source: vital-to8-sdk/mc09/src/fileio2.txt

FILE *fopen(name,mode)
char *name,*mode;
{char *p;
 int rd,wt,cm;
        rd = wt = cm = 0;
        for ( p = mode; *p; p++ ) {
                switch ( *p ) {
                case 'r':
                        rd = 1; break;
                case 'w':
                        wt = 1; break;
                case 'c':
                        cm = 1; break;
                default:
                        return NULL;
                }
        }
        if ( !(rd ^ wt) ) return NULL;
        if ( rd ) return _open(name,cm);
        else return _create(name,cm);
}

FILE *_open(name,cm)
char *name;
int cm;
{FILE *fp;
 int i;
        for ( i = 0; i < NFILES; i++)
                if ( _fptbl[i] == NULL ) break;
        if ( i >= NFILES) return NULL;
        if ( (fp = malloc(FBSIZE)) == NULL ) return NULL;
        if ( _setname(name,fp->_fcb) == 0 ) return NULL;
        if ( FMS(fp->_fcb,1) < 0 ) return NULL;
        fp->_fcb[59] = cm ? 0 : 0xff;
        fp->_fcb[60] = 0;
        return (_fptbl[i] = fp);
}

FILE *_create(name,cm)
char *name;
int cm;
{FILE *fp;
 int i;
        for ( i = 0; i < NFILES; i++)
                if ( _fptbl[i] == NULL ) break;
        if ( i >= NFILES) return NULL;
        if ( (fp = malloc(FBSIZE)) == NULL ) return NULL;
        if ( _setname(name,fp->_fcb) == 0 ) return NULL;
        if ( FMS(fp->_fcb,2) < 0 )
        {       if ( (fp[1] != 3) || (FMS(fp->_fcb,12) < 0) ) return NULL;
                _setname(name,fp->_fcb);
                if (FMS(fp->_fcb,2) < 0) return NULL;
        }
        fp->_fcb[15] = 0;
        fp->_fcb[59] = cm ? 0 : 0xff;
        fp->_fcb[60] = 0;
        return (_fptbl[i] = fp);
}

fclose(fp)
FILE *fp;
{int i;
        for ( i = 0; i < NFILES; i++ )
                if ( fp == _fptbl[i] ) break;
        if ( i >= NFILES ) return EOF;
        _fptbl[i] = NULL;
        if ( (fp == STDIN) || (fp == STDOUT) || (fp == STDERR) ) return 0;
        if ( fp->_fcb[2] == 2 ) fflush(fp);
        if ( FMS(fp->_fcb,4) < 0 ) return EOF;
        mfree(fp);
        return 0;
}

_setname(name,fcbp)
char *name;
char *fcbp;
{int i;
        while(isspace(*name)) ++name;
        if (isdigit(*name))
        {       fcbp[3] = *name++ - '0';
                if (*name++ != '.') return 0;
        }
        else fcbp[3] = 0xff;
        for (i = 4; i < 15; ++i) fcbp[i] = 0;
        if (!isalpha(*name)) return -1;
        for (i = 4; i < 12; ++i)
        {       if (!*name || (*name == '.')) break;
                fcbp[i] = *name++;
        }
        while (*name && (*name != '.')) ++name;
        if (*name == '.')
        {       ++name;
                for (i = 12; i < 15; ++i)
                {       if (!*name) break;
                        fcbp[i] = *name++;
                }
        }
        return 1;
}

fflush(fp)
FILE *fp;
{int i;
        if ( fp == STDIN ) return EOF;
        if ( fp == STDOUT || fp == STDERR ) return 0;
        if ( fp->_fcb[2] != 2 ) return EOF;
        for ( i = 0; i < fp->_fbp; i++ ) FMS(fp->_fcb,0,fp->fcb[i]);
        fp->_fbp = 0;
        return 0;
}

unlink(fname)
char *fname;
{char p[320];
        return ((_setname(fname,p) || FMS(p,12) < 0) ? -1 : 0);
}
        
rename(s,t)
char *s,*t;
{char p[320];
        return ((_setname(s,p) || _setname(t,p+49) || FMS(p,13) < 0) ? -1 : 0);
}