1116 lines
31 KiB
C
1116 lines
31 KiB
C
/* expr.c -operands, expressions-
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Copyright (C) 1987, 1990, 1991, 1992 Free Software Foundation, Inc.
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This file is part of GAS, the GNU Assembler.
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GAS is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GAS is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GAS; see the file COPYING. If not, write to
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the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
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/*
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* This is really a branch office of as-read.c. I split it out to clearly
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* distinguish the world of expressions from the world of statements.
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* (It also gives smaller files to re-compile.)
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* Here, "operand"s are of expressions, not instructions.
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*/
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#include <ctype.h>
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#include <string.h>
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#include "as.h"
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#include "obstack.h"
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#if __STDC__ == 1
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static void clean_up_expression(expressionS *expressionP);
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#else /* __STDC__ */
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static void clean_up_expression(); /* Internal. */
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#endif /* not __STDC__ */
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extern const char EXP_CHARS[]; /* JF hide MD floating pt stuff all the same place */
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extern const char FLT_CHARS[];
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/*
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* Build any floating-point literal here.
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* Also build any bignum literal here.
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*/
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/* LITTLENUM_TYPE generic_buffer [6]; */ /* JF this is a hack */
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/* Seems atof_machine can backscan through generic_bignum and hit whatever
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happens to be loaded before it in memory. And its way too complicated
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for me to fix right. Thus a hack. JF: Just make generic_bignum bigger,
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and never write into the early words, thus they'll always be zero.
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I hate Dean's floating-point code. Bleh.
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*/
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LITTLENUM_TYPE generic_bignum [SIZE_OF_LARGE_NUMBER+6];
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FLONUM_TYPE generic_floating_point_number =
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{
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& generic_bignum [6], /* low (JF: Was 0) */
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& generic_bignum [SIZE_OF_LARGE_NUMBER+6 - 1], /* high JF: (added +6) */
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0, /* leader */
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0, /* exponent */
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0 /* sign */
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};
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/* If nonzero, we've been asked to assemble nan, +inf or -inf */
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int generic_floating_point_magic;
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floating_constant(expressionP)
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expressionS *expressionP;
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{
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/* input_line_pointer->*/
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/* floating-point constant. */
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int error_code;
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error_code = atof_generic
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(& input_line_pointer, ".", EXP_CHARS,
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& generic_floating_point_number);
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if (error_code)
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{
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if (error_code == ERROR_EXPONENT_OVERFLOW)
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{
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as_bad("bad floating-point constant: exponent overflow, probably assembling junk");
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}
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else
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{
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as_bad("bad floating-point constant: unknown error code=%d.", error_code);
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}
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}
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expressionP->X_seg = SEG_BIG;
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/* input_line_pointer->just after constant, */
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/* which may point to whitespace. */
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expressionP->X_add_number =-1;
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}
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integer_constant(radix, expressionP)
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int radix;
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expressionS *expressionP;
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{
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register char * digit_2; /*->2nd digit of number. */
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char c;
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register valueT number; /* offset or (absolute) value */
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register short int digit; /* value of next digit in current radix */
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register short int maxdig = 0; /* highest permitted digit value. */
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register int too_many_digits = 0; /* if we see >= this number of */
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register char *name; /* points to name of symbol */
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register symbolS * symbolP; /* points to symbol */
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int small; /* true if fits in 32 bits. */
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extern char hex_value[]; /* in hex_value.c */
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/* may be bignum, or may fit in 32 bits. */
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/*
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* most numbers fit into 32 bits, and we want this case to be fast.
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* so we pretend it will fit into 32 bits. if, after making up a 32
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* bit number, we realise that we have scanned more digits than
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* comfortably fit into 32 bits, we re-scan the digits coding
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* them into a bignum. for decimal and octal numbers we are conservative: some
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* numbers may be assumed bignums when in fact they do fit into 32 bits.
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* numbers of any radix can have excess leading zeros: we strive
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* to recognise this and cast them back into 32 bits.
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* we must check that the bignum really is more than 32
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* bits, and change it back to a 32-bit number if it fits.
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* the number we are looking for is expected to be positive, but
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* if it fits into 32 bits as an unsigned number, we let it be a 32-bit
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* number. the cavalier approach is for speed in ordinary cases.
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*/
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switch (radix)
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{
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case 2:
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maxdig = 2;
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too_many_digits = 33;
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break;
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case 8:
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maxdig = radix = 8;
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too_many_digits = 11;
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break;
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case 16:
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maxdig = radix = 16;
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too_many_digits = 9;
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break;
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case 10:
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maxdig = radix = 10;
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too_many_digits = 11;
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}
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c = *input_line_pointer;
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input_line_pointer++;
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digit_2 = input_line_pointer;
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for (number=0; (digit=hex_value[c])<maxdig; c = * input_line_pointer ++)
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{
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number = number * radix + digit;
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}
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/* c contains character after number. */
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/* input_line_pointer->char after c. */
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small = input_line_pointer - digit_2 < too_many_digits;
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if (! small)
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{
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/*
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* we saw a lot of digits. manufacture a bignum the hard way.
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*/
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LITTLENUM_TYPE * leader; /*->high order littlenum of the bignum. */
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LITTLENUM_TYPE * pointer; /*->littlenum we are frobbing now. */
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long carry;
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leader = generic_bignum;
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generic_bignum [0] = 0;
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generic_bignum [1] = 0;
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/* we could just use digit_2, but lets be mnemonic. */
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input_line_pointer = --digit_2; /*->1st digit. */
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c = *input_line_pointer++;
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for (; (carry = hex_value[c]) < maxdig; c = *input_line_pointer++)
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{
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for (pointer = generic_bignum;
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pointer <= leader;
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pointer++)
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{
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long work;
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work = carry + radix * * pointer;
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*pointer = work & LITTLENUM_MASK;
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carry = work >> LITTLENUM_NUMBER_OF_BITS;
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}
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if (carry)
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{
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if (leader < generic_bignum + SIZE_OF_LARGE_NUMBER - 1)
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{ /* room to grow a longer bignum. */
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*++leader = carry;
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}
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}
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}
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/* again, c is char after number, */
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/* input_line_pointer->after c. */
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know(sizeof (int) * 8 == 32);
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know(LITTLENUM_NUMBER_OF_BITS == 16);
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/* hence the constant "2" in the next line. */
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if (leader < generic_bignum + 2)
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{ /* will fit into 32 bits. */
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number =
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((generic_bignum [1] & LITTLENUM_MASK) << LITTLENUM_NUMBER_OF_BITS)
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| (generic_bignum [0] & LITTLENUM_MASK);
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small = 1;
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}
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else
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{
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number = leader - generic_bignum + 1; /* number of littlenums in the bignum. */
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}
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}
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if (small) {
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/*
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* here with number, in correct radix. c is the next char.
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* note that unlike un*x, we allow "011f" "0x9f" to
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* both mean the same as the (conventional) "9f". this is simply easier
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* than checking for strict canonical form. syntax sux!
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*/
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switch (c) {
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#ifdef LOCAL_LABELS_FB
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case 'b': {
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/*
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* backward ref to local label.
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* because it is backward, expect it to be defined.
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*/
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/*
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* construct a local label.
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*/
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name = fb_label_name((int) number, 0);
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/* seen before, or symbol is defined: ok */
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symbolP = symbol_find(name);
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if ((symbolP != NULL) && (S_IS_DEFINED(symbolP))) {
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/* local labels are never absolute. don't waste time checking absoluteness. */
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know(SEG_NORMAL(S_GET_SEGMENT(symbolP)));
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expressionP->X_add_symbol = symbolP;
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expressionP->X_seg = S_GET_SEGMENT(symbolP);
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} else { /* either not seen or not defined. */
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as_bad("backw. ref to unknown label \"%d:\", 0 assumed.", number);
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expressionP->X_seg = SEG_ABSOLUTE;
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}
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expressionP->X_add_number = 0;
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break;
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} /* case 'b' */
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case 'f': {
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/*
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* forward reference. expect symbol to be undefined or
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* unknown. undefined: seen it before. unknown: never seen
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* it before.
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* construct a local label name, then an undefined symbol.
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* don't create a xseg frag for it: caller may do that.
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* just return it as never seen before.
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*/
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name = fb_label_name((int) number, 1);
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symbolP = symbol_find_or_make(name);
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/* we have no need to check symbol properties. */
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#ifndef many_segments
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/* since "know" puts its arg into a "string", we
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can't have newlines in the argument. */
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know(S_GET_SEGMENT(symbolP) == SEG_UNKNOWN || S_GET_SEGMENT(symbolP) == SEG_TEXT || S_GET_SEGMENT(symbolP) == SEG_DATA);
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#endif
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expressionP->X_add_symbol = symbolP;
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expressionP->X_seg = SEG_UNKNOWN;
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expressionP->X_subtract_symbol = NULL;
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expressionP->X_add_number = 0;
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break;
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} /* case 'f' */
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#endif /* LOCAL_LABELS_FB */
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#ifdef LOCAL_LABELS_DOLLAR
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case '$': {
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/* if the dollar label is *currently* defined, then this is just another
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reference to it. If it is not *currently* defined, then this is a
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fresh instantiation of that number, so create it. */
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if (dollar_label_defined(number)) {
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name = dollar_label_name(number, 0);
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symbolP = symbol_find(name);
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know(symbolP != NULL);
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} else {
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name = dollar_label_name(number, 1);
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symbolP = symbol_find_or_make(name);
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}
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expressionP->X_add_symbol = symbolP;
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expressionP->X_add_number = 0;
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expressionP->X_seg = S_GET_SEGMENT(symbolP);
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break;
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} /* case '$' */
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#endif /* LOCAL_LABELS_DOLLAR */
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default: {
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expressionP->X_add_number = number;
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expressionP->X_seg = SEG_ABSOLUTE;
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input_line_pointer--; /* restore following character. */
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break;
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} /* really just a number */
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} /* switch on char following the number */
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} else { /* not a small number */
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expressionP->X_add_number = number;
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expressionP->X_seg = SEG_BIG;
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input_line_pointer --; /*->char following number. */
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} /* if (small) */
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} /* integer_constant() */
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/*
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* Summary of operand().
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*
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* in: Input_line_pointer points to 1st char of operand, which may
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* be a space.
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*
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* out: A expressionS. X_seg determines how to understand the rest of the
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* expressionS.
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* The operand may have been empty: in this case X_seg == SEG_ABSENT.
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* Input_line_pointer->(next non-blank) char after operand.
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*
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*/
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static segT
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operand (expressionP)
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register expressionS * expressionP;
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{
|
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register char c;
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register symbolS * symbolP; /* points to symbol */
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register char *name; /* points to name of symbol */
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/* invented for humans only, hope */
|
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/* optimising compiler flushes it! */
|
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register short int radix; /* 2, 8, 10 or 16, 0 when floating */
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/* 0 means we saw start of a floating- */
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/* point constant. */
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/* digits, assume it is a bignum. */
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||
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SKIP_WHITESPACE(); /* leading whitespace is part of operand. */
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c = * input_line_pointer ++; /* input_line_pointer->past char in c. */
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switch (c)
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{
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#ifdef MRI
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case '%':
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integer_constant(2, expressionP);
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break;
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case '@':
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integer_constant(8, expressionP);
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break;
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case '$':
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integer_constant(16, expressionP);
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break;
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#endif
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case '1':
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case '2':
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case '3':
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||
case '4':
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||
case '5':
|
||
case '6':
|
||
case '7':
|
||
case '8':
|
||
case '9':
|
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input_line_pointer--;
|
||
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integer_constant(10, expressionP);
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break;
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||
|
||
case '0':
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/* non-decimal radix */
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c = *input_line_pointer;
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switch (c)
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{
|
||
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||
default:
|
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if (c && strchr(FLT_CHARS,c))
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{
|
||
input_line_pointer++;
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floating_constant(expressionP);
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||
}
|
||
else
|
||
{
|
||
|
||
|
||
/* The string was only zero */
|
||
expressionP->X_add_symbol = 0;
|
||
expressionP->X_add_number = 0;
|
||
expressionP->X_seg = SEG_ABSOLUTE;
|
||
}
|
||
|
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break;
|
||
|
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case 'x':
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case 'X':
|
||
input_line_pointer++;
|
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integer_constant(16, expressionP);
|
||
break;
|
||
case 'B':
|
||
case 'b':
|
||
input_line_pointer++;
|
||
integer_constant(2, expressionP);
|
||
break;
|
||
|
||
case '0':
|
||
case '1':
|
||
case '2':
|
||
case '3':
|
||
case '4':
|
||
case '5':
|
||
case '6':
|
||
case '7':
|
||
integer_constant(8, expressionP);
|
||
break;
|
||
|
||
case 'f':
|
||
/* if it says '0f' and the line ends or it doesn't look like
|
||
a floating point #, its a local label ref. dtrt */
|
||
/* likewise for the b's. xoxorich. */
|
||
if ((c == 'f' || c == 'b' || c == 'b')
|
||
&& (!*input_line_pointer ||
|
||
(!strchr("+-.0123456789",*input_line_pointer) &&
|
||
!strchr(EXP_CHARS,*input_line_pointer))))
|
||
{
|
||
input_line_pointer -= 2;
|
||
integer_constant(10, expressionP);
|
||
break;
|
||
}
|
||
|
||
case 'd':
|
||
case 'D':
|
||
case 'F':
|
||
case 'r':
|
||
case 'e':
|
||
case 'E':
|
||
case 'g':
|
||
case 'G':
|
||
|
||
input_line_pointer++;
|
||
floating_constant(expressionP);
|
||
break;
|
||
}
|
||
|
||
break;
|
||
case '(':
|
||
/* didn't begin with digit & not a name */
|
||
{
|
||
(void)expression(expressionP);
|
||
/* Expression() will pass trailing whitespace */
|
||
if (* input_line_pointer ++ != ')')
|
||
{
|
||
as_bad("Missing ')' assumed");
|
||
input_line_pointer --;
|
||
}
|
||
/* here with input_line_pointer->char after "(...)" */
|
||
}
|
||
return expressionP->X_seg;
|
||
|
||
|
||
case '\'':
|
||
/*
|
||
* Warning: to conform to other people's assemblers NO ESCAPEMENT is permitted
|
||
* for a single quote. The next character, parity errors and all, is taken
|
||
* as the value of the operand. VERY KINKY.
|
||
*/
|
||
expressionP->X_add_number = * input_line_pointer ++;
|
||
expressionP->X_seg = SEG_ABSOLUTE;
|
||
break;
|
||
|
||
case '~':
|
||
case '-':
|
||
case '+':
|
||
|
||
{
|
||
/* unary operator: hope for SEG_ABSOLUTE */
|
||
switch(operand (expressionP)) {
|
||
case SEG_ABSOLUTE:
|
||
/* input_line_pointer -> char after operand */
|
||
if ( c=='-' )
|
||
{
|
||
expressionP -> X_add_number = - expressionP -> X_add_number;
|
||
/*
|
||
* Notice: '-' may overflow: no warning is given. This is compatible
|
||
* with other people's assemblers. Sigh.
|
||
*/
|
||
}
|
||
else
|
||
{
|
||
expressionP -> X_add_number = ~ expressionP -> X_add_number;
|
||
}
|
||
break;
|
||
|
||
case SEG_TEXT:
|
||
case SEG_DATA:
|
||
case SEG_BSS:
|
||
case SEG_PASS1:
|
||
case SEG_UNKNOWN:
|
||
if(c=='-') { /* JF I hope this hack works */
|
||
expressionP->X_subtract_symbol=expressionP->X_add_symbol;
|
||
expressionP->X_add_symbol=0;
|
||
expressionP->X_seg=SEG_DIFFERENCE;
|
||
break;
|
||
}
|
||
default: /* unary on non-absolute is unsuported */
|
||
as_warn("Unary operator %c ignored because bad operand follows", c);
|
||
break;
|
||
/* Expression undisturbed from operand(). */
|
||
}
|
||
}
|
||
|
||
|
||
|
||
break;
|
||
|
||
case '.':
|
||
if( !is_part_of_name(*input_line_pointer))
|
||
{
|
||
extern struct obstack frags;
|
||
|
||
/*
|
||
JF: '.' is pseudo symbol with value of current location in current
|
||
segment. . .
|
||
*/
|
||
symbolP = symbol_new("L0\001",
|
||
now_seg,
|
||
(valueT)(obstack_next_free(&frags)-frag_now->fr_literal),
|
||
frag_now);
|
||
|
||
expressionP->X_add_number=0;
|
||
expressionP->X_add_symbol=symbolP;
|
||
expressionP->X_seg = now_seg;
|
||
break;
|
||
|
||
}
|
||
else
|
||
{
|
||
goto isname;
|
||
|
||
|
||
}
|
||
case ',':
|
||
case '\n':
|
||
/* can't imagine any other kind of operand */
|
||
expressionP->X_seg = SEG_ABSENT;
|
||
input_line_pointer --;
|
||
md_operand (expressionP);
|
||
break;
|
||
/* Fall through */
|
||
default:
|
||
if (is_name_beginner(c)) /* here if did not begin with a digit */
|
||
{
|
||
/*
|
||
* Identifier begins here.
|
||
* This is kludged for speed, so code is repeated.
|
||
*/
|
||
isname:
|
||
name = -- input_line_pointer;
|
||
c = get_symbol_end();
|
||
symbolP = symbol_find_or_make(name);
|
||
/*
|
||
* If we have an absolute symbol or a reg, then we know its value now.
|
||
*/
|
||
expressionP->X_seg = S_GET_SEGMENT(symbolP);
|
||
switch (expressionP->X_seg)
|
||
{
|
||
case SEG_ABSOLUTE:
|
||
case SEG_REGISTER:
|
||
expressionP->X_add_number = S_GET_VALUE(symbolP);
|
||
break;
|
||
|
||
default:
|
||
expressionP->X_add_number = 0;
|
||
expressionP->X_add_symbol = symbolP;
|
||
}
|
||
* input_line_pointer = c;
|
||
expressionP->X_subtract_symbol = NULL;
|
||
}
|
||
else
|
||
{
|
||
as_bad("Bad expression");
|
||
expressionP->X_add_number = 0;
|
||
expressionP->X_seg = SEG_ABSOLUTE;
|
||
|
||
}
|
||
|
||
}
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
/*
|
||
* It is more 'efficient' to clean up the expressionS when they are created.
|
||
* Doing it here saves lines of code.
|
||
*/
|
||
clean_up_expression (expressionP);
|
||
SKIP_WHITESPACE(); /*->1st char after operand. */
|
||
know(* input_line_pointer != ' ');
|
||
return (expressionP->X_seg);
|
||
} /* operand() */
|
||
|
||
|
||
/* Internal. Simplify a struct expression for use by expr() */
|
||
|
||
/*
|
||
* In: address of a expressionS.
|
||
* The X_seg field of the expressionS may only take certain values.
|
||
* Now, we permit SEG_PASS1 to make code smaller & faster.
|
||
* Elsewise we waste time special-case testing. Sigh. Ditto SEG_ABSENT.
|
||
* Out: expressionS may have been modified:
|
||
* 'foo-foo' symbol references cancelled to 0,
|
||
* which changes X_seg from SEG_DIFFERENCE to SEG_ABSOLUTE;
|
||
* Unused fields zeroed to help expr().
|
||
*/
|
||
|
||
static void
|
||
clean_up_expression (expressionP)
|
||
register expressionS * expressionP;
|
||
{
|
||
switch (expressionP->X_seg)
|
||
{
|
||
case SEG_ABSENT:
|
||
case SEG_PASS1:
|
||
expressionP->X_add_symbol = NULL;
|
||
expressionP->X_subtract_symbol = NULL;
|
||
expressionP->X_add_number = 0;
|
||
break;
|
||
|
||
case SEG_BIG:
|
||
case SEG_ABSOLUTE:
|
||
expressionP->X_subtract_symbol = NULL;
|
||
expressionP->X_add_symbol = NULL;
|
||
break;
|
||
|
||
case SEG_UNKNOWN:
|
||
expressionP->X_subtract_symbol = NULL;
|
||
break;
|
||
|
||
case SEG_DIFFERENCE:
|
||
/*
|
||
* It does not hurt to 'cancel' NULL==NULL
|
||
* when comparing symbols for 'eq'ness.
|
||
* It is faster to re-cancel them to NULL
|
||
* than to check for this special case.
|
||
*/
|
||
if (expressionP->X_subtract_symbol == expressionP->X_add_symbol
|
||
|| (expressionP->X_subtract_symbol
|
||
&& expressionP->X_add_symbol
|
||
&& expressionP->X_subtract_symbol->sy_frag==expressionP->X_add_symbol->sy_frag
|
||
&& S_GET_VALUE(expressionP->X_subtract_symbol) == S_GET_VALUE(expressionP->X_add_symbol))) {
|
||
expressionP->X_subtract_symbol = NULL;
|
||
expressionP->X_add_symbol = NULL;
|
||
expressionP->X_seg = SEG_ABSOLUTE;
|
||
}
|
||
break;
|
||
|
||
case SEG_REGISTER:
|
||
expressionP->X_add_symbol = NULL;
|
||
expressionP->X_subtract_symbol = NULL;
|
||
break;
|
||
|
||
default:
|
||
if (SEG_NORMAL(expressionP->X_seg)) {
|
||
expressionP->X_subtract_symbol = NULL;
|
||
}
|
||
else {
|
||
BAD_CASE (expressionP->X_seg);
|
||
}
|
||
break;
|
||
}
|
||
} /* clean_up_expression() */
|
||
|
||
/*
|
||
* expr_part ()
|
||
*
|
||
* Internal. Made a function because this code is used in 2 places.
|
||
* Generate error or correct X_?????_symbol of expressionS.
|
||
*/
|
||
|
||
/*
|
||
* symbol_1 += symbol_2 ... well ... sort of.
|
||
*/
|
||
|
||
static segT
|
||
expr_part (symbol_1_PP, symbol_2_P)
|
||
symbolS ** symbol_1_PP;
|
||
symbolS * symbol_2_P;
|
||
{
|
||
segT return_value;
|
||
#ifndef MANY_SEGMENTS
|
||
know((* symbol_1_PP) == NULL || (S_GET_SEGMENT(*symbol_1_PP) == SEG_TEXT) || (S_GET_SEGMENT(*symbol_1_PP) == SEG_DATA) || (S_GET_SEGMENT(*symbol_1_PP) == SEG_BSS) || (!S_IS_DEFINED(* symbol_1_PP)));
|
||
know(symbol_2_P == NULL || (S_GET_SEGMENT(symbol_2_P) == SEG_TEXT) || (S_GET_SEGMENT(symbol_2_P) == SEG_DATA) || (S_GET_SEGMENT(symbol_2_P) == SEG_BSS) || (!S_IS_DEFINED(symbol_2_P)));
|
||
#endif
|
||
if (* symbol_1_PP)
|
||
{
|
||
if (!S_IS_DEFINED(* symbol_1_PP))
|
||
{
|
||
if (symbol_2_P)
|
||
{
|
||
return_value = SEG_PASS1;
|
||
* symbol_1_PP = NULL;
|
||
}
|
||
else
|
||
{
|
||
know(!S_IS_DEFINED(* symbol_1_PP));
|
||
return_value = SEG_UNKNOWN;
|
||
}
|
||
}
|
||
else
|
||
{
|
||
if (symbol_2_P)
|
||
{
|
||
if (!S_IS_DEFINED(symbol_2_P))
|
||
{
|
||
* symbol_1_PP = NULL;
|
||
return_value = SEG_PASS1;
|
||
}
|
||
else
|
||
{
|
||
/* {seg1} - {seg2} */
|
||
as_bad("Expression too complex, 2 symbolS forgotten: \"%s\" \"%s\"",
|
||
S_GET_NAME(* symbol_1_PP), S_GET_NAME(symbol_2_P));
|
||
* symbol_1_PP = NULL;
|
||
return_value = SEG_ABSOLUTE;
|
||
}
|
||
}
|
||
else
|
||
{
|
||
return_value = S_GET_SEGMENT(* symbol_1_PP);
|
||
}
|
||
}
|
||
}
|
||
else
|
||
{ /* (* symbol_1_PP) == NULL */
|
||
if (symbol_2_P)
|
||
{
|
||
* symbol_1_PP = symbol_2_P;
|
||
return_value = S_GET_SEGMENT(symbol_2_P);
|
||
}
|
||
else
|
||
{
|
||
* symbol_1_PP = NULL;
|
||
return_value = SEG_ABSOLUTE;
|
||
}
|
||
}
|
||
#ifndef MANY_SEGMENTS
|
||
know(return_value == SEG_ABSOLUTE || return_value == SEG_TEXT || return_value == SEG_DATA || return_value == SEG_BSS || return_value == SEG_UNKNOWN || return_value == SEG_PASS1);
|
||
#endif
|
||
know((*symbol_1_PP) == NULL || (S_GET_SEGMENT(*symbol_1_PP) == return_value));
|
||
return (return_value);
|
||
} /* expr_part() */
|
||
|
||
/* Expression parser. */
|
||
|
||
/*
|
||
* We allow an empty expression, and just assume (absolute,0) silently.
|
||
* Unary operators and parenthetical expressions are treated as operands.
|
||
* As usual, Q==quantity==operand, O==operator, X==expression mnemonics.
|
||
*
|
||
* We used to do a aho/ullman shift-reduce parser, but the logic got so
|
||
* warped that I flushed it and wrote a recursive-descent parser instead.
|
||
* Now things are stable, would anybody like to write a fast parser?
|
||
* Most expressions are either register (which does not even reach here)
|
||
* or 1 symbol. Then "symbol+constant" and "symbol-symbol" are common.
|
||
* So I guess it doesn't really matter how inefficient more complex expressions
|
||
* are parsed.
|
||
*
|
||
* After expr(RANK,resultP) input_line_pointer->operator of rank <= RANK.
|
||
* Also, we have consumed any leading or trailing spaces (operand does that)
|
||
* and done all intervening operators.
|
||
*/
|
||
|
||
typedef enum
|
||
{
|
||
O_illegal, /* (0) what we get for illegal op */
|
||
|
||
O_multiply, /* (1) * */
|
||
O_divide, /* (2) / */
|
||
O_modulus, /* (3) % */
|
||
O_left_shift, /* (4) < */
|
||
O_right_shift, /* (5) > */
|
||
O_bit_inclusive_or, /* (6) | */
|
||
O_bit_or_not, /* (7) ! */
|
||
O_bit_exclusive_or, /* (8) ^ */
|
||
O_bit_and, /* (9) & */
|
||
O_add, /* (10) + */
|
||
O_subtract /* (11) - */
|
||
}
|
||
operatorT;
|
||
|
||
#define __ O_illegal
|
||
|
||
static const operatorT op_encoding [256] = { /* maps ASCII->operators */
|
||
|
||
__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
|
||
__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
|
||
|
||
__, O_bit_or_not, __, __, __, O_modulus, O_bit_and, __,
|
||
__, __, O_multiply, O_add, __, O_subtract, __, O_divide,
|
||
__, __, __, __, __, __, __, __,
|
||
__, __, __, __, O_left_shift, __, O_right_shift, __,
|
||
__, __, __, __, __, __, __, __,
|
||
__, __, __, __, __, __, __, __,
|
||
__, __, __, __, __, __, __, __,
|
||
__, __, __, __, __, __, O_bit_exclusive_or, __,
|
||
__, __, __, __, __, __, __, __,
|
||
__, __, __, __, __, __, __, __,
|
||
__, __, __, __, __, __, __, __,
|
||
__, __, __, __, O_bit_inclusive_or, __, __, __,
|
||
|
||
__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
|
||
__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
|
||
__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
|
||
__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
|
||
__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
|
||
__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
|
||
__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
|
||
__, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __
|
||
};
|
||
|
||
|
||
/*
|
||
* Rank Examples
|
||
* 0 operand, (expression)
|
||
* 1 + -
|
||
* 2 & ^ ! |
|
||
* 3 * / % << >>
|
||
*/
|
||
static const operator_rankT
|
||
op_rank [] = { 0, 3, 3, 3, 3, 3, 2, 2, 2, 2, 1, 1 };
|
||
|
||
/* Return resultP->X_seg. */
|
||
segT expr(rank, resultP)
|
||
register operator_rankT rank; /* Larger # is higher rank. */
|
||
register expressionS *resultP; /* Deliver result here. */
|
||
{
|
||
expressionS right;
|
||
register operatorT op_left;
|
||
register char c_left; /* 1st operator character. */
|
||
register operatorT op_right;
|
||
register char c_right;
|
||
|
||
know(rank >= 0);
|
||
(void)operand (resultP);
|
||
know(* input_line_pointer != ' '); /* Operand() gobbles spaces. */
|
||
c_left = * input_line_pointer; /* Potential operator character. */
|
||
op_left = op_encoding [c_left];
|
||
while (op_left != O_illegal && op_rank [(int) op_left] > rank)
|
||
{
|
||
input_line_pointer ++; /*->after 1st character of operator. */
|
||
/* Operators "<<" and ">>" have 2 characters. */
|
||
if (* input_line_pointer == c_left && (c_left == '<' || c_left == '>'))
|
||
{
|
||
input_line_pointer ++;
|
||
} /*->after operator. */
|
||
if (SEG_ABSENT == expr (op_rank[(int) op_left], &right))
|
||
{
|
||
as_warn("Missing operand value assumed absolute 0.");
|
||
resultP->X_add_number = 0;
|
||
resultP->X_subtract_symbol = NULL;
|
||
resultP->X_add_symbol = NULL;
|
||
resultP->X_seg = SEG_ABSOLUTE;
|
||
}
|
||
know(* input_line_pointer != ' ');
|
||
c_right = * input_line_pointer;
|
||
op_right = op_encoding [c_right];
|
||
if (* input_line_pointer == c_right && (c_right == '<' || c_right == '>'))
|
||
{
|
||
input_line_pointer ++;
|
||
} /*->after operator. */
|
||
know((int) op_right == 0 || op_rank [(int) op_right] <= op_rank[(int) op_left]);
|
||
/* input_line_pointer->after right-hand quantity. */
|
||
/* left-hand quantity in resultP */
|
||
/* right-hand quantity in right. */
|
||
/* operator in op_left. */
|
||
if (resultP->X_seg == SEG_PASS1 || right . X_seg == SEG_PASS1)
|
||
{
|
||
resultP->X_seg = SEG_PASS1;
|
||
}
|
||
else
|
||
{
|
||
if (resultP->X_seg == SEG_BIG)
|
||
{
|
||
as_warn("Left operand of %c is a %s. Integer 0 assumed.",
|
||
c_left, resultP->X_add_number > 0 ? "bignum" : "float");
|
||
resultP->X_seg = SEG_ABSOLUTE;
|
||
resultP->X_add_symbol = 0;
|
||
resultP->X_subtract_symbol = 0;
|
||
resultP->X_add_number = 0;
|
||
}
|
||
if (right . X_seg == SEG_BIG)
|
||
{
|
||
as_warn("Right operand of %c is a %s. Integer 0 assumed.",
|
||
c_left, right . X_add_number > 0 ? "bignum" : "float");
|
||
right . X_seg = SEG_ABSOLUTE;
|
||
right . X_add_symbol = 0;
|
||
right . X_subtract_symbol = 0;
|
||
right . X_add_number = 0;
|
||
}
|
||
if (op_left == O_subtract)
|
||
{
|
||
/*
|
||
* Convert - into + by exchanging symbolS and negating number.
|
||
* I know -infinity can't be negated in 2's complement:
|
||
* but then it can't be subtracted either. This trick
|
||
* does not cause any further inaccuracy.
|
||
*/
|
||
|
||
register symbolS * symbolP;
|
||
|
||
right . X_add_number = - right . X_add_number;
|
||
symbolP = right . X_add_symbol;
|
||
right . X_add_symbol = right . X_subtract_symbol;
|
||
right . X_subtract_symbol = symbolP;
|
||
if (symbolP)
|
||
{
|
||
right . X_seg = SEG_DIFFERENCE;
|
||
}
|
||
op_left = O_add;
|
||
}
|
||
|
||
if (op_left == O_add)
|
||
{
|
||
segT seg1;
|
||
segT seg2;
|
||
#ifndef MANY_SEGMENTS
|
||
know(resultP->X_seg == SEG_DATA || resultP->X_seg == SEG_TEXT || resultP->X_seg == SEG_BSS || resultP->X_seg ==
|
||
SEG_UNKNOWN || resultP->X_seg == SEG_DIFFERENCE || resultP->X_seg == SEG_ABSOLUTE || resultP->X_seg == SEG_PASS1
|
||
|| resultP->X_seg == SEG_REGISTER);
|
||
know(right.X_seg == SEG_DATA || right.X_seg == SEG_TEXT || right.X_seg == SEG_BSS || right.X_seg == SEG_UNKNOWN || right.X_seg == SEG_DIFFERENCE || right.X_seg == SEG_ABSOLUTE || right.X_seg == SEG_PASS1);
|
||
#endif
|
||
clean_up_expression (& right);
|
||
clean_up_expression (resultP);
|
||
|
||
seg1 = expr_part (& resultP->X_add_symbol, right . X_add_symbol);
|
||
seg2 = expr_part (& resultP->X_subtract_symbol, right . X_subtract_symbol);
|
||
if (seg1 == SEG_PASS1 || seg2 == SEG_PASS1) {
|
||
need_pass_2 = 1;
|
||
resultP->X_seg = SEG_PASS1;
|
||
} else if (seg2 == SEG_ABSOLUTE)
|
||
resultP->X_seg = seg1;
|
||
else if (seg1 != SEG_UNKNOWN
|
||
&& seg1 != SEG_ABSOLUTE
|
||
&& seg2 != SEG_UNKNOWN
|
||
&& seg1 != seg2) {
|
||
know(seg2 != SEG_ABSOLUTE);
|
||
know(resultP->X_subtract_symbol);
|
||
#ifndef MANY_SEGMENTS
|
||
know(seg1 == SEG_TEXT || seg1 == SEG_DATA || seg1== SEG_BSS);
|
||
know(seg2 == SEG_TEXT || seg2 == SEG_DATA || seg2== SEG_BSS);
|
||
#endif
|
||
know(resultP->X_add_symbol);
|
||
know(resultP->X_subtract_symbol);
|
||
as_bad("Expression too complex: forgetting %s - %s",
|
||
S_GET_NAME(resultP->X_add_symbol),
|
||
S_GET_NAME(resultP->X_subtract_symbol));
|
||
resultP->X_seg = SEG_ABSOLUTE;
|
||
/* Clean_up_expression() will do the rest. */
|
||
} else
|
||
resultP->X_seg = SEG_DIFFERENCE;
|
||
|
||
resultP->X_add_number += right . X_add_number;
|
||
clean_up_expression (resultP);
|
||
}
|
||
else
|
||
{ /* Not +. */
|
||
if (resultP->X_seg == SEG_UNKNOWN || right . X_seg == SEG_UNKNOWN)
|
||
{
|
||
resultP->X_seg = SEG_PASS1;
|
||
need_pass_2 = 1;
|
||
}
|
||
else
|
||
{
|
||
resultP->X_subtract_symbol = NULL;
|
||
resultP->X_add_symbol = NULL;
|
||
/* Will be SEG_ABSOLUTE. */
|
||
if (resultP->X_seg != SEG_ABSOLUTE || right . X_seg != SEG_ABSOLUTE)
|
||
{
|
||
as_bad("Relocation error. Absolute 0 assumed.");
|
||
resultP->X_seg = SEG_ABSOLUTE;
|
||
resultP->X_add_number = 0;
|
||
}
|
||
else
|
||
{
|
||
switch (op_left)
|
||
{
|
||
case O_bit_inclusive_or:
|
||
resultP->X_add_number |= right . X_add_number;
|
||
break;
|
||
|
||
case O_modulus:
|
||
if (right . X_add_number)
|
||
{
|
||
resultP->X_add_number %= right . X_add_number;
|
||
}
|
||
else
|
||
{
|
||
as_warn("Division by 0. 0 assumed.");
|
||
resultP->X_add_number = 0;
|
||
}
|
||
break;
|
||
|
||
case O_bit_and:
|
||
resultP->X_add_number &= right . X_add_number;
|
||
break;
|
||
|
||
case O_multiply:
|
||
resultP->X_add_number *= right . X_add_number;
|
||
break;
|
||
|
||
case O_divide:
|
||
if (right . X_add_number)
|
||
{
|
||
resultP->X_add_number /= right . X_add_number;
|
||
}
|
||
else
|
||
{
|
||
as_warn("Division by 0. 0 assumed.");
|
||
resultP->X_add_number = 0;
|
||
}
|
||
break;
|
||
|
||
case O_left_shift:
|
||
resultP->X_add_number <<= right . X_add_number;
|
||
break;
|
||
|
||
case O_right_shift:
|
||
resultP->X_add_number >>= right . X_add_number;
|
||
break;
|
||
|
||
case O_bit_exclusive_or:
|
||
resultP->X_add_number ^= right . X_add_number;
|
||
break;
|
||
|
||
case O_bit_or_not:
|
||
resultP->X_add_number |= ~ right . X_add_number;
|
||
break;
|
||
|
||
default:
|
||
BAD_CASE(op_left);
|
||
break;
|
||
} /* switch(operator) */
|
||
}
|
||
} /* If we have to force need_pass_2. */
|
||
} /* If operator was +. */
|
||
} /* If we didn't set need_pass_2. */
|
||
op_left = op_right;
|
||
} /* While next operator is >= this rank. */
|
||
return (resultP->X_seg);
|
||
}
|
||
|
||
/*
|
||
* get_symbol_end()
|
||
*
|
||
* This lives here because it belongs equally in expr.c & read.c.
|
||
* Expr.c is just a branch office read.c anyway, and putting it
|
||
* here lessens the crowd at read.c.
|
||
*
|
||
* Assume input_line_pointer is at start of symbol name.
|
||
* Advance input_line_pointer past symbol name.
|
||
* Turn that character into a '\0', returning its former value.
|
||
* This allows a string compare (RMS wants symbol names to be strings)
|
||
* of the symbol name.
|
||
* There will always be a char following symbol name, because all good
|
||
* lines end in end-of-line.
|
||
*/
|
||
char
|
||
get_symbol_end()
|
||
{
|
||
register char c;
|
||
|
||
while (is_part_of_name(c = * input_line_pointer ++))
|
||
;
|
||
* -- input_line_pointer = 0;
|
||
return (c);
|
||
}
|
||
|
||
|
||
unsigned int get_single_number()
|
||
{
|
||
expressionS exp;
|
||
operand(&exp);
|
||
return exp.X_add_number;
|
||
|
||
}
|
||
/*
|
||
* Local Variables:
|
||
* comment-column: 0
|
||
* fill-column: 131
|
||
* End:
|
||
*/
|
||
|
||
/* end of expr.c */
|