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DO*S to U$nix C environment

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Jul 28, 2001
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DO*S to U$nix C

I have some C programs which were used in DOS environment. Now I want to use these C programs in Unix environment. When I use them I am getting a totally a different result. My guess was that the data format ie, little indian and big indian is the cause for the wrong results, but I am not sure, can anyone confirm this. If so then is there any tool through which I can convert my DOS based C code to unix based c code.

Check that all constants are type defined. I mean, specify its type. For example:

#define some_constant 5L

Also verify all types (int, long, etc) are defined with the same number of bytes in your DOS and UNIX compilers.

I remember that in the C newsgroup Faq was this issue very well comented. Look for it.

Nevertheless, as a last resort you can always use dosemu...

The major problem won't be endian-ness (unless your unix machine uses a non-intel processor architecture) but merely the migration of 16-bit-code to 32-bit-code. The "processor" used on machines running DOS, the awful 8086, used to split memory in segments, each one being 64k in size and being nearly the same as the next one, merely shifted by 16 byte.
Thus the segmented address 0x1230:0x0010 is effectively the same address as 0x1231:0x000
or 0x122F:0x0020

Due to this fucked-up memory addressing scheme, 16-bit 8086 applications did some really strange stuff, which is difficult to port to machines having "straight" non-segmented memory access.

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