TweetFollow Us on Twitter

ADB Count
Volume Number:6
Issue Number:5
Column Tag:XCMD Corner

Related Info: ADB Manager

CountADBs and Reality

By Donald Koscheka, , Mark Armstrong

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

This column strives to present interesting insights into enhancing Hypercard through XCMDs. When I started writing this column almost two years ago, I was apprehensive; how would I come up with a new idea each month year in and year out. The answer to this question was something of a revelation to me -- once I decided to keep coming up with new ideas, I began looking in new places for those ideas. No part of Macintosh programming is off-limits, I explore everything. Of course there are limits to what one person can do and I find myself very often writing a column in response to some question asked by a colleague or a reader.

I’ve decided that it’s time to go one step further. Beginning this month, intermittently offer this space for “guest XCMDs” such as Mark Armstrong’s following ADB externals. The guest columnist idea appeals to me for two reasons: (1) it broadens the column’s “reach” by discussing areas that I may have not explored myself and (2) it provides you with different perspectives and coding styles so that you can see how others have solved specific problems in an XCMD. This is an open invitation. If you would like to have your XCMD published, send it to me via AppleLink (N0735) or America OnLine (AFC Donald) or to the Editor. Use Macwrite or TEXT only. I will respond as quickly as possible to inform you as to whether I can use the article or not. A few rules: If I can use the material, I will edit it and return it to you for approval. I edit for style and grammar, expect to have some work done to your prose. Don’t submit anything that you don’t want in the public domain and don’t submit any article without source code. You may use whatever language you like. Give yourself a “short plug” at the beginning of the column so that other readers get to know you better.

This month, I would like to introduce Mark Armstrong, Vice President of Research and Development at Pharos Technologies, Inc, a software development and systems integration company in Cincinnati, Ohio. Mark has written one commercial engineering application on the Macintosh called “UNITize” and has contributed to the arcade-style game “Marble Madness”. With his physics degree firmly in hand, he still wonders how he got mixed up in all this.

CountADBs and Reality

In some circumstances (such as on the factory floor), there is a need to monitor the Macintosh to determine whether the mouse or keyboard devices become detached from ADB. Some software may modify their behavior if certain input devices are available, hiding or showing functionality based on that result. Below are two simple XFCN’s, developed in Think C 4.0, that tell you if the mouse and keyboard are connected.

According to Inside Macintosh Volume 5, the function CountADBs() “returns a value representing the number of devices connected to the Apple Desktop Bus (ADB) by counting the number of entries in the device table....” The important word is representing. It does not really tell you what is connected out there on the bus. Consequently, even if you have no devices hooked up to ADB, CountADBs() will return a value of 2. This happens because the system always installs the keyboard and mouse drivers regardless of whether they are physically resident. To find out what is really connected to ADB you can poll devices that you believe are connected to the ADB. Connected devices will respond to the poll.

Before going too far, you must determine whether the host machine is equipped for ADB. The following call to SysEnvirons() determines whether ADB is installed.

/* 1 */

Boolean ADBExists()
 {
 SysEnvRectheWorld;
 OSErr  err;
 
 err = SysEnvirons(1,&theWorld);
 if (err) return (FALSE);
 else
 {
if ((theWorld.machineType >= 0) && (theWorld.machineType < 3)) 
 return (FALSE);
 else return (TRUE);
 }
 }

Once you have determined that ADB exists on your machine, you check to see what devices are actually there by looping from 1 to the maximum allowable number of ADB devices (16). Inside the loop, you call ADBIndAvail() which returns TRUE if the specified device is physically connected and functional or FALSE otherwise. ADBIndAvail() takes a device specified by the index and sends a command via ADBOp() to that device to see if it is responding. If the device receives the operation, it will signal that it has done so by executing a completion routine. If the completion routine ADBOp() doesn’t execute, then the device did not receive the message, and we can assume that the device is dysfunctional or disconnected. The completion routine ADBComplete() sets a global variable to TRUE. If completion does not occur, then the operation times out and the global variable remains FALSE. In the following code, we use the first byte of Scratch8 as the global variable. We chose to use Scratch8 because this code was developed for a Think C 4.0 XCMD where A4 had already been pushed using SetUpA4(). In most cases, a regular global variable will do the trick.

/* 2 */

#define ADB_TIMEOUT10000

extern char Scratch8[]  : 0x9FA;

ADBComplete(){
 *(char *)Scratch8 = TRUE;
}

ADBIndAvail(index)
 short  index;
 {
 ADBAddress addrs;
 ADBDataBlock  devBlock;
 OSErr  err;
 short  cmdNum;
 Str255 ADBData;
 
 addrs = GetIndADB(&devBlock,index);
 cmdNum = ((addrs*16)+0xF);
 ADBData[0] = 0;
 ADBData[1] = 0;
 ADBData[2] = 0;
 
 *(char *)Scratch8 = FALSE;
 err = ADBOp(NIL,ADBComplete,&ADBData,cmdNum);
 if (!err){
 short I= 0;
 do
 if (++I > ADB_TIMEOUT) *(char *)Scratch8 = TRUE; 
 while (!*(char *)Scratch8);
 if (ADBData[0] != 0) return (TRUE);
 }
 return (FALSE);
}

In both cases below, the first portion of the code checks to see if the first and only argument is a question mark (?) or an exclamation point (!). If so, the XFCN responds appropriately as suggested by MacDTS.

The XFCN checks first to see if ADB exists on this machine and returns an error code if it does not. Next, it loops through all the devices to see if any one of them is a responding mouse. If it finds one, it returns TRUE, otherwise it completes the loop and returns FALSE. Each time through the loop, we call GetIndADB(), as directed in Inside Mac, to determine if the device in question is, indeed, a mouse.

/* 3 */

#include “MacTypes.h”
#include “HyperXCmd.h”
#include “DeskBus.h”
#include “SetUpA4.h”

#define ADB_KEYBOARD 2
#define ADB_MOUSE3

#define STANDARD_KBD 1
#define EXTENDED_KBD 2

#define MAX_ADB_DEVICES 16

pascal main(paramPtr)
   XCmdBlockPtr  paramPtr;
   {
   Str255 str;
   shortix;
   
   RememberA0();
   SetUpA4();
   
   if(paramPtr->paramCount == 1){
   ZeroToPas(paramPtr,*((unsigned char **)paramPtr->params[0]),str);
      if (str[0] == 1){
        if (str[1] == ‘?’) 
 pstrcpy(str,”\pKBDAvail()”);
        else if (str[1] == ‘!’) 
 pstrcpy(str,”\pv1.0; © Pharos Technologies, Inc. 1989");
      }
      goto Done;
   }
   
   if (!ADBExists()){ 
 pstrcpy(str,”\p0\rnoADB”); 
 goto Done; 
 }
   
 for ( ix  =1; ix <=MAX_ADB_DEVICES; ix ++){
 ADBDataBlock    ADBinfo;
 ADBAddress ADBaddr;
 
 if (!ADBIndAvail( ix )) continue;
 ADBaddr = GetIndADB(&ADBinfo,I);
 if (ADBaddr <= 0) continue;
 if (ADBinfo.origADBAddr == ADB_MOUSE){ 
 pstrcpy(str,”\ptrue”); 
 goto Done; 
 }
 }
 pstrcpy(str,”\pfalse”);
Done:
   paramPtr->returnValue = PasToZero(paramPtr,(StringPtr)str);
   RestoreA4();
}

A similar routine checks for keyboard devices. This routine not only checks to see if it is a keyboard, but also returns the type of keyboard by examining the devType field of ADBInfo.

/* 4 */

#include “MacTypes.h”
#include “HyperXCmd.h”
#include “DeskBus.h”
#include “SetUpA4.h”

#define ADB_KEYBOARD 2
#define ADB_MOUSE3
#define STANDARD_KBD 1
#define EXTENDED_KBD 2
#define MAX_ADB_DEVICES 16

pascal main(paramPtr)
   XCmdBlockPtr  paramPtr;
   {
   Str255 str;
   shortI;
   
   RememberA0();
   SetUpA4();
   
   if (paramPtr->paramCount == 1){
   ZeroToPas(paramPtr,*((unsigned char **)paramPtr->params[0]),str);
      if (str[0] == 1){
        if (str[1] == ‘?’) 
 pstrcpy(str,”\pKBDAvail()”);
        else if (str[1] == ‘!’) 
 pstrcpy(str,”\pv1.0; © Pharos Technologies, Inc. 1989");
      }
      goto Done;
    }
   
   if (!ADBExists()){ 
 pstrcpy(str,”\p0\rnoADB”); 
 goto Done; 
 }
   
 for (I=1;I<=MAX_ADB_DEVICES;I++){
 ADBDataBlock    ADBinfo;
 ADBAddress ADBaddr;
 
 if (!ADBIndAvail(I)) continue;
 ADBaddr = GetIndADB(&ADBinfo,I);
 if (ADBaddr <= 0) continue;

 if (ADBinfo.origADBAddr == ADB_KEYBOARD){
 if (ADBinfo.devType == STANDARD_KBD){ 
 pstrcpy(str,”\ptrue,standard”); 
 goto Done; 
 }
 else if (ADBinfo.devType == EXTENDED_KBD){ 
 pstrcpy(str,”\ptrue,extended”); 
 goto Done; 
 }
 else{ 
 pstrcpy(str,”\ptrue,unknown”); 
 goto Done; 
 }
 }
 }
 pstrcpy(str,”\pfalse”);
Done:
   paramPtr->returnValue = PasToZero(paramPtr,(StringPtr)str);
   RestoreA4();
   }

Once you know how to identify a particular device, it is easy to check to see if it is present on ADB. If you don’t know how to identify a given device, then the code above can be easily modified to return all devices found on ADB. By the way, I would like to give special thanks and credit to Cameron Birse. If you don’t recognize the name from any number of “sources”, then never mind.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Latest Forum Discussions

See All

Six fantastic ways to spend National Vid...
As if anyone needed an excuse to play games today, I am about to give you one: it is National Video Games Day. A day for us to play games, like we no doubt do every day. Let’s not look a gift horse in the mouth. Instead, feast your eyes on this... | Read more »
Old School RuneScape players turn out in...
The sheer leap in technological advancements in our lifetime has been mind-blowing. We went from Commodore 64s to VR glasses in what feels like a heartbeat, but more importantly, the internet. It can be a dark mess, but it also brought hundreds of... | Read more »
Today's Best Mobile Game Discounts...
Every day, we pick out a curated list of the best mobile discounts on the App Store and post them here. This list won't be comprehensive, but it every game on it is recommended. Feel free to check out the coverage we did on them in the links below... | Read more »
Nintendo and The Pokémon Company's...
Unless you have been living under a rock, you know that Nintendo has been locked in an epic battle with Pocketpair, creator of the obvious Pokémon rip-off Palworld. Nintendo often resorts to legal retaliation at the drop of a hat, but it seems this... | Read more »
Apple exclusive mobile games don’t make...
If you are a gamer on phones, no doubt you have been as distressed as I am on one huge sticking point: exclusivity. For years, Xbox and PlayStation have done battle, and before this was the Sega Genesis and the Nintendo NES. On console, it makes... | Read more »
Regionally exclusive events make no sens...
Last week, over on our sister site AppSpy, I babbled excitedly about the Pokémon GO Safari Days event. You can get nine Eevees with an explorer hat per day. Or, can you? Specifically, you, reader. Do you have the time or funds to possibly fly for... | Read more »
As Jon Bellamy defends his choice to can...
Back in March, Jagex announced the appointment of a new CEO, Jon Bellamy. Mr Bellamy then decided to almost immediately paint a huge target on his back by cancelling the Runescapes Pride event. This led to widespread condemnation about his perceived... | Read more »
Marvel Contest of Champions adds two mor...
When I saw the latest two Marvel Contest of Champions characters, I scoffed. Mr Knight and Silver Samurai, thought I, they are running out of good choices. Then I realised no, I was being far too cynical. This is one of the things that games do best... | Read more »
Grass is green, and water is wet: Pokémo...
It must be a day that ends in Y, because Pokémon Trading Card Game Pocket has kicked off its Zoroark Drop Event. Here you can get a promo version of another card, and look forward to the next Wonder Pick Event and the next Mass Outbreak that will be... | Read more »
Enter the Gungeon review
It took me a minute to get around to reviewing this game for a couple of very good reasons. The first is that Enter the Gungeon's style of roguelike bullet-hell action is teetering on the edge of being straight-up malicious, which made getting... | Read more »

Price Scanner via MacPrices.net

Take $150 off every Apple 11-inch M3 iPad Air
Amazon is offering a $150 discount on 11-inch M3 WiFi iPad Airs right now. Shipping is free: – 11″ 128GB M3 WiFi iPad Air: $449, $150 off – 11″ 256GB M3 WiFi iPad Air: $549, $150 off – 11″ 512GB M3... Read more
Apple iPad minis back on sale for $100 off MS...
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
Apple’s 16-inch M4 Max MacBook Pros are on sa...
Amazon has 16-inch M4 Max MacBook Pros (Silver and Black colors) on sale for up to $410 off Apple’s MSRP right now. Shipping is free. Be sure to select Amazon as the seller, rather than a third-party... Read more
Red Pocket Mobile is offering a $150 rebate o...
Red Pocket Mobile has new Apple iPhone 17’s on sale for $150 off MSRP when you switch and open up a new line of service. Red Pocket Mobile is a nationwide MVNO using all the major wireless carrier... Read more
Switch to Verizon, and get any iPhone 16 for...
With yesterday’s introduction of the new iPhone 17 models, Verizon responded by running “on us” promos across much of the iPhone 16 lineup: iPhone 16 and 16 Plus show as $0/mo for 36 months with bill... Read more
Here is a summary of the new features in Appl...
Apple’s September 2025 event introduced major updates across its most popular product lines, focusing on health, performance, and design breakthroughs. The AirPods Pro 3 now feature best-in-class... Read more
Apple’s Smartphone Lineup Could Use A Touch o...
COMMENTARY – Whatever happened to the old adage, “less is more”? Apple’s smartphone lineup. — which is due for its annual refresh either this month or next (possibly at an Apple Event on September 9... Read more
Take $50 off every 11th-generation A16 WiFi i...
Amazon has Apple’s 11th-generation A16 WiFi iPads in stock on sale for $50 off MSRP right now. Shipping is free: – 11″ 11th-generation 128GB WiFi iPads: $299 $50 off MSRP – 11″ 11th-generation 256GB... Read more
Sunday Sale: 14-inch M4 MacBook Pros for up t...
Don’t pay full price! Amazon has Apple’s 14-inch M4 MacBook Pros (Silver and Black colors) on sale for up to $220 off MSRP right now. Shipping is free. Be sure to select Amazon as the seller, rather... Read more
Mac mini with M4 Pro CPU back on sale for $12...
B&H Photo has Apple’s Mac mini with the M4 Pro CPU back on sale for $1259, $140 off MSRP. B&H offers free 1-2 day shipping to most US addresses: – Mac mini M4 Pro CPU (24GB/512GB): $1259, $... Read more

Jobs Board

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