#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define TO_HEX(i) (i <= 9 ? '0' + i : 'a' - 10 + i)
//char * toHex(int val);
//void print_format(int * registers[], int regcc);
//int set_cc(int value);

int main(int argc, char**argv) {
    short *buffer;
    unsigned long fileLength;
    int regs[11] = {0};
    int rego;
    int opcode;
    int pc = 1;
    int regcc = 0;
    unsigned short offset;
    printf("Initial state\n");
    print_format(regs, regcc);
    printf("==================\n");
    printf("after executing instruction");
    FILE*f;
    f = fopen(argv[1], "r");
    fseek(f, 0, SEEK_END);
    fileLength = ftell(f);
    fseek(f, 0, SEEK_SET);
    buffer = malloc(fileLength + 1);
    fread(buffer, fileLength, 1, f);
    fclose(f);
    int i = 0;
    for (i = 0; i < sizeof (buffer); i++) {
        buffer[i] = ((buffer[i] & 0x00FF) << 8 | ((buffer[i] & 0xFF00) >> 8));
    }
    regs[8] = buffer[0];
    for (i = 1; i < sizeof (buffer); i++) {
        pc++;
        opcode = (buffer[i] & 0xf000) >> 12;
        if (opcode != 15) {
            if (opcode == 2) {
                regs[8] = regs[8] + 1;
                rego = (buffer[i] & 14) >> 12;
                offset = buffer[i] & 0x01ff;
                regs[rego] = buffer[pc + offset];
                regs[9] = buffer[i];
                regcc = set_cc(regs[rego]);
                break;
            }
        }
    }
    print_format(regs, regcc);
    printf("==================\n");
}

int set_cc(int value) {
    if (value < 0) {
        return -1;
    }
    if (value == 0x0000) {
        return 0;
    }
    if (value > 1) {
        return 1;
    }
}

char * toHex(int val) {
    int x = val;
    char *res = (char *) malloc(sizeof (char) * 5);
    if (x <= 0xFFFF) {
        res[0] = TO_HEX(((x & 0xF000) >> 12));
        res[1] = TO_HEX(((x & 0x0F00) >> 8));
        res[2] = TO_HEX(((x & 0x00F0) >> 4));
        res[3] = TO_HEX((x & 0x000F));
        res[4] = '\0';
    }
    return res;
}

void print_format(int * registers[], int regcc) {
    int i = 0;
    for (i; i < 11; i++) {
        if (i == 8) {
            printf("PC\t%s\n", toHex(registers[8]));
        } else if (i == 9) {
            printf("IR\t%s\n", toHex(registers[9]));
        } else if (i == 10) {
            if (regcc == 0x0000) {
                printf("CC\t%s\n", "Z");
            }
            if (regcc < 0) {
                printf("CC\t%s\n", "N");
            }
            if (regcc > 0) {
                printf("CC\t%s\n", "P");
            }
        } else {
            printf("R%d\t0x%s\n", i, toHex(registers[i]));
        }
    }
}