length = byteArrayPtr->used;

    /*
     * How much space will string rep need?
     */

    size = length;
    for (i = 0; (i < length) && (size != (size_t)-1); i++) {
    for (i = 0; (i < length) && (size != TCL_AUTO_LENGTH); i++) {
	if ((src[i] == 0) || (src[i] > 127)) {
	    size++;
	}
    }
    if (size == (size_t)-1) {
    if (size == TCL_AUTO_LENGTH) {
	Tcl_Panic("max size for a Tcl value exceeded");
    }

    dst = Tcl_Alloc(size + 1);
    objPtr->bytes = dst;
    objPtr->length = size;

{
    ByteArray *byteArrayPtr;
    size_t needed;

    if (Tcl_IsShared(objPtr)) {
	Tcl_Panic("%s called with shared object","TclAppendBytesToByteArray");
    }
    if (len == (size_t)-1) {
    if (len == TCL_AUTO_LENGTH) {
	Tcl_Panic("%s must be called with definite number of bytes to append",
		"TclAppendBytesToByteArray");
    }
    if (len == 0) {
	/* Append zero bytes is a no-op. */
	return;
    }