ysyx-workbench/nemu/src/monitor/sdb/addrexp.l

%{
    #include <isa.h>
    #include <addrexp.h>
    static bool success = false;
    void yyerror(word_t *result, const char *err); 
%}
%option noyywrap

%%

0[xX][0-9a-fA-F]+ { yylval = strtoul(yytext, NULL, 16); return HEX_NUMBER; }
$[a-zA-Z]{2,3}   {
    yylval = isa_reg_str2val(yytext + 1, &success);
    if(!success) {
        yyerror(NULL, "Failed to convert reg to value");
        return YYerror;
    }
}
[0-9]+            { yylval = strtoul(yytext, NULL, 10); return NUMBER; }
[+\-*/()]         { return *yytext; }
[ \t]             {  }
.                 { printf("Unexpected character: %s\n", yytext); return YYerror; }
%%