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Diffstat (limited to 'gnu/usr.bin/as/expr.c')
| -rw-r--r-- | gnu/usr.bin/as/expr.c | 1000 |
1 files changed, 1000 insertions, 0 deletions
diff --git a/gnu/usr.bin/as/expr.c b/gnu/usr.bin/as/expr.c new file mode 100644 index 0000000..c46961c --- /dev/null +++ b/gnu/usr.bin/as/expr.c @@ -0,0 +1,1000 @@ +/* expr.c -operands, expressions- + Copyright (C) 1987, 1990, 1991, 1992 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 2, 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. */ + +/* + * 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. + */ + +#ifndef lint +static char rcsid[] = "$FreeBSD$"; +#endif + +#include <ctype.h> +#include <string.h> + +#include "as.h" + +#include "obstack.h" + +#if __STDC__ == 1 +static void clean_up_expression(expressionS *expressionP); +#else /* __STDC__ */ +static void clean_up_expression(); /* Internal. */ +#endif /* not __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 const char hex_value[]; /* In hex_value.c */ + +#ifdef PIC +/* XXX */ expressionP->X_got_symbol = 0; +#endif + SKIP_WHITESPACE(); /* Leading whitespace is part of operand. */ + c = * input_line_pointer ++; /* Input_line_pointer->past char in c. */ + if (isdigit(c) || (c == 'H' && input_line_pointer[0] == '\'')) + { + 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 == 'H' || c == '0') { /* non-decimal radix */ + if ((c = *input_line_pointer ++) == 'x' || c == 'X' || c == '\'') { + c = *input_line_pointer ++; /* read past "0x" or "0X" or H' */ + 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("+-.0123456789iInN",*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 == '$' && local_label_defined[number]) +#endif + ) + { + /* + * Backward ref to local label. + * Because it is backward, expect it to be DEFINED. + */ + /* + * Construct a local label. + */ + name = local_label_name ((int)number, 0); + if (((symbolP = symbol_find(name)) != NULL) /* seen before */ + && (S_IS_DEFINED(symbolP))) /* symbol is defined: OK */ + { /* Expected path: symbol defined. */ + /* Local labels are never absolute. Don't waste time checking absoluteness. */ + know(SEG_NORMAL(S_GET_SEGMENT(symbolP))); + + expressionP->X_add_symbol = symbolP; + expressionP->X_add_number = 0; + expressionP->X_seg = S_GET_SEGMENT(symbolP); + } + else + { /* Either not seen or not defined. */ + as_bad("Backw. ref to unknown label \"%d:\", 0 assumed.", + number); + expressionP->X_add_number = 0; + expressionP->X_seg = SEG_ABSOLUTE; + } + } + else + { + if (0 +#ifdef LOCAL_LABELS_FB + || c == 'f' +#endif +#ifdef LOCAL_LABELS_DOLLAR + || (c == '$' && !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. */ +#ifndef MANY_SEGMENTS + /* Since "know" puts its arg into a "string", we + can't have newlines in the argument. */ + know(S_GET_SEGMENT(symbolP) == SEG_UNKNOWN || S_GET_SEGMENT(symbolP) == SEG_TEXT || S_GET_SEGMENT(symbolP) == SEG_DATA); +#endif + 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("\001L0", + 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 - 1; + 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; +#ifdef PIC + if (symbolP == GOT_symbol) { + expressionP->X_got_symbol = symbolP; + got_referenced = 1; + } else +#endif + expressionP->X_add_symbol = symbolP; + } + *input_line_pointer = c; + expressionP->X_subtract_symbol = NULL; + } else if (c == '(' || c == '[') {/* didn't begin with digit & not a name */ + (void)expression(expressionP); + /* Expression() will pass trailing whitespace */ + if (c == '(' && *input_line_pointer++ != ')' || + c == '[' && *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; + + default: /* unary on non-absolute is unsuported */ + if (!SEG_NORMAL(operand(expressionP))) + { + as_bad("Unary operator %c ignored because bad operand follows", c); + break; + } + /* Fall through for normal segments ****/ + 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; + } + /* 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_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() */ + +void ps (s) +symbolS *s; +{ + fprintf (stdout, "%s type %s%s", + S_GET_NAME(s), + S_IS_EXTERNAL(s) ? "EXTERNAL " : "", + segment_name(S_GET_SEGMENT(s))); +} +void pe (e) +expressionS *e; +{ + fprintf (stdout, " segment %s\n", segment_name (e->X_seg)); + fprintf (stdout, " add_number %ld (%lx)\n", + e->X_add_number, e->X_add_number); + if (e->X_add_symbol) { + fprintf (stdout, " add_symbol "); + ps (e->X_add_symbol); + fprintf (stdout, "\n"); + } + if (e->X_subtract_symbol) { + fprintf (stdout, " sub_symbol "); + ps (e->X_subtract_symbol); + fprintf (stdout, "\n"); + } +} + +/* 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); + 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); + +#ifdef PIC +/* XXX - kludge here to accomodate "_GLOBAL_OFFSET_TABLE + (x - y)" + * expressions: this only works for this special case, the + * _GLOBAL_OFFSET_TABLE thing *must* be the left operand, the whole + * expression is given the segment of right expression (always a DIFFERENCE, + * which should get resolved by fixup_segment()) + */ + if (resultP->X_got_symbol) { + resultP->X_add_symbol = right.X_add_symbol; + resultP->X_subtract_symbol = right.X_subtract_symbol; + seg1 = S_GET_SEGMENT(right.X_add_symbol); + seg2 = S_GET_SEGMENT(right.X_subtract_symbol); + resultP->X_seg = right.X_seg; + } else { +#endif + seg1 = expr_part(&resultP->X_add_symbol, right.X_add_symbol); + seg2 = expr_part(&resultP->X_subtract_symbol, right.X_subtract_symbol); +#ifdef PIC + } +#endif + 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); +} /* expr() */ + +/* + * 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 */ |
