TweetFollow Us on Twitter

Mar 89 Letters
Volume Number:5
Issue Number:3
Column Tag:Letters

Letters

By David E. Smith, Editor & Publisher, MacTutor

INIT29 & Hpat Virsus Wanted!

Steve Sequist is requesting an infected disk with the new INIT29 and Hpat (nVir type) virus so he can update last month's Security Patrol anit-virus program to detect and destroy them. If you have one or both, please send an infected disk, clearly marked with a skull and crossbones, to MacTutor, PO Box 400, Placentia, CA 92670, attn: Virus! -Ed

Watch Cursor Revisited

Jan Eugenides

Waterbury Center, VT

David Stoops’ Animated Cursors from the December issue was interesting, but it had two deficiencies:

1) It was hard-coded for eight cursors, instead of obtaining the real number of cursors from the ‘acur’ resource,

2) It used SetUpA5 and RestoreA5, which should no longer be used.

I recoded the example in MPW C 3.0b1, with the modifications, and here is the result. I also changed to an ‘acur’ resource with an ID of 128, so as not to conflict with any system resources. The Rez source code for the watch ‘acur’ and the associated cursors are as follows:

/* 1 */

#include <Types.h>
#include <Resources.h>
#include <QuickDraw.h>
#include <OSUtils.h>
#include <Retrace.h>
#include <Memory.h>
#include <ToolUtils.h>
#include <Strings.h>
#include <Errors.h>

typedef struct {
 short  numCurs; /*number of cursor “frames” */
 short  whichCur;/*used as “frame” counter*/
 CursHandle Curs[1]; /*can actually be any number of cursors here*/
 }acur;
typedef acur*acurPtr,**acurHandle;

static acurHandleCurList;
static VBLTask   VBL;

pascal void AnimateWatch()  /*the VBL routine*/
{
long    oldA5;

oldA5 = SetCurrentA5();
if((*CurList)->whichCur >= (*CurList)->numCurs-1 )
 (*CurList)->whichCur = 0;
else
 (*CurList)->whichCur ++;
SetCursor(*((*CurList)->Curs[(*CurList)->whichCur]));
VBL.vblCount = 10;
SetA5(oldA5);
}

InitWatch()
{
short   curCount;

CurList = (acurHandle)GetResource(‘acur’,128);
for(curCount = 0; curCount < (*CurList)->numCurs; curCount++)
 (*CurList)->Curs[curCount] = GetCursor(HiWord((long)(*CurList)->Curs[curCount]));
(*CurList)->whichCur = 0;
}
StartWatch()
{
OSErr   err;

VBL.qType = vType;
VBL.vblAddr = (VBLProcPtr)AnimateWatch;
VBL.vblCount = 10;
VBL.vblPhase = 0;
err = VInstall((QElemPtr)&VBL);
}

StopWatch()
{
OSErr err;

err = VRemove((QElemPtr)&VBL);
}
/* 2 */

#include “types.r”

data ‘acur’ (128, locked, preload) {
 $”00 08 00 00 01 00 00 00 01 01 00 00 01 02 00 00"
 $”01 03 00 00 01 04 00 00 01 05 00 00 01 06 00 00"
 $”01 07 00 00"
};
resource ‘CURS’ (263, locked, preload) {
 $”3F 00 3F 00 3F 00 3F 00 40 80 80 40 90 40 88 60"
 $”9C 60 80 40 80 40 40 80 3F 00 3F 00 3F 00 3F”,
 $”3F 00 3F 00 3F 00 3F 00 7F 80 FF C0 FF C0 FF C0"
 $”FF C0 FF C0 FF C0 7F 80 3F 00 3F 00 3F 00 3F”,
 {8, 8}
};
resource ‘CURS’ (262, locked, preload) {
 $”3F 00 3F 00 3F 00 3F 00 40 80 80 40 80 40 80 60"
 $”BC 60 80 40 80 40 40 80 3F 00 3F 00 3F 00 3F”,
 $”3F 00 3F 00 3F 00 3F 00 7F 80 FF C0 FF C0 FF C0"
 $”FF C0 FF C0 FF C0 7F 80 3F 00 3F 00 3F 00 3F”,
 {8, 8}
};
resource ‘CURS’ (261, locked, preload) {
 $”3F 00 3F 00 3F 00 3F 00 40 80 80 40 80 40 80 60"
 $”9C 60 88 40 90 40 40 80 3F 00 3F 00 3F 00 3F”,
 $”3F 00 3F 00 3F 00 3F 00 7F 80 FF C0 FF C0 FF C0"
 $”FF C0 FF C0 FF C0 7F 80 3F 00 3F 00 3F 00 3F”,
 {8, 8}
};
resource ‘CURS’ (260, locked, preload) {
 $”3F 00 3F 00 3F 00 3F 00 40 80 80 40 80 40 80 60"
 $”9C 60 84 40 84 40 40 80 3F 00 3F 00 3F 00 3F”,
 $”3F 00 3F 00 3F 00 3F 00 7F 80 FF C0 FF C0 FF C0"
 $”FF C0 FF C0 FF C0 7F 80 3F 00 3F 00 3F 00 3F”,
 {8, 8}
};
resource ‘CURS’ (259, locked, preload) {
 $”3F 00 3F 00 3F 00 3F 00 40 80 80 40 80 40 80 60"
 $”9C 60 82 40 80 40 40 80 3F 00 3F 00 3F 00 3F”,
 $”3F 00 3F 00 3F 00 3F 00 7F 80 FF C0 FF C0 FF C0"
 $”FF C0 FF C0 FF C0 7F 80 3F 00 3F 00 3F 00 3F”,
 {8, 8}
};
resource ‘CURS’ (258, locked, preload) {
 $”3F 00 3F 00 3F 00 3F 00 40 80 80 40 80 40 80 60"
 $”9F 60 80 40 80 40 40 80 3F 00 3F 00 3F 00 3F”,
 $”3F 00 3F 00 3F 00 3F 00 7F 80 FF C0 FF C0 FF C0"
 $”FF C0 FF C0 FF C0 7F 80 3F 00 3F 00 3F 00 3F”,
 {8, 8}
};
resource ‘CURS’ (257, locked, preload) {
 $”3F 00 3F 00 3F 00 3F 00 40 80 80 40 81 40 82 60"
 $”9C 60 80 40 80 40 40 80 3F 00 3F 00 3F 00 3F”,
 $”3F 00 3F 00 3F 00 3F 00 7F 80 FF C0 FF C0 FF C0"
 $”FF C0 FF C0 FF C0 7F 80 3F 00 3F 00 3F 00 3F”,
 {8, 8}
};
resource ‘CURS’ (256, locked, preload) {
 $”3F 00 3F 00 3F 00 3F 00 40 80 84 40 84 40 84 60"
 $”9C 60 80 40 80 40 40 80 3F 00 3F 00 3F 00 3F”,
 $”3F 00 3F 00 3F 00 3F 00 7F 80 FF C0 FF C0 FF C0"
 $”FF C0 FF C0 FF C0 7F 80 3F 00 3F 00 3F 00 3F”,
 {8, 8}
};

Animated Cursors Again

Erny Tontlinger

Steinfort, Luxembourg

Here are some comments to David Stoops’ Animated Cursors from the December 1988 Letters Column.

There is an error in the procedure InitWatch. The cursor id should be replaced by the cursor handle in the loop this:

/* 3 */

Watch[watchcount] := GetCursor(HiWord(longint(Watch[watchcount])));

The correct structure of a ‘acur’ resource is:

/* 4 */

acur = record
 frames: integer; {Number of frames(cursors) }
 whichWatch : integer;
 Watch : array[1..99] of CursHandle
 { size depends on frames }
end;

Then instead of using a fixed number of eight cursors, use Watch^^.frames, which happens to be eight for the Finder.

The ‘acur’ and ‘CURS’ resources should be locked, otherwise the VBL task runs into troubles with the memory Manager. The Finder uses the ‘CURS’ id 4 (classic watch cursor), which in the System file is not locked. This cursor is also in ROM, from the Mac Plus machines on, so it would be good to set RomMapInsert to mapTrue before calling GetCursor.

SetUpA5 and RestoreA5 might not work as expected under MultiFinder. The value of A5 should be placed in a position, other than CurrentA5 in low memory globals, where the application can find it from within the VBL task. See “Programmer’s Guide to MultiFinder” (APDA# KMB017) the chapter “The A5 world/VBL tasks”.

Now something different. Why is it so difficult to print READABLE program listing in MacTutor? Your desktop publishing program seems to have problems with regular spaced tab positions. Anyhow I appreciate MacTutor very much. [Basically, we convert the source into WriteNow in a 3 1/2" width single column with tabs set at every eighth of an inch. Then we place it into PageMaker. Here is where a number of problems occur as you surmised. PageMaker doesn't exactly import tab information correctly and we have to manually fix it. -Ed]

More Animated Watch Cursors

Rob Terrell

Chapel Hill, NC

In the December issue, you printed a letter that showed how to animate the watch cursor as a VBL task, which I thought was strange since a few issues back you printed another letter that gave a very good reason not to: a VBL task can go on and on while the application has crashed, and the poor user will be stuck thinking everything is okay.

A better way to implement the animated watch is through a unit that just takes a single call to increment the cursor. Support for this exists in TML Pascal II; for those not fortunate as to own TML, here’s a unit that does essentially the same thing:

{5}

Unit WatchItSpin;
(*Make sure you have copied the ‘acur’ and ‘CURS’ *)
(* resources from the Finder into your application *)
(* ResEdit is quite handy for this *)

Interface

Uses MemTypes, QuickDraw, OSintf, Toolintf;

type
 aCur = record
 whichWatch : longint;
 watch : array[1..8] of CursHandle;
 end;
 acurPtr = ^ acur;
 acurHandle = ^acurPtr;
var
 currentWatch : integer;
 WatchList : acurHandle;

Procedure InitSpinner;
Procedure SpinWatch;

Implementation

Procedure InitSpinner;
var
 count : integer;
begin
 watchList := acurHandle(GetResource(‘acur’,0));
 with watchList^^ do begin
 for count := 1 to 8 do
 Watch[count] := GetCursor(HiWord(longint( Watch[count])));
 whichWatch := 0;
 end;
end; (* InitSpinner *)

Procedure SpinWatch;
begin
 with WatchList^^ do begin
 if whichWatch >= 8 then whichWatch := 1
 else whichWatch := whichWatch + 1;
 SetCursor(Watch[whichWatch]^^);
 end;
end; (* SpinWatch *)
end.

Most of this code was simply taken from David Stoops’ letter. However, to use this, you call InitSpinner when you initialize everything else at the beginning of your program; then you call SpinWatch each time through a loop or time-consuming process to increment it. Not quite as nice as having a VBL take care of it, but this way, if you crash, the hands will stop.

Correction to CompareString

Steve Brecher

Sunnyvale, CA

In John S. Stokes III's CompareString routine (Jan 89 Letters), use of the Ext.W instruction introduces an error:

 Move.B (A0),D1  ; length of the first string
 Ext..W D1; dbra uses word

Ext.W propagates the value in bit 15 of the register through bits 16..31. Therefore, it will not have the desired effect of clearing bits 8..15. Ext.B would not work either for cases in which the string length is greater than 127,i.e. , negative considered as a signed byte; in such cases Ext.B would set bits 8..15, making the unsigned word value very large. To convert an unsigned byte value to a word in a register, first clear the word and then move the byte into it:

;6

 Clr.W  D1
 Move.B (A0),D1

Often programmers will write MoveQ #0,Dn instead of Clr.W Dn when the value in the upper word of the register either needs to be cleared also or is not of concern. MoveQ is always a longword operation.

A corrected CompareString would look like this:

;7

; A0  --> Pascal string 1
; A1 --> Pascal string 2
; Returns D0.L=1 if equal, 0 if not equal
; Alters A0-A1

CompareString:
 MoveQ  #0,D0
 Move.B (A0),D0  ;gross len - 1
@0 Cmp.B(A0)+,(A1)+ ;loop until...
 DBne D0,@0 ;...not equal or end
 Seq  D0;D0 := $FF if equal, else 0
 Neg.B  D0;D0 := 1 if equal, else 0
 Rts

The Move.B instruction puts the length byte of string 1 into D0. We want to compare the entire string structures, including their length bytes. The length of the entire structure--the gross length--of a string is the the number of text bytes, plus one for the length byte. For a DBxx instruction, we want the gross length - 1, which is just the value of the length byte.

We use the DBne instruction to control the loop. DBxx will branch to the start of the loop if either the test condition (in this case, “ne”) is false or the loop count is exhausted. Thus DBxx should be read as “branch until xx or counter expired.” When control falls through the DBne, we use the Seq instruction to condition D0 to the result of the last Cmp.B; DBxx instructions do not alter the condition codes. If the strings (including their lengths) are equal, the result of the last Cmp.B will be “eq” and the DBne will have not branched because the D1 counter expired. If the length bytes or contents of the strings are not equal, the last Cmp.B result will have been “ne” and the DBne will have not branched because its “until” condition was met.

[Steve Brecher is a long time friend of MacTutor. We welcome his comments and hope to hear more from him in the coming months. -Ed]

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Latest Forum Discussions

See All

Combo Quest (Games)
Combo Quest 1.0 Device: iOS Universal Category: Games Price: $.99, Version: 1.0 (iTunes) Description: Combo Quest is an epic, time tap role-playing adventure. In this unique masterpiece, you are a knight on a heroic quest to retrieve... | Read more »
Hero Emblems (Games)
Hero Emblems 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: ** 25% OFF for a limited time to celebrate the release ** ** Note for iPhone 6 user: If it doesn't run fullscreen on your device... | Read more »
Puzzle Blitz (Games)
Puzzle Blitz 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: Puzzle Blitz is a frantic puzzle solving race against the clock! Solve as many puzzles as you can, before time runs out! You have... | Read more »
Sky Patrol (Games)
Sky Patrol 1.0.1 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0.1 (iTunes) Description: 'Strategic Twist On The Classic Shooter Genre' - Indie Game Mag... | Read more »
The Princess Bride - The Official Game...
The Princess Bride - The Official Game 1.1 Device: iOS Universal Category: Games Price: $3.99, Version: 1.1 (iTunes) Description: An epic game based on the beloved classic movie? Inconceivable! Play the world of The Princess Bride... | Read more »
Frozen Synapse (Games)
Frozen Synapse 1.0 Device: iOS iPhone Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: Frozen Synapse is a multi-award-winning tactical game. (Full cross-play with desktop and tablet versions) 9/10 Edge 9/10 Eurogamer... | Read more »
Space Marshals (Games)
Space Marshals 1.0.1 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.1 (iTunes) Description: ### IMPORTANT ### Please note that iPhone 4 is not supported. Space Marshals is a Sci-fi Wild West adventure taking place... | Read more »
Battle Slimes (Games)
Battle Slimes 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: BATTLE SLIMES is a fun local multiplayer game. Control speedy & bouncy slime blobs as you compete with friends and family.... | Read more »
Spectrum - 3D Avenue (Games)
Spectrum - 3D Avenue 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: "Spectrum is a pretty cool take on twitchy/reaction-based gameplay with enough complexity and style to stand out from the... | Read more »
Drop Wizard (Games)
Drop Wizard 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: Bring back the joy of arcade games! Drop Wizard is an action arcade game where you play as Teo, a wizard on a quest to save his... | Read more »

Price Scanner via MacPrices.net

Our MacBook Price Trackers will show you the...
Our Apple award-winning MacBook Price Trackers are continually updated with the latest information on prices, bundles, and availability for 16″ and 14″ MacBook Pros along with 13″ and 15″ MacBook... Read more
Amazon is offering a 10% discount on Apple’s...
Don’t pay full price! Amazon has 16-inch M4 Pro MacBook Pros (Silver and Black colors) on sale today for 10% off Apple’s MSRP. Shipping is free. These are the lowest prices currently available for 16... Read more
13-inch M4 MacBook Airs on sale for $150 off...
Amazon has new 13″ M4 MacBook Airs on sale for $150 off MSRP right now, starting at $849. Sale prices apply to most colors and configurations. Be sure to select Amazon as the seller, rather than a... Read more
15-inch M4 MacBook Airs on sale for $150 off...
Amazon has new 15″ M4 MacBook Airs on sale for $150 off Apple’s MSRP, starting at $1049. Be sure to select Amazon as the seller, rather than a third-party: – 15″ M4 MacBook Air (16GB/256GB): $1049, $... Read more
Amazon is offering a $50 discount on Apple’s...
Amazon has Apple’s 11th-generation A16 iPads in stock on sale for $50 (or a little more) off MSRP this week. Shipping is free: – 11″ 11th-generation 128GB WiFi iPads: $299 $50 off MSRP – 11″ 11th-... Read more
Clearance 13-inch M1 MacBook Airs available f...
Walmart has clearance, but new, Apple 13″ M1 MacBook Airs (8GB RAM, 256GB SSD) available online for $649, $360 off original MSRP, in Space Gray, Silver, and Gold colors. These are new MacBooks for... Read more
iPad minis on sale for $100 off Apple’s MSRP...
Amazon is offering $100 discounts (up to 20% off) on Apple’s newest 2024 WiFi iPad minis, each with free shipping. These are the lowest prices available for new minis among the Apple retailers we... Read more
AirPods Max headphones on sale for $479, $70...
Amazon has AirPods Max with USB-C on sale for $479.99 in all colors. Shipping is free. Their price is $70 off Apple’s MSRP, and it’s the lowest price available today for AirPods Max. Keep an eye on... Read more
14-inch M4 Pro/M4 Max MacBook Pros on sale th...
Don’t pay full price! Get a new 14″ MacBook Pro with an M4 Pro or M4 Max CPU for up to $320 off Apple’s MSRP this weekend at these retailers…they are the lowest prices available for these MacBook... Read more
Get a 15-inch M4 MacBook Air for $150 off App...
A couple of Apple retailers are offering $150 discounts on new 15″ M4 MacBook Airs this weekend. Prices at these retailers start at $1049: (1): Amazon has new 15″ M4 MacBook Airs on sale for $150 off... Read more

Jobs Board

All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.