126 lines
3 KiB
C
126 lines
3 KiB
C
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/***************************************************************************************
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* Copyright (c) 2014-2022 Zihao Yu, Nanjing University
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*
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* NEMU is licensed under Mulan PSL v2.
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* You can use this software according to the terms and conditions of the Mulan PSL v2.
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* You may obtain a copy of Mulan PSL v2 at:
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* http://license.coscl.org.cn/MulanPSL2
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*
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* THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND,
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* EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT,
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* MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
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*
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* See the Mulan PSL v2 for more details.
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***************************************************************************************/
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#include <isa.h>
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/* We use the POSIX regex functions to process regular expressions.
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* Type 'man regex' for more information about POSIX regex functions.
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*/
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#include <regex.h>
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enum {
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TK_NOTYPE = 256, TK_EQ,
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/* TODO: Add more token types */
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};
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static struct rule {
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const char *regex;
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int token_type;
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} rules[] = {
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/* TODO: Add more rules.
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* Pay attention to the precedence level of different rules.
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*/
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{" +", TK_NOTYPE}, // spaces
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{"\\+", '+'}, // plus
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{"==", TK_EQ}, // equal
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};
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#define NR_REGEX ARRLEN(rules)
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static regex_t re[NR_REGEX] = {};
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/* Rules are used for many times.
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* Therefore we compile them only once before any usage.
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*/
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void init_regex() {
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int i;
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char error_msg[128];
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int ret;
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for (i = 0; i < NR_REGEX; i ++) {
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ret = regcomp(&re[i], rules[i].regex, REG_EXTENDED);
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if (ret != 0) {
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regerror(ret, &re[i], error_msg, 128);
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panic("regex compilation failed: %s\n%s", error_msg, rules[i].regex);
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}
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}
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}
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typedef struct token {
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int type;
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char str[32];
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} Token;
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static Token tokens[32] __attribute__((used)) = {};
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static int nr_token __attribute__((used)) = 0;
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static bool make_token(char *e) {
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int position = 0;
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int i;
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regmatch_t pmatch;
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nr_token = 0;
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while (e[position] != '\0') {
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/* Try all rules one by one. */
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for (i = 0; i < NR_REGEX; i ++) {
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if (regexec(&re[i], e + position, 1, &pmatch, 0) == 0 && pmatch.rm_so == 0) {
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char *substr_start = e + position;
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int substr_len = pmatch.rm_eo;
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Log("match rules[%d] = \"%s\" at position %d with len %d: %.*s",
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i, rules[i].regex, position, substr_len, substr_len, substr_start);
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position += substr_len;
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/* TODO: Now a new token is recognized with rules[i]. Add codes
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* to record the token in the array `tokens'. For certain types
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* of tokens, some extra actions should be performed.
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*/
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switch (rules[i].token_type) {
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default: TODO();
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}
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break;
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}
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}
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if (i == NR_REGEX) {
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printf("no match at position %d\n%s\n%*.s^\n", position, e, position, "");
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return false;
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}
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}
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return true;
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}
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word_t expr(char *e, bool *success) {
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if (!make_token(e)) {
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*success = false;
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return 0;
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}
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/* TODO: Insert codes to evaluate the expression. */
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TODO();
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return 0;
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}
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