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sml.c
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sml.c
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#include <stdio.h>
#include "sml.h"
#include "memory.h"
#define ZEROERR 1
#define UNVALIDOPCODE 2
#define ACCOVERFLOW 3
// Registers
static int acc, // Accumulator
inscnt, // Instruction counter
insreg, // Instruction register
opcode, // Operation code
oprand; // Oprand
void welcome() {
printf("Welcome to Simpletron\n");
}
void input(int hasinputfile) {
int i, t;
for (i = 0; i < MEMORYSIZE; i++) {
if (!hasinputfile) {
printf("%d", i);
}
scanf("%d", &t);
if (t == -99999) break;
memory[i] = t;
}
}
void dump() {
int i;
printf("acc:%d\n", acc);
printf("inscnt:%d\n", inscnt);
printf("insreg:%d\n", insreg);
printf("opcode:%d\n", opcode);
printf("oprand:%d\n", oprand);
for (i = 0; i < MEMORYSIZE; i++) {
printf("%d: %d\n", i, memory[i]);
}
}
int sim(){
int s; // Temp var for overflow checking
while (1) {
insreg = memory[inscnt];
opcode = get_opcode(insreg);
oprand = get_oprand(insreg);
switch (opcode) {
case 0:
break;
case READ:
printf("input %d:", oprand);
scanf("%d", &memory[oprand]);
break;
case WRITE:
printf("%d\n", memory[oprand]);
break;
case LOAD:
acc = memory[oprand];
break;
case STORE:
memory[oprand] = acc;
break;
case ADD:
s = acc + memory[oprand];
if (s>9999 || s<-9999) return ACCOVERFLOW;
acc = s;
break;
case SUBSTRACT:
s = acc - memory[oprand];
if (s>9999 || s<-9999) return ACCOVERFLOW;
acc -= memory[oprand];
break;
case DEVIDE:
if (memory[oprand] == 0) return ZEROERR;
acc /= memory[oprand];
break;
case MULTIPLY:
acc *= memory[oprand];
break;
case BRANCH:
inscnt = oprand-1;
break;
case BRANCHNEG:
if (acc < 0)
inscnt = oprand-1;
break;
case BRANCHZERO:
if (acc == 0)
inscnt = oprand-1;
break;
case HALT:
return 0;
default:
return UNVALIDOPCODE;
}
inscnt++;
}
}
int main(int argc, char *argv[]) {
int r;
welcome();
if (argc > 1) {
freopen(argv[1], "r", stdin);
}
if (argc == 3) {
freopen(argv[2], "w", stdout);
}
input(argc > 1);
freopen("/dev/tty", "r", stdin);
r = sim();
switch(r) {
case 0:
break;
case ZEROERR:
printf("Attempt to divided by zero");
break;
case UNVALIDOPCODE:
printf("OPCODE IS UNVALID");
break;
case ACCOVERFLOW:
printf("Accumulator overflow");
break;
}
dump();
return 0;
}