TweetFollow Us on Twitter

May 95 Challenge
Volume Number:11
Issue Number:5
Column Tag:Programmer’s Challenge

Programmer’s Challenge

By Mike Scanlin, Mountain View, CA

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

Hy-phen-a-tion

Hyphenation algorithms come in two flavors: rule-based and dictionary-based. Of the two, dictionary-based is more reliable but has the downside of requiring a lot of storage space. Rule-based methods require considerably less space and have the option of using an “exceptions” dictionary to improve accuracy. This month’s Challenge is to implement a rule-based hyphenation algorithm.

The algorithm is this: Each part of the word on either side of the hyphen must include a vowel, not counting a final e, es or ed. The part of the word after the hyphen cannot begin with a vowel or a double consonant. No break is made between any two of the following letter combinations: sh, gh, ph, ch, th, wh, gr, pr, cr, tr, wr, br, fr, dr, vowel-r, vowel-n, or om. That means that if any two of those pairs occur next to each other, you can’t break them apart (i.e. ‘from’ contains ‘fr’ and ‘om’, which are both on the list; therefore you would not split it between the ‘r’ and the ‘o’). The letter ‘y’ is not a vowel.

The two routines you’ll write are:

void *
InitHyphenation(maxRAM)
ulong   maxRAM;

void
Hyphenate(privateDataPtr, inPtr, outPtr)
void  *privateDataPtr;
Str255  *inPtr;
Str255  *outPtr;

The InitHyphenation routine is an untimed routine called once that can set up whatever tables you might want to use. It must not allocate more than maxRAM bytes, which will be between 16K and 64K.

Hyphenate is the routine that does the work. PrivateDataPtr is the return value from the InitHyphenation routine. InPtr is a pointer to a read-only unhyphenated Pascal word (containing only letters ‘a’..‘z’ and ‘A’..‘Z’). OutPtr is a pointer to 256 bytes of space where you store the hyphenated word. You need to preserve the case of the input and you should insert a kHyphen byte (0x2D) everywhere the above algorithm tells you to (yes, the complete output is guaranteed to fit within a Str255).

Note that this algorithm is valid for English only. It will find about 70% of all valid hyphens and will make mistakes about 45% of the time. It is assumed that if this was part of a real application that a hyphenation exception word list would be kept. That list would be checked before calling this function. You, however, don’t need to be concerned with that.

Write to me if you have any questions.

Two Months Ago Winner

Congrats to Gustav Larsson (Mountain View, CA) for winning the Method Dispatcher Challenge. Gustav was a virtual unknown to this column a few months ago but he is rising fast in the Top 20 rankings. The 20 points he wins this month move him from 10th place to 4th place.

Here are the times and code sizes for each entry. Numbers in parens after a person’s name indicate that person’s cumulative point total for all previous Programmer Challenges, not including this one:

Name time code

Gustav Larsson (40) 261 1040

Kevin Cutts (36) 304 266

Jeff Mallett (27) 338 1192

Xan Gregg 349 158

Ernst Munter (51) 385 1466

Thomas Studer 437 572

David Howarth 632 130

Scanlin’s brute force method 420 122

Everyone who entered implemented some kind of cache. Gustav chose a 10-way set-associative cache. He splits the 16K of usable cache space into 256 cache sets, each of which holds 10 entries. He uses a hash based on the class and method numbers to map to one of the 256 caches. Once he’s got that he checks the 10 entries for a match. If he doesn’t find a match he uses an efficient binary search to look for the method within the class.

In designing any cache, the choice of hash function and amount of set-associativity (if any) is highly dependent on your data and access pattern. Gustav’s code could be tuned for a variety of efficient cache uses. Nice job, Gustav.

Poker Winner Disqualified

Turns out that I failed to do adequate testing on the winning entry for the Poker Hand Evaluator Challenge, in which Kevin Cutts was the published winner. Unfortunately, I’m going to have to retro-actively disqualify Kevin and award the 1st place prize to Gustav Larsson. My apologies to Kevin and the other MacTech readers. Rather than publish Gustav’s well-commented winning solution (it’s quite long) I’ll make it available via e-mail. If you’re interested, send me a note at scanlin@genmagic.com or at any of the Programmer Challenge electronic addresses (see p. 2).

This latent win for Gustav means that he’s 3 for 3 in the last 3 challenges, which is an unmatched winning streak. Congrats, Gustav! Also, Dave Darrah was the first person to point out the flaws in Kevin’s code and so he receives 5 extra points in the cumulative point totals for doing so. Thanks, Dave!

Top 20 Contestants of All Time

Here are the Top 20 Contestants for the 33 Programmer’s Challenges to date. The numbers below include points awarded for this months’ top 5 entrants. (Note: ties are listed alphabetically by last name -- there are 23 people listed this month because 7 people have 20 points each.)

1. Boonstra, Bob 176

2. Karsh, Bill 71

3. Stenger, Allen 65

4. Larsson, Gustav 60

5. Munter, Ernst 53

6. Riha, Stepan 51

7. Goebel, James 49

8. Cutts, Kevin 46

9. Nepsund, Ronald 40

10. Vineyard, Jeremy 40

11. Darrah, Dave 34

12. Mallet, Jeff 34

13. Landry, Larry 29

14. Elwertowski, Tom 24

15. Kasparian, Raffi 24

16. Lee, Johnny 22

17. Anderson, Troy 20

18. Burgoyne, Nick 20

19. Galway, Will 20

20. Israelson, Steve 20

21. Landweber, Greg 20

22. Noll, Bob 20

23. Pinkerton, Tom 20

There are three ways to earn points: (1) by scoring in the top 5 of any challenge, (2) by being the first person to find a bug in a published winning solution or, (3) being the first person to suggest a challenge that I use. The points you can win are:

1st place 20 points

2nd place 10 points

3rd place 7 points

4th place 4 points

5th place 2 points

finding bug 5 points

suggesting challenge 2 points

Here is Gustav’s winning solution:

Dispatch.c

Copyright ©1995 Gustav K. Larsson

#define kMethodNotFound ((void *) 0)
#define kClassNotFound  ((void *) -1)

typedef unsigned char uchar;
typedef unsigned short ushort;
typedef unsigned long ulong;

typedef ushort  ClassID;
typedef ushort  MethodNumber;
typedef void *  MethodAddress;

typedef struct {
  MethodNumber  methodNumber;
  MethodAddress methodAddress;
} MethodEntry;

typedef struct {
  ushort        inheritedCount;
  ushort        inheritedClasses[15];
  MethodNumber  largestMethodNumber;
  ushort        methodCount;
  MethodEntry   methods[];
} Class, *ClassPtr;

/* Each block in the cache is 64 bytes and holds 10 entries. The id field distinguishes class/method pairs 
that map to the same cache block. The hits field has a bit for each entry, which is set whenever there is a 
hit on the entry.  The "next" field is 0..9 and indicates where to check first when deciding which entry to replace. 
*/

#define BLOCK_SIZE 10

typedef struct {
  ushort          id [ BLOCK_SIZE ];
  ushort          hits;
  ushort          next;
  MethodAddress   methodAddress [ BLOCK_SIZE ];
} CacheBlock;

static CacheBlock Cache[256]; /* exactly 16K */
GetClassPtr
extern ClassPtr GetClassPtr( ClassID );
MethodAddress FindMethod( ClassID, MethodNumber );
static MethodAddress HandleMiss( ClassID, MethodNumber,
                                 CacheBlock *, ushort );
FindMethod
MethodAddress
FindMethod( ClassID classID, MethodNumber methodNumber )
{
  register ulong hash;
  register ushort *idPtr;
  register CacheBlock *block;
Check cache for this class & method.

/* First, generate a hash key that is unique for each class/method pair. The formula classID + 437 * method 
works since 437 is greater than the highest class ID, 400. The ideal multiplier depends heavily on the distribution 
of class/method pairs, but 437 seems to give a reasonable spread under a variety of conditions.
    The low byte of the hash key becomes the block number, and the higher bytes become the "id" (to distinguish 
class/method pairs that map to the same block). Add one to the id so it is never zero (zero indicates an unused 
cache entry). */

  hash = classID + 437L * methodNumber;
  block = &Cache[ (uchar)hash ];
  hash = (hash >> 8) + 1;   /* now hash holds just the id */

  idPtr = block->id;
  if ( *idPtr++ == (ushort)hash ) goto hit0;
  if ( *idPtr++ == (ushort)hash ) goto hit1;
  if ( *idPtr++ == (ushort)hash ) goto hit2;
  if ( *idPtr++ == (ushort)hash ) goto hit3;
  if ( *idPtr++ == (ushort)hash ) goto hit4;
  if ( *idPtr++ == (ushort)hash ) goto hit5;
  if ( *idPtr++ == (ushort)hash ) goto hit6;
  if ( *idPtr++ == (ushort)hash ) goto hit7;
  if ( *idPtr++ == (ushort)hash ) goto hit8;
  if ( *idPtr++ == (ushort)hash ) goto hit9;

  return HandleMiss( classID, methodNumber,
                     block, (ushort)hash );

/* Handle cache hit */
hit0: block->hits |= 0x001;  return block->methodAddress[0];
hit1: block->hits |= 0x002;  return block->methodAddress[1];
hit2: block->hits |= 0x004;  return block->methodAddress[2];
hit3: block->hits |= 0x008;  return block->methodAddress[3];
hit4: block->hits |= 0x010;  return block->methodAddress[4];
hit5: block->hits |= 0x020;  return block->methodAddress[5];
hit6: block->hits |= 0x040;  return block->methodAddress[6];
hit7: block->hits |= 0x080;  return block->methodAddress[7];
hit8: block->hits |= 0x100;  return block->methodAddress[8];
hit9: block->hits |= 0x200;  return block->methodAddress[9];
}
HandleMiss
static MethodAddress
HandleMiss( ClassID classID, MethodNumber methodNumber,
            CacheBlock *blockPtr, ushort id )
{
  register ClassPtr classPtr;
  MethodAddress methodAddress;
  register ushort *temp;  /* shared address register */

  /* Not in cache, so look it up the hard way */
  classPtr = GetClassPtr( classID );
  if ( classPtr != kClassNotFound ) {

    /* Look in this class. Use a binary search. */
    {
      register MethodEntry *methods = classPtr->methods;
      ushort searchSize = classPtr->methodCount;
      register MethodNumber methodReg = methodNumber;
                                /* method # in a register */

/* Unroll the binary search for the most common cases. The BINARY macro reduces the search to progressively 
more elementary cases. If classPtr->methodCount is greater than 32, we run a general binary search until 
the search is reduced to an unrolled case.  */

continueBinarySearch:
      switch ( searchSize )
      {
        bin2: case 2:
          if ( methods[1].methodNumber == methodReg ) {
            methodAddress = methods[1].methodAddress;
            goto addCache;
          }
          /* else fall through... */
        bin1: case 1:
          if ( methods[0].methodNumber == methodReg ) {
            methodAddress = methods[0].methodAddress;
            goto addCache;
          }
          else goto checkSuperclasses;

      #define BINARY(mid,mid1)                        \
        if ( methodReg < methods[mid].methodNumber )  \
          goto bin##mid;  /* like "hi = mid" */       \
        else {                                        \
          methods += mid; /* like "lo = mid" */       \
          goto bin##mid1;                             \
        }

        /* binN: case N: BINARY(N/2,(N+1)/2) */
        bin3:  case  3: BINARY(1,2)
        bin4:  case  4: BINARY(2,2)
        bin5:  case  5: BINARY(2,3)
        bin6:  case  6: BINARY(3,3)
        bin7:  case  7: BINARY(3,4)
        bin8:  case  8: BINARY(4,4)
        bin9:  case  9: BINARY(4,5)
        bin10: case 10: BINARY(5,5)
        bin11: case 11: BINARY(5,6)
        bin12: case 12: BINARY(6,6)
        bin13: case 13: BINARY(6,7)
        bin14: case 14: BINARY(7,7)
        bin15: case 15: BINARY(7,8)
        bin16: case 16: BINARY(8,8)
        bin17: case 17: BINARY(8,9)
        bin18: case 18: BINARY(9,9)
        bin19: case 19: BINARY(9,10)
        bin20: case 20: BINARY(10,10)
        bin21: case 21: BINARY(10,11)
        bin22: case 22: BINARY(11,11)
        bin23: case 23: BINARY(11,12)
        bin24: case 24: BINARY(12,12)
        bin25: case 25: BINARY(12,13)
        bin26: case 26: BINARY(13,13)
        bin27: case 27: BINARY(13,14)
        bin28: case 28: BINARY(14,14)
        bin29: case 29: BINARY(14,15)
        bin30: case 30: BINARY(15,15)
        bin31: case 31: BINARY(15,16)
        bin32: case 32: BINARY(16,16)

        #define NUM_UNROLLED 32 /* # of unrolled cases */

        default:
          if (methodReg <= classPtr->largestMethodNumber) {
            register ushort lo, mid, hi, mn;
            lo = 0;
            hi = classPtr->methodCount - 1;
            while ( lo + NUM_UNROLLED - 1 < hi ) {
              mid = (lo + hi) >> 1;
              mn = methods[mid].methodNumber;
              if ( methodReg < mn )
                hi = mid;
              else if ( methodReg > mn )
                lo = mid;
              else {
                methodAddress = methods[mid].methodAddress;
                goto addCache;
              }
            }
            /* reduced to an unrolled case */
            searchSize = hi-lo+1;
            methods += lo;
            goto continueBinarySearch;
          }
      }
    }

/* Look in superclasses. Eliminating the recursion by keeping a custom stack of critical variables doesn't 
buy us much. Recursion also makes the code clearer. */

checkSuperclasses:
    {
      register ulong i, max = classPtr->inheritedCount;
           /* shared address register points into class list */
      temp = classPtr->inheritedClasses;

      for ( i = 0; i < max; i++ ) {
        methodAddress = FindMethod(*temp++, methodNumber);
        if ( methodAddress != kMethodNotFound )
          goto addCache;
      }
    }
  }

/* There are two ways to get here: classPtr is kClassNotFound (hopefully rare), or the method was not found 
in any of the superclasses. Either way, put a "not found" entry into the cache. This helps when searching 
complicated inheritance hierarchies or repeatedly looking up the same method in several related subclasses. 
*/

  methodAddress = kMethodNotFound;

Add an entry to the cache.
addCache:

// shared address register holds block pointer
  temp = (ushort*) blockPtr;
  #define block ((CacheBlock*) temp)
  {
    register ulong hits = block->hits;
    register ulong next = block->next;
    register ulong mask = 1L << next;

/* Choose the entry to replace. Look for a cleared bit in "hits" starting at "next". If all the bits are 1 initially, 
go all the way around; we are guaranteed to stop since we clear bits as we go. */

    while ( hits & mask ) {
      hits &= ~mask;              /* no, clear the bit */
      mask <<= 1;                 /* and try next bit */
      if ( mask == (1 << BLOCK_SIZE) )
        mask = 1;
      next++;
    }
    if ( next >= BLOCK_SIZE )
      next -= BLOCK_SIZE;

    block->methodAddress[ next ] = methodAddress;
    block->id[ next ] = id;
    block->hits = hits;
    block->next = ( next < BLOCK_SIZE-1 ? next+1 : 0 );
  }

  return methodAddress;
}

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Macs Fan Control 1.3.1.0 - Monitor and c...
Macs Fan Control allows you to monitor and control almost any aspect of your computer's fans, with support for controlling fan speed, temperature sensors pane, menu-bar icon, and autostart with... Read more
NetShade 6.3.1 - Browse privately using...
NetShade is an anonymous proxy and VPN app+service for Mac. Unblock your Internet through NetShade's high-speed proxy and VPN servers spanning seven countries. NetShade masks your IP address as you... Read more
Dragon Dictate 4.0.7 - Premium voice-rec...
With Dragon Dictate speech recognition software, you can use your voice to create and edit text or interact with your favorite Mac applications. Far more than just speech-to-text, Dragon Dictate lets... Read more
Persecond 1.0.2 - Timelapse video made e...
Persecond is the easy, fun way to create a beautiful timelapse video. Import an image sequence from any camera, trim the length of your video, adjust the speed and playback direction, and you’re done... Read more
GIMP 2.8.14p2 - Powerful, free image edi...
GIMP is a multi-platform photo manipulation tool. GIMP is an acronym for GNU Image Manipulation Program. The GIMP is suitable for a variety of image manipulation tasks, including photo retouching,... Read more
Sandvox 2.10.2 - Easily build eye-catchi...
Sandvox is for Mac users who want to create a professional looking website quickly and easily. With Sandvox, you don't need to be a Web genius to build a stylish, feature-rich, standards-compliant... Read more
LibreOffice 5.0.1.2 - Free, open-source...
LibreOffice is an office suite (word processor, spreadsheet, presentations, drawing tool) compatible with other major office suites. The Document Foundation is coordinating development and... Read more
f.lux 36.1 - Adjusts the color of your d...
f.lux makes the color of your computer's display adapt to the time of day, warm at night and like sunlight during the day. Ever notice how people texting at night have that eerie blue glow? Or wake... Read more
VirtualBox 5.0.2 - x86 virtualization so...
VirtualBox is a family of powerful x86 virtualization products for enterprise as well as home use. Not only is VirtualBox an extremely feature rich, high performance product for enterprise customers... Read more
File Juicer 4.43 - Extract images, video...
File Juicer is a drag-and-drop can opener and data archaeologist. Its specialty is to find and extract images, video, audio, or text from files which are hard to open in other ways. In computer... Read more

ReBoard: Revolutionary Keyboard (Utilit...
ReBoard: Revolutionary Keyboard 1.0 Device: iOS Universal Category: Utilities Price: $1.99, Version: 1.0 (iTunes) Description: Do everything within the keyboard without switching apps! If you are in WhatsApp, how do you schedule a... | Read more »
Tiny Empire (Games)
Tiny Empire 1.1.3 Device: iOS Universal Category: Games Price: $2.99, Version: 1.1.3 (iTunes) Description: Launch cannonballs and blow tiny orcs into thousands of pieces in this intuitive fantasy-themed puzzle shooter! Embark on an... | Read more »
Astropad Mini (Productivity)
Astropad Mini 1.0 Device: iOS iPhone Category: Productivity Price: $4.99, Version: 1.0 (iTunes) Description: *** 50% off introductory price! ​*** Get the high-end experience of a Wacom tablet at a fraction of the price with Astropad... | Read more »
Emo Chorus (Music)
Emo Chorus 1.0.0 Device: iOS Universal Category: Music Price: $1.99, Version: 1.0.0 (iTunes) Description: Realistic Choir simulator ranging from simple Chorus emulation to full ensemble Choir with 128 members. ### introductory offer... | Read more »
Forest Spirit (Games)
Forest Spirit 1.0.5 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0.5 (iTunes) Description: | Read more »
Ski Safari 2 (Games)
Ski Safari 2 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: The world's most fantastical, fun, family-friendly skiing game is back and better than ever! Play as Sven's sister Evana, share... | Read more »
Lara Croft GO (Games)
Lara Croft GO 1.0.47768 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.47768 (iTunes) Description: Lara Croft GO is a turn based puzzle-adventure set in a long-forgotten world. Explore the ruins of an ancient... | Read more »
Whispering Willows (Games)
Whispering Willows 1.23 Device: iOS Universal Category: Games Price: $4.99, Version: 1.23 (iTunes) Description: **LAUNCH SALE 50% OFF** - Whispering Willows is on sale for 50% off ($4.99) until September 9th. | Read more »
Calvino Noir (Games)
Calvino Noir 1.1 Device: iOS iPhone Category: Games Price: $3.99, Version: 1.1 (iTunes) Description: The film noir stealth game. Calvino Noir is the exploratory, sneaking adventure through the 1930s European criminal underworld.... | Read more »
Angel Sword (Games)
Angel Sword 1.0 Device: iOS Universal Category: Games Price: $6.99, Version: 1.0 (iTunes) Description: Prepare to adventure in the most epic full scale multiplayer 3D RPG for mobile! Experience amazing detailed graphics in full HD.... | Read more »

Price Scanner via MacPrices.net

Apple offering refurbished 2015 13-inch Retin...
The Apple Store is offering Apple Certified Refurbished 2015 13″ Retina MacBook Pros for up to $270 (15%) off the cost of new models. An Apple one-year warranty is included with each model, and... Read more
Apple refurbished 2015 MacBook Airs available...
The Apple Store has Apple Certified Refurbished 2015 11″ and 13″ MacBook Airs (the latest models), available for up to $180 off the cost of new models. An Apple one-year warranty is included with... Read more
21-inch iMacs on sale for up to $120 off MSRP
B&H Photo has 21″ iMacs on sale for up to $120 off MSRP including free shipping plus NY sales tax only: - 21″ 1.4GHz iMac: $999.99 $100 off - 21″ 2.7GHz iMac: $1199.99 $100 off - 21″ 2.9GHz iMac... Read more
5K iMacs on sale for up to $150 off MSRP, fre...
B&H Photo has the 27″ 3.3GHz 5K iMac on sale for $1899.99 including free shipping plus NY tax only. Their price is $100 off MSRP. They have the 27″ 3.5GHz 5K iMac on sale for $2149.99 $2199.99, $... Read more
1.4GHz Mac mini, refurbished, available for $...
The Apple Store has Apple Certified Refurbished 1.4GHz Mac minis available for $419. Apple’s one-year warranty is included, and shipping is free. Their price is $80 off MSRP, and it’s the lowest... Read more
iPad Air 2 on sale for up to $100 off MSRP
Best Buy has iPad Air 2s on sale for up to $100 off MSRP on their online store for a limited time. Choose free shipping or free local store pickup (if available). Sale prices available for online... Read more
MacBook Airs on sale for $100 off MSRP
Best Buy has MacBook Airs on sale for $100 off MSRP on their online store. Choose free shipping or free local store pickup (if available). Sale prices for online orders only, in-store prices may vary... Read more
Big Grips Lift Handle For iPad Air and iPad A...
KEM Ventures, Inc. which pioneered the extra-large, super-protective iPad case market with the introduction of Big Grips Frame and Stand in 2011, is launching Big Grips Lift featuring a new super-... Read more
Samsung Launches Galaxy Tab S2, Its Most Powe...
Samsung Electronics America, Inc. has announced the U.S. release of the Galaxy Tab S2, its thinnest, lightest, ultra-fast tablet. Blending form and function, elegant design and multitasking power,... Read more
Tablet Screen Sizes Expanding as iPad Pro App...
Larger screen sizes are gaining favor as the tablet transforms into a productivity device, with shipments growing 185 percent year-over-year in 2015. According to a new Strategy Analytics’ Tablet... Read more

Jobs Board

*Apple* Music, Business Operations - Apple (...
**Job Summary** This role in Apple Music and in iTunes is working with…the songs that we all enjoy listening to in Apple Music. Your job will be to work wit Read more
Hardware Systems Integration Engineer - *App...
**Job Summary** We are seeking an enthusiastic electrical engineer for the Apple Watch team. This is a design engineering position that entails working with Read more
Engineering Project Manager - *Apple* TV -...
**Job Summary** The iTunes Apps project management team oversees iTunes, Apple TV, DRM and iOS Applications. We are looking for a project manager to help manage and Read more
*Apple* Retail - Multiple Positions (US) - A...
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
*Apple* Retail Online Store: Customer Insigh...
**Job Summary** Apple Retail (Online Store) is seeking an experienced e-commerce analytics professional to join the Customer Insights Team. The Web e-Commerce Analyst Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.