C
hallo muhi,
hier ein kleiner Compiler, der eigentlich genau das tut was du brauchst:
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#define MODE_POSTFIX 0
#define MODE_ASSEMBLY 1
char lookahead;
int pos;
int compile_mode;
char expression[20+1];
void error()
{
printf("Syntax error!\n");
}
void match( char t )
{
if( lookahead == t )
{
pos++;
lookahead = expression[pos];
}
else
error();
}
void digit()
{
switch( lookahead )
{
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
if( compile_mode == MODE_POSTFIX )
printf("%c", lookahead);
else
printf("\tPUSH %c\n", lookahead);
match( lookahead );
break;
default:
error();
break;
}
}
void term()
{
digit();
while(1)
{
switch( lookahead )
{
case '*':
match('*');
digit();
printf( "%s", compile_mode == MODE_POSTFIX ? "*"
: "\tPOP B\n\tPOP A\n\tMUL A, B\n\tPUSH A\n");
break;
case '/':
match('/');
digit();
printf( "%s", compile_mode == MODE_POSTFIX ? "/"
: "\tPOP B\n\tPOP A\n\tDIV A, B\n\tPUSH A\n");
break;
default:
return;
}
}
}
void expr()
{
term();
while(1)
{
switch( lookahead )
{
case '+':
match('+');
term();
printf( "%s", compile_mode == MODE_POSTFIX ? "+"
: "\tPOP B\n\tPOP A\n\tADD A, B\n\tPUSH A\n");
break;
case '-':
match('-');
term();
printf( "%s", compile_mode == MODE_POSTFIX ? "-"
: "\tPOP B\n\tPOP A\n\tSUB A, B\n\tPUSH A\n");
break;
default:
return;
}
}
}
int main ( int argc, char** argv )
{
printf("Please enter an infix-notated expression with single digits:\n\n\t");
scanf("%20s", expression);
printf("\nCompiling to postfix-notated expression:\n\n\t");
compile_mode = MODE_POSTFIX;
pos = 0;
lookahead = *expression;
expr();
printf("\n\nCompiling to assembly-notated machine code:\n\n");
compile_mode = MODE_ASSEMBLY;
pos = 0;
lookahead = *expression;
expr();
return 0;
}
