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Sep 93 Challenge
Volume Number:9
Issue Number:9
Column Tag:Programmers’ Challenge

Programmers’ Challenge

By Mike Scanlin, MacTech Magazine Regular Contributing Author

Note: Source code files accompanying article are located on MacTech CD-ROM or source code disks.

BLOCKMOVEBITS

Because I’ve had several requests for it and because I’ve wanted to do it for a while and because this column is primarily about about efficient coding and because the lazy days of summer are over and it’s time to get serious, I’m happy to say that September will from now on be the annual MacTech Assembly Language Programmer’s Challenge. When submitting entries to September challenges you may use as much in-line 68040 assembly source inside of a Think C function as you like. In fact, a C wrapper around a 100% assembly language solution is allowed (and preferred). You should optimize for the 040 cause that’s what I’ll run the time tests on (and your code can require an 020, 030 and/or 040 if it wants to). You must preserve all registers except A0-A1/D0-D2. OK. Let’s get to it.

This first assembly language challenge is to move a block of contiguous bits when given the number of bits to move along with source and destination byte and bit offsets (the source and destination bit ranges do not overlap). This could be used, for example, inside a bit-blitting graphics routine that’s working with bitMaps.

The prototype of the function you write is:

void BlockMoveBits(srcBytePtr, 
 destBytePtr, srcBitOffset, 
 destBitOffset, bitCount)
char    *srcBytePtr;
char    *destBytePtr;
unsigned char    srcBitOffset;
unsigned char    destBitOffset;
unsigned short bitCount;

The srcBytePtr and destBytePtr point to the bytes containing the first source bit and first destination bit. The actual bits are at bit offsets srcBitOffset and destBitOffset (both of which will be less than 8). The most number of bits you can move at one time with this routine is 2^16 - 1 or 65535 (it’s possible that bitCount will be zero, which means you should move zero bits, not 64K bits). You should not disturb any of the bits in the destination bytes that aren’t part of the move.

Here’s an example. Say srcBitOffset is 2, destBitOffset is 5 and bitCount is 10. You have the following before the move (‘s’ is a source bit, ‘d’ is a destination bit and the ‘S’ bits (capital S) are going to be copied:

bit position : 76543210 76543210
srcBytePtr  -> ssSSSSSS SSSSssss
destBytePtr -> dddddddd dddddddd

and you have this after the move:

bit position : 76543210 76543210
srcBytePtr  -> ssSSSSSS SSSSssss
destBytePtr -> dddddSSS SSSSSSSd

It’s very likely that your implementation will have this shell:

void BlockMoveBits(srcBytePtr, 
 destBytePtr, srcBitOffset, 
 destBitOffset, bitCount)
char    *srcBytePtr;
char    *destBytePtr;
unsigned char    srcBitOffset;
unsigned char    destBitOffset;
unsigned short bitCount;
{
 asm {
 ;get parameters into registers
 Move.L srcBytePtr,A0
 Move.L destBytePtr,A1
 ... and so on
 }
}

Please note that because of the increased level of difficulty of reading assembly compared to C, it is very important that your code contains at least a few comments explaining what’s going on. I don’t want to see 200 lines of blazingly fast completely undocumented code. That won’t be of much use to anyone. And use meaningful labels where you can (rather than randomly ordered numeric ones from @258 to @431 or whatever).

TWO MONTHS AGO WINNER

I guess I scared away too many people with my “don’t use MoveWindow or SizeWindow” suggestion in the Tile Windows challenge because I only received three entries this month. However, all three entrants managed to find ways around using those traps and their times were very close to each other (and all three were at least an order of magnitude faster than the MoveWindow/SizeWindow equivalent). Congrats to Raffi Kasparian (Baltimore, MD) for being somewhat faster than the other guys. Raffi’s performance gain comes from manipulating some of the window’s fields directly, which is less than ideal in terms of future compatibility but it works on today’s machines so I’ll let it stand.

Here are the times (for tiling 80 windows) and sizes:

Name bytes ticks

Raffi Kasparian 716 81

Jordan Zimmerman 948 123

Ken Franklin/Michael Staw 806 126

Note that tiling 80 windows in 2 seconds (120 ticks) or less is quite fast. MPW, for comparison, took 10 seconds to tile 20 windows (and I found out that the “New” menu item becomes disabled after you create 45 Untitled windows).

The key to winning this challenge was to make use of the routines MovePortTo, PortSize, PaintBehind and CalcVisBehind. If you do it right then you can have the entire desktop (spread over multiple devices) updated with all the new windows blinking into place with a single call to PaintBehind. It’s really interesting to trap on PaintBehind in a debugger and then to step over that one trap and watch the whole desktop get rearranged (after all ports have been positioned and sized correctly, of course).

Since the winning solution does things in a less than future compatible way (it doesn’t call the window’s defProc to calculate the new regions, for instance) and since my goal with this challenge was to release a generic, efficient window tiling and stacking mechanism into the world, I’ve included some of my own code after Raffi’s.

If you think about minimal screen updating, which parts of the desktop need to be invalidated by rearranging the windows? The answer is the sum of the strucRgns in the windows’ old positions and the sum of the strucRgns in the windows’ new positions. No other area on the screen needs to be invalidated or redrawn. Therefore, my routine keeps track of the sum of these two sets of regions as it works. The resulting region, sumOfStructRgns, is then used as the clobberedRgn parameter to PaintBehind and CalcVisBehind. Any desktop pixel or background app pixel not in this region is not redrawn (i.e. there is no unnecessary flicker).

My routine, TileStackWindows, takes a function pointer parameter to a proc you write that does something with a list of windows inside a given rectangle (the function callback is similar to the challenge’s TileWindows function). This callback is called once per device, with the device’s gdRect given as the rect (inset a few pixels) and the list of windows set to all windows that are more on that device than on any other device. Thus, TileStackWindows is a generic, per-device window rearranging routine. All you have to do is come up with interesting tiling algorithms and bake them into the proc you pass to TileStackWindows. The efficient updating of the desktop and region maintenance is taken care of for you.

There are a couple of restrictions for the callback. First, it must resize a window before it repositions a window. Second, it must call MySizeWindow and MyMoveWindow instead of SizeWindow and MoveWindow. The callback should return TRUE if it moved or sized at least one window and FALSE if it did nothing. The reason for this is because if you have a Tile Windows menu item in your application and the user chooses it twice in a row, it is nice if the second time it is chosen the code is smart enough to see that things are already as they should be and does not cause any flickering or redrawing to take place.

An example callback function, StackWindows, is given here. It takes advantage of the fact that the list of windows it is passed is in order from the frontmost window to the backmost window (for that device). The last window in the list (the backmost) ends up being the largest window after the set has been stacked and the frontmost window (first in the list) ends up being the smallest window after the set has been stacked. It is done this way so that you can read all window titles after they’ve been stacked.

If you want to do tiling rather than stacking, all you have to do is replace StackWindows with your own TileWindows function and come up with a way to calculate each window’s new size and position. Hopefully application writers who have tiling and stacking options within their programs (including MPW) will implement this type of a scheme so that we no longer have to wait so long while we watch windows being moved and sized one at a time with maximum intermediate screen updating.

Here’s Raffi’s winning solution followed by my own version of a generic window tiling/stacking routine and a piece of test code so you can try it out:

TileWindows.c Listing
/*----------------------------------------------------
TileWindows
by Raffi Kasparian
----------------------------------------------------*/
#define StackingOffset 10
 
void TileWindows(enclosingRectPtr, windowPtrArray,
                 windowCount, pixelsBetween,
                 minHorzSize, minVertSize)
 
Rect            *enclosingRectPtr;
WindowPtr       windowPtrArray[];
unsigned short  windowCount;
unsigned short  pixelsBetween;
unsigned short  minHorzSize;
unsigned short  minVertSize;
 
#define mx minHorzSize
#define my minVertSize
#define d  pixelsBetween
 
#define struc  ((WindowPeek)(windowPtrArray[num]))->strucRgn
#define strucL (**struc).rgnBBox.left
#define strucT (**struc).rgnBBox.top
#define strucR (**struc).rgnBBox.right
#define strucB (**struc).rgnBBox.bottom
 
#define cont  ((WindowPeek)(windowPtrArray[num]))->contRgn
#define contL (**cont).rgnBBox.left
#define contT (**cont).rgnBBox.top
#define contR (**cont).rgnBBox.right
#define contB (**cont).rgnBBox.bottom
 
#define pBits  windowPtrArray[num]->portBits.bounds
#define pBitsL pBits.left
#define pBitsT pBits.top
#define pBitsR pBits.right
#define pBitsB pBits.bottom
 
#define pRect  windowPtrArray[num]->portRect
#define pRectL pRect.left
#define pRectT pRect.top
#define pRectR pRect.right
#define pRectB pRect.bottom
 
{
 register short dL, dT, dR, dB, BR, x, y, maxx, maxy,
                num, rL, rT, rR, rB;
 Rect           er = *enclosingRectPtr;
 
#define erL er.left
#define erT er.top
#define erR er.right
#define erB er.bottom
 
 num = 0;
 
 while (true) {
 
  maxy = (erB - erT + d)/(my + d);
  maxx = (erR - erL + d)/(mx + d);
  if ((BR = maxx * maxy) > windowCount) {
   maxx = (windowCount - 1) / maxy + 1;
   maxy = (windowCount - 1) / maxx + 1;
   BR = windowCount;
  }
  BR--;
 
  if (num <= BR) {
   mx = ((erR - erL) - ((maxx - 1) * d)) / maxx;
   my = ((erB - erT) - ((maxy - 1) * d)) / maxy;
  }
 
  rT = erT - (my + d);
  for (y = 1; y <= maxy; y++) {
   rL = erL - (mx + d);
   rT += my + d;
   rB = (y == maxy) && (num <= BR) ? erB : rT + my;
   for (x = 1; x <= maxx; x++, num++) {
 
    rL += mx + d;
    rR = ((x == maxx) && (num <= BR)) ||
      (num == BR) ? erR : rL + mx;
 
    dL = rL - strucL;
    dT = rT - strucT;
    dR = rR - strucR;
    dB = rB - strucB;
 
    SetRectRgn(struc, rL, rT, rR, rB);
    SetRectRgn(cont, contL + dL, contT + dT,
      contR + dR,  contB + dB);
      
    pBitsL -= dL;
    pBitsT -= dT;
    pBitsR -= dL;
    pBitsB -= dT;
 
    pRectR = contR - contL + pRectL;
    pRectB = contB - contT + pRectT;
 
    if (num == windowCount - 1) {
     PaintBehind((WindowPeek)FrontWindow(),
       GrayRgn);
     CalcVisBehind((WindowPeek)FrontWindow(),
       GrayRgn);
     return;
    }
   }
  }
  if (erR - erL - StackingOffset >= mx)
   erL += StackingOffset;
  if (erB - erT - StackingOffset >= my)
   erT += StackingOffset;
 }
}
TileStackWindows.h Listing
/*****************************************************
 * TileStackWindowsWindows.h
 ****************************************************/

/*****************************************************
 * typedefs
 ****************************************************/

typedef struct WindowElement {
 WindowPeek theWindowPtr;
 GDHandle theDevHndl;
} WindowElement, *WindowElementPtr;

typedef Boolean (*TileStackWindowsProc)
 (Rect *enclosingRectPtr,
 WindowElementPtr p, int wCount);
 
 
/*****************************************************
 * prototypes
 ****************************************************/
 
void  TileStackWindows(TileStackWindowsProc
 theTileStackProc);
Boolean MyMoveWindow(WindowPtr w, int leftGlobal,
 int topGlobal, Boolean sizeChanged);
Boolean MySizeWindow(WindowPtr w, int width,
 int height);
TileStackWindows.c Listing
/*****************************************************
 * TileStackWindows.c
 *
 * Set of routines to quickly rearrange windows
 * on multiple devices.
 *
 * Mike Scanlin  10 July 1993
 ****************************************************/

#include <GestaltEqu.h>
#include <Traps.h>
#include "TileStackWindows.h"

/*****************************************************
 * defines
 ****************************************************/

#define BAD_DEVICE ((GDHandle) -1)
#define TOPLEFT_SLOP 2
#define BOTRIGHT_SLOP3
#define NIL 0L

/* MAX_WINDOWS is not a real limit but stack space
 * requirements for TileStackWindows are equal to
 * (sizeof(WindowElement) * 2 * MAX_WINDOWS) so
 * don't make it too big. It's the max number of
 * windows that TileStackWindows can deal with.
 */
#define MAX_WINDOWS100

/*****************************************************
 * typedefs
 ****************************************************/

typedef pascal long(**WDefProcHndl)(int var,
 WindowPtr w, int message, long param);

/*****************************************************
 * prototypes
 ****************************************************/
 
static GDHandle DominantDevice(Rect *theRect);

/*****************************************************
 * TileStackWindows
 *
 * Calls theTileStackProc on a per-device basis to
 * clean up (stack, tile or whatever else you can
 * think of) all the windows on that device. Once
 * all devices have been taken care of the part of
 * the screen that needs to be updated is updated.
 ****************************************************/
void TileStackWindows(TileStackWindowsProc
 theTileStackProc)
{
 WindowElementPtrp, dp;
 WindowPeek w;
 GDHandle deviceHndl;
 RgnHandle  sumOfStructRgns;
 WindowElement   theWindows[MAX_WINDOWS],
 theDeviceWindows[MAX_WINDOWS];
 long   theQDVers;
 Rect   enclosingRect;
 int    i, totalWindows,
 windowsToClean,
 deviceWindows;
 BooleanneedToRedraw, hasColorQD;
 
 /* check for color QuickDraw */
 hasColorQD = FALSE;
 if (TrapIsAvailable(_Gestalt)) {
 Gestalt(gestaltQuickdrawVersion, &theQDVers);
 hasColorQD = theQDVers >= 0x0100;
 }

 sumOfStructRgns = NewRgn();
 needToRedraw = FALSE;
 
 /* find the dominant device for each window
  * as we add it to our list of windows
  */
 p = theWindows;
 totalWindows = 0;
 w = (WindowPeek) FrontWindow();
 while (w != NIL && totalWindows < MAX_WINDOWS) {
 p->theWindowPtr = w;
 p->theDevHndl = NIL;
 if (hasColorQD)
 p->theDevHndl =
   DominantDevice(&(*w->strucRgn)->rgnBBox);
 p++;
 totalWindows++;
 /* or the old struct region into the
  * update region
  */
 UnionRgn(sumOfStructRgns, w->strucRgn,
 sumOfStructRgns);
 w = w->nextWindow;
 }
 
 if (totalWindows == 0)
 goto Exit;
 
 /* set up enclosingRect here in case we don't
  * have color QD; if we do have colorQD then
  * enclosingRect is set again in the loop below
  * on a per-device basis
  */
 enclosingRect = (*GetGrayRgn())->rgnBBox;
 enclosingRect.top += TOPLEFT_SLOP;
 enclosingRect.left += TOPLEFT_SLOP;
 enclosingRect.bottom -= BOTRIGHT_SLOP;
 enclosingRect.right -= BOTRIGHT_SLOP;

 windowsToClean = totalWindows;
 do {
 /* find the first device in the list that we
  * haven't already done and copy all elements
  * from that device into a new list
  */
 p = theWindows;
 dp = theDeviceWindows;
 deviceWindows = 0;
 deviceHndl = BAD_DEVICE;
 i = totalWindows;
 do {
 if (p->theDevHndl != BAD_DEVICE) {
 if (deviceHndl == BAD_DEVICE) {
 /* this is the first time we've
  * seen this device so we do a
  * little set up first
  */
 deviceHndl = p->theDevHndl;
 /* if we have colorQD, use the
  * device's rect
  */
 if (deviceHndl != NIL) {
 enclosingRect = (*deviceHndl)->gdRect;
 enclosingRect.top += TOPLEFT_SLOP;
 enclosingRect.left += TOPLEFT_SLOP;
 enclosingRect.bottom -= BOTRIGHT_SLOP;
 enclosingRect.right -= BOTRIGHT_SLOP;
 if (deviceHndl == GetMainDevice())
 enclosingRect.top += GetMBarHeight();
 }
 }
 if (deviceHndl == p->theDevHndl) {
 /* it's on the current device,
  * add it to the list
  */
 *dp++ = *p;
 deviceWindows++;
 /* we don't want to see this
  * one again
  */
 p->theDevHndl = BAD_DEVICE;
 }
 }
 p++;
 } while (--i);
 
 if (deviceWindows > 0) {
 /* do something to the windows on
  * this device
  */
 needToRedraw |= (*theTileStackProc)
   (&enclosingRect, theDeviceWindows,
   deviceWindows);
 windowsToClean -= deviceWindows;
 }
 
 } while (windowsToClean > 0);
 
 if (needToRedraw) {
 
 /* add all of the new struct regions to the
  * update region
  */
 p = theWindows;
 do {
 UnionRgn(sumOfStructRgns,
   p->theWindowPtr->strucRgn,
   sumOfStructRgns);
 p++;
 } while (--totalWindows);
 
 /* To see a cool effect, trap on the next
  * instruction and watch the screen as you
  * step over it. All window frames are drawn
  * with this one call to the ROMs.
  */
 PaintBehind(theWindows[0].theWindowPtr,
   sumOfStructRgns);
 
 /* Need to reset the visRgns since
  * MySizeWindow nuked 'em.
  */
 CalcVisBehind(theWindows[0].theWindowPtr,
   sumOfStructRgns);
 }

Exit:

 DisposeRgn(sumOfStructRgns);
}


/*****************************************************
 * DominantDevice
 *
 * This returns a device hndl to the device that
 * owns most of the given Rect (which is in global
 * coordinates). This routine requires ColorQD.
 ****************************************************/
static GDHandle DominantDevice(Rect *theRect)
{
 GDHandle nthDevice, theDevice;
 long   greatestArea, sectArea;
 Rect   theSect;
 
 nthDevice = theDevice = GetDeviceList();
 greatestArea = 0;
 do {
 if (TestDeviceAttribute(nthDevice, screenDevice) &&
   TestDeviceAttribute(nthDevice, screenActive)) {
 SectRect(theRect, &(*nthDevice)->gdRect,
   &theSect);
 sectArea =
   ((long) (theSect.bottom - theSect.top)) *
   ((long) (theSect.right - theSect.left));
 if (sectArea > greatestArea) {
 greatestArea = sectArea;
 theDevice = nthDevice;
 }
 }
 nthDevice = GetNextDevice(nthDevice);
 } while (nthDevice != NIL);
 
 return (theDevice);
}


/*****************************************************
 * MyMoveWindow
 *
 * Quickly move the window. No screen updating
 * will take place.
 ****************************************************/
Boolean MyMoveWindow(WindowPtr w, int leftGlobal,
 int topGlobal, Boolean sizeChanged)
{
 Handle theDefProc;
 GrafPtroldPort;
 Point  upperLeft;
 char   oldState;
 BooleanitMoved;
 
 itMoved = FALSE;

 oldPort = thePort;
 SetPort(w);
 
 /* Don't move it if it's already there, unless
  * it was just resized (in which case we don't
  * really need to call MovePortTo but we do
  * need to call the windowDefProc below to fix
  * up the regions).
  */
 if (!sizeChanged) {
 upperLeft = topLeft(w->portRect);
 LocalToGlobal(&upperLeft);
 if (upperLeft.h == leftGlobal &&
   upperLeft.v == topGlobal)
 goto Exit;
 }
 
 itMoved = TRUE;
 
 MovePortTo(leftGlobal, topGlobal);
 
 theDefProc = ((WindowPeek) w)->windowDefProc;
 oldState = HGetState(theDefProc);
 HLock(theDefProc);
 
 /* call the WDEF to update the regions */
 (*(WDefProcHndl) theDefProc)(zoomDocProc, w,
   wCalcRgns, 0);

 HSetState(theDefProc, oldState);

Exit:

 SetPort(oldPort);
 
 return (itMoved);
}


/*****************************************************
 * MySizeWindow
 *
 * Quickly set the size of a window. Set the
 * visRgn to NIL so that no screen updating takes
 * place. The visRgn will be reset when we call
 * CalcVisBehind later.
 ****************************************************/
Boolean MySizeWindow(WindowPtr w, int width,
 int height)
{
 GrafPtroldPort;
 
 /* don't size it if it's already the right size */
 if (w->portRect.right - w->portRect.left == width &&
   w->portRect.bottom - w->portRect.top == height)
   return(FALSE);
   
 oldPort = thePort;
 SetPort(w);
 
 PortSize(width, height);
 
 /* nuke the visRgn so that moving this port
  * (in MyMoveWindow) won't cause any screen
  * drawing
  */
 SetEmptyRgn(((GrafPtr) w)->visRgn);
 
 SetPort(oldPort);
 
 return(TRUE);
}
test.c Listing
/*****************************************************
 * test.c
 *
 * Driver function and example TileStackWindows
 * function to test out TileStackWindows.
 ****************************************************/

#include "TileStackWindows.h"

/*****************************************************
 * defines
 ****************************************************/

#define NUM_TEST_WINDOWS  20

/*****************************************************
 * prototypes
 ****************************************************/
 
static Boolean StackWindows(Rect *enclosingRectPtr,
 WindowElementPtr p, int wCount);

/*****************************************************
 * main
 ****************************************************/
void main()
{
 WindowPtr*p, windowPtrArray[NUM_TEST_WINDOWS];
 Rect   theBounds;
 int    i;
 
 theBounds.top = 50;
 theBounds.left = 50;
 theBounds.bottom = 200;
 theBounds.right = 200;
 
 p = windowPtrArray;
 i = NUM_TEST_WINDOWS;
 do {
 *p++ = NewWindow(0L, &theBounds, "\pTest",
 TRUE, 0, (WindowPtr) -1, TRUE, 0);
 OffsetRect(&theBounds, 3, 2);
 } while (--i);
 
 TileStackWindows(StackWindows);
}


/* window stacking variables used by StackWindows */
#define WTitleHeight 18
#define StaggerH 7
#define StaggerV (WTitleHeight - 2)
#define MinVertSize200
#define NextRowOffsetH    2
#define NextRowOffsetV    4

/*****************************************************
 * StackWindows -- example TileStackWindows proc
 *
 * Stack all the windows so you can see their
 * titles. Returns TRUE if we moved or sized at
 * least one window (if not then we don't need to
 * redraw the screen).
 ****************************************************/
static Boolean StackWindows(enclosingRectPtr, p, wCount)
Rect    *enclosingRectPtr;
WindowElementPtr p;
intwCount;
{
 WindowPtrw;
 Rect   theBounds;
 Point  upperLeft;
 int    width;
 BooleandidOne, sizeChanged;
 
 theBounds = *enclosingRectPtr;
 theBounds.top += WTitleHeight;
 upperLeft = topLeft(theBounds);
 width = theBounds.right - theBounds.left;
 
 didOne = FALSE;
 
 /* this particular routine starts at the back
  * of the list and works it's way forward
  * (to the frontmost window)
  */
 p += wCount;
 do {
 p--;
 w = (WindowPtr) p->theWindowPtr;
 sizeChanged = MySizeWindow(w,
 theBounds.right - theBounds.left,
 theBounds.bottom - theBounds.top);
 didOne |= sizeChanged;
 didOne |= MyMoveWindow(w, theBounds.left,
 theBounds.top, sizeChanged);
 theBounds.left += StaggerH;
 theBounds.right += StaggerH;
 theBounds.top += StaggerV;
 if (theBounds.top >
   enclosingRectPtr->bottom - MinVertSize) {
 upperLeft.h += NextRowOffsetH;
 upperLeft.v += NextRowOffsetV;
 topLeft(theBounds) = upperLeft;
 theBounds.right = theBounds.left + width;
 }
 if (theBounds.right > enclosingRectPtr->right)
 theBounds.right = enclosingRectPtr->right;
 } while (--wCount);
 
 return (didOne);
}

The Rules

Here’s how it works: Each month there will be a different programming challenge presented here. First, you must write some code that solves the challenge. Second, you must optimize your code (a lot). Then, submit your solution to MacTech Magazine (formerly MacTutor). A winner will be chosen based on code correctness, speed, size and elegance (in that order of importance) as well as the postmark of the answer. In the event of multiple equally desirable solutions, one winner will be chosen at random (with honorable mention, but no prize, given to the runners up). The prize for the best solution each month is $50 and a limited edition “The Winner! MacTech Magazine Programming Challenge” T-shirt (not to be found in stores).

In order to make fair comparisons between solutions, all solutions must be in ANSI compatible C (i.e., don’t use Think’s Object extensions). Only pure C code can be used. Any entries with any assembly in them will be disqualified (except for those challenges specifically stated to be in assembly). However, you may call any routine in the Macintosh toolbox you want (i.e., it doesn’t matter if you use NewPtr instead of malloc). All entries will be tested with the FPU and 68020 flags turned off in THINK C. When timing routines, the latest version of THINK C will be used (with ANSI Settings plus “Honor ‘register’ first” and “Use Global Optimizer” turned on) so beware if you optimize for a different C compiler. All code should be limited to 60 characters wide. This will aid us in dealing with e-mail gateways and page layout.

The solution and winners for this month’s Programmers’ Challenge will be published in the issue two months later. All submissions must be received by the 10th day of the month printed on the front of this issue.

All solutions should be marked “Attn: Programmers’ Challenge Solution” and sent to Xplain Corporation (the publishers of MacTech Magazine) via “snail mail” or preferably, e-mail - AppleLink: MT.PROGCHAL, Internet: progchallenge@xplain.com, CompuServe: 71552,174 and America Online: MT PRGCHAL. If you send via snail mail, please include a disk with the solution and all related files (including contact information). See page 2 for information on “How to Contact Xplain Corporation.”

MacTech Magazine reserves the right to publish any solution entered in the Programming Challenge of the Month and all entries are the property of MacTech Magazine upon submission. The submission falls under all the same conventions of an article submission.

 

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VueScan is a scanning program that works with most high-quality flatbed and film scanners to produce scans that have excellent color fidelity and color balance. VueScan is easy to use, and has... Read more
Fantastical 2.3.2 - Create calendar even...
Fantastical 2 is the Mac calendar you'll actually enjoy using. Creating an event with Fantastical is quick, easy, and fun: Open Fantastical with a single click or keystroke Type in your event... Read more
PCalc 4.4.4 - Full-featured scientific c...
PCalc is a full-featured, scriptable scientific calculator with support for hexadecimal, octal, and binary calculations, as well as an RPN mode, programmable functions, and an extensive set of unit... Read more

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Track Santa with these three festive app...
Christmas is fast approaching and that means it's time to prepare for Santa's yearly pilgrimage around the globe. Christmas Eve is an exciting time as parents help their kids get ready to welcome Santa. You've got the cookies and milk all planned... | Read more »
Galaxy on Fire 3 and four other fantasti...
Galaxy on Fire 3 - Manticore brings the series back for another round of daring space battles. It's familiar territory for folks who are familiar with the franchise. If you've beaten the game and are looking to broaden your horizons, might we... | Read more »
The best apps for your holiday gift exch...
What's that, you say? You still haven't started your holiday shopping? Don't beat yourself up over it -- a lot of people have been putting it off, too. It's become easier and easier to procrastinate gift shopping thanks to a number of apps that... | Read more »
Toca Hair Salon 3 (Education)
Toca Hair Salon 3 1.0 Device: iOS Universal Category: Education Price: $2.99, Version: 1.0 (iTunes) Description: | Read more »
Winter comes to Darkwood as Seekers Note...
MyTona, based in the chilly Siberian city of Yakutsk, has brought a little festive fun to its hidden object game Seekers Notes: Hidden Mystery. The Christmas update introduces some new inhabitants to players, and with them a chance to win plenty of... | Read more »
Bully: Anniversary Edition (Games)
Bully: Anniversary Edition 1.03.1 Device: iOS Universal Category: Games Price: $6.99, Version: 1.03.1 (iTunes) Description: *** PLEASE NOTE: This game is officially supported on the following devices: iPhone 5 and newer, iPod Touch... | Read more »
PINE GROVE (Games)
PINE GROVE 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: A pine grove where there are no footsteps of people due to continuous missing cases. The case is still unsolved and nothing has... | Read more »
Niantic teases new Pokémon announcement...
After rumors started swirling yesterday, it turns out there is an official Pokémon GO update on its way. We’ll find out what’s in store for us and our growing Pokémon collections tomorrow during the Starbucks event, but Niantic will be revealing... | Read more »
3 reasons why Nicki Minaj: The Empire is...
Nicki Minaj is as business-savvy as she is musically talented and she’s proved that by launching her own game. Designed by Glu, purveyors of other fine celebrity games like cult favorite Kim Kardashian: Hollywood, Nicki Minaj: The Empire launched... | Read more »
Clash of Clans is getting its own animat...
Riding on its unending wave of fame and success, Clash of Clans is getting an animated web series based on its Clash-A-Rama animated shorts.As opposed to the current shorts' 60 second run time, the new and improved Clash-A-Rama will be comprised of... | Read more »

Price Scanner via MacPrices.net

Never Settle for Low Performing Wifi With iOS...
AppYogi Software has announced the release of WiFi Signal Strength Status App 1.0, the company’s new utility developed exclusively for macOS. WiFi Signal Strength Status App features a unique, single... Read more
New 2016 13-inch Touch Bar MacBook Pros in st...
B&H Photo has stock of new 2016 Apple 13″ Touch Bar MacBook Pro models, each including free shipping plus NY sales tax only: - 13″ 2.9GHz/512GB Touch Bar MacBook Pro Space Gray: $1999 - 13″ 2.... Read more
New 2016 15″ Touch Bar MacBook Pros in stock...
B&H Photo has new 2016 Apple 15″ Touch Bar MacBook Pro models in stock today including free shipping plus NY sales tax only: - 15″ 2.7GHz Touch Bar MacBook Pro Space Gray: $2799 - 15″ 2.7GHz... Read more
DietSensor App Targeting Diabetes and Obesity...
DietSensor, Inc., a developer of smart food and nutrition applications designed to fight diabetes and obesity and help improve overall fitness, has announced the launch of its DietSensor app for... Read more
Holiday 2016 13-inch 2.0GHz MacBook Pro sales...
B&H has the non-Touch Bar 13″ MacBook Pros in stock today for $50-$100 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 13″ 2.0GHz MacBook Pro Space Gray (MLL42LL/A): $1449 $... Read more
Holiday sale: Apple TVs for $51-$40 off MSRP,...
Best Buy has dropped their price on the 64GB Apple TV to $159.99 including free shipping. That’s $40 off MSRP. 32GB Apple TVs are on sale right now for $98 on Sams Club’s online store. That’s $51 off... Read more
12-inch Retina MacBooks, Apple refurbished, n...
Apple has restocked a full line of Certified Refurbished 2016 12″ Retina MacBooks, now available for $200-$260 off MSRP. Refurbished 2015 models are available starting at $929. Apple will include a... Read more
Holiday sale: 12-inch Retina MacBook for $100...
B&H has 12″ Retina MacBooks on sale for $100 off MSRP as part of their Holiday sale. Shipping is free, and B&H charges NY sales tax only: - 12″ 1.1GHz Space Gray Retina MacBook: $1199 $100... Read more
Apple refurbished 13-inch MacBook Airs availa...
Apple has Certified Refurbished 13″ MacBook Airs available starting at $849. An Apple one-year warranty is included with each MacBook, and shipping is free: - 13″ 1.6GHz/8GB/128GB MacBook Air: $849 $... Read more
Apple refurbished iMacs available for up to $...
Apple has Certified Refurbished 2015 21″ & 27″ iMacs available for up to $350 off MSRP. Apple’s one-year warranty is standard, and shipping is free. The following models are available: - 21″ 3.... Read more

Jobs Board

*Apple* Retail - Multiple Positions - Apple,...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
US- *Apple* Store Leader Program - Apple (Un...
…Summary Learn and grow as you explore the art of leadership at the Apple Store. You'll master our retail business inside and out through training, hands-on Read more
Automotive Detailer - *Apple* Used Autos -...
We are currently conductinginterviews and will be accepting applications for a part-time detailer. Apple Used Autos is a great place to work andstart a career. We Read more
*Apple* Retail - Multiple Positions - Apple,...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
*Apple* Retail - Multiple Positions- Trumbul...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
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