/* * 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. */ /* * HISTORY * $Log: db_expr.c,v $ * Revision 1.1.1.1 1993/03/21 09:45:37 cgd * initial import of 386bsd-0.1 sources * * Revision 1.1 1992/03/25 21:45:09 pace * Initial revision * * Revision 2.3 91/02/05 17:06:25 mrt * Changed to new Mach copyright * [91/01/31 16:17:46 mrt] * * Revision 2.2 90/08/27 21:50:57 dbg * Use '..' instead of '$$' for db_prev. * Use '+' for db_next. * [90/08/22 dbg] * * Allow repeated unary operators. * [90/08/20 dbg] * * Reflected back rename of db_symbol_value->db_value_of_name * [90/08/20 af] * Reduce lint. * [90/08/07 dbg] * Created. * [90/07/25 dbg] * */ /* * Author: David B. Golub, Carnegie Mellon University * Date: 7/90 */ #include "param.h" #include "proc.h" #include #include #include #include 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); } 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(int), FALSE); return (TRUE); } db_unread_token(t); return (db_term(valuep)); } 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); } 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); } 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)); }