( seg2 != SEG_ABSOLUTE );
850 know( resultP -> X_subtract_symbol );
851
852 know( seg1 == SEG_TEXT || seg1 == SEG_DATA || seg1== SEG_BSS );
853 know( seg2 == SEG_TEXT || seg2 == SEG_DATA || seg2== SEG_BSS );
854 know( resultP -> X_add_symbol );
855 know( resultP -> X_subtract_symbol );
856 as_warn("Expression too complex: forgetting %s - %s",
857 resultP -> X_add_symbol -> sy_name,
858 resultP -> X_subtract_symbol -> sy_name);
859 resultP -> X_seg = SEG_ABSOLUTE;
860 /* Clean_up_expression() will do the rest. */
861 } else
862 resultP -> X_seg = SEG_DIFFERENCE;
863
864 resultP -> X_add_number += right . X_add_number;
865 clean_up_expression (resultP);
866 }
867 else
868 { /* Not +. */
869 if ( resultP -> X_seg == SEG_UNKNOWN || right . X_seg == SEG_UNKNOWN )
870 {
871 resultP -> X_seg = SEG_PASS1;
872 need_pass_2 = TRUE;
873 }
874 else
875 {
876 resultP -> X_subtract_symbol = NULL;
877 resultP -> X_add_symbol = NULL;
878 /* Will be SEG_ABSOLUTE. */
879 if ( resultP -> X_seg != SEG_ABSOLUTE || right . X_seg != SEG_ABSOLUTE )
880 {
881 as_warn( "Relocation error. Absolute 0 assumed.");
882 resultP -> X_seg = SEG_ABSOLUTE;
883 resultP -> X_add_number = 0;
884 }
885 else
886 {
887 switch ( op_left )
888 {
889 case O_bit_inclusive_or:
890 resultP -> X_add_number |= right . X_add_number;
891 break;
892
893 case O_modulus:
894 if (right . X_add_number)
895 {
896 resultP -> X_add_number %= right . X_add_number;
897 }
898 else
899 {
900 as_warn( "Division by 0. 0 assumed." );
901 resultP -> X_add_number = 0;
902 }
903 break;
904
905 case O_bit_and:
906 resultP -> X_add_number &= right . X_add_number;
907 break;
908
909 case O_multiply:
910 resultP -> X_add_number *= right . X_add_number;
911 break;
912
913 case O_divide:
914 if (right . X_add_number)
915 {
916 resultP -> X_add_number /= right . X_add_number;
917 }
918 else
919 {
920 as_warn( "Division by 0. 0 assumed." );
921 resultP -> X_add_number = 0;
922 }
923 break;
924
925 case O_left_shift:
926 resultP -> X_add_number <<= right . X_add_number;
927 break;
928
929 case O_right_shift:
930 resultP -> X_add_number >>= right . X_add_number;
931 break;
932
933 case O_bit_exclusive_or:
934 resultP -> X_add_number ^= right . X_add_number;
935 break;
936
937 case O_bit_or_not:
938 resultP -> X_add_number |= ~ right . X_add_number;
939 break;
940
941 default:
942 BAD_CASE( op_left );
943 break;
944 } /* switch(operator) */
945 }
946 } /* If we have to force need_pass_2. */
947 } /* If operator was +. */
948 } /* If we didn't set need_pass_2. */
949 op_left = op_right;
950 } /* While next operator is >= this rank. */
951 return (resultP -> X_seg);
952}
953\f
954/*
955 * get_symbol_end()
956 *
957 * This lives here because it belongs equally in expr.c & read.c.
958 * Expr.c is just a branch office read.c anyway, and putting it
959 * here lessens the crowd at read.c.
960 *
961 * Assume input_line_pointer is at start of symbol name.
962 * Advance input_line_pointer past symbol name.
963 * Turn that character into a '\0', returning its former value.
964 * This allows a string compare (RMS wants symbol names to be strings)
965 * of the symbol name.
966 * There will always be a char following symbol name, because all good
967 * lines end in end-of-line.
968 */
969char
970get_symbol_end()
971{
972 register char c;
973
974 while ( is_part_of_name( c = * input_line_pointer ++ ) )
975 ;
976 * -- input_line_pointer = 0;
977 return (c);
978}
979
980/* end: expr.c */
Continuous source code history from original PDP-7 UNIX to FreeBSD 2, the first fully unencumbered FreeBSD release.