unsigned length, int type);
/* Binary ensemble commands */
static int		BinaryFormatCmd(ClientData clientData,
			    Tcl_Interp *interp,
			    int objc, Tcl_Obj *const objv[]);
static int		BinaryScanCmd(ClientData clientData,
			    Tcl_Interp *interp,
			    int objc, Tcl_Obj *const objv[]);
static int		BinarySetCmd(ClientData clientData,
			    Tcl_Interp *interp,
			    int objc, Tcl_Obj *const objv[]);
/* Binary encoding sub-ensemble commands */
static int		BinaryEncodeHex(ClientData clientData,
			    Tcl_Interp *interp,
			    int objc, Tcl_Obj *const objv[]);
static int		BinaryDecodeHex(ClientData clientData,
			    Tcl_Interp *interp,

/*
 * How to construct the ensembles.
 */

static const EnsembleImplMap binaryMap[] = {
    { "format", BinaryFormatCmd, TclCompileBasicMin1ArgCmd, NULL, NULL, 0 },
    { "scan",   BinaryScanCmd, TclCompileBasicMin2ArgCmd, NULL, NULL, 0 },
    { "set",	BinarySetCmd, TclCompileBasicMin2ArgCmd, NULL, NULL, 0 },
    { "encode", NULL, NULL, NULL, NULL, 0 },
    { "decode", NULL, NULL, NULL, NULL, 0 },
    { NULL, NULL, NULL, NULL, NULL, 0 }
};
static const EnsembleImplMap encodeMap[] = {
    { "hex",      BinaryEncodeHex, TclCompileBasic1ArgCmd, NULL, NULL, 0 },
    { "uuencode", BinaryEncodeUu,  NULL, NULL, NULL, 0 },

	    }
	    break;
	}
    }
    Tcl_SetObjResult(interp, resultPtr);
    return TCL_OK;

 badValue:
    Tcl_ResetResult(interp);
    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
	    "expected %s string but got \"%s\" instead",
	    errorString, errorValue));
    return TCL_ERROR;

 badCount:
    errorString = "missing count for \"@\" field specifier";
    goto error;

 badIndex:
    errorString = "not enough arguments for all format specifiers";
    goto error;

 badField:
    {
	Tcl_UniChar ch = 0;
	char buf[TCL_UTF_MAX + 1] = "";

	TclUtfToUniChar(errorString, &ch);
	buf[Tcl_UniCharToUtf(ch, buf)] = '\0';
	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
		"bad field specifier \"%s\"", buf));
	return TCL_ERROR;
    }

 error:
    Tcl_SetObjResult(interp, Tcl_NewStringObj(errorString, -1));
    return TCL_ERROR;
}

/*
 *----------------------------------------------------------------------
 *
 * BinarySetCmd --
 *
 *	This procedure implements the "binary set" Tcl command.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

static int
BinarySetCmd(
    ClientData dummy,		/* Not used. */
    Tcl_Interp *interp,		/* Current interpreter. */
    int objc,			/* Number of arguments. */
    Tcl_Obj *const objv[])	/* Argument objects. */
{
    int arg;			/* Index of next argument to consume. */
    int value = 0;		/* Current integer value to be packed.
				 * Initialized to avoid compiler warning. */
    char cmd;			/* Current format character. */
    int count;			/* Count associated with current format
				 * character. */
    int flags;			/* Format field flags */
    const char *format;		/* Pointer to current position in format
				 * string. */
    Tcl_Obj *valuePtr;		/* Object holding binary value buffer. */
    unsigned char *buffer;	/* Start of result buffer. */
    unsigned char *cursor;	/* Current position within result buffer. */
    unsigned char *maxPos;	/* Greatest position within result buffer that
				 * cursor has visited.*/
    const char *errorString;
    const char *errorValue, *str;
    int offset, size, length, originalLength;

    if (objc < 3) {
	Tcl_WrongNumArgs(interp, 1, objv, "varName formatString ?arg ...?");
	return TCL_ERROR;
    }

    valuePtr = Tcl_ObjGetVar2(interp, objv[1], NULL, 0);
    if (valuePtr == NULL) {
	valuePtr = Tcl_NewByteArrayObj(NULL, 0);
    }
    buffer = Tcl_GetByteArrayFromObj(valuePtr, &originalLength);
    length = originalLength;

    /*
     * To avoid copying the data, we format the string in two passes. The
     * first pass computes the size of the output buffer. The second pass
     * places the formatted data into the buffer.
     */

    format = TclGetString(objv[2]);
    arg = 3;
    offset = 0;
    while (*format != '\0') {
	str = format;
	flags = 0;
	if (!GetFormatSpec(&format, &cmd, &count, &flags)) {
	    break;
	}
	switch (cmd) {
	case 'a':
	case 'A':
	case 'b':
	case 'B':
	case 'h':
	case 'H':
	    /*
	     * For string-type specifiers, the count corresponds to the number
	     * of bytes in a single argument.
	     */

	    if (arg >= objc) {
		goto badIndex;
	    }
	    if (count == BINARY_ALL) {
		Tcl_GetByteArrayFromObj(objv[arg], &count);
	    } else if (count == BINARY_NOCOUNT) {
		count = 1;
	    }
	    arg++;
	    if (cmd == 'a' || cmd == 'A') {
		offset += count;
	    } else if (cmd == 'b' || cmd == 'B') {
		offset += (count + 7) / 8;
	    } else {
		offset += (count + 1) / 2;
	    }
	    break;
	case 'c':
	    size = 1;
	    goto doNumbers;
	case 't':
	case 's':
	case 'S':
	    size = 2;
	    goto doNumbers;
	case 'n':
	case 'i':
	case 'I':
	    size = 4;
	    goto doNumbers;
	case 'm':
	case 'w':
	case 'W':
	    size = 8;
	    goto doNumbers;
	case 'r':
	case 'R':
	case 'f':
	    size = sizeof(float);
	    goto doNumbers;
	case 'q':
	case 'Q':
	case 'd':
	    size = sizeof(double);

	doNumbers:
	    if (arg >= objc) {
		goto badIndex;
	    }

	    /*
	     * For number-type specifiers, the count corresponds to the number
	     * of elements in the list stored in a single argument. If no
	     * count is specified, then the argument is taken as a single
	     * non-list value.
	     */

	    if (count == BINARY_NOCOUNT) {
		arg++;
		count = 1;
	    } else {
		int listc;
		Tcl_Obj **listv;

		/*
		 * The macro evals its args more than once: avoid arg++
		 */

		if (TclListObjGetElements(interp, objv[arg], &listc,
			&listv) != TCL_OK) {
		    return TCL_ERROR;
		}
		arg++;

		if (count == BINARY_ALL) {
		    count = listc;
		} else if (count > listc) {
		    Tcl_SetObjResult(interp, Tcl_NewStringObj(
			    "number of elements in list does not match count",
			    -1));
		    return TCL_ERROR;
		}
	    }
	    offset += count*size;
	    break;

	case 'x':
	    if (count == BINARY_ALL) {
		Tcl_SetObjResult(interp, Tcl_NewStringObj(
			"cannot use \"*\" in format string with \"x\"", -1));
		return TCL_ERROR;
	    } else if (count == BINARY_NOCOUNT) {
		count = 1;
	    }
	    offset += count;
	    break;
	case 'X':
	    if (count == BINARY_NOCOUNT) {
		count = 1;
	    }
	    if ((count > offset) || (count == BINARY_ALL)) {
		count = offset;
	    }
	    if (offset > length) {
		length = offset;
	    }
	    offset -= count;
	    break;
	case '@':
	    if (offset > length) {
		length = offset;
	    }
	    if (count == BINARY_ALL) {
		offset = length;
	    } else if (count == BINARY_NOCOUNT) {
		goto badCount;
	    } else {
		offset = count;
	    }
	    break;
	default:
	    errorString = str;
	    goto badField;
	}
    }
    if (offset > length) {
	length = offset;
    }

    /*
     * Prepare the result object by preallocating the caclulated number of
     * bytes and filling with nulls.
     */

    if (Tcl_IsShared(valuePtr)) {
	valuePtr = Tcl_DuplicateObj(valuePtr);
    }
    buffer = Tcl_SetByteArrayLength(valuePtr, length);
    if (length > originalLength) {
	memset(buffer + originalLength, 0, length - originalLength);
    }
    Tcl_IncrRefCount(valuePtr);

    /*
     * Pack the data into the result object. Note that we can skip the error
     * checking during this pass, since we have already parsed the string
     * once.
     */

    arg = 3;
    format = TclGetString(objv[2]);
    cursor = buffer;
    maxPos = cursor;
    while (*format != 0) {
	flags = 0;
	if (!GetFormatSpec(&format, &cmd, &count, &flags)) {
	    break;
	}
	if ((count == 0) && (cmd != '@')) {
	    if (cmd != 'x') {
		arg++;
	    }
	    continue;
	}
	switch (cmd) {
	case 'a':
	case 'A': {
	    char pad = (char) (cmd == 'a' ? '\0' : ' ');
	    unsigned char *bytes;

	    bytes = Tcl_GetByteArrayFromObj(objv[arg++], &length);

	    if (count == BINARY_ALL) {
		count = length;
	    } else if (count == BINARY_NOCOUNT) {
		count = 1;
	    }
	    if (length >= count) {
		memcpy(cursor, bytes, count);
	    } else {
		memcpy(cursor, bytes, length);
		memset(cursor + length, pad, count - length);
	    }
	    cursor += count;
	    break;
	}
	case 'b':
	case 'B': {
	    unsigned char *last;

	    str = TclGetStringFromObj(objv[arg], &length);
	    arg++;
	    if (count == BINARY_ALL) {
		count = length;
	    } else if (count == BINARY_NOCOUNT) {
		count = 1;
	    }
	    last = cursor + ((count + 7) / 8);
	    if (count > length) {
		count = length;
	    }
	    value = 0;
	    errorString = "binary";
	    if (cmd == 'B') {
		for (offset = 0; offset < count; offset++) {
		    value <<= 1;
		    if (str[offset] == '1') {
			value |= 1;
		    } else if (str[offset] != '0') {
			errorValue = str;
			Tcl_DecrRefCount(valuePtr);
			goto badValue;
		    }
		    if (((offset + 1) % 8) == 0) {
			*cursor++ = UCHAR(value);
			value = 0;
		    }
		}
	    } else {
		for (offset = 0; offset < count; offset++) {
		    value >>= 1;
		    if (str[offset] == '1') {
			value |= 128;
		    } else if (str[offset] != '0') {
			errorValue = str;
			Tcl_DecrRefCount(valuePtr);
			goto badValue;
		    }
		    if (!((offset + 1) % 8)) {
			*cursor++ = UCHAR(value);
			value = 0;
		    }
		}
	    }
	    if ((offset % 8) != 0) {
		if (cmd == 'B') {
		    value <<= 8 - (offset % 8);
		} else {
		    value >>= 8 - (offset % 8);
		}
		*cursor++ = UCHAR(value);
	    }
	    while (cursor < last) {
		*cursor++ = '\0';
	    }
	    break;
	}
	case 'h':
	case 'H': {
	    unsigned char *last;
	    int c;

	    str = TclGetStringFromObj(objv[arg], &length);
	    arg++;
	    if (count == BINARY_ALL) {
		count = length;
	    } else if (count == BINARY_NOCOUNT) {
		count = 1;
	    }
	    last = cursor + ((count + 1) / 2);
	    if (count > length) {
		count = length;
	    }
	    value = 0;
	    errorString = "hexadecimal";
	    if (cmd == 'H') {
		for (offset = 0; offset < count; offset++) {
		    value <<= 4;
		    if (!isxdigit(UCHAR(str[offset]))) {     /* INTL: digit */
			errorValue = str;
			Tcl_DecrRefCount(valuePtr);
			goto badValue;
		    }
		    c = str[offset] - '0';
		    if (c > 9) {
			c += ('0' - 'A') + 10;
		    }
		    if (c > 16) {
			c += ('A' - 'a');
		    }
		    value |= (c & 0xf);
		    if (offset % 2) {
			*cursor++ = (char) value;
			value = 0;
		    }
		}
	    } else {
		for (offset = 0; offset < count; offset++) {
		    value >>= 4;

		    if (!isxdigit(UCHAR(str[offset]))) {     /* INTL: digit */
			errorValue = str;
			Tcl_DecrRefCount(valuePtr);
			goto badValue;
		    }
		    c = str[offset] - '0';
		    if (c > 9) {
			c += ('0' - 'A') + 10;
		    }
		    if (c > 16) {
			c += ('A' - 'a');
		    }
		    value |= ((c << 4) & 0xf0);
		    if (offset % 2) {
			*cursor++ = UCHAR(value & 0xff);
			value = 0;
		    }
		}
	    }
	    if (offset % 2) {
		if (cmd == 'H') {
		    value <<= 4;
		} else {
		    value >>= 4;
		}
		*cursor++ = UCHAR(value);
	    }

	    while (cursor < last) {
		*cursor++ = '\0';
	    }
	    break;
	}
	case 'c':
	case 't':
	case 's':
	case 'S':
	case 'n':
	case 'i':
	case 'I':
	case 'm':
	case 'w':
	case 'W':
	case 'r':
	case 'R':
	case 'd':
	case 'q':
	case 'Q':
	case 'f': {
	    int listc, i;
	    Tcl_Obj **listv;

	    if (count == BINARY_NOCOUNT) {
		/*
		 * Note that we are casting away the const-ness of objv, but
		 * this is safe since we aren't going to modify the array.
		 */

		listv = (Tcl_Obj **) (objv + arg);
		listc = 1;
		count = 1;
	    } else {
		TclListObjGetElements(interp, objv[arg], &listc, &listv);
		if (count == BINARY_ALL) {
		    count = listc;
		}
	    }
	    arg++;
	    for (i = 0; i < count; i++) {
		if (FormatNumber(interp, cmd, listv[i], &cursor) != TCL_OK) {
		    Tcl_DecrRefCount(valuePtr);
		    return TCL_ERROR;
		}
	    }
	    break;
	}
	case 'x':
	    if (count == BINARY_NOCOUNT) {
		count = 1;
	    }
	    memset(cursor, 0, count);
	    cursor += count;
	    break;
	case 'X':
	    if (cursor > maxPos) {
		maxPos = cursor;
	    }
	    if (count == BINARY_NOCOUNT) {
		count = 1;
	    }
	    if ((count == BINARY_ALL) || (count > (cursor - buffer))) {
		cursor = buffer;
	    } else {
		cursor -= count;
	    }
	    break;
	case '@':
	    if (cursor > maxPos) {
		maxPos = cursor;
	    }
	    if (count == BINARY_ALL) {
		cursor = maxPos;
	    } else {
		cursor = buffer + count;
	    }
	    break;
	}
    }
    if (!Tcl_ObjSetVar2(interp, objv[1], NULL, valuePtr, TCL_LEAVE_ERR_MSG)) {
	TclDecrRefCount(valuePtr);
	return TCL_ERROR;
    }
    TclDecrRefCount(valuePtr);
    return TCL_OK;

 badValue:
    Tcl_ResetResult(interp);
    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
	    "expected %s string but got \"%s\" instead",
	    errorString, errorValue));
    return TCL_ERROR;