C/C++ Users Group Library 1996 July/C-C++ Users Group Library July 1996.iso/vol_300/348_01/dis48.c

C/C++ Source or Header | 1991-05-01 | 4.8 KB | 279 lines

/*
**    Disassembler for 8048, 8041 microcode.
**
**    Copyright (c) 1990, Michael G. Panas
**
*/

#include <stdio.h>
#include <fcntl.h>

#include "dis48.h"

int    infd, pc, lincnt, pass, eoflg;
char    opcode, op2;
char    infile[80], outfile[80], labelbuf[10];
char    *lp, *label, *text, *operand, *tabzone, *hexdata;
FILE    *outfd;

char    *prog = "8048/8041 Disassembler\n";
char    *copy = "Copyright (c) 1990, Michael G. Panas\n";
char    *tab = "\t";
char    *nolabel = "";

struct    symbol    sym[SYMS];    /* the symbol table */
int    symcnt = 0;        /* number of symbols used */

#include "dis48tbl.c"

int findlabel(), dolabel(), addlabel();

main(argc, argv)
char **argv;
int argc;
{
    if (argc == 1) { /* no args */
        printf("%s%s", prog, copy);
        printf("Input filename: ");
        if (gets(infile) == NULL) {
            perror("Line error:");
            exit(1);
        }
        if (infile[0] == '\0')
            exit(0);
        printf("Output filename: ");
        if (gets(outfile) == NULL) {
            perror("Line error:");
            exit(1);
        }
        if (outfile[0] == '\0')
            exit(0);
    }
    else {
        strcpy(infile, argv[1]);
        strcpy(outfile, argv[2]);
    }

#ifdef MSC
    if ((infd = open(infile, O_RDONLY|O_BINARY)) == -1) {
#else
    if ((infd = open(infile, O_RDONLY)) == -1) {
#endif
        perror("Can't open input file:");
        exit(1);
    }
    if ((outfd = fopen(outfile, "w")) == NULL) {
        perror("Can't open output file:");
        exit(1);
    }

    prolog();            /* assembly startup stuff */

    pass = 0;
    while (pass++ < 2) {        /* do 2 passes */
        lseek(infd, 0, 0);    /* reset pointer */
        eoflg = 0;
        pc = 0;
        lincnt = 0;
        disasm();
    }

    cleansym();

    epilog();            /* "END" statement */

    printf("Disassembly done, %d lines\n", lincnt);
}

disasm()
{
    int address, len, origpc, nl;
    unsigned char index, oper;
    struct table *tb;
    char buf[40], operbuf[10];

    do {
        origpc = pc;
        nl = 0;

        index = (unsigned char) getbyte();
        if (eoflg) {
            break;
        }

        tb = &dis48[index];

        /* set up defaults */
        label = nolabel;
        text = tb->text;
        operand = tab;
        tabzone = tab;
        sprintf(&buf[0], ";%04X %02X", pc-1, index);
        hexdata = (char *) &buf[0];

        switch (tb->type) {

            case RET:
                nl = 1;
            case NOP:
            case DBC:
                break;

            case IMM:
                oper = (unsigned char) getbyte();
                sprintf(&operbuf[0], "0%02XH\t", oper);
                operand = &operbuf[0];
                sprintf(&buf[strlen(&buf[0])], " %02X", oper);
                if ((tb->width + 4) >= 8)
                    tabzone = nolabel;
                break;

            case JMP:
                nl = 1;
            case CAL:
                oper = (unsigned char) getbyte();
                sprintf(&buf[strlen(&buf[0])], " %02X", oper);
                address = ((index&0xe0) <<3) | oper;
                sprintf(&operbuf[0], "L%04X\t", address);
                operand = &operbuf[0];
                addlabel(address);
                break;

            case BRA:
                oper = (unsigned char) getbyte();
                sprintf(&buf[strlen(&buf[0])], " %02X", oper);
                address = ((pc-2) & 0xff00) | oper;
                sprintf(&operbuf[0], "L%04X\t", address);
                operand = &operbuf[0];
                addlabel(address);
                if ((tb->width + 5) >= 8)
                    tabzone = nolabel;
                break;

        }


        if (pass == 2) {
            if (findlabel(origpc))
                dolabel(origpc);
            putline();
            if (nl)
                fprintf(outfd, "\n");
        }
    }
    while (eoflg == 0);
}

/*
** read the next byte from the input file
*/
getbyte()
{
    char byte;

    if(read(infd, &byte, 1) == 0) {
        eoflg = 1;
    }
    pc++;
    return(byte);
}

putline()
{
    fprintf(outfd, "%s%s%s%s%s\n", label, text, operand, tabzone, hexdata);

    lincnt++;
}

addlabel(address)
int address;
{
    int i;

    if (findlabel(address))
        return;

    if ((i = symcnt++) == SYMS) {
        printf("Symbol table overflow!\n");
        exit(1);
    }

    sym[i].flags |= USED;
    sym[i].address = address;
}

doref(address)
int address;
{
    int i;

    i = findlabel(address) - 1;

    fprintf(outfd, "L%04X\tEQU\t%04XH\n", address, address);
    sym[i].flags |= PRINT;
}

dolabel(address)
int address;
{
    int i;

    i = findlabel(address) - 1;

    sprintf(&labelbuf[0], "L%04X", address);
    label = &labelbuf[0];
    sym[i].flags |= PRINT;
}

int
findlabel(address)
int address;
{
    int i;
    for (i = 0; i <= symcnt; i++) {
        if (address == sym[i].address) {
            return(i+1);
        }
    }
    return(0);
}

cleansym()
{
    int i, k;


    for (i = 0, k = 0; i <= symcnt; i++) {
        if ((sym[i].flags & PRINT) == 0) {
            k++;
        }
    }

    if (k == 0)
        return;

    fprintf(outfd, "\n");
    fprintf(outfd, ";    The following %d symbols are not within\n", k);
    fprintf(outfd, ";    the address range of this file or are not\n");
    fprintf(outfd, ";    on an instruction boundary.\n");

    for (i = 0; i <= symcnt; i++) {
        if ((sym[i].flags & PRINT) == 0) {
            doref(sym[i].address);
        }
    }
}

prolog()
{
    fprintf(outfd, "\tORG\t0\n");
    lincnt++;
}

epilog()
{
    fprintf(outfd, "\tEND\n");
    lincnt++;
}