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binutils-gdb/gas/expr.c

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Initial revision
1991-04-05 02:19:53 +08:00
/* expr.c -operands, expressions-
Copyright (C) 1987, 1990, 1991 Free Software Foundation, Inc.
This file is part of GAS, the GNU Assembler.
GAS is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 1, or (at your option)
any later version.
GAS is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with GAS; see the file COPYING. If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
/* static const char rcsid[] = "$Id$"; */
/*
* This is really a branch office of as-read.c. I split it out to clearly
* distinguish the world of expressions from the world of statements.
* (It also gives smaller files to re-compile.)
* Here, "operand"s are of expressions, not instructions.
*/
#include <ctype.h>
#include <string.h>
#include "as.h"
#include "obstack.h"
#ifdef __STDC__
static void clean_up_expression(expressionS *expressionP);
#else /* __STDC__ */
static void clean_up_expression(); /* Internal. */
#endif /* __STDC__ */
extern const char EXP_CHARS[]; /* JF hide MD floating pt stuff all the same place */
extern const char FLT_CHARS[];
#ifdef LOCAL_LABELS_DOLLAR
extern int local_label_defined[];
#endif
/*
* Build any floating-point literal here.
* Also build any bignum literal here.
*/
/* LITTLENUM_TYPE generic_buffer [6]; */ /* JF this is a hack */
/* Seems atof_machine can backscan through generic_bignum and hit whatever
happens to be loaded before it in memory. And its way too complicated
for me to fix right. Thus a hack. JF: Just make generic_bignum bigger,
and never write into the early words, thus they'll always be zero.
I hate Dean's floating-point code. Bleh.
*/
LITTLENUM_TYPE generic_bignum [SIZE_OF_LARGE_NUMBER+6];
FLONUM_TYPE generic_floating_point_number =
{
& generic_bignum [6], /* low (JF: Was 0) */
& generic_bignum [SIZE_OF_LARGE_NUMBER+6 - 1], /* high JF: (added +6) */
0, /* leader */
0, /* exponent */
0 /* sign */
};
/* If nonzero, we've been asked to assemble nan, +inf or -inf */
int generic_floating_point_magic;
/*
* Summary of operand().
*
* in: Input_line_pointer points to 1st char of operand, which may
* be a space.
*
* out: A expressionS. X_seg determines how to understand the rest of the
* expressionS.
* The operand may have been empty: in this case X_seg == SEG_ABSENT.
* Input_line_pointer->(next non-blank) char after operand.
*
*/
static segT
operand (expressionP)
register expressionS * expressionP;
{
register char c;
register char *name; /* points to name of symbol */
register symbolS * symbolP; /* Points to symbol */
extern char hex_value[]; /* In hex_value.c */
SKIP_WHITESPACE(); /* Leading whitespace is part of operand. */
c = * input_line_pointer ++; /* Input_line_pointer->past char in c. */
if (isdigit(c))
{
register valueT number; /* offset or (absolute) value */
register short int digit; /* value of next digit in current radix */
/* invented for humans only, hope */
/* optimising compiler flushes it! */
register short int radix; /* 2, 8, 10 or 16 */
/* 0 means we saw start of a floating- */
/* point constant. */
register short int maxdig = 0;/* Highest permitted digit value. */
register int too_many_digits = 0; /* If we see >= this number of */
/* digits, assume it is a bignum. */
register char * digit_2; /*->2nd digit of number. */
int small; /* TRUE if fits in 32 bits. */
if (c == '0') { /* non-decimal radix */
if ((c = *input_line_pointer ++)=='x' || c=='X') {
c = *input_line_pointer ++; /* read past "0x" or "0X" */
maxdig = radix = 16;
too_many_digits = 9;
} else {
/* 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)))) {
maxdig = radix = 10;
too_many_digits = 11;
c = '0';
input_line_pointer -= 2;
} else if (c == 'b' || c == 'B') {
c = *input_line_pointer++;
maxdig = radix = 2;
too_many_digits = 33;
} else if (c && strchr(FLT_CHARS,c)) {
radix = 0; /* Start of floating-point constant. */
/* input_line_pointer->1st char of number. */
expressionP->X_add_number = -(isupper(c) ? tolower(c) : c);
} else { /* By elimination, assume octal radix. */
radix = maxdig = 8;
too_many_digits = 11;
}
} /* c == char after "0" or "0x" or "0X" or "0e" etc. */
} else {
maxdig = radix = 10;
too_many_digits = 11;
} /* if operand starts with a zero */
if (radix) { /* Fixed-point integer constant. */
/* May be bignum, or may fit in 32 bits. */
/*
* Most numbers fit into 32 bits, and we want this case to be fast.
* So we pretend it will fit into 32 bits. If, after making up a 32
* bit number, we realise that we have scanned more digits than
* comfortably fit into 32 bits, we re-scan the digits coding
* them into a bignum. For decimal and octal numbers we are conservative: some
* numbers may be assumed bignums when in fact they do fit into 32 bits.
* Numbers of any radix can have excess leading zeros: we strive
* to recognise this and cast them back into 32 bits.
* We must check that the bignum really is more than 32
* bits, and change it back to a 32-bit number if it fits.
* The number we are looking for is expected to be positive, but
* if it fits into 32 bits as an unsigned number, we let it be a 32-bit
* number. The cavalier approach is for speed in ordinary cases.
*/
digit_2 = input_line_pointer;
for (number=0; (digit=hex_value[c])<maxdig; c = * input_line_pointer ++)
{
number = number * radix + digit;
}
/* C contains character after number. */
/* Input_line_pointer->char after C. */
small = input_line_pointer - digit_2 < too_many_digits;
if (! small)
{
/*
* We saw a lot of digits. Manufacture a bignum the hard way.
*/
LITTLENUM_TYPE * leader; /*->high order littlenum of the bignum. */
LITTLENUM_TYPE * pointer; /*->littlenum we are frobbing now. */
long carry;
leader = generic_bignum;
generic_bignum [0] = 0;
generic_bignum [1] = 0;
/* We could just use digit_2, but lets be mnemonic. */
input_line_pointer = -- digit_2; /*->1st digit. */
c = *input_line_pointer ++;
for (; (carry = hex_value [c]) < maxdig; c = * input_line_pointer ++)
{
for (pointer = generic_bignum;
pointer <= leader;
pointer ++)
{
long work;
work = carry + radix * * pointer;
* pointer = work & LITTLENUM_MASK;
carry = work >> LITTLENUM_NUMBER_OF_BITS;
}
if (carry)
{
if (leader < generic_bignum + SIZE_OF_LARGE_NUMBER - 1)
{ /* Room to grow a longer bignum. */
* ++ leader = carry;
}
}
}
/* Again, C is char after number, */
/* input_line_pointer->after C. */
know(sizeof (int) * 8 == 32);
know(LITTLENUM_NUMBER_OF_BITS == 16);
/* Hence the constant "2" in the next line. */
if (leader < generic_bignum + 2)
{ /* Will fit into 32 bits. */
number =
((generic_bignum [1] & LITTLENUM_MASK) << LITTLENUM_NUMBER_OF_BITS)
| (generic_bignum [0] & LITTLENUM_MASK);
small = 1;
}
else
{
number = leader - generic_bignum + 1; /* Number of littlenums in the bignum. */
}
}
if (small)
{
/*
* Here with number, in correct radix. c is the next char.
* Note that unlike Un*x, we allow "011f" "0x9f" to
* both mean the same as the (conventional) "9f". This is simply easier
* than checking for strict canonical form. Syntax sux!
*/
if (number<10)
{
if (0
#ifdef LOCAL_LABELS_FB
|| c=='b'
#endif
#ifdef LOCAL_LABELS_DOLLAR
|| (c=='$' && local_label_defined[number])
#endif
)
{
/*
* Backward ref to local label.
* Because it is backward, expect it to be DEFINED.
*/
/*
* Construct a local label.
*/
name = local_label_name ((int)number, 0);
if (((symbolP = symbol_find(name)) != NULL) /* seen before */
&& (S_IS_DEFINED(symbolP))) /* symbol is defined: OK */
{ /* Expected path: symbol defined. */
/* Local labels are never absolute. Don't waste time checking absoluteness. */
know((S_GET_SEGMENT(symbolP) == SEG_DATA) || (S_GET_SEGMENT(symbolP) == SEG_TEXT));
expressionP->X_add_symbol = symbolP;
expressionP->X_add_number = 0;
expressionP->X_seg = S_GET_SEGMENT(symbolP);
}
else
{ /* Either not seen or not defined. */
as_bad("Backw. ref to unknown label \"%d:\", 0 assumed.",
number);
expressionP->X_add_number = 0;
expressionP->X_seg = SEG_ABSOLUTE;
}
}
else
{
if (0
#ifdef LOCAL_LABELS_FB
|| c == 'f'
#endif
#ifdef LOCAL_LABELS_DOLLAR
|| (c=='$' && !local_label_defined[number])
#endif
)
{
/*
* Forward reference. Expect symbol to be undefined or
* unknown. Undefined: seen it before. Unknown: never seen
* it in this pass.
* Construct a local label name, then an undefined symbol.
* Don't create a XSEG frag for it: caller may do that.
* Just return it as never seen before.
*/
name = local_label_name((int)number, 1);
symbolP = symbol_find_or_make(name);
/* We have no need to check symbol properties. */
know(S_GET_SEGMENT(symbolP) == SEG_UNKNOWN
|| S_GET_SEGMENT(symbolP) == SEG_TEXT
|| S_GET_SEGMENT(symbolP) == SEG_DATA);
expressionP->X_add_symbol = symbolP;
expressionP->X_seg = SEG_UNKNOWN;
expressionP->X_subtract_symbol = NULL;
expressionP->X_add_number = 0;
}
else
{ /* Really a number, not a local label. */
expressionP->X_add_number = number;
expressionP->X_seg = SEG_ABSOLUTE;
input_line_pointer --; /* Restore following character. */
} /* if (c=='f') */
} /* if (c=='b') */
}
else
{ /* Really a number. */
expressionP->X_add_number = number;
expressionP->X_seg = SEG_ABSOLUTE;
input_line_pointer --; /* Restore following character. */
} /* if (number<10) */
}
else
{
expressionP->X_add_number = number;
expressionP->X_seg = SEG_BIG;
input_line_pointer --; /*->char following number. */
} /* if (small) */
} /* (If integer constant) */
else
{ /* input_line_pointer->*/
/* floating-point constant. */
int error_code;
error_code = atof_generic
(& input_line_pointer, ".", EXP_CHARS,
& generic_floating_point_number);
if (error_code)
{
if (error_code == ERROR_EXPONENT_OVERFLOW)
{
as_bad("Bad floating-point constant: exponent overflow, probably assembling junk");
}
else
{
as_bad("Bad floating-point constant: unknown error code=%d.", error_code);
}
}
expressionP->X_seg = SEG_BIG;
/* input_line_pointer->just after constant, */
/* which may point to whitespace. */
know(expressionP->X_add_number < 0); /* < 0 means "floating point". */
} /* if (not floating-point constant) */
}
else if(c=='.' && !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;
} else 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.
*/
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 if (c=='(')/* 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 "(...)" */
}
else if (c == '~' || c == '-' || c == '+') {
/* 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 if (c == '~') {
expressionP->X_add_number = ~ expressionP->X_add_number;
} else if (c != '+') {
know(0);
} /* switch on unary operator */
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_bad("Unary operator %c ignored because bad operand follows", c);
break;
/* Expression undisturbed from operand(). */
}
}
else if (c=='\'')
{
/*
* 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;
}
else
{
/* can't imagine any other kind of operand */
expressionP->X_seg = SEG_ABSENT;
input_line_pointer --;
md_operand (expressionP);
}
/*
* 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_TEXT:
case SEG_DATA:
case SEG_BSS:
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:
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;
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)));
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;
}
}
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);
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;
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);
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);
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);
know(seg1 == SEG_TEXT || seg1 == SEG_DATA || seg1== SEG_BSS);
know(seg2 == SEG_TEXT || seg2 == SEG_DATA || seg2== SEG_BSS);
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);
}
/*
* Local Variables:
* comment-column: 0
* fill-column: 131
* End:
*/
/* end: expr.c */
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