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expr.c
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expr.c
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/*
* Assembler for the Intel 8048 microcontroller family.
* Copyright (c) 2003 David H. Hovemeyer <daveho@cs.umd.edu>
*
* Enhanced in 2012, 2013 by JustBurn and sy2002 of MEGA
* http://www.adventurevision.net
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject
* to the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
* KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
* WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include "parse.tab.h"
#include "asm48.h"
/*
* Make an Expr object with given field values.
*/
static struct Expr *mk_expr(int op, struct Expr *left, struct Expr *right, const char *sym, int value, int line_num, int mustexist)
{
struct Expr *expr = (struct Expr*) pool_alloc_buf(gen_pool, sizeof(struct Expr));
expr->op = op;
expr->left = left;
expr->right = right;
expr->sym = sym;
expr->value = value;
expr->line_num = line_num;
expr->cur_offset = cur_offset;
expr->mustexist = mustexist;
return expr;
}
/*
* Make a constant expression with given value.
*/
struct Expr *mk_const_expr(int ival, int line_num)
{
return mk_expr(INT_VALUE, NULL, NULL, NULL, ival, line_num, 1);
}
/*
* Make a symbolic expression referring to given symbol.
*/
struct Expr *mk_symbolic_expr(const char *sym, int line_num, int mustexist)
{
return mk_expr(IDENTIFIER, NULL, NULL, sym, -1, line_num, mustexist);
}
/*
* Make a unary expression.
*/
struct Expr *mk_unary_expr(int op, struct Expr *subexpr, int line_num)
{
return mk_expr(op, subexpr, NULL, NULL, -1, line_num, 1);
}
/*
* Make a binary expression.
*/
struct Expr *mk_binary_expr(int op, struct Expr *left, struct Expr *right, int line_num)
{
return mk_expr(op, left, right, NULL, -1, line_num, 1);
}
/*
* Evaluate an expression.
*/
int eval_expr(char *cur_file, struct Expr *expr)
{
struct Symbol *symbol;
int lval, rval;
switch (expr->op) {
case INT_VALUE:
return expr->value;
case IDENTIFIER:
if (strcmp(expr->sym, ".here") == 0) /* addr of current instruction */
return expr->cur_offset;
symbol = lookup_symbol(expr->sym);
if (symbol == NULL) {
if (expr->mustexist)
err_printf("[%s] Line %d: Unknown symbol '%s'\n", cur_file, expr->line_num, expr->sym);
else
return 0;
}
return symbol->value;
case UMINUS:
return 0 - eval_expr(cur_file, expr->left);
case UNOTLOGIC:
return ~eval_expr(cur_file, expr->left);
case ULOW:
return eval_expr(cur_file, expr->left) & 255;
case UHIGH:
return (eval_expr(cur_file, expr->left) >> 8) & 255;
}
lval = eval_expr(cur_file, expr->left);
rval = eval_expr(cur_file, expr->right);
switch (expr->op) {
case '=':
return lval == rval;
case '!':
return lval != rval;
case '<':
return lval < rval;
case '>':
return lval > rval;
case 'l':
return lval <= rval;
case 'g':
return lval >= rval;
case 'a':
return lval && rval;
case 'o':
return lval || rval;
case '+':
return lval + rval;
case '-':
return lval - rval;
case '*':
return lval * rval;
case '/':
if (rval == 0)
err_printf("[%s] Line %d: Attempt to divide by zero\n", cur_file, expr->line_num);
return lval / rval;
case '%':
if (rval == 0)
err_printf("[%s] Line %d: Attempt to modulo by zero\n", cur_file, expr->line_num);
return lval % rval;
case LSHIFT:
return lval << rval;
case RSHIFT:
return lval >> rval;
case '&':
return lval & rval;
case '|':
return lval | rval;
case '^':
return lval ^ rval;
default:
assert(0); /* Unknown operation! */
}
return -1;
}