Initial revision

1 files changed, 1013 insertions, 0 deletions

diff --git a/generic/tclBinary.c b/generic/tclBinary.c
new file mode 100644
index 0000000..e15fe4c
--- /dev/null
+++ b/generic/tclBinary.c
@@ -0,0 +1,1013 @@
+/* 
+ * tclBinary.c --
+ *
+ *	This file contains the implementation of the "binary" Tcl built-in
+ *	command .
+ *
+ * Copyright (c) 1997 by Sun Microsystems, Inc.
+ *
+ * See the file "license.terms" for information on usage and redistribution
+ * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
+ *
+ * SCCS: @(#) tclBinary.c 1.26 97/11/05 13:02:05
+ */
+
+#include <math.h>
+#include "tclInt.h"
+#include "tclPort.h"
+
+/*
+ * The following constants are used by GetFormatSpec to indicate various
+ * special conditions in the parsing of a format specifier.
+ */
+
+#define BINARY_ALL -1		/* Use all elements in the argument. */
+#define BINARY_NOCOUNT -2	/* No count was specified in format. */
+
+/*
+ * Prototypes for local procedures defined in this file:
+ */
+
+static int		GetFormatSpec _ANSI_ARGS_((char **formatPtr,
+			    char *cmdPtr, int *countPtr));
+static int		FormatNumber _ANSI_ARGS_((Tcl_Interp *interp, int type,
+			    Tcl_Obj *src, char **cursorPtr));
+static Tcl_Obj *	ScanNumber _ANSI_ARGS_((char *buffer, int type));
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_BinaryObjCmd --
+ *
+ *	This procedure implements the "binary" Tcl command.
+ *
+ * Results:
+ *	A standard Tcl result.
+ *
+ * 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. */
+{
+    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. */
+    char *format;		/* Pointer to current position in format
+				 * string. */
+    char *cursor;		/* Current position within result buffer. */
+    char *maxPos;		/* Greatest position within result buffer that
+				 * cursor has visited.*/
+    char *buffer;		/* Start of data buffer. */
+    char *errorString, *errorValue, *str;
+    int offset, size, length;
+    Tcl_Obj *resultPtr;
+    
+    static char *subCmds[] = { "format", "scan", (char *) NULL };
+    enum { BinaryFormat, BinaryScan } index;
+
+    if (objc < 2) {
+    	Tcl_WrongNumArgs(interp, 1, objv, "option ?arg arg ...?");
+	return TCL_ERROR;
+    }
+
+    if (Tcl_GetIndexFromObj(interp, objv[1], subCmds, "option", 0,
+	    (int *) &index) != TCL_OK) {
+    	return TCL_ERROR;
+    }
+
+    switch (index) {
+	case BinaryFormat:
+	    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 places the formatted data into the buffer.
+	     */
+
+	    format = Tcl_GetStringFromObj(objv[2], NULL);
+	    arg = 3;
+	    offset = length = 0;
+	    while (*format != 0) {
+		if (!GetFormatSpec(&format, &cmd, &count)) {
+		    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 characters in a single argument.
+			 */
+
+			if (arg >= objc) {
+			    goto badIndex;
+			}
+			if (count == BINARY_ALL) {
+			    (void)Tcl_GetStringFromObj(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 's':
+		    case 'S':
+			size = 2;
+			goto doNumbers;
+		    case 'i':
+		    case 'I':
+			size = 4;
+			goto doNumbers;
+		    case 'f':
+			size = sizeof(float);
+			goto doNumbers;
+		    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;
+			    if (Tcl_ListObjGetElements(interp, objv[arg++],
+				    &listc, &listv) != TCL_OK) {
+				return TCL_ERROR;
+			    }
+			    if (count == BINARY_ALL) {
+				count = listc;
+			    } else if (count > listc) {
+				errorString = "number of elements in list does not match count";
+				goto error;
+			    }
+			}
+			offset += count*size;
+			break;
+			
+		    case 'x':
+			if (count == BINARY_ALL) {
+			    errorString = "cannot use \"*\" in format string with \"x\"";
+			    goto 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: {
+			char buf[2];
+			
+			Tcl_ResetResult(interp);
+			buf[0] = cmd;
+			buf[1] = '\0';
+			Tcl_AppendStringsToObj(Tcl_GetObjResult(interp),
+				"bad field specifier \"", buf, "\"", NULL);
+			return TCL_ERROR;
+		    }
+		}
+	    }
+	    if (offset > length) {
+		length = offset;
+	    }
+	    if (length == 0) {
+		return TCL_OK;
+	    }
+
+	    /*
+	     * Prepare the result object by preallocating the caclulated
+	     * number of bytes and filling with nulls.
+	     */
+
+	    resultPtr = Tcl_GetObjResult(interp);
+	    Tcl_SetObjLength(resultPtr, length);
+	    buffer = Tcl_GetStringFromObj(resultPtr, NULL);
+	    memset(buffer, 0, (size_t) length);
+
+	    /*
+	     * 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_GetStringFromObj(objv[2], NULL);
+	    cursor = buffer;
+	    maxPos = cursor;
+	    while (*format != 0) {
+		if (!GetFormatSpec(&format, &cmd, &count)) {
+		    break;
+		}
+		if ((count == 0) && (cmd != '@')) {
+		    arg++;
+		    continue;
+		}
+		switch (cmd) {
+		    case 'a':
+		    case 'A': {
+			char pad = (char) (cmd == 'a' ? '\0' : ' ');
+
+			str = Tcl_GetStringFromObj(objv[arg++], &length);
+
+			if (count == BINARY_ALL) {
+			    count = length;
+			} else if (count == BINARY_NOCOUNT) {
+			    count = 1;
+			}
+			if (length >= count) {
+			    memcpy((VOID *) cursor, (VOID *) str,
+				    (size_t) count);
+			} else {
+			    memcpy((VOID *) cursor, (VOID *) str,
+				    (size_t) length);
+			    memset(cursor+length, pad,
+			            (size_t) (count - length));
+			}
+			cursor += count;
+			break;
+		    }
+		    case 'b':
+		    case 'B': {
+			char *last;
+			
+			str = Tcl_GetStringFromObj(objv[arg++], &length);
+			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;
+				    goto badValue;
+				}
+				if (((offset + 1) % 8) == 0) {
+				    *cursor++ = (char)(value & 0xff);
+				    value = 0;
+				}
+			    }
+			} else {
+			    for (offset = 0; offset < count; offset++) {
+				value >>= 1;
+				if (str[offset] == '1') {
+				    value |= 128;
+				} else if (str[offset] != '0') {
+				    errorValue = str;
+				    goto badValue;
+				}
+				if (!((offset + 1) % 8)) {
+				    *cursor++ = (char)(value & 0xff);
+				    value = 0;
+				}
+			    }
+			}
+			if ((offset % 8) != 0) {
+			    if (cmd == 'B') {
+				value <<= 8 - (offset % 8);
+			    } else {
+				value >>= 8 - (offset % 8);
+			    }
+			    *cursor++ = (char)(value & 0xff);
+			}
+			while (cursor < last) {
+			    *cursor++ = '\0';
+			}
+			break;
+		    }
+		    case 'h':
+		    case 'H': {
+			char *last;
+			int c;
+			
+			str = Tcl_GetStringFromObj(objv[arg++], &length);
+			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;
+				c = tolower(((unsigned char *) str)[offset]);
+				if ((c >= 'a') && (c <= 'f')) {
+				    value |= ((c - 'a' + 10) & 0xf);
+				} else if ((c >= '0') && (c <= '9')) {
+				    value |= (c - '0') & 0xf;
+				} else {
+				    errorValue = str;
+				    goto badValue;
+				}
+				if (offset % 2) {
+				    *cursor++ = (char) value;
+				    value = 0;
+				}
+			    }
+			} else {
+			    for (offset = 0; offset < count; offset++) {
+				value >>= 4;
+				c = tolower(((unsigned char *) str)[offset]);
+				if ((c >= 'a') && (c <= 'f')) {
+				    value |= ((c - 'a' + 10) << 4) & 0xf0;
+				} else if ((c >= '0') && (c <= '9')) {
+				    value |= ((c - '0') << 4) & 0xf0;
+				} else {
+				    errorValue = str;
+				    goto badValue;
+				}
+				if (offset % 2) {
+				    *cursor++ = (char)(value & 0xff);
+				    value = 0;
+				}
+			    }
+			}
+			if (offset % 2) {
+			    if (cmd == 'H') {
+				value <<= 4;
+			    } else {
+				value >>= 4;
+			    }
+			    *cursor++ = (char) value;
+			}
+
+			while (cursor < last) {
+			    *cursor++ = '\0';
+			}
+			break;
+		    }
+		    case 'c':
+		    case 's':
+		    case 'S':
+		    case 'i':
+		    case 'I':
+		    case 'd':
+		    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 {
+			    Tcl_ListObjGetElements(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) {
+				return TCL_ERROR;
+			    }
+			}
+			break;
+		    }
+		    case 'x':
+			if (count == BINARY_NOCOUNT) {
+			    count = 1;
+			}
+			memset(cursor, 0, (size_t) 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;
+		}
+	    }
+	    break;
+	
+	case BinaryScan: {
+	    int i;
+	    Tcl_Obj *valuePtr, *elementPtr;
+
+	    if (objc < 4) {
+		Tcl_WrongNumArgs(interp, 2, objv,
+			"value formatString ?varName varName ...?");
+		return TCL_ERROR;
+	    }
+	    buffer = Tcl_GetStringFromObj(objv[2], &length);
+	    format = Tcl_GetStringFromObj(objv[3], NULL);
+	    cursor = buffer;
+	    arg = 4;
+	    offset = 0;
+	    while (*format != 0) {
+		if (!GetFormatSpec(&format, &cmd, &count)) {
+		    goto done;
+		}
+		switch (cmd) {
+		    case 'a':
+		    case 'A':
+			if (arg >= objc) {
+			    goto badIndex;
+			}
+			if (count == BINARY_ALL) {
+			    count = length - offset;
+			} else {
+			    if (count == BINARY_NOCOUNT) {
+				count = 1;
+			    }
+			    if (count > (length - offset)) {
+				goto done;
+			    }
+			}
+
+			str = buffer + offset;
+			size = count;
+
+			/*
+			 * Trim trailing nulls and spaces, if necessary.
+			 */
+
+			if (cmd == 'A') {
+			    while (size > 0) {
+				if (str[size-1] != '\0' && str[size-1] != ' ') {
+				    break;
+				}
+				size--;
+			    }
+			}
+			valuePtr = Tcl_NewStringObj(str, size);
+			resultPtr = Tcl_ObjSetVar2(interp, objv[arg++], NULL,
+				valuePtr,
+				TCL_LEAVE_ERR_MSG | TCL_PARSE_PART1);
+			if (resultPtr == NULL) {
+			    Tcl_DecrRefCount(valuePtr);	/* unneeded */
+			    return TCL_ERROR;
+			}
+			offset += count;
+			break;
+		    case 'b':
+		    case 'B': {
+			char *dest;
+
+			if (arg >= objc) {
+			    goto badIndex;
+			}
+			if (count == BINARY_ALL) {
+			    count = (length - offset)*8;
+			} else {
+			    if (count == BINARY_NOCOUNT) {
+				count = 1;
+			    }
+			    if (count > (length - offset)*8) {
+				goto done;
+			    }
+			}
+			str = buffer + offset;
+			valuePtr = Tcl_NewObj();
+			Tcl_SetObjLength(valuePtr, count);
+			dest = Tcl_GetStringFromObj(valuePtr, NULL);
+
+			if (cmd == 'b') {
+			    for (i = 0; i < count; i++) {
+				if (i % 8) {
+				    value >>= 1;
+				} else {
+				    value = *str++;
+				}
+				*dest++ = (char) ((value & 1) ? '1' : '0');
+			    }
+			} else {
+			    for (i = 0; i < count; i++) {
+				if (i % 8) {
+				    value <<= 1;
+				} else {
+				    value = *str++;
+				}
+				*dest++ = (char) ((value & 0x80) ? '1' : '0');
+			    }
+			}
+			
+			resultPtr = Tcl_ObjSetVar2(interp, objv[arg++], NULL,
+				valuePtr,
+				TCL_LEAVE_ERR_MSG | TCL_PARSE_PART1);
+			if (resultPtr == NULL) {
+			    Tcl_DecrRefCount(valuePtr);	/* unneeded */
+			    return TCL_ERROR;
+			}
+			offset += (count + 7 ) / 8;
+			break;
+		    }
+		    case 'h':
+		    case 'H': {
+			char *dest;
+			int i;
+			static char hexdigit[] = "0123456789abcdef";
+
+			if (arg >= objc) {
+			    goto badIndex;
+			}
+			if (count == BINARY_ALL) {
+			    count = (length - offset)*2;
+			} else {
+			    if (count == BINARY_NOCOUNT) {
+				count = 1;
+			    }
+			    if (count > (length - offset)*2) {
+				goto done;
+			    }
+			}
+			str = buffer + offset;
+			valuePtr = Tcl_NewObj();
+			Tcl_SetObjLength(valuePtr, count);
+			dest = Tcl_GetStringFromObj(valuePtr, NULL);
+
+			if (cmd == 'h') {
+			    for (i = 0; i < count; i++) {
+				if (i % 2) {
+				    value >>= 4;
+				} else {
+				    value = *str++;
+				}
+				*dest++ = hexdigit[value & 0xf];
+			    }
+			} else {
+			    for (i = 0; i < count; i++) {
+				if (i % 2) {
+				    value <<= 4;
+				} else {
+				    value = *str++;
+				}
+				*dest++ = hexdigit[(value >> 4) & 0xf];
+			    }
+			}
+			
+			resultPtr = Tcl_ObjSetVar2(interp, objv[arg++], NULL,
+				valuePtr,
+				TCL_LEAVE_ERR_MSG | TCL_PARSE_PART1);
+			if (resultPtr == NULL) {
+			    Tcl_DecrRefCount(valuePtr);	/* unneeded */
+			    return TCL_ERROR;
+			}
+			offset += (count + 1) / 2;
+			break;
+		    }
+		    case 'c':
+			size = 1;
+			goto scanNumber;
+		    case 's':
+		    case 'S':
+			size = 2;
+			goto scanNumber;
+		    case 'i':
+		    case 'I':
+			size = 4;
+			goto scanNumber;
+		    case 'f':
+			size = sizeof(float);
+			goto scanNumber;
+		    case 'd':
+			size = sizeof(double);
+			/* fall through */
+		    scanNumber:
+			if (arg >= objc) {
+			    goto badIndex;
+			}
+			if (count == BINARY_NOCOUNT) {
+			    if ((length - offset) < size) {
+				goto done;
+			    }
+			    valuePtr = ScanNumber(buffer+offset, cmd);
+			    offset += size;
+			} else {
+			    if (count == BINARY_ALL) {
+				count = (length - offset) / size;
+			    }
+			    if ((length - offset) < (count * size)) {
+				goto done;
+			    }
+			    valuePtr = Tcl_NewObj();
+			    str = buffer+offset;
+			    for (i = 0; i < count; i++) {
+				elementPtr = ScanNumber(str, cmd);
+				str += size;
+				Tcl_ListObjAppendElement(NULL, valuePtr,
+					elementPtr);
+			    }
+			    offset += count*size;
+			}
+
+			resultPtr = Tcl_ObjSetVar2(interp, objv[arg++], NULL,
+				valuePtr,
+				TCL_LEAVE_ERR_MSG | TCL_PARSE_PART1);
+			if (resultPtr == NULL) {
+			    Tcl_DecrRefCount(valuePtr);	/* unneeded */
+			    return TCL_ERROR;
+			}
+			break;
+		    case 'x':
+			if (count == BINARY_NOCOUNT) {
+			    count = 1;
+			}
+			if ((count == BINARY_ALL)
+				|| (count > (length - offset))) {
+			    offset = length;
+			} else {
+			    offset += count;
+			}
+			break;
+		    case 'X':
+			if (count == BINARY_NOCOUNT) {
+			    count = 1;
+			}
+			if ((count == BINARY_ALL) || (count > offset)) {
+			    offset = 0;
+			} else {
+			    offset -= count;
+			}
+			break;
+		    case '@':
+			if (count == BINARY_NOCOUNT) {
+			    goto badCount;
+			}
+			if ((count == BINARY_ALL) || (count > length)) {
+			    offset = length;
+			} else {
+			    offset = count;
+			}
+			break;
+		    default: {
+			char buf[2];
+			
+			Tcl_ResetResult(interp);
+			buf[0] = cmd;
+			buf[1] = '\0';
+			Tcl_AppendStringsToObj(Tcl_GetObjResult(interp),
+				"bad field specifier \"", buf, "\"", NULL);
+			return TCL_ERROR;
+		    }
+		}
+	    }
+
+	    /*
+	     * Set the result to the last position of the cursor.
+	     */
+
+	    done:
+	    Tcl_ResetResult(interp);
+	    Tcl_SetLongObj(Tcl_GetObjResult(interp), arg - 4);
+	    break;
+	}
+    }
+    return TCL_OK;
+
+    badValue:
+    Tcl_ResetResult(interp);
+    Tcl_AppendStringsToObj(Tcl_GetObjResult(interp), "expected ", errorString,
+	    " string but got \"", errorValue, "\" instead", NULL);
+    return TCL_ERROR;
+
+    badCount:
+    errorString = "missing count for \"@\" field specifier";
+    goto error;
+
+    badIndex:
+    errorString = "not enough arguments for all format specifiers";
+    goto error;
+
+    error:
+    Tcl_ResetResult(interp);
+    Tcl_AppendToObj(Tcl_GetObjResult(interp), errorString, -1);
+    return TCL_ERROR;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * 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 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 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. */
+{
+    /*
+     * Skip any leading blanks.
+     */
+
+    while (**formatPtr == ' ') {
+	(*formatPtr)++;
+    }
+
+    /*
+     * The string was empty, except for whitespace, so fail.
+     */
+
+    if (!(**formatPtr)) {
+	return 0;
+    }
+
+    /*
+     * Extract the command character and any trailing digits or '*'.
+     */
+
+    *cmdPtr = **formatPtr;
+    (*formatPtr)++;
+    if (**formatPtr == '*') {
+	(*formatPtr)++;
+	(*countPtr) = BINARY_ALL;
+    } else if (isdigit(**formatPtr)) {
+	(*countPtr) = strtoul(*formatPtr, formatPtr, 10);
+    } else {
+	(*countPtr) = BINARY_NOCOUNT;
+    }
+    return 1;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * FormatNumber --
+ *
+ *	This routine is called by Tcl_BinaryObjCmd to format a number
+ *	into a location pointed at by cursor.
+ *
+ * Results:
+ *	 A standard Tcl result.
+ *
+ * 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
+				 * errors. */
+    int type;			/* Type of number to format. */
+    Tcl_Obj *src;		/* Number to format. */
+    char **cursorPtr;		/* Pointer to index into destination buffer. */
+{
+    int value;
+    double dvalue;
+    char cmd = (char)type;
+
+    if (cmd == 'd' || cmd == 'f') {
+	/*
+	 * For floating point types, we need to copy the data using
+	 * memcpy to avoid alignment issues.
+	 */
+
+	if (Tcl_GetDoubleFromObj(interp, src, &dvalue) != TCL_OK) {
+	    return TCL_ERROR;
+	}
+	if (cmd == 'd') {
+	    memcpy((*cursorPtr), &dvalue, sizeof(double));
+	    (*cursorPtr) += sizeof(double);
+	} else {
+	    float fvalue;
+
+	    /*
+	     * Because some compilers will generate floating point exceptions
+	     * on an overflow cast (e.g. Borland), we restrict the values
+	     * to the valid range for float.
+	     */
+
+	    if (fabs(dvalue) > (double)FLT_MAX) {
+		fvalue = (dvalue >= 0.0) ? FLT_MAX : -FLT_MAX;
+	    } else {
+		fvalue = (float) dvalue;
+	    }
+	    memcpy((*cursorPtr), &fvalue, sizeof(float));
+	    (*cursorPtr) += sizeof(float);
+	}
+    } else {
+	if (Tcl_GetIntFromObj(interp, src, &value) != TCL_OK) {
+	    return TCL_ERROR;
+	}
+	if (cmd == 'c') {
+	    *(*cursorPtr)++ = (char)(value & 0xff);
+	} else if (cmd == 's') {
+	    *(*cursorPtr)++ = (char)(value & 0xff);
+	    *(*cursorPtr)++ = (char)((value >> 8) & 0xff);
+	} else if (cmd == 'S') {
+	    *(*cursorPtr)++ = (char)((value >> 8) & 0xff);
+	    *(*cursorPtr)++ = (char)(value & 0xff);
+	} else if (cmd == 'i') {
+	    *(*cursorPtr)++ = (char)(value & 0xff);
+	    *(*cursorPtr)++ = (char)((value >> 8) & 0xff);
+	    *(*cursorPtr)++ = (char)((value >> 16) & 0xff);
+	    *(*cursorPtr)++ = (char)((value >> 24) & 0xff);
+	} else if (cmd == 'I') {
+	    *(*cursorPtr)++ = (char)((value >> 24) & 0xff);
+	    *(*cursorPtr)++ = (char)((value >> 16) & 0xff);
+	    *(*cursorPtr)++ = (char)((value >> 8) & 0xff);
+	    *(*cursorPtr)++ = (char)(value & 0xff);
+	}
+    }
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * ScanNumber --
+ *
+ *	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.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static Tcl_Obj *
+ScanNumber(buffer, type)
+    char *buffer;		/* Buffer to scan number from. */
+    int type;			/* Format character from "binary scan" */
+{
+    int value;
+
+    /*
+     * 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
+     * extension explicitly by checking the high bit and padding with 1's as
+     * needed.
+     */
+
+    switch ((char) type) {
+	case 'c':
+	    value = buffer[0];
+
+	    if (value & 0x80) {
+		value |= -0x100;
+	    }
+	    return Tcl_NewLongObj((long)value);
+	case 's':
+	    value = (((unsigned char)buffer[0])
+		    + ((unsigned char)buffer[1] << 8));
+	    goto shortValue;
+	case 'S':
+	    value = (((unsigned char)buffer[1])
+		    + ((unsigned char)buffer[0] << 8));
+	    shortValue:
+	    if (value & 0x8000) {
+		value |= -0x10000;
+	    }
+	    return Tcl_NewLongObj((long)value);
+	case 'i':
+	    value =  (((unsigned char)buffer[0])
+		    + ((unsigned char)buffer[1] << 8)
+		    + ((unsigned char)buffer[2] << 16)
+		    + ((unsigned char)buffer[3] << 24));
+	    goto intValue;
+	case 'I':
+	    value = (((unsigned char)buffer[3])
+		    + ((unsigned char)buffer[2] << 8)
+		    + ((unsigned char)buffer[1] << 16)
+		    + ((unsigned char)buffer[0] << 24));
+	    intValue:
+	    /*
+	     * Check to see if the value was sign extended properly on
+	     * systems where an int is more than 32-bits.
+	     */
+
+	    if ((value & (((unsigned int)1)<<31)) && (value > 0)) {
+		value -= (((unsigned int)1)<<31);
+		value -= (((unsigned int)1)<<31);
+	    }
+		
+	    return Tcl_NewLongObj((long)value);
+	case 'f': {
+	    float fvalue;
+	    memcpy(&fvalue, buffer, sizeof(float));
+	    return Tcl_NewDoubleObj(fvalue);
+	}
+	case 'd': {
+	    double dvalue;
+	    memcpy(&dvalue, buffer, sizeof(double));
+	    return Tcl_NewDoubleObj(dvalue);
+	}
+    }
+    return NULL;
+}