/*
 * tclBinary.c --
 *
 *	This file contains the implementation of the "binary" Tcl built-in
 *	command and the Tcl binary data object.
 *
 * Copyright (c) 1997 by Sun Microsystems, Inc.
 * Copyright (c) 1998-1999 by Scriptics Corporation.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 * See the file "license.terms" for information on usage and redistribution of
 * this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * RCS: @(#) $Id: tclBinary.c,v 1.13.4.8 2005/07/26 04:11:52 dgp Exp $
 * RCS: @(#) $Id: tclBinary.c,v 1.13.4.9 2005/10/18 20:46:18 dgp Exp $
 */

#include "tclInt.h"

#include <math.h>

/*

/*
 * The following defines the maximum number of different (integer) numbers
 * placed in the object cache by 'binary scan' before it bails out and
 * switches back to Plan A (creating a new object for each value.)
 * Theoretically, it would be possible to keep the cache about for the values
 * that are already in it, but that makes the code slower in practise when
 * overflow happens, and makes little odds the rest of the time (as measured
 * on my machine.)  It is also slower (on the sample I tried at least) to grow
 * on my machine.) It is also slower (on the sample I tried at least) to grow
 * the cache to hold all items we might want to put in it; presumably the
 * extra cost of managing the memory for the enlarged table outweighs the
 * benefit from allocating fewer objects.  This is probably because as the
 * benefit from allocating fewer objects. This is probably because as the
 * number of objects increases, the likelihood of reuse of any particular one
 * drops, and there is very little gain from larger maximum cache sizes (the
 * value below is chosen to allow caching to work in full with conversion of
 * bytes.) - DKF
 */

#define BINARY_SCAN_MAX_CACHE	260

/*
 * Prototypes for local procedures defined in this file:
 */

static void		DupByteArrayInternalRep _ANSI_ARGS_((Tcl_Obj *srcPtr,
			    Tcl_Obj *copyPtr));
static int		FormatNumber _ANSI_ARGS_((Tcl_Interp *interp, int type,
			    Tcl_Obj *src, unsigned char **cursorPtr));
static void		FreeByteArrayInternalRep _ANSI_ARGS_((Tcl_Obj *objPtr));
static int		GetFormatSpec _ANSI_ARGS_((char **formatPtr,
			    char *cmdPtr, int *countPtr));
static Tcl_Obj *	ScanNumber _ANSI_ARGS_((unsigned char *buffer,
			    int type, Tcl_HashTable **numberCachePtr));
static int		SetByteArrayFromAny _ANSI_ARGS_((Tcl_Interp *interp,
			    Tcl_Obj *objPtr));
static void		UpdateStringOfByteArray _ANSI_ARGS_((Tcl_Obj *listPtr));
static void		DeleteScanNumberCache _ANSI_ARGS_((
static void		DupByteArrayInternalRep(Tcl_Obj *srcPtr,
			    Tcl_Obj *copyPtr);
static int		FormatNumber(Tcl_Interp *interp, int type,
			    Tcl_Obj *src, unsigned char **cursorPtr);
static void		FreeByteArrayInternalRep(Tcl_Obj *objPtr);
static int		GetFormatSpec(char **formatPtr, char *cmdPtr,
			    int *countPtr);
static Tcl_Obj *	ScanNumber(unsigned char *buffer, int type,
			    Tcl_HashTable **numberCachePtr);
static int		SetByteArrayFromAny(Tcl_Interp *interp,
			    Tcl_Obj *objPtr);
static void		UpdateStringOfByteArray(Tcl_Obj *listPtr);
static void		DeleteScanNumberCache(Tcl_HashTable *numberCachePtr);
			    Tcl_HashTable *numberCachePtr));
static int		NeedReversing _ANSI_ARGS_((int format));
static void		CopyNumber _ANSI_ARGS_((CONST void *from, void *to,
			    unsigned int length, int type));
static int		NeedReversing(int format);
static void		CopyNumber(CONST void *from, void *to,
			    unsigned int length, int type);

/*
 * The following object type represents an array of bytes.  An array of bytes
 * is not equivalent to an internationalized string.  Conceptually, a string
 * is an array of 16-bit quantities organized as a sequence of properly formed
 * The following object type represents an array of bytes. An array of bytes
 * is not equivalent to an internationalized string. Conceptually, a string is
 * an array of 16-bit quantities organized as a sequence of properly formed
 * UTF-8 characters, while a ByteArray is an array of 8-bit quantities.
 * Accessor functions are provided to convert a ByteArray to a String or a
 * String to a ByteArray.  Two or more consecutive bytes in an array of bytes
 * String to a ByteArray. Two or more consecutive bytes in an array of bytes
 * may look like a single UTF-8 character if the array is casually treated as
 * a string.  But obtaining the String from a ByteArray is guaranteed to
 * a string. But obtaining the String from a ByteArray is guaranteed to
 * produced properly formed UTF-8 sequences so that there is a one-to-one map
 * between bytes and characters.
 *
 * Converting a ByteArray to a String proceeds by casting each byte in the
 * array to a 16-bit quantity, treating that number as a Unicode character,
 * and storing the UTF-8 version of that Unicode character in the String.  For
 * and storing the UTF-8 version of that Unicode character in the String. For
 * ByteArrays consisting entirely of values 1..127, the corresponding String
 * representation is the same as the ByteArray representation.
 *
 * 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.
 */

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

/*
 * The following structure is the internal rep for a ByteArray object.  Keeps
 * 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
 * fewer mallocs.
 */

typedef struct ByteArray {
    int used;			/* The number of bytes used in the byte
				 * array. */
    int allocated;		/* The amount of space actually allocated
				 * minus 1 byte. */
    unsigned char bytes[4];	/* The array of bytes.  The actual size of
				 * this field depends on the 'allocated' field
    unsigned char bytes[4];	/* The array of bytes. The actual size of this
				 * field depends on the 'allocated' field
				 * above. */
} ByteArray;

#define BYTEARRAY_SIZE(len)	\
		((unsigned) (sizeof(ByteArray) - 4 + (len)))
#define GET_BYTEARRAY(objPtr) \
		((ByteArray *) (objPtr)->internalRep.otherValuePtr)
#define SET_BYTEARRAY(objPtr, baPtr) \
		(objPtr)->internalRep.otherValuePtr = (VOID *) (baPtr)


/*
 *----------------------------------------------------------------------
 *
 * Tcl_NewByteArrayObj --
 *
 *	This procedure is creates a new ByteArray object and initializes it
 *	from the given array of bytes.
 *
 * Results:
 *	The newly create object is returned.  This object will have no initial
 *	string representation.  The returned object has a ref count of 0.
 *	The newly create object is returned. This object will have no initial
 *	string representation. The returned object has a ref count of 0.
 *
 * Side effects:
 *	Memory allocated for new object and copy of byte array argument.
 *
 *----------------------------------------------------------------------
 */

#ifdef TCL_MEM_DEBUG
#undef Tcl_NewByteArrayObj

Tcl_Obj *
Tcl_NewByteArrayObj(bytes, length)
    CONST unsigned char *bytes;	/* The array of bytes used to initialize the
Tcl_NewByteArrayObj(
    CONST unsigned char *bytes,	/* The array of bytes used to initialize the
				 * new object. */
    int length;			/* Length of the array of bytes, which must be
    int length)			/* Length of the array of bytes, which must be
				 * >= 0. */
{
    return Tcl_DbNewByteArrayObj(bytes, length, "unknown", 0);
}

#else /* if not TCL_MEM_DEBUG */

Tcl_Obj *
Tcl_NewByteArrayObj(bytes, length)
    CONST unsigned char *bytes;	/* The array of bytes used to initialize the
Tcl_NewByteArrayObj(
    CONST unsigned char *bytes,	/* The array of bytes used to initialize the
				 * new object. */
    int length;			/* Length of the array of bytes, which must be
    int length)			/* Length of the array of bytes, which must be
				 * >= 0. */
{
    Tcl_Obj *objPtr;

    TclNewObj(objPtr);
    Tcl_SetByteArrayObj(objPtr, bytes, length);
    return objPtr;

 *	the [memory active] command will report the correct file name and line
 *	number when reporting objects that haven't been freed.
 *
 *	When TCL_MEM_DEBUG is not defined, this procedure just returns the
 *	result of calling Tcl_NewByteArrayObj.
 *
 * Results:
 *	The newly create object is returned.  This object will have no initial
 *	string representation.  The returned object has a ref count of 0.
 *	The newly create object is returned. This object will have no initial
 *	string representation. The returned object has a ref count of 0.
 *
 * Side effects:
 *	Memory allocated for new object and copy of byte array argument.
 *
 *----------------------------------------------------------------------
 */

#ifdef TCL_MEM_DEBUG

Tcl_Obj *
Tcl_DbNewByteArrayObj(bytes, length, file, line)
    CONST unsigned char *bytes;	/* The array of bytes used to initialize the
Tcl_DbNewByteArrayObj(
    CONST unsigned char *bytes,	/* The array of bytes used to initialize the
				 * new object. */
    int length;			/* Length of the array of bytes, which must be
    int length,			/* Length of the array of bytes, which must be
				 * >= 0. */
    CONST char *file;		/* The name of the source file calling this
    CONST char *file,		/* The name of the source file calling this
				 * procedure; used for debugging. */
    int line;			/* Line number in the source file; used for
    int line)			/* Line number in the source file; used for
				 * debugging. */
{
    Tcl_Obj *objPtr;

    TclDbNewObj(objPtr, file, line);
    Tcl_SetByteArrayObj(objPtr, bytes, length);
    return objPtr;
}

#else /* if not TCL_MEM_DEBUG */

Tcl_Obj *
Tcl_DbNewByteArrayObj(bytes, length, file, line)
    CONST unsigned char *bytes;	/* The array of bytes used to initialize the
Tcl_DbNewByteArrayObj(
    CONST unsigned char *bytes,	/* The array of bytes used to initialize the
				 * new object. */
    int length;			/* Length of the array of bytes, which must be
    int length,			/* Length of the array of bytes, which must be
				 * >= 0. */
    CONST char *file;		/* The name of the source file calling this
    CONST char *file,		/* The name of the source file calling this
				 * procedure; used for debugging. */
    int line;			/* Line number in the source file; used for
    int line)			/* Line number in the source file; used for
				 * debugging. */
{
    return Tcl_NewByteArrayObj(bytes, length);
}
#endif /* TCL_MEM_DEBUG */

/*
 *---------------------------------------------------------------------------
 *
 * Tcl_SetByteArrayObj --
 *
 *	Modify an object to be a ByteArray object and to have the specified
 *	array of bytes as its value.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The object's old string rep and internal rep is freed.  Memory
 *	The object's old string rep and internal rep is freed. Memory
 *	allocated for copy of byte array argument.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_SetByteArrayObj(objPtr, bytes, length)
    Tcl_Obj *objPtr;		/* Object to initialize as a ByteArray. */
    CONST unsigned char *bytes;	/* The array of bytes to use as the new
Tcl_SetByteArrayObj(
    Tcl_Obj *objPtr,		/* Object to initialize as a ByteArray. */
    CONST unsigned char *bytes,	/* The array of bytes to use as the new
				 * value. */
    int length;			/* Length of the array of bytes, which must be
    int length)			/* Length of the array of bytes, which must be
				 * >= 0. */
{
    ByteArray *byteArrayPtr;

    if (Tcl_IsShared(objPtr)) {
	Tcl_Panic("Tcl_SetByteArrayObj called with shared object");
    }

}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_GetByteArrayFromObj --
 *
 *	Attempt to get the array of bytes from the Tcl object.  If the object
 *	Attempt to get the array of bytes from the Tcl object. If the object
 *	is not already a ByteArray object, an attempt will be made to convert
 *	it to one.
 *
 * Results:
 *	Pointer to array of bytes representing the ByteArray object.
 *
 * Side effects:
 *	Frees old internal rep.  Allocates memory for new internal rep.
 *	Frees old internal rep. Allocates memory for new internal rep.
 *
 *----------------------------------------------------------------------
 */

unsigned char *
Tcl_GetByteArrayFromObj(objPtr, lengthPtr)
    Tcl_Obj *objPtr;		/* The ByteArray object. */
    int *lengthPtr;		/* If non-NULL, filled with length of the
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;

    SetByteArrayFromAny(NULL, objPtr);
    baPtr = GET_BYTEARRAY(objPtr);

 *	bytes are undefined. When shrinking, the old array is truncated to the
 *	specified length.
 *
 *----------------------------------------------------------------------
 */

unsigned char *
Tcl_SetByteArrayLength(objPtr, length)
    Tcl_Obj *objPtr;		/* The ByteArray object. */
    int length;			/* New length for internal byte array. */
Tcl_SetByteArrayLength(
    Tcl_Obj *objPtr,		/* The ByteArray object. */
    int length)			/* New length for internal byte array. */
{
    ByteArray *byteArrayPtr, *newByteArrayPtr;

    if (Tcl_IsShared(objPtr)) {
	Tcl_Panic("Tcl_SetObjLength called with shared object");
    }
    if (objPtr->typePtr != &tclByteArrayType) {

 * Side effects:
 *	A ByteArray object is stored as the internal rep of objPtr.
 *
 *----------------------------------------------------------------------
 */

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

 * Side effects:
 *	Frees memory.
 *
 *----------------------------------------------------------------------
 */

static void
FreeByteArrayInternalRep(objPtr)
    Tcl_Obj *objPtr;		/* Object with internal rep to free. */
FreeByteArrayInternalRep(
    Tcl_Obj *objPtr)		/* Object with internal rep to free. */
{
    ckfree((char *) GET_BYTEARRAY(objPtr));
}

/*
 *----------------------------------------------------------------------
 *

 * Side effects:
 *	Allocates memory.
 *
 *----------------------------------------------------------------------
 */

static void
DupByteArrayInternalRep(srcPtr, copyPtr)
    Tcl_Obj *srcPtr;		/* Object with internal rep to copy. */
    Tcl_Obj *copyPtr;		/* Object with internal rep to set. */
DupByteArrayInternalRep(
    Tcl_Obj *srcPtr,		/* Object with internal rep to copy. */
    Tcl_Obj *copyPtr)		/* Object with internal rep to set. */
{
    int length;
    ByteArray *srcArrayPtr, *copyArrayPtr;

    srcArrayPtr = GET_BYTEARRAY(srcPtr);
    length = srcArrayPtr->used;

 *	The object becomes a string object -- the internal rep is discarded
 *	and the typePtr becomes NULL.
 *
 *----------------------------------------------------------------------
 */

static void
UpdateStringOfByteArray(objPtr)
    Tcl_Obj *objPtr;		/* ByteArray object whose string rep to
UpdateStringOfByteArray(
    Tcl_Obj *objPtr)		/* ByteArray object whose string rep to
				 * update. */
{
    int i, length, size;
    unsigned char *src;
    char *dst;
    ByteArray *byteArrayPtr;

 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

int
Tcl_BinaryObjCmd(dummy, interp, objc, objv)
    ClientData dummy;		/* Not used. */
    Tcl_Interp *interp;		/* Current interpreter. */
    int objc;			/* Number of arguments. */
    Tcl_Obj *CONST objv[];	/* Argument objects. */
Tcl_BinaryObjCmd(
    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. */

    case BINARY_FORMAT:
	if (objc < 3) {
	    Tcl_WrongNumArgs(interp, 2, objv, "formatString ?arg arg ...?");
	    return TCL_ERROR;
	}

	/*
	 * 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
	 * 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 = Tcl_GetString(objv[2]);
	arg = 3;
	offset = 0;
	length = 0;

	 */

	resultPtr = Tcl_NewObj();
	buffer = Tcl_SetByteArrayLength(resultPtr, length);
	memset((VOID *) buffer, 0, (size_t) length);

	/*
	 * Pack the data into the result object.  Note that we can skip the
	 * 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 = Tcl_GetString(objv[2]);
	cursor = buffer;

		break;
	    }
	    case 'h':
	    case 'H': {
		char *dest;
		unsigned char *src;
		int i;
		static char hexdigit[] = "0123456789abcdef";
		static CONST char hexdigit[] = "0123456789abcdef";

		if (arg >= objc) {
		    DeleteScanNumberCache(numberCachePtr);
		    goto badIndex;
		}
		if (count == BINARY_ALL) {
		    count = (length - offset)*2;

 * GetFormatSpec --
 *
 *	This function parses the format strings used in the binary format and
 *	scan commands.
 *
 * Results:
 *	Moves the formatPtr to the start of the next command. Returns the
 *	current command character and count in cmdPtr and countPtr.  The count
 *	current command character and count in cmdPtr and countPtr. The count
 *	is set to BINARY_ALL if the count character was '*' or BINARY_NOCOUNT
 *	if no count was specified.  Returns 1 on success, or 0 if the string
 *	if no count was specified. Returns 1 on success, or 0 if the string
 *	did not have a format specifier.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

static int
GetFormatSpec(formatPtr, cmdPtr, countPtr)
    char **formatPtr;		/* Pointer to format string. */
    char *cmdPtr;		/* Pointer to location of command char. */
    int *countPtr;		/* Pointer to repeat count value. */
GetFormatSpec(
    char **formatPtr,		/* Pointer to format string. */
    char *cmdPtr,		/* Pointer to location of command char. */
    int *countPtr)		/* Pointer to repeat count value. */
{
    /*
     * Skip any leading blanks.
     */

    while (**formatPtr == ' ') {
	(*formatPtr)++;

 *----------------------------------------------------------------------
 *
 * NeedReversing --
 *
 *	This routine determines, if bytes of a number need to be reversed.
 *	This depends on the endiannes of the machine and the desired format.
 *	It is in effect a table (whose contents depend on the endianness of
 *	the system) describing whether a value needs reversing or not.  Anyone
 *	the system) describing whether a value needs reversing or not. Anyone
 *	porting the code to a big-endian platform should take care to make
 *	sure that they define WORDS_BIGENDIAN though this is already done by
 *	configure for the Unix build; little-endian platforms (including
 *	Windows) don't need to do anything.
 *
 * Results:
 *	1 if reversion is required, 0 if not.
 *
 * Side effects:
 *	None
 *
 *----------------------------------------------------------------------
 */

static int
NeedReversing(format)
    int format;
NeedReversing(
    int format)
{
    switch (format) {
	/* native floats and doubles: never reverse */
    case 'd':
    case 'f':
	/* big endian ints: never reverse */
    case 'I':


/*
 *----------------------------------------------------------------------
 *
 * CopyNumber --
 *
 *	This routine is called by FormatNumber and ScanNumber to copy a
 *	floating-point number.  If required, bytes are reversed while copying.
 *	floating-point number. If required, bytes are reversed while copying.
 *	The behaviour is only fully defined when used with IEEE float and
 *	double values (guaranteed to be 4 and 8 bytes long, respectively.)
 *
 * Results:
 *	None
 *
 * Side effects:
 *	Copies length bytes
 *
 *----------------------------------------------------------------------
 */

static void
CopyNumber(from, to, length, type)
    CONST void *from;		/* source */
    void *to;			/* destination */
    unsigned int length;	/* Number of bytes to copy */
    int type;			/* What type of thing are we copying? */
CopyNumber(
    CONST void *from,		/* source */
    void *to,			/* destination */
    unsigned int length,	/* Number of bytes to copy */
    int type)			/* What type of thing are we copying? */
{
    if (NeedReversing(type)) {
	CONST unsigned char *fromPtr = (CONST unsigned char *) from;
	unsigned char *toPtr = (unsigned char *) to;

	switch (length) {
	case 4:

 * Side effects:
 *	Moves the cursor to the next location to be written into.
 *
 *----------------------------------------------------------------------
 */

static int
FormatNumber(interp, type, src, cursorPtr)
    Tcl_Interp *interp;		/* Current interpreter, used to report
FormatNumber(
    Tcl_Interp *interp,		/* Current interpreter, used to report
				 * errors. */
    int type;			/* Type of number to format. */
    Tcl_Obj *src;		/* Number to format. */
    unsigned char **cursorPtr;	/* Pointer to index into destination buffer. */
    int type,			/* Type of number to format. */
    Tcl_Obj *src,		/* Number to format. */
    unsigned char **cursorPtr)	/* Pointer to index into destination buffer. */
{
    long value;
    double dvalue;
    Tcl_WideInt wvalue;
    float fvalue;

    switch (type) {
    case 'd':
    case 'q':
    case 'Q':
	/*
	 * Double-precision floating point values.  Tcl_GetDoubleFromObj
	 * Double-precision floating point values. Tcl_GetDoubleFromObj
	 * returns TCL_ERROR for NaN, but we can check by comparing the
	 * object's type pointer.
	 */

	if (Tcl_GetDoubleFromObj(interp, src, &dvalue) != TCL_OK) {
	    if ( src->typePtr != &tclDoubleType ) {
		return TCL_ERROR;
	    }
	    dvalue = src->internalRep.doubleValue;
	}
	CopyNumber(&dvalue, *cursorPtr, sizeof(double), type);
	*cursorPtr += sizeof(double);
	return TCL_OK;

    case 'f':
    case 'r':
    case 'R':
	/*
	 * Single-precision floating point values.  Tcl_GetDoubleFromObj
	 * Single-precision floating point values. Tcl_GetDoubleFromObj
	 * returns TCL_ERROR for NaN, but we can check by comparing the
	 * object's type pointer.
	 */

	if (Tcl_GetDoubleFromObj(interp, src, &dvalue) != TCL_OK) {
	    if ( src->typePtr != &tclDoubleType ) {
		return TCL_ERROR;

}

/*
 *----------------------------------------------------------------------
 *
 * ScanNumber --
 *
 *	This routine is called by Tcl_BinaryObjCmd to scan a number
 *	out of a buffer.
 *	This routine is called by Tcl_BinaryObjCmd to scan a number out of a
 *	buffer.
 *
 * Results:
 *	Returns a newly created object containing the scanned number.
 *	This object has a ref count of zero.
 *	Returns a newly created object containing the scanned number. This
 *	object has a ref count of zero.
 *
 * Side effects:
 *	Might reuse an object in the number cache, place a new object
 *	in the cache, or delete the cache and set the reference to
 *	it (itself passed in by reference) to NULL.
 *	Might reuse an object in the number cache, place a new object in the
 *	cache, or delete the cache and set the reference to it (itself passed
 *	in by reference) to NULL.
 *
 *----------------------------------------------------------------------
 */

static Tcl_Obj *
ScanNumber(buffer, type, numberCachePtrPtr)
    unsigned char *buffer;	/* Buffer to scan number from. */
    int type;			/* Format character from "binary scan" */
    Tcl_HashTable **numberCachePtrPtr;
ScanNumber(
    unsigned char *buffer,	/* Buffer to scan number from. */
    int type,			/* Format character from "binary scan" */
    Tcl_HashTable **numberCachePtrPtr)
				/* Place to look for cache of scanned
				 * value objects, or NULL if too many
				 * different numbers have been scanned. */
{
    long value;
    float fvalue;
    double dvalue;
    Tcl_WideUInt uwvalue;

    /*
     * We cannot rely on the compiler to properly sign extend integer values
     * when we cast from smaller values to larger values because we don't know
     * the exact size of the integer types.  So, we have to handle sign
     * the exact size of the integer types. So, we have to handle sign
     * extension explicitly by checking the high bit and padding with 1's as
     * needed.
     */

    switch (type) {
    case 'c':
	/*
	 * Characters need special handling.  We want to produce a signed
	 * Characters need special handling. We want to produce a signed
	 * result, but on some platforms (such as AIX) chars are unsigned. To
	 * deal with this, check for a value that should be negative but
	 * isn't.
	 */

	value = buffer[0];
	if (value & 0x80) {
	    value |= -0x100;
	}
	goto returnNumericObject;

	/*
	 * 16-bit numeric values.  We need the sign extension trick (see
	 * above) here as well.
	 * 16-bit numeric values. We need the sign extension trick (see above)
	 * here as well.
	 */

    case 's':
    case 'S':
    case 't':
	if (NeedReversing(type)) {
	    value = (long) (buffer[0] + (buffer[1] << 8));

	    int isNew;

	    hPtr = Tcl_CreateHashEntry(tablePtr, (char *)value, &isNew);
	    if (!isNew) {
		return (Tcl_Obj *) Tcl_GetHashValue(hPtr);
	    }
	    if (tablePtr->numEntries > BINARY_SCAN_MAX_CACHE) {

		/*
		 * We've overflowed the cache!  Someone's parsing a LOT of
		 * varied binary data in a single call!  Bail out by switching
		 * We've overflowed the cache! Someone's parsing a LOT of
		 * varied binary data in a single call! Bail out by switching
		 * back to the old behaviour for the rest of the scan.
		 *
		 * Note that anyone just using the 'c' conversion (for bytes)
		 * cannot trigger this.
		 */

		DeleteScanNumberCache(tablePtr);

 * Side effects:
 *	Decrements the reference counts of the objects in the cache.
 *
 *----------------------------------------------------------------------
 */

static void
DeleteScanNumberCache(numberCachePtr)
    Tcl_HashTable *numberCachePtr;	/* Pointer to the hash table, or NULL
					 * (when the cache has already been
					 * deleted due to overflow.) */
DeleteScanNumberCache(
    Tcl_HashTable *numberCachePtr)
				/* Pointer to the hash table, or NULL (when
				 * the cache has already been deleted due to
				 * overflow.) */
{
    Tcl_HashEntry *hEntry;
    Tcl_HashSearch search;

    if (numberCachePtr == NULL) {
	return;
    }