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From: bright@Data-IO.COM (Walter Bright)
Newsgroups: comp.lang.c++,comp.lang.c
Subject: Re: Zortech "limitation"
Message-ID: <2328@dataio.Data-IO.COM>
Date: 12 Feb 90 20:00:08 GMT
References: <4895d648.20b6d@apollo.HP.COM>
Reply-To: bright@Data-IO.COM (Walter Bright)
Followup-To: comp.lang.c++
Distribution: usa
Organization: Data I/O Corporation; Redmond, WA
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Newsgroups: comp.lang.c++,comp.lang.c
Subject: Re: Zortech "limitation"
Summary: 
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References: <48910321.20b6d@apollo.HP.COM>
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Reply-To: bright@Data-IO.COM (Walter Bright)
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Distribution: usa
Organization: Data I/O Corporation; Redmond, WA
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In article <48910321.20b6d@apollo.HP.COM> nelson_p@apollo.HP.COM (Peter Nelson) writes:
<  But I DO need to handle large, 2-dimensional arrays
<  and Zortech seems to have a problem with that.
<  The problem is that my total global memory will exceed 
<  64K, although I am grudgingly willing to settle for having
<  no *one* array exceed that size if that would help here.

Instead of having:
	int array[N][M];	/* array of N columns		*/
try:
	int (*array[N])[M];	/* array of N pointers to columns */

	/* Create the columns	*/
	for (i = 0; i < N; i++)
		array[i] = (int (*)[M])malloc(sizeof(int [M]));

	#define array_access(i,j)	((*array[i])[j])

(I wrote this off the cuff, so it may have a syntax error, but I've done
this before and it works fine. In fact, it is *faster* than doing huge
arithmetic.)

<  If I wanted to do pointer arithmetic all over the place I would
<  use Assembler!   Zortech C/C++ is allegedly a high-level language
<  but their manual describes this as a "limitation" of their product.
<  I would call it a bug. 

There's no assembler in the example above. One man's bug is another's feature.
C is not a high-level language, it's a "portable assembler", thus the
limitations and capabilities of the underlying instruction set are
reflected in the source code. I occasionally get "bug" reports that the
compiler does not make the PC look like a VAX.

<  PS-  The Arlington office mentioned a Zortech BBS in Washington
<       state which I dialed and got a carrier, but for some reason 
<       I couldn't talk to it.

The phone number is (206) 822-6907. The BBS works fine, and has been for
years. It gets heavy use. It uses a Hayes 2400 baud external modem. I
suggest you try again.