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#include <stdlib.h>
#include <stdio.h>
#include "turng.h"
#ifndef __CMIX
#define __CMIX(X)
#endif
int instrs; /* number of instructions in current program */
Instruction instruction[MAXINSTRS] /* = { */
/* 0 { IfGoto, '0', 3 },*/
/* 1 { Right },*/
/* 2 { Goto, '-', 0 },*/
/* 3 { Write, '1' },*/
/* 4 { Stop }}*/;
char* turing(char tape[], int tapelen) {
int i;
int p;
i = 0; p = 0;
while (instruction[i].tag != Stop) {
printstatus("i=%d ", i);
printstatus("p=%d\n", p);
switch (instruction[i].tag) {
case Left : if (p > 0) p--; break;
case Right :
if (p < tapelen - 2) {
p++;
if (tape[p] == '\0') {
tape[p + 1] = '\0';
tape[p] = ' ';
}
}
break;
case Write : tape[p] = instruction[i].a; break;
case Goto : i = instruction[i].i; continue;
case IfGoto :
if (tape[p] == instruction[i].a) {
i = instruction[i].i; continue;
}
break;
case ReadGoto :
/*****************************************************/
/************* EXERCISE: CODE THIS UP ****************/
printstatus("ReadGoto not implemented\n", 0);
__CMIX(pure)exit(-1);
/*****************************************************/
case Stop : printstatus("interpreter error\n", 0);
}
i++;
}
printstatus("\n", 0);
return tape + p;
}
char* loadAndRunTuring(char* filename, char tape[], int tapelen) {
readTuringProgram(filename);
return turing(tape, tapelen);
}
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