TweetFollow Us on Twitter

Sep 93 Tips, Tidbits
Volume Number:9
Issue Number:9
Column Tag:Tips & Tidbits

Related Into: Standard File Memory Manager

Tips & Tidbits

By Neil Ticktin, Editor-in-Chief

This column is your opportunity to spread the word about little bits of information that you find out about. These tidbits can be programming related or they can be user tips that are particularly useful to programmers.

MacTech Magazine will pay $25 for every tip used, and $50 for the Tip of the Month. Or you can take your award in orders or subscriptions.

To submit a tip, send in a letter to the magazine. E-mail is our preferred method, but feel free to send something via the US Mail. See page two for all addresses. If you do send snail mail, enclose a printed copy and a disk copy of the letter so that it does not have to be retyped.

Tip of the Month

The toolbox call BlockMove is quite efficient and smart, especially for large chunks of data. In moving smaller pieces of memory, a very simple macro can do as well and execute much faster:

/* 1 (/
#define BLOCKMOVE(source,dest,len) \
{ typedef struct { char s[len] ; } _sss ;  \
  *(_sss*) (dest) = *(_sss*) (source) ;\
}

This macro generates a temporary structure of size 'len', and assigns the source structure to the destination structure. In this case the compiler will generate a tight loop moving 2 or 4 bytes of data whenever possible. There is no space penalty, i.e., it compiles to exactly the same number of bytes as a normal BlockMove.

Two restrictions apply in using BLOCKMOVE:

• the parameter 'len' must be a constant.

• the source and destinations cannot overlap.

Some performance comparisons:

Bytes BlockMove memcpy BLOCKMOVE

50 9 9 2

100 11 15 4

150 12 21 7

200 14 28 8

250 15 34 11

300 17 41 13

350 18 49 14

400 20 55 16

450 21 61 19

500 22 68 21

These comparisons were done on a PowerBook Duo 230 using Think C 6.0. Times are all measured in ticks for 5000 samples.

- Jan Bruyndonckx, Wave Research, Belgium

[If you are interested in more information on BlockMove, you might want to check out an article by Mike Scanlin in the May, 1993 issue of MacTech Magazine. The article is about writing a more efficient 68040 BlockMove. - Ed.]

Dump obj formatter

The MPW command 'dumpobj SomeLibrary > LibraryObjectCode.a' disassembles compiled library code into the form:

Module: Flags=$00=(Local Code) Module="SomeProcedure"(8) Segment="Main"(7)

Reference: Flags=$90=(A5Relative 16BitPatch 16BitOffsets FromCode)

Ref="arrow"(12)

0006

Content: Flags $08

Contents offset $0000 size $003A

00000000: 4E56 FFFC 'NV..' LINK A6,#$FFFC

00000004: 4AAE 0008 'J...' TST.L $0008(A6)

00000008: 6606 'f.' BNE.S *+$0008 ;00000010

The script below modifies the disassembled code into the form:

Module="SomeProcedure"(8) Segment="Main"(7)
 LINK   A6,#$FFFC
 TST.L  $0008(A6)
 BNE.S  *+$0008

The script:

          #2
format -f geneva -s 9 -t 26  #Set font, font size, tab size

#STEP1 - removes code comments 
find •
Loop
  #Find ; preceded by spaces & select to
  #  the end of line
find /" "+;/:/ /
  #Replace selection with nothing
replace § ""
End

#STEP2 - removes routine text header
find •
Loop
#Selects all lines between Reference &
#  second word Content
#end of line to the.
find /Reference/:/Content/:/Content/:/ /
replace § ""#Replace selection with nothing
End

#STEP3 - Delete everything before exprssn
#"Module="
find •
Loop
#Select everything in front of
#Module= to the beginning of the line
find /"Module="/:\•\
replace § ""#Replace with nothing
find !1 #Select next line
End

#STEP4 - Formats instruction lines
find •
Loop
#Find the line that starts with 4 0's
find /"0000"????/
 #followed by any 4 characters.
find /?«43»/#Select 43 characters from beginning of line
replace § "t"   #Replace selection w/tab
#Select spaces between Opcode and operand
find /" "+/ 
replace § "t"   #Replace with a tab
End#Repeat the Loop until done

In MPW, make the window that contains your disassemble routine the target window - click on it and then click back to the window that contains the above script. Select the lines under each step separately and hit the "Enter" key. Your code should align nicely into the format shown above.

- Greg Pribyl, Incline Village, NV

Customgetfile customization

I recently had to customize a CustomGetFile dialog to select folders. The returned StandardFileReply record contains the file specificatins of the target folder. But I needed to create files inside that folder while the directory ID in the specifications refers to its parent directory.

A simple method for getting a FSSpec record having as parID the directory ID of the selected folder, thus allowing to put the name of the new file into FSSpec.name without further actions, uses FSMakeFSSpec, documented in Inside Macintosh VI (25-30):

FUNCTION FSMakeFSSpec  (vRefNum:Integer;  dirID: LongInt; fileName: Str255; 
VAR spec: FSSpec): OSErr;

The first two parameters will be the same as in the file specifications of the target folder while fileName will contain a partial path.

/* 3 */

function  FileInFolderSpec (theSpec: 
 FSSpec): FSSpec;
var
 target:  FSSpec;
 fn: Str255;
 error:  OSErr;
begin
{theSpec: folder specifications}
 fn:=Concat(':' ,theSpec.name,': ');

 {create a partial path}
 error:=FSMakeFSSpec(theSpec.vRefNum,
 theSpec.parID, fn, target);
 FileInFolderSpec:= target;
end;

A fnfErr (file or directory does not exist) error will be returned because the partial path was incomplete, ending with ':' instead of a filename, but target is nonetheless valid.

- Luigi Belverato, Milano, Italy

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Grab it now: Game Craft’s Legend of War...
The real time strategy game is now available for you to sink your teeth into, through the App Store and Google Play. Combining elements of skill, strategy and empire building, Legend of War is a real gamers’ game. [Read more] | Read more »
Skateboard Party 3 ft. Greg Lutzka (Gam...
Skateboard Party 3 ft. Greg Lutzka 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: Skateboard Party is back! This third edition of the popular sports franchise features professional skater... | Read more »
Cubious (Games)
Cubious 1.0 Device: iOS Universal Category: Games Price: $.99, Version: 1.0 (iTunes) Description: Cubious – How smart are you? How high is your IQube? Solve the impossible puzzles to find out, and help a lost little cube find his... | Read more »
Goat Simulator Waste of Space (Games)
Goat Simulator Waste of Space 1.1 Device: iOS Universal Category: Games Price: $4.99, Version: 1.1 (iTunes) Description: ** IMPORTANT - SUPPORTED DEVICESiPhone 4S, iPad 2, iPod Touch 5 or better.** | Read more »
Wildfulness - Unwind in nature and calm...
Wildfulness - Unwind in nature and calm your mind with nature sounds and illustrations 1.0 Device: iOS Universal Category: Healthcare & Fitness Price: $1.99, Version: 1.0 (iTunes) Description: Spending time in nature helps you to... | Read more »
Dr. Panda Racers (Education)
Dr. Panda Racers 1.0 Device: iOS Universal Category: Education Price: $2.99, Version: 1.0 (iTunes) Description: STEP ON THE GAS, RACE AND WIN!Fasten your seat belts and get ready to race! Speed your way to the finish line while doing... | Read more »
ROMANCING SAGA 2 (Games)
ROMANCING SAGA 2 1.0.0 Device: iOS Universal Category: Games Price: $17.99, Version: 1.0.0 (iTunes) Description: Romancing SaGa 2, originally released only in Japan in 1993, has been completely remastered and now receives its first... | Read more »
WRIO Keyboard (Utilities)
WRIO Keyboard 1.0 Device: iOS iPhone Category: Utilities Price: $2.99, Version: 1.0 (iTunes) Description: 40% OFF DURING LIMITED INTRODUCTORY OFFER | Read more »
Hatoful Boyfriend (Games)
Hatoful Boyfriend 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: The hit PC game that everybirdie loves has now migrated to your mobile device! Now you are free to explore the wonders of St... | Read more »
Warp Shift (Games)
Warp Shift 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: [ CHECK YOUR HARDWARE: Warp Shift does NOT run on iPhone 4, iPad 1 and iPod touch 4G or older devices! It requires at least iOS8... | Read more »

Price Scanner via MacPrices.net

Goal Zero and OtterBox Partner to Expand iPh...
Goal Zero, specialists in portable power, have announced a partnership with OtterBox, brand smartphone case protection, to offer the Slide and Slide Plus Batteries as modules compatible with the new... Read more
15-inch Retina MacBook Pros on sale for up to...
B&H Photo has 15″ Retina MacBook Pros on sale for up to $210 off MSRP. Shipping is free, and B&H charges NY tax only: - 15″ 2.2GHz Retina MacBook Pro: $1799 $200 off MSRP - 15″ 2.5GHz Retina... Read more
Clearance 2015 13-inch MacBook Airs available...
B&H Photo has clearance 2015 13″ MacBook Airs available for $250 off original MSRP. Shipping is free, and B&H charges NY sales tax only: - 13″ 1.6GHz/4GB/128GB MacBook Air (MJVE2LL/A): $799... Read more
Apple refurbished Apple TVs available for up...
Apple has Certified Refurbished 32GB and 64GB Apple TVs available for up to $30 off the cost of new models. Apple’s standard one-year warranty is included with each model, and shipping is free: -... 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″ 3.1GHz iMac 4K: $1379.99 $120 off MSRP - 21″ 2.8GHz iMac: $1189 $110 off MSRP - 21″ 1... Read more
Kanex Introduces GoPower USB-C Rechargeable B...
Kanex has announced its GoPower USB-C portable battery for the USB-C MacBook, featuring the new industry standard connector and cable used for connectivity and power. Providing users with a new... Read more
Convertible and Detachable Devices Winning Ov...
According to the latest figures published by International Data Corporation (IDC), Western European shipments of ultraslim convertibles and detachables posted positive growth (44.7%) to account for... Read more
New MacBook Pros And Will MacBook Air Be Upgr...
With my mid-2013 13-inch MacBook Air closing on its third anniversary come November, I’m in system upgrade mode. Actually the Haswell CPU equipped Air is still doing a fine job, but my good wife is... Read more
Apple’s Education discount saves up to $300 o...
Purchase a new Mac or iPad using Apple’s Education Store and take up to $300 off MSRP. All teachers, students, and staff of any educational institution qualify for the discount. Shipping is free, and... Read more
13-inch 2.5GHz MacBook Pro on sale for $999,...
B&H Photo has the 13″ 2.5GHz MacBook Pro on sale for $999 including free shipping plus NY sales tax only. Their price is $100 off MSRP. Read more

Jobs Board

Editor, *Apple* News - APPLE (United States...
Job Summary The Apple News team is looking for a passionate and knowledgeable editor with experience covering entertainment/pop culture and experience running social Read more
*Apple* Nissan Service Technicians - Apple A...
Apple Automotive is one of the fastest growing dealer...and it shows. Consider making the switch to the Apple Automotive Group today! At Apple Automotive , Read more
ISCS *Apple* ID Site Support Engineer - APP...
…position, we are looking for an individual who has experience supporting customers with Apple ID issues and enjoys this area of support. This person should be Read more
Automotive Sales Consultant - Apple Ford Linc...
…you. The best candidates are smart, technologically savvy and are customer focused. Apple Ford Lincoln Apple Valley is different, because: $30,000 annual salary Read more
*Apple* Support Technician II - Worldventure...
…global, fast growing member based travel company, is currently sourcing for an Apple Support Technician II to be based in our Plano headquarters. WorldVentures is Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.