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

Rodeo Stampede guide to running a better...
In Rodeo Stampede, honing your skills so you can jump from animal to animal and outrun the herd as long as possible is only half the fun. Once you've tamed a few animals, you can bring them home with you. [Read more] | Read more »
VoxSyn (Music)
VoxSyn 1.0 Device: iOS Universal Category: Music Price: $6.99, Version: 1.0 (iTunes) Description: VoxSyn turns your voice into the most flexible vocal sound generator ever. Instantly following even subtle modulations of pitch and... | Read more »
Catch Battleplans on Google Play from Ju...
Real-time strategy title Battleplans is due for release on Google Play on June 30th, following its release for iOS systems last month. With its simple interface and pretty graphics, the crowd-pleaser brings a formerly overlooked genre out for the... | Read more »
iDoyle: The interactive Adventures of Sh...
iDoyle: The interactive Adventures of Sherlock Holmes - A Scandal in Bohemia 1.0 Device: iOS Universal Category: Books Price: $1.99, Version: 1.0 (iTunes) Description: Special Release Price $1.99 (Normally $3.99) | Read more »
Five popular free apps to help you slim...
Thanks to retail and advertising, we're used to thinking one season ahead. Here we are just a week into the summer and we're conditioned to start thinking about the fall. [Read more] | Read more »
How to ride longer and tame more animals...
It's hard to accurately describe Rodeo Stampede to people who haven't seen it yet. It's like if someone took Crossy Roadand Disco Zoo and put them in a blender, yet with a unique game mechanic that's still simple and fun for anyone. [Read more] | Read more »
Teeny Titans - A Teen Titans Go! Figure...
Teeny Titans - A Teen Titans Go! Figure Battling Game 1.0.0 Device: iOS Universal Category: Games Price: $3.99, Version: 1.0.0 (iTunes) Description: Teeny Titans, GO! Join Robin for a figure battling RPG of epic proportions! TEENY... | Read more »
NinjAwesome: Tips and tricks to be a mor...
Sorry about that headline, but I'm going to go ahead and assume that GameResort would not have named its game NinjAwesome without expecting some of that. It is, in fact, pretty awesome the way it combines an endless runner and old school arcade... | Read more »
Into Mirror (Games)
Into Mirror 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: "Is all that we see or seem, but a dream within a dream?"- Edgar Allan Poe New game by Lemon Jam Studio, the team behind Pursuit... | Read more »
Perchang (Games)
Perchang 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: Welcome to Perchang! A test of skill and puzzle solving across 60 stunning levels. | Read more »

Price Scanner via MacPrices.net

15-inch Retina MacBook Pros on sale for $200-...
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: $1799.99 $200 off MSRP - 15″ 2.5GHz... Read more
Mac minis on sale for up to $100 off MSRP
B&H Photo has Mac minis on sale for up to $100 off MSRP including free shipping plus NY sales tax only: - 1.4GHz Mac mini: $449 $50 off MSRP - 2.6GHz Mac mini: $649 $50 off MSRP - 2.8GHz Mac mini... Read more
Clearance 2015 13-inch MacBook Airs available...
B&H Photo has clearance 2015 13″ MacBook Airs available for $300 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 Mac minis available for up...
Apple has Certified Refurbished Mac minis available starting at $419. Apple’s one-year warranty is included with each mini, and shipping is free: - 1.4GHz Mac mini: $419 $80 off MSRP - 2.6GHz Mac... Read more
ABBYY TextGrabber: 1,000,000 Installs in 5 Da...
ABBYY, an international OCR technologies provider, has announced that their image-to-text application TextGrabber, got installed 1,000,000 times in just five days while being featured by the App... Read more
New SkinIt Waterproof Case For iPhone 6
With its impact and waterproof design, the Skinit Waterproof case provides security and protection to guarantee your phone will get you through even the most demanding outdoor conditions. The impact-... Read more
iMacs on sale for up to $150 off MSRP
B&H Photo has 21″ and 27″ iMacs on sale for up to $150 off MSRP including free shipping plus NY sales tax only: - 27″ 3.3GHz iMac 5K: $2181.11 $118 off MSRP - 27″ 3.2GHz/1TB Fusion iMac 5K: $1949... Read more
12-inch 1.1GHz Retina MacBooks on sale for $5...
B&H Photo has 2016 12″ 1.1GHz/256GB Retina MacBooks on sale for up to $50 off MSRP. Shipping is free, and B&H charges NY tax only: - 12″ 1.1GHz Space Gray Retina MacBook: $1249 $50 off MSRP... Read more
WWDC Announcements Revisited Still Underwhelm...
I was disappointed that no new MacBook hardware was announced at this year’s all-software World Wide Developer’s Conference. Not even a hint about what’s in the development pipeline. Of course, we... Read more
Twelve South Compass 2 iPad Stand Now Availab...
Twelve South has updated its most popular iPad stand, Compass 2, with the introduction of two new colors — Gold and Rose Gold. These new color options n perfectly complement the new Rose Gold iPad... Read more

Jobs Board

*Apple* New Products Testers Needed - Apple...
…we therefore look forward to put out products to quality test for durability. Apple leads the digital music revolution with its iPods and iTunes online store, Read more
*Apple* Solutions Consultant - APPLE (United...
Job Summary As an Apple Solutions Consultant, you'll be the link between our future customers and our products. You'll showcase your entrepreneurial spirit as you 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, Towson...
Job Description:SalesSpecialist - Retail Customer Service and SalesTransform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
*Apple* Professional Learning Specialist - A...
Job Summary The Apple Professional Learning Specialist is a full-time position for one year with Apple in the Phoenix, AZ area. This position requires a high Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.