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249 lines
5.0 KiB
C
249 lines
5.0 KiB
C
/*
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* Mach Operating System
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* Copyright (c) 1991,1990 Carnegie Mellon University
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* All Rights Reserved.
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*
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* Permission to use, copy, modify and distribute this software and its
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* documentation is hereby granted, provided that both the copyright
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* notice and this permission notice appear in all copies of the
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* software, derivative works or modified versions, and any portions
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* thereof, and that both notices appear in supporting documentation.
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*
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* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS
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* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
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* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
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*
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* Carnegie Mellon requests users of this software to return to
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*
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* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
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* School of Computer Science
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* Carnegie Mellon University
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* Pittsburgh PA 15213-3890
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*
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* any improvements or extensions that they make and grant Carnegie the
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* rights to redistribute these changes.
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*/
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/*
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* HISTORY
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* $Log: db_expr.c,v $
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* Revision 1.1 1992/03/25 21:45:09 pace
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* Initial revision
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*
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* Revision 2.3 91/02/05 17:06:25 mrt
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* Changed to new Mach copyright
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* [91/01/31 16:17:46 mrt]
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*
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* Revision 2.2 90/08/27 21:50:57 dbg
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* Use '..' instead of '$$' for db_prev.
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* Use '+' for db_next.
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* [90/08/22 dbg]
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*
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* Allow repeated unary operators.
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* [90/08/20 dbg]
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*
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* Reflected back rename of db_symbol_value->db_value_of_name
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* [90/08/20 af]
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* Reduce lint.
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* [90/08/07 dbg]
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* Created.
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* [90/07/25 dbg]
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*
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*/
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/*
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* Author: David B. Golub, Carnegie Mellon University
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* Date: 7/90
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*/
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#include "param.h"
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#include "proc.h"
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#include <machine/db_machdep.h>
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#include <ddb/db_lex.h>
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#include <ddb/db_access.h>
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#include <ddb/db_command.h>
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boolean_t
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db_term(valuep)
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db_expr_t *valuep;
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{
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int t;
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t = db_read_token();
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if (t == tIDENT) {
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if (!db_value_of_name(db_tok_string, valuep)) {
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db_error("Symbol not found\n");
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/*NOTREACHED*/
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}
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return (TRUE);
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}
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if (t == tNUMBER) {
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*valuep = (db_expr_t)db_tok_number;
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return (TRUE);
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}
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if (t == tDOT) {
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*valuep = (db_expr_t)db_dot;
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return (TRUE);
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}
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if (t == tDOTDOT) {
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*valuep = (db_expr_t)db_prev;
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return (TRUE);
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}
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if (t == tPLUS) {
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*valuep = (db_expr_t) db_next;
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return (TRUE);
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}
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if (t == tDITTO) {
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*valuep = (db_expr_t)db_last_addr;
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return (TRUE);
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}
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if (t == tDOLLAR) {
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if (!db_get_variable(valuep))
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return (FALSE);
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return (TRUE);
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}
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if (t == tLPAREN) {
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if (!db_expression(valuep)) {
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db_error("Syntax error\n");
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/*NOTREACHED*/
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}
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t = db_read_token();
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if (t != tRPAREN) {
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db_error("Syntax error\n");
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/*NOTREACHED*/
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}
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return (TRUE);
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}
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db_unread_token(t);
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return (FALSE);
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}
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boolean_t
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db_unary(valuep)
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db_expr_t *valuep;
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{
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int t;
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t = db_read_token();
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if (t == tMINUS) {
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if (!db_unary(valuep)) {
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db_error("Syntax error\n");
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/*NOTREACHED*/
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}
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*valuep = -*valuep;
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return (TRUE);
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}
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if (t == tSTAR) {
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/* indirection */
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if (!db_unary(valuep)) {
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db_error("Syntax error\n");
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/*NOTREACHED*/
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}
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*valuep = db_get_value((db_addr_t)*valuep, sizeof(int), FALSE);
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return (TRUE);
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}
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db_unread_token(t);
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return (db_term(valuep));
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}
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boolean_t
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db_mult_expr(valuep)
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db_expr_t *valuep;
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{
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db_expr_t lhs, rhs;
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int t;
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if (!db_unary(&lhs))
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return (FALSE);
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t = db_read_token();
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while (t == tSTAR || t == tSLASH || t == tPCT || t == tHASH) {
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if (!db_term(&rhs)) {
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db_error("Syntax error\n");
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/*NOTREACHED*/
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}
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if (t == tSTAR)
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lhs *= rhs;
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else {
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if (rhs == 0) {
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db_error("Divide by 0\n");
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/*NOTREACHED*/
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}
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if (t == tSLASH)
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lhs /= rhs;
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else if (t == tPCT)
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lhs %= rhs;
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else
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lhs = ((lhs+rhs-1)/rhs)*rhs;
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}
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t = db_read_token();
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}
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db_unread_token(t);
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*valuep = lhs;
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return (TRUE);
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}
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boolean_t
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db_add_expr(valuep)
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db_expr_t *valuep;
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{
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db_expr_t lhs, rhs;
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int t;
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if (!db_mult_expr(&lhs))
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return (FALSE);
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t = db_read_token();
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while (t == tPLUS || t == tMINUS) {
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if (!db_mult_expr(&rhs)) {
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db_error("Syntax error\n");
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/*NOTREACHED*/
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}
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if (t == tPLUS)
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lhs += rhs;
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else
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lhs -= rhs;
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t = db_read_token();
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}
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db_unread_token(t);
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*valuep = lhs;
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return (TRUE);
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}
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boolean_t
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db_shift_expr(valuep)
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db_expr_t *valuep;
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{
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db_expr_t lhs, rhs;
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int t;
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if (!db_add_expr(&lhs))
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return (FALSE);
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t = db_read_token();
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while (t == tSHIFT_L || t == tSHIFT_R) {
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if (!db_add_expr(&rhs)) {
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db_error("Syntax error\n");
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/*NOTREACHED*/
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}
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if (rhs < 0) {
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db_error("Negative shift amount\n");
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/*NOTREACHED*/
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}
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if (t == tSHIFT_L)
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lhs <<= rhs;
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else {
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/* Shift right is unsigned */
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lhs = (unsigned) lhs >> rhs;
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}
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t = db_read_token();
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}
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db_unread_token(t);
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*valuep = lhs;
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return (TRUE);
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}
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int
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db_expression(valuep)
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db_expr_t *valuep;
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{
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return (db_shift_expr(valuep));
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}
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