Thread: Help on brookshear machine

Hi, I am trying to code a brookshear machine and I am getting weird results with my code.

My Code:

Code:

#include <stdio.h>


void display_values(unsigned int pc, unsigned char mem[], unsigned char reg[]);


FILE *f;


int main() {
    unsigned int pc = 0, i = 0, temp = 0;
    unsigned char reg[16], mem[256], a, b, c, d, cd;
    
    for(i = 0; i < sizeof(reg); i++) {
        reg[i] = 0x00;
    }
    
    for(i = 0; i < sizeof(mem); i++) {
        mem[i] = 0x00;
    }
    
    f = fopen("a3.txt", "r");
    if(f == NULL) {
        printf("Error: File not found!\n");
        return 0;
    }
    
    while(fscanf(f, "%X", &temp) != EOF) {
        mem[i] = (temp & 0xff00) >> 8;
        mem[i+1] = temp & 0xff;
        i+=2;
    }
    fclose(f);
    
    while(mem[pc] != 0xC0) {
        a = (mem[i] & 0xf0) >> 4;
        b = mem[i] & 0xf;
        c = (mem[i+1] & 0xf0) >> 4;
        d = mem[i+1] & 0xf;
        cd = mem[i+1];
        
        display_values(pc, mem, reg);
        
        if(a == 0x1) {
            // Load the register R with the value at memory address XY.
            reg[b] = mem[cd];
        }
        if(a == 0x2) {
            // Load register R with the value XY.
            reg[b] = cd;
        }
        if(a == 0x3) {
            // Store the value in register R at memory address XY.
            mem[cd] = reg[b];
        }
        if(a == 0x4) {
            // Move the value in register R to register S.
            reg[d] = reg[c];
            reg[c] = 0x00;
        }
        if(a == 0x5) {
            // Add(+) values in registers R and S and put the answer in register T.
            reg[d] = reg[b] + reg[c];
        }
        if(a == 0x7) {
            // Bit-wise OR(|) the values in registers R and S and put the answer in register T.
            reg[d] = reg[b] | reg[c];
        }
        if(a == 0x8) {
            // Bit-wise AND(&) the values in registers R and S and put the answer in register T.
            reg[d] = reg[b] & reg[c];
        }
        if(a == 0x9) {
            // Bit-wise XOR(^) the values in registers R and S and put the answer in register T.
            reg[d] = reg[b] ^ reg[c];
        }
        if(a == 0xA) {
            // Rotate the contents of register R X times to the right.
            reg[b] >>= 1;
            reg[b] = reg[b] | ((reg[b] & 0x1) << 31);
        }
        if(a == 0xB) {
            // Jump to the instruction located at memory address XY if register R = register 0.
            if(mem[b] == reg[0]) {
                pc = cd;
            }
        }
        
        pc = pc + 2;
        
        display_values(pc, mem, reg);
    }
    
    return 0;
}


void display_values(unsigned int pc, unsigned char mem[], unsigned char reg[]) {    
    unsigned int i = 0;
    
    printf("%02X", pc);
    printf(" %02X%02X ", mem[pc], mem[pc+1]);
    for(i = 0; i < sizeof(reg); i++) {
        printf(" %02X ", reg[i]);
    }
    printf("\n");
}

I am reading from a text file that contains:

B404
239A
2412
5345
350C
C000

The right result is:

00 B404 – [00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00]
04 2412 - [00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00]
06 5345 - [00 00 00 00 12 00 00 00 00 00 00 00 00 00 00 00]
08 350C - [00 00 00 00 12 12 00 00 00 00 00 00 00 00 00 00]
0A C000 - [00 00 00 00 12 12 00 00 00 00 00 00 00 00 00 00]

But I am getting: (Note: it started from 00...)



Need help.