Image SXM Xcode

From CodeWarrior to Xcode

Image SXM was originally compiled in 1993 using THINK Pascal and since about 1995 I have been using the CodeWarrior compiler to create each new version.

CodeWarrior has seen me through Apple's hardware transition from using Motorola 68000 processors to the PowerPC range, and also the software transition from Mac OS 7/8/9 to Mac OS X. If Image SXM was to survive the next hardware transition, from Motorola to Intel processors, I had to change from CodeWarrior to Apple's development system, Xcode.

Rosetta

Image SXM ran on Intel-based Macs because Rosetta, part of the Mac OS, translates Motorola code into Intel code. The catch is that Rosetta is no longer supported in versions of the Mac OS from 10.7 (Lion) onwards.

The CodeWarrior compiler does not compile Mac applications into Intel code. Apple's compiler Xcode does not (officially) support Pascal, but since the release of Snow Leopard I was working on compiling Image SXM with Xcode and the GNU Pascal compiler. Now that I have compiled an Intel version of Image SXM, the Motorola version is redundant except for those who want legacy software to run on older (Motorola) Macs.

GNU Pascal

CodeWarrior Pascal and GNU Pascal are 99% compatible, but it's that 1% that caused all the problems. Image SXM comprises about 2500 procedures and 1000 functions, spread across 150 source files. CW Pascal doesn't really care in which file any particular procedure is defined, but GNU Pascal does -- procedures cannot call other procedures that have not yet been compiled. This involved a lot of reorganisation and moving many procedures and functions between source files so that everything compiles in the right order. It took me a long time to figure out all the interdependencies of the 3500 procedures/functions and so map out what the internal structure of Image SXM needed to be to accommodate GNU Pascal.

Changing from CodeWarrior to Xcode and GNU Pascal

Rewriting the source code so that it compiles with both CodeWarrior (CW) to generate Motorola code and with Xcode and the GNU Pascal compiler (GPC) to generate Intel code has involved a number of changes. I was keen to keep the code compatible with both compilers as I did not want to maintain two sets of source code during the transition from Motorola to Intel.

The letters used to identify the different versions of the application are:

C = CodeWarrior version - the original Carbon application (v192)
M = Motorola version created by Xcode and GPC
X = Intel version created by Xcode and GPC

The principal changes to the source code have been:

Data structures such as image file headers are defined to have the same (or similar) structures to those defined in CW. It is impossible to make the data structures identical, but I think that all important information in old files will be read by the new version of Image SXM.
Intel and Motorola have opposite definitions of byte ordering when storing data longer than one byte (ie, 16-bit or 32-bit integers or real numbers). This means that the (new) Intel version of Image SXM will open image files and interpret the headers correctly for images saved with the (old) Motorola version, but NOT vice versa. In other words, the change from Motorola to Intel will be backwards compatible but not forwards compatible.
Bit operations have a different syntax between CW and GPC. This is awkward, but seems to work OK.
Strings are stored differently between CW (which follows the UCSD standard as adopted by Apple) and GPC (which doesn't). This means all strings have to be converted back and forth when they are sent to or obtained from a Mac system toolbox routine. This is awkward, but seems to work OK.

Bugs that I know about (• fixed, • pending):

Keyboard scans crash. Bug (in GPC, not Image SXM) fixed.
Saving QuickTime movies. Bug fixed.
Some image formats were not recognised. Bug fixed.
Opening BioRad images (byte-swapping problem). Bug fixed.
Byte-swapping problems in some data acquisition parameters. Gave code a tidy up.
FFTs crash (a problem with bit operations). Bug fixed.
Spray Can problem (mod and div operators behave differently). Bug fixed.
Pasting rectangular ROIs (yet another byte-swapping problem). Bug fixed.
Opening PICT files. Bug fixed.
M/X versions now open SXM images saved as PICT/TIFF from C/M/X versions with correct XYZ calibration.
'Stack to Windows' crash if the images are larger than the screen. Bug fixed.
Compressed NEF (Nikon DSLR camera) files got mangled (a problem with bit operations). Bug fixed.
Opening TIFF images with an 'Image Description Tag' would crash. Bug fixed.
Some PrinCIPia bugs fixed - ordering of images in stack; display of CLUT; display of Pole Figure.
Pasting text.

File icons now display correctly:

and files with these file types can be dragged onto the Image SXM icon as usual.
File binding (making Image SXM the default application for one or more files of a given type) also works better now.

P.S. I have managed to get the compilation time down from 15 hours (!) to 20 minutes. That's still a lot slower than CodeWarrior, but at least it's more sensible.

P.P.S. The Intel application runs a bit faster on an Intel Mac than the Motorola application (translated by Rosetta). The speed increase is sometimes rather modest, implying that Rosetta is very efficient.

This is going to need...

Beta testers, preferably lots of them. These are the people who ensure that Image SXM is reasonably bug-free:

William Barvosa-Carter	Hughes Research Laboratories, Malibu, USA
Barry Bickmore	Brigham Young University, Provo, USA
George Boyan	University of Muenchen, Germany
Robert Geisler	Karlsruhe Institute of Technology, Germany
Renée Heilbronner	University of Basel, Switzerland
Richard Legeckis	National Oceanic and Atmospheric Administration, USA
Daniel Manocchio	Kaercher, Winnenden, Germany
Christoph Meier	University of Ulm, Germany
Ernst Niggli	University of Bern, Switzerland
Enique Núñez	Quantimetrix Corporation
Colin Shaw	Montana State University, USA
Dale Stokes	Scripps Institution of Oceanography, UCSD, USA
Anders Thorsen	Institute of Marine Research, Bergen, Norway
Daniel Westhaver	Roffer's Ocean Fishing Forecasting Service, Florida, USA
Jeremy Young	University College London, UK

and I would be glad to hear from any other users who would like to act as beta testers for future versions.

Steve Barrett April 2012

S.D.Barrett@liv.ac.uk