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comp.lang.pascal.borland FAQ, v0.6comp.lang.pascal.borland FAQ, version 0.6Table of ContentsPrefacePassing Parameters To Programs (Reading The Command Line)1.1 How do I readcommand line parameters?1.2 How do I readthe whole command line?Logarithms, Trigonometry, and Other Numerical Calculations2.1 How do I calculate X^Y(aka X**Y)?2.2 How do I take 'un-natural'logarithms?2.3 Why do the trig functions like Sin()and Cos() give the wrong answers?2.4 How do I calculate ArcSin() or ArcCos()?2.5 Can I trap (and recover from) floating pointoverflow errors?2.6 Why do I always get the same random numbersevery time I run my program?Strings and Numbers3.1 How do I convert a string to a number?3.2 How do I convert a number to a string?Breaking The 64K Limit4.1 I have 64K of global data and can'tadd anymore - what do I do?4.2 Can I have more than 64K of global data in myWindows program?4.3 How can I build an array bigger than 64K?4.4 How do I handle .BMP and/or .WAV files withmore than 64K of data?Procedural Types5.1 Can I make an indirect call to anobject's method, using a pointer or a procedural type?Windows Sound Programming6.1 Where can I find documentation onWindows sound programming?Delphi and/or BP87.1 What about Delphi?7.2 Will there be a BP8?Other Pascal ResourcesRuntime Error 200 when using CRT unit on fast computersPrefaceThis file was originally intended to be an officialnews.answers/rtfm.mit.eduFAQ for comp.lang.pascal.borland.However, work and Delphi intervened, and now I no longer use BP at all. This filewill never go beyond this draft stage; the only work I've done on it in four yearsis to add the section on Runtime Error200 when using CRT unit on fast computers.I have only included answers to questions that seem to me to begenuinely frequently asked. I have no desire to write a Pascal primer,nor do I want to produce a intimidatingly large document. On the otherhand, if this FAQ does get out of hand, it's being written andmaintained as an HTML file, so you can use Mosaic or Lynx to jumpstraight from the Table Of Contents to the answer to a particularquestion. I'll post the ASCII version periodically to comp.lang.pascal.borland;you can always get the latest version via the World Wide Web at<http://www.midnightbeach.com/jon/pubs/clp-faq.htm>.This FAQ began life as a draft of a comp.lang.pascal FAQ, back before that groupwas split up. This heritage shows primarily in phrases like in Turbo/BorlandPascal that are no longer necessary. Some of the questions and answersmay apply to other Pascal's, but it's up to you to decide if this is thecase.Please note that this FAQ file is a free public service, and comeswith no warranty as to accuracy. Use any information you find here withdiscretion and caution.ContributorsAt this point, most of the material in this FAQ isby me, Jon Shemitz,aka [jds] orjon@midnightbeach.com.Some of the material is borrowed fromProfessor Timo Salmi's (ts@uwasa.fi)Turbo Pascal FAQ file, which may be downloaded from ftp://garbo.uwasa.fi/pc/link/tsfaqp.zip. Such material is generally'signed' [ts].Duncan Murdoch,dmurdoch@mast.queensu.ca,contributed the material signed [dm].Passing Parameters To Programs (Reading The Command Line)1.1: How do I read command lineparameters?The standard function ParamCount: word will return thenumber of command line parameters, while function ParamStr(N: word): string will return the N-th parameter. (Under DOS 3.0 or greater, the 0-th parameter (ie, ParamStr(0))is the path and file name of the currentprogram.) Thus, function CommandLine: string; var Idx: word; Result: string; begin Result := ''; for Idx := 1 to ParamCount do begin if Idx > 1 then Result := Result + ' '; Result := Result + ParamStr(Idx); end; CommandLine := Result; end;will return the whole command line, with any embedded whitespace (spacesor tabs) converted to single spaces. If you care about the amount or type of whitespace, or you want commas, semicolons, and equal signs to count as parameter separators (as per ancient versions of DOS manuals),see the next question:1.2: How do I read the wholecommand line?ParamCount and ParamStr are for parsed parts of the command line and cannot be used to get the command line exactly as it was. If you try to capture "Hello. I'm here" you'll end up with a false number of blanks. For obtaining the command line unaltered use type CommandLines = string[127]; function CommandLine: CommandLines; type CommandLinePtr = ^CommandLines; begin CommandLine := CommandLinePtr( Ptr(PrefixSeg, $80) )^; end;A warning. If you want to get this correct (the same goes for TP's own ParamStr and ParamCount) apply them early in your program, before any disk I/O takes place.For the contents of the Program Segment Prefix (PSP) see a DOS TechnicalReference Manual (available on the Microsoft DevNet CD) or Tischer, Michael (1992), PC Intern System Programming, p. 753.- Based on [ts]'s Turbo Pascal FAQLogarithms, Trigonometry, and Other Numerical CalculationsI often find it convenient to define floating-pointfunctions in terms of a type float = {$ifopt N+} double {$else}real {$endif}, rather than either explicitly usingreal or double.This way, the same function will automatically usethe 'best' argument and result type for either the N+ (80x87) orN- state, without any changes and without obscuring its logic with lotsof {$ifdef}s.2.1: How do I calculate X^Y (X**Y)?Prof. Timo Salmi writesPascals do not have an inbuilt power function. You have to writeone yourself. The common, but non-general method is defining function POWERFN(number, exponent: float): float; begin PowerFn := Exp(Exponent*Ln(Number)); end;To make it general use: (* Generalized power function by [ts] *) { Some modifications by jds } function GenPowFn(Number, Exponent: float): float; begin if (Exponent = 0.0) then GenPowFn := 1.0 else if Number = 0.0 then GenPowFn := 0.0 else if Abs(Exponent*Ln(Abs(Number))) > 87.498 then RunError(205) {Floating point overflow} else if Number > 0.0 then GenPowFn := Exp(Exponent*Ln(Number)) else if (Number < 0.0) and (Frac(Exponent) = 0.0) then if Odd(Round(Exponent)) then GenPowFn := -GenPowFn(-Number, Exponent) else GenPowFn := GenPowFn(-Number, Exponent) else RunError(207); {Invalid float-op} end; (* genpowfn *)On the lighter side of things, here's an extract from an answer of mine [TS] in the comp.lang.pascal UseNet newsgroup:> anyone point out why X**Y is not allowed in Turbo Pascal?The situation in TP is a left-over from standard Pascal. You'll recall that Pascal was originally devised for teaching programming, not for something as silly and frivolous as actually writing programs. :-)For the common special-case where you're raising a floating pointnumber to an integral power (eg, X^7 or Y^3), you can use thisfast code: function RealPower(Base: Float; Power: word): Float; begin if Odd(Power) then if Power = 1 then RealPower := Base else RealPower := Base * RealPower(Base, Power - 1) else if Power = 0 then RealPower := 1 else RealPower := Sqr(RealPower(Base, Power shr 1)); end;2.2: How do I take 'un-natural'logarithms?Just define function Log(X, Base: float): float; begin Log := Ln(X) / Ln(Base); end;This result is based on some elementary math. By definitiony = log(x) in base B is equivalent to x = B^y (where the ^indicates an exponent). Thus ln(x) = y ln(B) and hencey = ln(x) / ln(B).- A lightly-edited version of the answer from[ts]'s Turbo Pascal FAQ2.3: Why do the trig functions likeSin() and Cos() give the wrong answers?While most people express angles in degrees, the trig functionpect their arguments to be in radians. For historical reasons,a complete rotation is 360 degrees; for more cosmological reasons,the same complete rotation is 2 * Pi radians (the circumference of acircle with a radius of 1). Thus, to convert degrees to radians, justdivide by 180 / Pi.2.4: How do I calculate ArcSin() orArcCos()?Borland Pascal does not have ArcSin or ArcCosfunctions. It does have an ArcTan function, andthe online help for that function gives the following conversion formulae: ArcSin(x) = ArcTan (x/sqrt (1-sqr (x))) ArcCos(x) = ArcTan (sqrt (1-sqr (x)) /x)Dr. John Stockton,jrs@merlin.dclf.npl.co.uk,points outthat ArcTan will always return a value between-Pi / 2 and Pi / 2. Also,there are two angles in the range from 0 to 2 pifor any given sine or cosine value, even though the formulae above willonly give you one of them. For this reason, the formulaArcCos(x) = (Pi / 2) - ArcSin(X) from theCRC Standard Mathematical Tables handbook is generally better.2.5: Can I trap (and recover from) floating pointoverflow errors?Duncan Murdoch [dm] writes:Because the floating point processor operates in parallel to the integerprocessor, this is generally quite tricky. The best approach is not totrap the errors, but just to mask them, and at the end of a calculationcheck whether they have occurred by examining the coprocessor statusword.Be aware that Borland's string-conversion routines (used in Str, Write andWriteln) clear the FPU's status word. If you do any I/O of floating pointvalues in between status checks, you may miss seeing signs of errors.I would add that it's probably best to leave the floating point overflowexception on (unmasked) in the vast majority of your code, and that youshould only mask it off around the few calculations where you expect andcan handle a possible overflow. That is, a runtime error is probablybetter than allowing the program to continue with unnoticed math errors!The following demo code may be helpful: function Get87CtrlWord: word; assembler; var CtrlWord: word; asm fstcw [CtrlWord] mov ax,[CtrlWord] end; procedure Set87CtrlWord(NewCtrlWord: word); assembler; asm fldcw [NewCtrlWord] end; function Get87StatusWord: word; assembler; var StatusWord: word; asm fstsw [StatusWord] mov ax,[StatusWord] end; const InvalidOp = $01; DenormalOp = $02; ZeroDivide = $04; Overflow = $08; Underflow = $10; Precision = $20; var Ctrl, Status: word; X, Y: double; begin Ctrl := Get87CtrlWord; Set87CtrlWord(Ctrl or Overflow); {Setting a bit masks the exception} X := 1e308; Y := X * X; Status := Get87StatusWord; Set87CtrlWord(Ctrl); if (Status and Overflow) 0 {A set bit indicates an exception} then WriteLn('Overflow flag set') else WriteLn('Overflow flag clear'); end.[dm] adds const StackFault = $40; StackOverflow = $200;These bits are supported in the 387 and up; together they indicate a stackoverflow (both set) or stack underflow (just StackFault).Zweitze de Vries<Z.A.deVries@et.tudelft.nl> addsWindows programmers who want to deal with floating point code arealways dealing with WIN87EM.DLL. This DLL manages the FP processor,and, when not available, emulates it.Explanation on this DLL, as well as exception handling, is explainedin WINFLO.ZIP. This technical article is on the MSN CD.2.6: Why do I always get the same randomnumbers every time I run my program?Software random number generators apply a function to aRandSeed which cycles the seed through its possible valuesin a quasi-random way. Each call to the random number generatordoes one iteration of the function, and returns a result based on thenew seed value.When your program loads, this seed will have some default value (probably0). If you do not change the seed, a series of calls to the randomnumber generator will yield the same series of "random" numbers everytime your program is run. (Obviously, this will make it easier totrack down the bugs!) Typically, the system clock is used to providea value for the random number seed: Even if a given task is alwaysrun at the same time of day, a difference of a few milliseconds is enoughto put a good random number generator in an entirely different part ofits sequence.In Borland Pascal, the command to randomize the seed is (surprise!)Randomize. Note that you should only call this routineonce per program, when it first loads, or at the very least at timesseparated by minutes or hours - calling it on every timer tick (say) willjust reset the 'random' sequence several times a second!Strings and Numbers3.1: How do I convert a string to a number?In Turbo/Borland Pascal, you can use the standard Val()procedure. The first argument is a string, and the second argument isa numeric variable which will be set to the numeric value representedby the string. The result variable can be any of the numeric types -from byte or ShortInt to comp orextended - the compiler will automagically pass thevariable's type to the Val() procedure.Val() is a procedure, not a function, which meansthat it does not return any sort of error code to indicate thatit couldn't set the result variable because eg the string was'Four score and seven' not '87', or because the stringwas '3.14159' and the result variable was a word,or even because '12261958' is too big for a wordvariable. Obviously, you do want to be able to find outwhether Val() was able to decode the string. This is where thethird parameter - an integer (or word) variable which willreceive a result code - comes in. If the result code is0, then the string represents a number which could be (and was) placed inthe result variable; a nonzero result code means that the string doesnot represent a compatible number: the result variable has not beenchanged, and the error code is the index of the first illegal characterin the string.Note that Val() and ReadLn() can handlehexadecimal numbers, using the $1234 format.3.2: How do I convert a number to a string?In Turbo/Borland Pascal, you can use the standard Str()procedure. The first argument is a number, and the second is a stringvariable which will be set to the formatted value. Just as withWrite() and WriteLn(), the number may(but does not have to) be followed by a colon and a width specifierand (for float point numbers) a second colon and a number of digitsafter the decimal point.Str() is a procedure, not a function, which makesit a lot harder to use than, say, WriteLn(). Obviously,it's pretty trivial to put a 'wrapper' around it so that you can writestring expressions like Fmt(Month,2) + DateSep + Fmt(Day,2) +DateSep + Fmt(Year,2): type NString = string[20]; function Fmt(N: LongInt; Width: word): NString; var Result: NString; begin Str(N: Width, Result); {A width of 0 is the same as no width at all} Fmt := Result; end;While Val() can read hex strings, there's no way to forceStr() to produce a hex string. For that, you canuse type HexString = string[8]; function HexFmt(Int: LongInt; Width: integer): HexString; const Hex: array[0..$000F] of char = '0123456789ABCDEF'; begin if (Width <= 1) and (Int and $FFFFFFF0 = 0) then HexFmt := Hex[Int] else HexFmt := HexFmt(Int shr 4, Width-1) + Hex[Int and $000F]; end;Breaking The 64K Limit4.1: I have 64K of global data andcan't add anymore - what do I do?What you have to do is to find the largest data structures. A good wayto do this is to look at a .map file with the addresses of "public"names, and look for large jumps between names. Often, a big jump flags a big variable. However, the .map file will not show any variables that are private to a unit, so a big jump may just indicate a lot of private variables within a unit. In that case, you'll have to look at the unit's source code to see what's taking up so much space.When you find your largest data structures, look at how they're used. (The cross-reference tool in the BP7 IDE is an excellent way to do this.) If they're only used in a single function or procedure, you can move them into that procedure's local variables section, which will get them out of the global data segment and onto the stack.Of course, this may now cause the stack to be too big. If so, or if the data are used in more than one place, you'll have to move the data structure onto the heap. To do this, you'll have to do three things:Replace a declaration like var BigVar: BigType; with var SmallVar: ^BigType;Change all references to BigVar to SmallVar^.Because BP is so fast, it's usually quite practical to just keep compilinguntil you get no more 'BigVar unknown' or 'need a ^' errors.Somewhere in your program initialization, before you ever execute any code that refers to SmallVar^, do a New(SmallVar); to allocate space on the heap.It's a good idea to get in the habit of using Dispose() whenever you no longer need the space you've allocated, but it's not strictly necessary, here: neither DOS nor Windows will 'lose' any memory that you allocate but don't free when your program terminates.One thing to keep in mind is that reading or writing (dereferencing) a pointer is slower than reading or writing a global or local variable, especially in protected mode. Generally, you shouldn't worry about this sort of thing except in bottleneck code but, where efficiency does matter, you should definitely replace a series of dereferences of the same pointer with a singlewith statement. (BP7 is significantly better at"peephole" optimization than its predecessors, but even in BP7 there arecases where a with PtrVar^ statement produces better codethan the equivalent series of 'raw' pointer statements. Certainlyreplacing multiple instances of Row[Idx]^ or evenRecordPtr^.RecordField with a single with willresult in smaller and faster code.)Finally, a word of admonition: You should use global data very sparingly. If you are pushing the 64K limit, and it's not all in a handful of large buffers, you're almost certainly using too many global variables. Obviously, global variables that are only used in one place waste space; less obviously, using global variables tends to produce bugs. A seemingly innocuous change to a variable here can have effects way over there. You can fight this sort of potentially crippling interdepence by explicitly passing parameters to a function, and explicitly returning results. It can be impossible to totally avoid writing code that has side-effects, but such code should be avoided as much as possible -- and always documented.4.2: Can I have more than 64K of global data inmy Windows program?Yes and no. Your .exe module can only have a single 64K data-and-stack segment, but each .dll has its own, up-to-64K data segment. Thus, if you run out of room in your global data segment, you can move some units and their global data into a DLL.There are two things to keep in mind if you do this:A call to a DLL is more expensive than a call within an EXE. Each call into a DLL swaps data segments on the way in and on the way out.If a user is running two or more copies of your program at the same time, each copy shares the code, but has its own copy of the .exe's global data. However, there will only be one copy of the .dll's global data, no matter how many copies of your application (or how many different applications) are using it.That is, any global variables in your .exe are a task resource; any global variables in a .dll are a system resource.4.3: How can I build an array bigger than64K?Break the array into two (types of) pieces: an array of row ptrs,and a set of rows on the heap. That is, replace type BigArrayType = array[0..Rows, 0..Cols] of DataType; var BigArray: BigArrayType;with type BigArrayRow = array[0..Cols] of DataType; BigArrayType = array[0..Rows] of ^ BigArrayRow; var BigArray: BigArrayTypeand replace any references toBigArray[Row, Col] with references toBigArray[Row]^[Col]. (As per the answer to4.1, don't forget to allocate memoryfor each row!)If performance isn't a major issue, you might well want to encapsulate the array behavior in an object. That is, instead of replacing BigArray[Row, Col] with BigArray[Row]^[Col], you would replace it with calls to BigArray.Get(Row, Col) or BigArray.Set(Row, Col, NewVal). While this is a bit slower than direct array references, the object (compiled) code is smaller and the source code is both easier to read and easier to change. If you need to add virtual memory (swapping to and from disk, EMS, or XMS) or to move your code to a 32-bit compiler, you would only have to change the object definitions, not every reference to your big array.(One way to maintain both modifiability and good performance is toreplace the array of row pointers with a function that returns a row pointer. Since you only need to call this once, no matter how many operations you're doing on the row, using your huge array might not be much slower than a normal array. Since the function can doanything from simply looking up a pointer in an array to swapping out theLeast Recently Used row and swapping in the one you need, you maintainflexibility.) If the array has a lot of rows, and the rows are not somemultiple of 8 (or 16 bytes) long, you might end up wasting a lot ofspace at the end of each row. If so, and if you're just barely runningout of room, you might want to New() a "multi-row" type, that consistsof an array of 8 (or 16) individual rows. This will eliminate the wastedpad bytes, and will only complicate your setup and teardown code: sincethe row pointer array will still point to the start of each individualrow, access to any individual array element will be no different than ifeach row is its own heap block.Of course, decomposing an array in this way only works if the array has two (or more) dimensions. See the next question if you have to deal with a one-dimensional data stream that's larger than 64K.4.4: How do I handle .BMP and/or .WAV fileswith more than 64K of data?There are two issues here: allocating a single heap block that's bigger than 64K,and accessing it. Both are significantly different inreal mode than inprotected mode.Real mode:In real mode, the primary issue is allocating the space: BP's heap manager won't let you allocate blocks bigger than 63 and a bit K-bytes. One approach is to simply rely on the current implementation's behavior and break your large heap request into multiple subrequests. If previous allocation and deallocation hasn't left the heap fragmented, back-to-back allocations will all be contiguous: The last byte of one will be just below the first byte of the next. This behavior is not guaranteed by Borland, though, and may change in future releases; similarly, if the heap is fragmented, back-to-back allocations will probably not be contiguous. A better approach is to restrict the size of the heap, and to use DOS services to allocate memory outside of your .exe's memory map.However you allocate it, you will still have to access it. In real mode, this is simply a matter of understanding that the segment part of a pointer is multiplied by 16 and added to the offset part to obtain a linear address within the first meg of memory. You can thus use a function like function RealPtrTo(Base: pointer; Offset: LongInt): pointer; {Note: This function has NOT been pulled from existing code and has NOT been tested. JDS, 30 September 1994} var Normal: record Segment, Offset: word; end; begin Normal.Segment := Seg(Base^) + Ofs(Base^) shr 4; Normal.Offset := Ofs(Base^) and $000F; {Normalise the Base pointer} Inc(Offset, Normal.Offset); {# bytes from start of Base seg} RealPtrTo := Ptr(Normal.Segment + Offset shr 4, Normal.Offset + Offset and $0000000F); end;to generate a pointer to any byte within your huge data structure. This pointer can then be used just as you use any other 16-bit pointer, to address an up-to-64K window within your huge data.Protected mode:In protected mode, allocation is easy, and access is hard. Just use GlobalAlloc() or GlobalAllocPtr() to allocate however much space you need. (Well, if your program is running in Windows standard mode, this had better be less than or equal to one meg.)Once you've allocated it, life continues to be easy - if you're using 386Enhanced Mode and a 32-bit compiler or assembler. The selector you getfrom GlobalAllocPtr can be used with any 32-bit offset within thedeclared size of the heap block. If you're using Standard Mode, or16-bit compilers like TPW or BP7, though, you'll have to work a bit.To start with, you can't do segment arithmetic: segments have beenreplaced with selectors, which are essentially indices into a system-global table of allocated segments. Doing arithmetic with selectors will either result in value that points to the wrong selector or (more likely) produce an invalid selector. In either case, using the resulting pointer will probably produce a General Protection Fault.This is a complicated subject that I've already covered elsewhere (see http://www.midnightbeach.com/jon/pubs/huge-model.htm for myPC Techniques article on huge model programming): All I'll say here is thatYou have to use SelectorInc to 'step' the selector fromone 64K window to the next, andYou can't make a single reference that starts in one 64K window and ends in the next.Procedural Types5.1: Can I make an indirect call to anobject's method, using a pointer or a procedural type?Yes, but you'll need to make aggressive use of casting,and to have a bit of background on just what a method call is.While method calls look and act very differently than normal calls -- the call looks like a reference to one of the object's fields, and there'sthe implicit with Self do that lets us refer to the object'sfields as if they were global variables -- at the level of words on the stack they're not all that different from a normal procedure or functioncall. All methods have an `invisible', or implicit, parameter,var Self, after any regular, or explicit, parameters;constructors and destructors also add an implicit wordparameter (the 16-bit VMT pointer) between the explicit parameters and Self. Also, while constructors act as if they return a boolean, they actually return a pointer which contains@ Self if Fail was not called, and Nil if itwas.The implicit parameters and the special handling of constructor results are the only differences between method calls and normal calls: there's no magic involved. If we simply define a procedural type, ProcType, that explicitly declares the method's implicitparameters after any normal parameters, we can then useProcType to cast any pointer variable to a proceduralvariable. Once it's cast, the pointer acts just like a normal procedural variable; we can assign it to another procedural variable or use it to call a procedure. Just as with a normal procedural type, the only difference between a direct and indirect call lies in the way we make the call: The parameters are pushed and popped in the same way; the called code operates just the same; and indirectly called methods have the same full access to their object's fields (through the Self pointer) as directly called methods do.Thus, if we have a method with no arguments and no results, we would simply make the declaration type Niladic = procedure (varSelf);. To use it, we remember that we can only cast pointervariables, not pointer expressions, and so do something like PtrVar:= @ ObjectType.Method; Niladic(PtrVar)(Self); Now, while thereis something strange looking about a cast (in parentheses) followed by an argument list (in parentheses), indirect method calls are typically rare and concentrated in a few key routines, even in programs that rely heavily on them. (My typical uses for indirect method calls involve things like executing a list of object/method pairs on every timer tick, or calling a window object's message handler after DMT lookup reveals that it does have a handler.) What's more, the strange look of an indirect method call does not translate into strange object code: Using a cast to a procedural type generates theexact same code as using an normal procedural type, and that's both alittle smaller and only slightly slower than a normal, direct procedureor function call.Methods that require parameters or that return results are only slightly different than our Niladic example above. We simply have to remember to put any explicit parameters before the implicit parameter(s). Thus, we might use type SimplePredicate = function (var Self): boolean;for a method that takes no arguments and returns a boolean, and typeUntypedDyadic = procedure (var A, B; var Self); for a method thatrequires two untyped memory references.Just as with a normal procedure call, the compiler will not let us make an indirect method call with the wrong number or type of arguments. This is obviously desirable behavior, but it's tempered with a bit of a caveat: When we make a cast, we are effectively telling the compiler that we know exactly what we are doing. If we accidentally use a pointer to a UntypedDyadic method as a Niladic, the compiler will neither require nor accept the two var parameters to the UntypedDyadic method but the procedure will probably use them and the result will not be pretty! Similarly, the compiler will not complain if youcast a data pointer or the address of a near routine into a procedural type: it will blithely generate code that will (at best!) crash yourcomputer.This answer is based on my [jds] articleThree MythsAbout Procedural Variables which originally appeared in theDec/Jan 1993 issue of PC Techniques.Windows Sound Programming6.1: Where can I find documentation onWindows sound programming?For a start, try MMSYSTEM.HLP, in your \bp\bindirectory.(The BP7 install program creates an icon for this in the BorlandPascal program group, but many people simply copy the BPW icon to aworking group, and zap the BP group. Then, when they want to do somesound programming, they find there is no mention of it in the onlinehelp file, and they don't know where to turn.)Unfortunately, MMSYSTEM.HLP only contains part of material inthe SDK's Multimedia Programmer's Reference. Piecing together thesequence of steps to properly open a MIDI or WAV device from the helpfile can be tough! I strongly recommend the SDK - or, better, the DevNet CD.Delphi and/or BP87.1: What about Delphi?At the time of this writing, Delphi groups are still being voted on. In themeantime, please post your Delphi questions incomp.lang.pascal.misc, not here incomp.lang.pascal.borland. Yes, I know this is silly - Delphi is a BorlandPascal product - but if you post your Delphi questions here, you'll just givesome stupid twits yet another excuse to flame.7.2: Will there be a BP8?Why are you asking me? I don't work for Borland!But, this sure is a FAQ, so here's my opinion:No way!Anders Hjeilsberg is undoubtedly a genius, but even he can be spreadtoo thin.Since Delphi can compile TPW and BP7 Windows programs, the only real point to aBP8 would be DOS support. I doubt there's enough demand to justify the expense ofreleasing even as easy a BP8 as the Delphi compiler with the BP7 DOS IDE.Other Pascal ResourcesProfessor Timo Salmi(ts@uwasa.fi) of the University ofVaasa in Finland maintains a Turbo Pascal archives, which includes bothsource code and a Turbo Pascal FAQfile. You can find these by ftp-ing to garbo.uwasa.fi andlooking in the /pc/ts directory.I have written a number of articles on Turbo Pascal esoterica. An online bibliography is available via the World Wide Web at http://www.midnightbeach.com/jon/pubs.Some of the actual articles are also availableonline and I can post most of the others on request.I heartily recommend Microsoft'sDevNet CD. It's not exactly aPascal resource, but many of thequestions on comp.lang.pascal these days have to do with Windowsprogramming. The CD includes not only the referencematerial in the .HLP files but also electronic copies of the SDK'sprogrammer's guides; Petzold's Programming Windows 3.1; DOSand hardware references; and much, much more. Best of all, it'tensively indexed, so it's very easy to find the answers to yourquestions. If you're at all serious about Windows programming, get aCD-ROM drive and this CD. (For somewhat more info, you can see theon-line version of the review I wrote for PC Techniques athttp://www.midnightbeach.com/jon/pubs/DevNet-CD.htm).Runtime Error 200 when using CRT unit on fast computersThe CRT unit has a 'speed-independent' Delay() routine thatworks pretty well on machines from a 4.77MHz 8088 to all the way up to Pentiumsrunning at nearly 200 MHz. Above that speed, though, programs using the CRTunit give a Runtime Error 200 (division by 0) error when they start running.The reason for this error is that the CRT unit's initialization code'tares' the CPU speed by seeing how many iterations of an empty loop it can runbetween one clock tick and the next. This lets it calculate how many empty loopsit needs for each millisecond of Delay(). The problem is that on fastmachines, the very large number of idle loops the machine can do in 55 millisecondsdivided by 55 is too big a number to fit in a 16-bit register. The processor throwsthe same exception (interrupt) for overflow as for division by 0, so the errorsurfaces as a Runtime Error 200.For more information: http://www.merlyn.demon.co.uk/pas-r200.htmFor patches: http://www.geocities.com/SiliconValley/2926/tp_pat.htmlJon Shemitz -jon@midnightbeach.com -30-Sep-94..22-Jan-99 |
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