/*-
 * SPDX-License-Identifier: MIT-CMU
 *
 * 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.
 */
/*
 *      Author: David B. Golub, Carnegie Mellon University
 *      Date:   7/90
 */

#include <sys/param.h>
#include <sys/systm.h>

#include <ddb/ddb.h>
#include <ddb/db_lex.h>
#include <ddb/db_access.h>
#include <ddb/db_command.h>

static bool     db_add_expr(db_expr_t *valuep);
static bool     db_mult_expr(db_expr_t *valuep);
static bool     db_shift_expr(db_expr_t *valuep);
static bool     db_term(db_expr_t *valuep);
static bool     db_unary(db_expr_t *valuep);
static bool     db_logical_or_expr(db_expr_t *valuep);
static bool     db_logical_and_expr(db_expr_t *valuep);
static bool     db_logical_relation_expr(db_expr_t *valuep);

static bool
db_term(db_expr_t *valuep)
{
        int     t;

        t = db_read_token();
        if (t == tIDENT) {
            if (!db_value_of_name(db_tok_string, valuep) &&
                !db_value_of_name_pcpu(db_tok_string, valuep) &&
                !db_value_of_name_vnet(db_tok_string, valuep)) {
                db_printf("Symbol '%s' not found\n", db_tok_string);
                db_error(NULL);
                /*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_printf("Expression syntax error after '%c'\n", '(');
                db_error(NULL);
                /*NOTREACHED*/
            }
            t = db_read_token();
            if (t != tRPAREN) {
                db_printf("Expression syntax error -- expected '%c'\n", ')');
                db_error(NULL);
                /*NOTREACHED*/
            }
            return (true);
        }
        db_unread_token(t);
        return (false);
}

static bool
db_unary(db_expr_t *valuep)
{
        int     t;

        t = db_read_token();
        if (t == tMINUS) {
            if (!db_unary(valuep)) {
                db_printf("Expression syntax error after '%c'\n", '-');
                db_error(NULL);
                /*NOTREACHED*/
            }
            *valuep = -*valuep;
            return (true);
        }
        if (t == tEXCL) {
            if (!db_unary(valuep)) {
                db_printf("Expression syntax error after '%c'\n", '!');
                db_error(NULL);
                /* NOTREACHED  */
            }
            *valuep = (!(*valuep));
            return (true);
        }
        if (t == tBIT_NOT) {
            if (!db_unary(valuep)) {
                db_printf("Expression syntax error after '%c'\n", '~');
                db_error(NULL);
                /* NOTREACHED */
            }
            *valuep = (~(*valuep));
            return (true);
        }
        if (t == tSTAR) {
            /* indirection */
            if (!db_unary(valuep)) {
                db_printf("Expression syntax error after '%c'\n", '*');
                db_error(NULL);
                /*NOTREACHED*/
            }
            *valuep = db_get_value((db_addr_t)*valuep, sizeof(void *),
                false);
            return (true);
        }
        db_unread_token(t);
        return (db_term(valuep));
}

static bool
db_mult_expr(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 ||
            t == tBIT_AND ) {
            if (!db_term(&rhs)) {
                db_printf("Expression syntax error after '%c'\n",
                    t == tSTAR ? '*' : t == tSLASH ? '/' : t == tPCT ? '%' :
                    t == tHASH ? '#' : '&');
                db_error(NULL);
                /*NOTREACHED*/
            }
            switch(t)  {
                case tSTAR:
                    lhs *= rhs;
                    break;
                case tBIT_AND:
                    lhs &= rhs;
                    break;
                default:
                    if (rhs == 0) {
                        db_error("Division by 0\n");
                        /*NOTREACHED*/
                    }
                    if (t == tSLASH)
                        lhs /= rhs;
                    else if (t == tPCT)
                        lhs %= rhs;
                    else
                        lhs = roundup(lhs, rhs);
            }
            t = db_read_token();
        }
        db_unread_token(t);
        *valuep = lhs;
        return (true);
}

static bool
db_add_expr(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 || t == tBIT_OR) {
            if (!db_mult_expr(&rhs)) {
                db_printf("Expression syntax error after '%c'\n",
                    t == tPLUS ? '+' : t == tMINUS ? '-' : '|');
                db_error(NULL);
                /*NOTREACHED*/
            }
            switch (t) {
            case tPLUS:
                lhs += rhs;
                break;
            case tMINUS:
                lhs -= rhs;
                break;
            case tBIT_OR:
                lhs |= rhs;
                break;
            default:
                __assert_unreachable();
            }
            t = db_read_token();
        }
        db_unread_token(t);
        *valuep = lhs;
        return (true);
}

static bool
db_shift_expr(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_printf("Expression syntax error after '%s'\n",
                    t == tSHIFT_L ? "<<" : ">>");
                db_error(NULL);
                /*NOTREACHED*/
            }
            if (rhs < 0) {
                db_printf("Negative shift amount %jd\n", (intmax_t)rhs);
                db_error(NULL);
                /*NOTREACHED*/
            }
            if (t == tSHIFT_L)
                lhs <<= rhs;
            else {
                /* Shift right is unsigned */
                lhs = (db_addr_t)lhs >> rhs;
            }
            t = db_read_token();
        }
        db_unread_token(t);
        *valuep = lhs;
        return (true);
}

static bool
db_logical_relation_expr(
        db_expr_t *valuep)
{
        db_expr_t       lhs, rhs;
        int             t;

        if (!db_shift_expr(&lhs))
            return (false);

        t = db_read_token();
        while (t == tLOG_EQ || t == tLOG_NOT_EQ || t == tGREATER ||
            t == tGREATER_EQ || t == tLESS || t == tLESS_EQ) {
            if (!db_shift_expr(&rhs)) {
                db_printf("Expression syntax error after '%s'\n",
                    t == tLOG_EQ ? "==" : t == tLOG_NOT_EQ ? "!=" :
                    t == tGREATER ? ">" : t == tGREATER_EQ ? ">=" :
                    t == tLESS ? "<" : "<=");
                db_error(NULL);
                /*NOTREACHED*/
            }
            switch(t) {
                case tLOG_EQ:
                    lhs = (lhs == rhs);
                    break;
                case tLOG_NOT_EQ:
                    lhs = (lhs != rhs);
                    break;
                case tGREATER:
                    lhs = (lhs > rhs);
                    break;
                case tGREATER_EQ:
                    lhs = (lhs >= rhs);
                    break;
                case tLESS:
                    lhs = (lhs < rhs);
                    break;
                case tLESS_EQ:
                    lhs = (lhs <= rhs);
                    break;
                default:
                    __assert_unreachable();
            }
            t = db_read_token();
        }
        db_unread_token(t);
        *valuep = lhs;
        return (true);
}

static bool
db_logical_and_expr(
        db_expr_t *valuep)
{
        db_expr_t       lhs, rhs;
        int             t;

        if (!db_logical_relation_expr(&lhs))
            return (false);

        t = db_read_token();
        while (t == tLOG_AND) {
            if (!db_logical_relation_expr(&rhs)) {
                db_printf("Expression syntax error after '%s'\n", "&&");
                db_error(NULL);
                /*NOTREACHED*/
            }
            lhs = (lhs && rhs);
            t = db_read_token();
        }
        db_unread_token(t);
        *valuep = lhs;
        return (true);
}

static bool
db_logical_or_expr(
        db_expr_t *valuep)
{
        db_expr_t       lhs, rhs;
        int             t;

        if (!db_logical_and_expr(&lhs))
                return(false);

        t = db_read_token();
        while (t == tLOG_OR) {
                if (!db_logical_and_expr(&rhs)) {
                        db_printf("Expression syntax error after '%s'\n", "||");
                        db_error(NULL);
                        /*NOTREACHED*/
                }
                lhs = (lhs || rhs);
                t = db_read_token();
        }
        db_unread_token(t);
        *valuep = lhs;
        return (true);
}

int
db_expression(db_expr_t *valuep)
{
        return (db_logical_or_expr(valuep));
}