source: liacs/ca/opdr2b/src/memory.c@ 6

/* Author      : Rick van der Zwet
 * S-number    : 0433373
 * Version     : $Id: memory.c 365 2007-12-03 08:54:04Z rick $
 * Copyright   : FreeBSD Licence
 * Description : Memory unit
 */

#include <stdlib.h>
#include <stdio.h>
#include <sysexits.h>
#include "memory.h"

/* Initial value */
boolean mem_busy = FALSE;


void
readmem()
{
    int address = 0;
    uint32_t input = 0;

    //read 4-byte integer numbers in hexadecimal from input
    while (scanf("%x", &input) != EOF) {
        mem_operation(address * 4, input, WRITE_WORD);
        address++;
    }
    //zero the end
    for (; address < 1024; address++)
        mem_operation(address * 4, 0, WRITE_WORD);
}


void
writemem()
{
    int zeros = 0;
    int address = 0;
    word value = 0;
    for (address = 0; address < 1024; address++) {
        value = mem_operation(address * 4, 0, READ);
        if (value == 0)
            zeros++;
        else {
            for (; zeros > 0; zeros--)
                printf("%#010x\n", 0);
            printf("%#010x\n", value);
        }
    }
}


word
mem_operation(const word address, const word value,
              const mem_control_t action)
{
    static union memword_t memory[1024];

    int coreAddress = address / 4;
    int8_t offset = address % 4;

    if (coreAddress > 1024) {
        fprintf(stderr, "Memory which is greater than 1024 word, '%i'\n",
                         coreAddress);
        exit(EX_SOFTWARE);
    }

    switch (action) {
    case READ:
        if (offset != 0) {
            fprintf(stderr, "Read needs mod 4 bytes alligned\n");
            exit(EX_SOFTWARE);
        } else {
            mem_busy = FALSE;
            return(memory[coreAddress].fullword);
        }
        break;
    case WRITE_BYTE:
        memory[coreAddress].byte[offset] = (byte)value;
        break;
    case WRITE_HALFWORD:
        if ((offset % 2) != 0) {
            fprintf(stderr, "Halfword need mod 16 bits alligned\n");
            exit(EX_SOFTWARE);
        }
        memory[coreAddress].halfword[offset / 2] = (halfword)value;
        break;
    case WRITE_WORD:
        if (offset != 0) {
            fprintf(stderr, "Write needs mod 4 bytes alligned\n");
            exit(EX_SOFTWARE);
        }
        memory[coreAddress].fullword = value;
        break;
    default:
        fprintf(stderr, "Memory control '%i' not implemented\n", action);
        exit(EX_SOFTWARE);
        break;
    };
    mem_busy = FALSE;
    return(0);
}