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/*
* Mach Operating System
* Copyright (c) 1991,1990 Carnegie Mellon University
* All Rights Reserved.
*
* Permission to use, copy, modify and distribute this software and its
* documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
*
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS
* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* Carnegie Mellon requests users of this software to return to
*
* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
* School of Computer Science
* Carnegie Mellon University
* Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie the
* rights to redistribute these changes.
*
* $FreeBSD$
*/
/*
* Author: David B. Golub, Carnegie Mellon University
* Date: 7/90
*/
#include <sys/param.h>
#include <ddb/ddb.h>
#include <ddb/db_lex.h>
#include <ddb/db_access.h>
#include <ddb/db_command.h>
static boolean_t db_add_expr(db_expr_t *valuep);
static boolean_t db_mult_expr(db_expr_t *valuep);
static boolean_t db_shift_expr(db_expr_t *valuep);
static boolean_t db_term(db_expr_t *valuep);
static boolean_t db_unary(db_expr_t *valuep);
static boolean_t
db_term(valuep)
db_expr_t *valuep;
{
int t;
t = db_read_token();
if (t == tIDENT) {
if (!db_value_of_name(db_tok_string, valuep)) {
db_error("Symbol not found\n");
/*NOTREACHED*/
}
return (TRUE);
}
if (t == tNUMBER) {
*valuep = (db_expr_t)db_tok_number;
return (TRUE);
}
if (t == tDOT) {
*valuep = (db_expr_t)db_dot;
return (TRUE);
}
if (t == tDOTDOT) {
*valuep = (db_expr_t)db_prev;
return (TRUE);
}
if (t == tPLUS) {
*valuep = (db_expr_t) db_next;
return (TRUE);
}
if (t == tDITTO) {
*valuep = (db_expr_t)db_last_addr;
return (TRUE);
}
if (t == tDOLLAR) {
if (!db_get_variable(valuep))
return (FALSE);
return (TRUE);
}
if (t == tLPAREN) {
if (!db_expression(valuep)) {
db_error("Syntax error\n");
/*NOTREACHED*/
}
t = db_read_token();
if (t != tRPAREN) {
db_error("Syntax error\n");
/*NOTREACHED*/
}
return (TRUE);
}
db_unread_token(t);
return (FALSE);
}
static boolean_t
db_unary(valuep)
db_expr_t *valuep;
{
int t;
t = db_read_token();
if (t == tMINUS) {
if (!db_unary(valuep)) {
db_error("Syntax error\n");
/*NOTREACHED*/
}
*valuep = -*valuep;
return (TRUE);
}
if (t == tSTAR) {
/* indirection */
if (!db_unary(valuep)) {
db_error("Syntax error\n");
/*NOTREACHED*/
}
*valuep = db_get_value((db_addr_t)*valuep, sizeof(void *), FALSE);
return (TRUE);
}
db_unread_token(t);
return (db_term(valuep));
}
static boolean_t
db_mult_expr(valuep)
db_expr_t *valuep;
{
db_expr_t lhs, rhs;
int t;
if (!db_unary(&lhs))
return (FALSE);
t = db_read_token();
while (t == tSTAR || t == tSLASH || t == tPCT || t == tHASH) {
if (!db_term(&rhs)) {
db_error("Syntax error\n");
/*NOTREACHED*/
}
if (t == tSTAR)
lhs *= rhs;
else {
if (rhs == 0) {
db_error("Divide by 0\n");
/*NOTREACHED*/
}
if (t == tSLASH)
lhs /= rhs;
else if (t == tPCT)
lhs %= rhs;
else
lhs = ((lhs+rhs-1)/rhs)*rhs;
}
t = db_read_token();
}
db_unread_token(t);
*valuep = lhs;
return (TRUE);
}
static boolean_t
db_add_expr(valuep)
db_expr_t *valuep;
{
db_expr_t lhs, rhs;
int t;
if (!db_mult_expr(&lhs))
return (FALSE);
t = db_read_token();
while (t == tPLUS || t == tMINUS) {
if (!db_mult_expr(&rhs)) {
db_error("Syntax error\n");
/*NOTREACHED*/
}
if (t == tPLUS)
lhs += rhs;
else
lhs -= rhs;
t = db_read_token();
}
db_unread_token(t);
*valuep = lhs;
return (TRUE);
}
static boolean_t
db_shift_expr(valuep)
db_expr_t *valuep;
{
db_expr_t lhs, rhs;
int t;
if (!db_add_expr(&lhs))
return (FALSE);
t = db_read_token();
while (t == tSHIFT_L || t == tSHIFT_R) {
if (!db_add_expr(&rhs)) {
db_error("Syntax error\n");
/*NOTREACHED*/
}
if (rhs < 0) {
db_error("Negative shift amount\n");
/*NOTREACHED*/
}
if (t == tSHIFT_L)
lhs <<= rhs;
else {
/* Shift right is unsigned */
lhs = (unsigned) lhs >> rhs;
}
t = db_read_token();
}
db_unread_token(t);
*valuep = lhs;
return (TRUE);
}
int
db_expression(valuep)
db_expr_t *valuep;
{
return (db_shift_expr(valuep));
}
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