parser.c

/* parser.c   source line parser for the Netwide Assembler
 *
 * The Netwide Assembler is copyright (C) 1996 Simon Tatham and
 * Julian Hall. All rights reserved. The software is
 * redistributable under the licence given in the file "Licence"
 * distributed in the NASM archive.
 *
 * initial version 27/iii/95 by Simon Tatham
 */

#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <string.h>
#include <ctype.h>

#include "nasm.h"
#include "nasmlib.h"
#include "parser.h"
#include "float.h"

static long reg_flags[] = {	       /* sizes and special flags */
    0, REG8, REG_AL, REG_AX, REG8, REG8, REG16, REG16, REG8, REG_CL,
    REG_CREG, REG_CREG, REG_CREG, REG_CR4, REG_CS, REG_CX, REG8,
    REG16, REG8, REG_DREG, REG_DREG, REG_DREG, REG_DREG, REG_DREG,
    REG_DREG, REG_DESS, REG_DX, REG_EAX, REG32, REG32, REG_ECX,
    REG32, REG32, REG_DESS, REG32, REG32, REG_FSGS, REG_FSGS,
    MMXREG, MMXREG, MMXREG, MMXREG, MMXREG, MMXREG, MMXREG, MMXREG,
    REG16, REG16, REG_DESS, FPU0, FPUREG, FPUREG, FPUREG, FPUREG,
    FPUREG, FPUREG, FPUREG, REG_TREG, REG_TREG, REG_TREG, REG_TREG,
    REG_TREG
};

enum {				       /* special tokens */
    S_BYTE, S_DWORD, S_FAR, S_LONG, S_NEAR, S_NOSPLIT, S_QWORD,
    S_SHORT, S_TO, S_TWORD, S_WORD
};

static int is_comma_next (void);

static int i;
static struct tokenval tokval;
static efunc error;

insn *parse_line (int pass, char *buffer, insn *result,
		  efunc errfunc, evalfunc evaluate, evalinfofunc einfo) {
    int operand;
    int critical;
    struct eval_hints hints;

    result->forw_ref = FALSE;
    error = errfunc;
    einfo ("", 0L, 0L);

    stdscan_reset();
    stdscan_bufptr = buffer;
    i = stdscan(NULL, &tokval);

    result->eops = NULL;	       /* must do this, whatever happens */
    result->operands = 0;	       /* must initialise this */

    if (i==0) {			       /* blank line - ignore */
	result->label = NULL;	       /* so, no label on it */
	result->opcode = -1;	       /* and no instruction either */
	return result;
    }
    if (i != TOKEN_ID && i != TOKEN_INSN && i != TOKEN_PREFIX &&
	(i!=TOKEN_REG || (REG_SREG & ~reg_flags[tokval.t_integer]))) {
	error (ERR_NONFATAL, "label or instruction expected"
	       " at start of line");
	result->label = NULL;
	result->opcode = -1;
	return result;
    }

    if (i == TOKEN_ID) {	       /* there's a label here */
	result->label = tokval.t_charptr;
	einfo (result->label, 0L, 0L);
	i = stdscan(NULL, &tokval);
	if (i == ':') {		       /* skip over the optional colon */
	    i = stdscan(NULL, &tokval);
	} else if (i == 0 && pass == 1) {
	    error (ERR_WARNING|ERR_WARN_OL,
		   "label alone on a line without a colon might be in error");
	}
    } else			       /* no label; so, moving swiftly on */
	result->label = NULL;

    if (i==0) {
	result->opcode = -1;	       /* this line contains just a label */
	return result;
    }

    result->nprefix = 0;
    result->times = 1L;

    while (i == TOKEN_PREFIX ||
	   (i==TOKEN_REG && !(REG_SREG & ~reg_flags[tokval.t_integer]))) {
	/*
	 * Handle special case: the TIMES prefix.
	 */
	if (i == TOKEN_PREFIX && tokval.t_integer == P_TIMES) {
	    expr *value;

	    i = stdscan(NULL, &tokval);
	    value = evaluate (stdscan, NULL, &tokval, NULL, pass, error, NULL);
	    i = tokval.t_type;
	    if (!value) {	       /* but, error in evaluator */
		result->opcode = -1;   /* unrecoverable parse error: */
		return result;	       /* ignore this instruction */
	    }
	    if (!is_simple (value)) {
		error (ERR_NONFATAL,
		       "non-constant argument supplied to TIMES");
		result->times = 1L;
	    } else {
		result->times = value->value;
		if (value->value < 0)
		    error(ERR_NONFATAL, "TIMES value %d is negative",
			  value->value);
	    }
	} else {
	    if (result->nprefix == MAXPREFIX)
		error (ERR_NONFATAL,
		       "instruction has more than %d prefixes", MAXPREFIX);
	    else
		result->prefixes[result->nprefix++] = tokval.t_integer;
	    i = stdscan(NULL, &tokval);
	}
    }

    if (i != TOKEN_INSN) {
	if (result->nprefix > 0 && i == 0) {
	    /*
	     * Instruction prefixes are present, but no actual
	     * instruction. This is allowed: at this point we
	     * invent a notional instruction of RESB 0.
	     */
	    result->opcode = I_RESB;
	    result->operands = 1;
	    result->oprs[0].type = IMMEDIATE;
	    result->oprs[0].offset = 0L;
	    result->oprs[0].segment = result->oprs[0].wrt = NO_SEG;
	    return result;
	} else {
	    error (ERR_NONFATAL, "parser: instruction expected");
	    result->opcode = -1;
	    return result;
	}
    }

    result->opcode = tokval.t_integer;
    result->condition = tokval.t_inttwo;

    /*
     * RESB, RESW and RESD cannot be satisfied with incorrectly
     * evaluated operands, since the correct values _must_ be known
     * on the first pass. Hence, even in pass one, we set the
     * `critical' flag on calling evaluate(), so that it will bomb
     * out on undefined symbols. Nasty, but there's nothing we can
     * do about it.
     *
     * For the moment, EQU has the same difficulty, so we'll
     * include that.
     */
    if (result->opcode == I_RESB ||
	result->opcode == I_RESW ||
	result->opcode == I_RESD ||
	result->opcode == I_RESQ ||
	result->opcode == I_REST ||
	result->opcode == I_EQU)
	critical = pass;
    else
	critical = (pass==2 ? 2 : 0);

    if (result->opcode == I_DB ||
	result->opcode == I_DW ||
	result->opcode == I_DD ||
	result->opcode == I_DQ ||
	result->opcode == I_DT ||
	result->opcode == I_INCBIN) {
	extop *eop, **tail = &result->eops;
	int oper_num = 0;

	/*
	 * Begin to read the DB/DW/DD/DQ/DT operands.
	 */
	while (1) {
	    i = stdscan(NULL, &tokval);
	    if (i == 0)
		break;
	    eop = *tail = nasm_malloc(sizeof(extop));
	    tail = &eop->next;
	    eop->next = NULL;
	    eop->type = EOT_NOTHING;
	    oper_num++;

	    if (i == TOKEN_NUM && tokval.t_charptr && is_comma_next()) {
		eop->type = EOT_DB_STRING;
		eop->stringval = tokval.t_charptr;
		eop->stringlen = tokval.t_inttwo;
		i = stdscan(NULL, &tokval);       /* eat the comma */
		continue;
	    }

	    if (i == TOKEN_FLOAT || i == '-') {
		long sign = +1L;

		if (i == '-') {
		    char *save = stdscan_bufptr;
		    i = stdscan(NULL, &tokval);
		    sign = -1L;
		    if (i != TOKEN_FLOAT) {
			stdscan_bufptr = save;
			i = tokval.t_type = '-';
		    }
		}

		if (i == TOKEN_FLOAT) {
		    eop->type = EOT_DB_STRING;
		    if (result->opcode == I_DD)
			eop->stringlen = 4;
		    else if (result->opcode == I_DQ)
			eop->stringlen = 8;
		    else if (result->opcode == I_DT)
		    eop->stringlen = 10;
		    else {
			error(ERR_NONFATAL, "floating-point constant"
			      " encountered in `D%c' instruction",
			      result->opcode == I_DW ? 'W' : 'B');
			eop->type = EOT_NOTHING;
		    }
		    eop = nasm_realloc(eop, sizeof(extop)+eop->stringlen);
		    eop->stringval = (char *)eop + sizeof(extop);
		    if (!float_const (tokval.t_charptr, sign,
				      (unsigned char *)eop->stringval,
				      eop->stringlen, error))
			eop->type = EOT_NOTHING;
		    i = stdscan(NULL, &tokval);       /* eat the comma */
		    continue;
		}
	    }

	    /* anything else */ {
		expr *value;
		value = evaluate (stdscan, NULL, &tokval, NULL,
				  critical, error, NULL);
		i = tokval.t_type;
		if (!value) {	       /* error in evaluator */
		    result->opcode = -1;/* unrecoverable parse error: */
		    return result;     /* ignore this instruction */
		}
		if (is_unknown(value)) {
		    eop->type = EOT_DB_NUMBER;
		    eop->offset = 0;   /* doesn't matter what we put */
		    eop->segment = eop->wrt = NO_SEG;   /* likewise */
		} else if (is_reloc(value)) {
		    eop->type = EOT_DB_NUMBER;
		    eop->offset = reloc_value(value);
		    eop->segment = reloc_seg(value);
		    eop->wrt = reloc_wrt(value);
		} else {
		    error (ERR_NONFATAL,
			   "operand %d: expression is not simple"
			   " or relocatable", oper_num);
		}
	    }

	    /*
	     * We're about to call stdscan(), which will eat the
	     * comma that we're currently sitting on between
	     * arguments. However, we'd better check first that it
	     * _is_ a comma.
	     */
	    if (i == 0)		       /* also could be EOL */
		break;
	    if (i != ',') {
		error (ERR_NONFATAL, "comma expected after operand %d",
		       oper_num);
		result->opcode = -1;/* unrecoverable parse error: */
		return result;     /* ignore this instruction */
	    }
	}

	if (result->opcode == I_INCBIN) {
	    /*
	     * Correct syntax for INCBIN is that there should be
	     * one string operand, followed by one or two numeric
	     * operands.
	     */
	    if (!result->eops || result->eops->type != EOT_DB_STRING)
		error (ERR_NONFATAL, "`incbin' expects a file name");
	    else if (result->eops->next &&
		     result->eops->next->type != EOT_DB_NUMBER)
		error (ERR_NONFATAL, "`incbin': second parameter is",
		       " non-numeric");
	    else if (result->eops->next && result->eops->next->next &&
		     result->eops->next->next->type != EOT_DB_NUMBER)
		error (ERR_NONFATAL, "`incbin': third parameter is",
		       " non-numeric");
	    else if (result->eops->next && result->eops->next->next &&
		     result->eops->next->next->next)
		error (ERR_NONFATAL, "`incbin': more than three parameters");
	    else
		return result;
	    /*
	     * If we reach here, one of the above errors happened.
	     * Throw the instruction away.
	     */
	    result->opcode = -1;
	    return result;
	}

	return result;
    }

    /* right. Now we begin to parse the operands. There may be up to three
     * of these, separated by commas, and terminated by a zero token. */

    for (operand = 0; operand < 3; operand++) {
	expr *value;		       /* used most of the time */
	int mref;		       /* is this going to be a memory ref? */
	int bracket;		       /* is it a [] mref, or a & mref? */

	result->oprs[operand].addr_size = 0;/* have to zero this whatever */
	result->oprs[operand].eaflags = 0;   /* and this */
	i = stdscan(NULL, &tokval);
	if (i == 0) break;	       /* end of operands: get out of here */
	result->oprs[operand].type = 0;   /* so far, no override */
	while (i == TOKEN_SPECIAL)	{/* size specifiers */
	    switch ((int)tokval.t_integer) {
	      case S_BYTE:
		result->oprs[operand].type |= BITS8;
		break;
	      case S_WORD:
		result->oprs[operand].type |= BITS16;
		break;
	      case S_DWORD:
	      case S_LONG:
		result->oprs[operand].type |= BITS32;
		break;
	      case S_QWORD:
		result->oprs[operand].type |= BITS64;
		break;
	      case S_TWORD:
		result->oprs[operand].type |= BITS80;
		break;
	      case S_TO:
		result->oprs[operand].type |= TO;
		break;
	      case S_FAR:
		result->oprs[operand].type |= FAR;
		break;
	      case S_NEAR:
		result->oprs[operand].type |= NEAR;
		break;
	      case S_SHORT:
		result->oprs[operand].type |= SHORT;
		break;
	    }
	    i = stdscan(NULL, &tokval);
	}

	if (i == '[' || i == '&') {    /* memory reference */
	    mref = TRUE;
	    bracket = (i == '[');
	    i = stdscan(NULL, &tokval);	    
	    if (i == TOKEN_SPECIAL) {  /* check for address size override */
		switch ((int)tokval.t_integer) {
		  case S_NOSPLIT:
		    result->oprs[operand].eaflags |= EAF_TIMESTWO;
		    break;
		  case S_BYTE:
		    result->oprs[operand].eaflags |= EAF_BYTEOFFS;
		    break;
		  case S_WORD:
		    result->oprs[operand].addr_size = 16;
		    result->oprs[operand].eaflags |= EAF_WORDOFFS;
		    break;
		  case S_DWORD:
		  case S_LONG:
		    result->oprs[operand].addr_size = 32;
		    result->oprs[operand].eaflags |= EAF_WORDOFFS;
		    break;
		  default:
		    error (ERR_NONFATAL, "invalid size specification in"
			   " effective address");
		}
		i = stdscan(NULL, &tokval);
	    }
	} else {		       /* immediate operand, or register */
	    mref = FALSE;
	    bracket = FALSE;	       /* placate optimisers */
	}

	value = evaluate (stdscan, NULL, &tokval,
			  &result->forw_ref, critical, error, &hints);
	i = tokval.t_type;
	if (!value) {		       /* error in evaluator */
	    result->opcode = -1;       /* unrecoverable parse error: */
	    return result;	       /* ignore this instruction */
	}
	if (i == ':' && mref) {	       /* it was seg:offset */
	    /*
	     * Process the segment override.
	     */
	    if (value[1].type!=0 || value->value!=1 ||
		REG_SREG & ~reg_flags[value->type])
		error (ERR_NONFATAL, "invalid segment override");
	    else if (result->nprefix == MAXPREFIX)
		error (ERR_NONFATAL,
		       "instruction has more than %d prefixes",
		       MAXPREFIX);
	    else
		result->prefixes[result->nprefix++] = value->type;

	    i = stdscan(NULL, &tokval);	       /* then skip the colon */
	    if (i == TOKEN_SPECIAL) {  /* another check for size override */
		switch ((int)tokval.t_integer) {
		  case S_WORD:
		    result->oprs[operand].addr_size = 16;
		    break;
		  case S_DWORD:
		  case S_LONG:
		    result->oprs[operand].addr_size = 32;
		    break;
		  default:
		    error (ERR_NONFATAL, "invalid size specification in"
			   " effective address");
		}
		i = stdscan(NULL, &tokval);
	    }
	    value = evaluate (stdscan, NULL, &tokval,
			      &result->forw_ref, critical, error, &hints);
	    i = tokval.t_type;
	    /* and get the offset */
	    if (!value) {	       /* but, error in evaluator */
		result->opcode = -1;   /* unrecoverable parse error: */
		return result;	       /* ignore this instruction */
	    }
	}
	if (mref && bracket) {	       /* find ] at the end */
	    if (i != ']') {
		error (ERR_NONFATAL, "parser: expecting ]");
		do {		       /* error recovery again */
		    i = stdscan(NULL, &tokval);
		} while (i != 0 && i != ',');
	    } else		       /* we got the required ] */
		i = stdscan(NULL, &tokval);
	} else {		       /* immediate operand */
	    if (i != 0 && i != ',' && i != ':') {
		error (ERR_NONFATAL, "comma or end of line expected");
		do {		       /* error recovery */
		    i = stdscan(NULL, &tokval);
		} while (i != 0 && i != ',');
	    } else if (i == ':') {
		result->oprs[operand].type |= COLON;
	    }
	}

	/* now convert the exprs returned from evaluate() into operand
	 * descriptions... */

	if (mref) {		       /* it's a memory reference */
	    expr *e = value;
	    int b, i, s;	       /* basereg, indexreg, scale */
	    long o;		       /* offset */

	    b = i = -1, o = s = 0;
	    result->oprs[operand].hintbase = hints.base;
	    result->oprs[operand].hinttype = hints.type;

	    if (e->type <= EXPR_REG_END) {   /* this bit's a register */
		if (e->value == 1) /* in fact it can be basereg */
		    b = e->type;
		else	       /* no, it has to be indexreg */
		    i = e->type, s = e->value;
		e++;
	    }
	    if (e->type && e->type <= EXPR_REG_END) {/* it's a 2nd register */
		if (e->value != 1) {   /* it has to be indexreg */
		    if (i != -1) {     /* but it can't be */
			error(ERR_NONFATAL, "invalid effective address");
			result->opcode = -1;
			return result;
		    } else
			i = e->type, s = e->value;
		} else {	       /* it can be basereg */
		    if (b != -1)       /* or can it? */
			i = e->type, s = 1;
		    else
			b = e->type;
		}
		e++;
	    }
	    if (e->type != 0) {	       /* is there an offset? */
		if (e->type <= EXPR_REG_END) {/* in fact, is there an error? */
		    error (ERR_NONFATAL, "invalid effective address");
		    result->opcode = -1;
		    return result;
		} else {
		    if (e->type == EXPR_UNKNOWN) {
			o = 0;	       /* doesn't matter what */
			result->oprs[operand].wrt = NO_SEG;   /* nor this */
			result->oprs[operand].segment = NO_SEG;  /* or this */
			while (e->type) e++;   /* go to the end of the line */
		    } else {
			if (e->type == EXPR_SIMPLE) {
			    o = e->value;
			    e++;
			}
			if (e->type == EXPR_WRT) {
			    result->oprs[operand].wrt = e->value;
			    e++;
			} else
			    result->oprs[operand].wrt = NO_SEG;
			/*
			 * Look for a segment base type.
			 */
			if (e->type && e->type < EXPR_SEGBASE) {
			    error (ERR_NONFATAL, "invalid effective address");
			    result->opcode = -1;
			    return result;
			}
			while (e->type && e->value == 0)
			    e++;
			if (e->type && e->value != 1) {
			    error (ERR_NONFATAL, "invalid effective address");
			    result->opcode = -1;
			    return result;
			}
			if (e->type) {
			    result->oprs[operand].segment =
				e->type - EXPR_SEGBASE;
			    e++;
			} else
			    result->oprs[operand].segment = NO_SEG;
			while (e->type && e->value == 0)
			    e++;
			if (e->type) {
			    error (ERR_NONFATAL, "invalid effective address");
			    result->opcode = -1;
			    return result;
			}
		    }
		}
	    } else {
		o = 0;
		result->oprs[operand].wrt = NO_SEG;
		result->oprs[operand].segment = NO_SEG;
	    }

	    if (e->type != 0) {    /* there'd better be nothing left! */
		error (ERR_NONFATAL, "invalid effective address");
		result->opcode = -1;
		return result;
	    }

	    result->oprs[operand].type |= MEMORY;
	    if (b==-1 && (i==-1 || s==0))
		result->oprs[operand].type |= MEM_OFFS;
	    result->oprs[operand].basereg = b;
	    result->oprs[operand].indexreg = i;
	    result->oprs[operand].scale = s;
	    result->oprs[operand].offset = o;
	} else {		       /* it's not a memory reference */
	    if (is_just_unknown(value)) {     /* it's immediate but unknown */
		result->oprs[operand].type |= IMMEDIATE;
		result->oprs[operand].offset = 0;   /* don't care */
		result->oprs[operand].segment = NO_SEG; /* don't care again */
		result->oprs[operand].wrt = NO_SEG;/* still don't care */
	    } else if (is_reloc(value)) {     /* it's immediate */
		result->oprs[operand].type |= IMMEDIATE;
		result->oprs[operand].offset = reloc_value(value);
		result->oprs[operand].segment = reloc_seg(value);
		result->oprs[operand].wrt = reloc_wrt(value);
		if (is_simple(value) && reloc_value(value)==1)
		    result->oprs[operand].type |= UNITY;
	    } else {	       /* it's a register */
		if (value->type>=EXPR_SIMPLE || value->value!=1) {
		    error (ERR_NONFATAL, "invalid operand type");
		    result->opcode = -1;
		    return result;
		}
		/* clear overrides, except TO which applies to FPU regs */
		result->oprs[operand].type &= TO;
		result->oprs[operand].type |= REGISTER;
		result->oprs[operand].type |= reg_flags[value->type];
		result->oprs[operand].basereg = value->type;
	    }
	}
    }

    result->operands = operand;       /* set operand count */

    while (operand<3)		       /* clear remaining operands */
	result->oprs[operand++].type = 0;

    /*
     * Transform RESW, RESD, RESQ, REST into RESB.
     */
    switch (result->opcode) {
      case I_RESW: result->opcode=I_RESB; result->oprs[0].offset*=2; break;
      case I_RESD: result->opcode=I_RESB; result->oprs[0].offset*=4; break;
      case I_RESQ: result->opcode=I_RESB; result->oprs[0].offset*=8; break;
      case I_REST: result->opcode=I_RESB; result->oprs[0].offset*=10; break;
    }

    return result;
}

static int is_comma_next (void) {
    char *p;
    int i;
    struct tokenval tv;

    p = stdscan_bufptr;
    i = stdscan (NULL, &tv);
    stdscan_bufptr = p;
    return (i == ',' || i == ';' || !i);
}

void cleanup_insn (insn *i) {
    extop *e;

    while (i->eops) {
	e = i->eops;
	i->eops = i->eops->next;
	nasm_free (e);
    }
}