*
 * Converting a String to a ByteArray proceeds by getting the Unicode
 * representation of each character in the String, casting it to a byte by
 * truncating the upper 8 bits, and then storing the byte in the ByteArray.
 * Converting from ByteArray to String and back to ByteArray is not lossy, but
 * converting an arbitrary String to a ByteArray may be.
 */

static const Tcl_ObjType properByteArrayType = {
    "proper bytearray",
    FreeByteArrayInternalRep,
    DupByteArrayInternalRep,
    UpdateStringOfByteArray,
    NULL
};

const Tcl_ObjType tclByteArrayType = {
    "bytearray",
    FreeByteArrayInternalRep,
    DupByteArrayInternalRep,
    NULL,
    SetByteArrayFromAny
};

/*
 * The following structure is the internal rep for a ByteArray object. Keeps
 * track of how much memory has been used and how much has been allocated for
 * the byte array to enable growing and shrinking of the ByteArray object with

#define BYTEARRAY_SIZE(len) \
		((unsigned) (TclOffset(ByteArray, bytes) + (len)))
#define GET_BYTEARRAY(objPtr) \
		((ByteArray *) (objPtr)->internalRep.twoPtrValue.ptr1)
#define SET_BYTEARRAY(objPtr, baPtr) \
		(objPtr)->internalRep.twoPtrValue.ptr1 = (void *) (baPtr)

int
TclIsPureByteArray(
    Tcl_Obj * objPtr)
{
    return (objPtr->typePtr == &properByteArrayType);
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_NewByteArrayObj --
 *
 *	This procedure is creates a new ByteArray object and initializes it

    byteArrayPtr = ckalloc(BYTEARRAY_SIZE(length));
    byteArrayPtr->used = length;
    byteArrayPtr->allocated = length;

    if ((bytes != NULL) && (length > 0)) {
	memcpy(byteArrayPtr->bytes, bytes, (size_t) length);
    }
    objPtr->typePtr = &properByteArrayType;
    SET_BYTEARRAY(objPtr, byteArrayPtr);
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_GetByteArrayFromObj --

Tcl_GetByteArrayFromObj(
    Tcl_Obj *objPtr,		/* The ByteArray object. */
    int *lengthPtr)		/* If non-NULL, filled with length of the
				 * array of bytes in the ByteArray object. */
{
    ByteArray *baPtr;

    if ((objPtr->typePtr != &properByteArrayType)
	    && (objPtr->typePtr != &tclByteArrayType)) {
	SetByteArrayFromAny(NULL, objPtr);
    }
    baPtr = GET_BYTEARRAY(objPtr);

    if (lengthPtr != NULL) {
	*lengthPtr = baPtr->used;
    }

    int length)			/* New length for internal byte array. */
{
    ByteArray *byteArrayPtr;

    if (Tcl_IsShared(objPtr)) {
	Tcl_Panic("%s called with shared object", "Tcl_SetByteArrayLength");
    }
    if ((objPtr->typePtr != &properByteArrayType)
	    && (objPtr->typePtr != &tclByteArrayType)) {
	SetByteArrayFromAny(NULL, objPtr);
    }

    byteArrayPtr = GET_BYTEARRAY(objPtr);
    if (length > byteArrayPtr->allocated) {
	byteArrayPtr = ckrealloc(byteArrayPtr, BYTEARRAY_SIZE(length));
	byteArrayPtr->allocated = length;

 */

static int
SetByteArrayFromAny(
    Tcl_Interp *interp,		/* Not used. */
    Tcl_Obj *objPtr)		/* The object to convert to type ByteArray. */
{
    int length, improper = 0;
    const char *src, *srcEnd;
    unsigned char *dst;
    ByteArray *byteArrayPtr;
    Tcl_UniChar ch;

    if (objPtr->typePtr == &properByteArrayType) {
	return TCL_OK;
    }
    if (objPtr->typePtr == &tclByteArrayType) {
	return TCL_OK;
    }

    src = TclGetStringFromObj(objPtr, &length);
    srcEnd = src + length;

    byteArrayPtr = ckalloc(BYTEARRAY_SIZE(length));
    for (dst = byteArrayPtr->bytes; src < srcEnd; ) {
	src += Tcl_UtfToUniChar(src, &ch);
	improper = improper || (ch > 255);
	*dst++ = UCHAR(ch);
    }

    byteArrayPtr->used = dst - byteArrayPtr->bytes;
    byteArrayPtr->allocated = length;

    TclFreeIntRep(objPtr);
    objPtr->typePtr = improper ? &tclByteArrayType : &properByteArrayType;
    SET_BYTEARRAY(objPtr, byteArrayPtr);

    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * FreeByteArrayInternalRep --

    copyArrayPtr = ckalloc(BYTEARRAY_SIZE(length));
    copyArrayPtr->used = length;
    copyArrayPtr->allocated = length;
    memcpy(copyArrayPtr->bytes, srcArrayPtr->bytes, (size_t) length);
    SET_BYTEARRAY(copyPtr, copyArrayPtr);

    copyPtr->typePtr = srcPtr->typePtr;
}

/*
 *----------------------------------------------------------------------
 *
 * UpdateStringOfByteArray --
 *

	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;
    }
    if ((objPtr->typePtr != &properByteArrayType)
	    && (objPtr->typePtr != &tclByteArrayType)) {
	SetByteArrayFromAny(NULL, objPtr);
    }
    byteArrayPtr = GET_BYTEARRAY(objPtr);

    if (len > INT_MAX - byteArrayPtr->used) {
	Tcl_Panic("max size for a Tcl value (%d bytes) exceeded", INT_MAX);
    }