Data type problem
ralf.corsepius at rtems.org
Mon Oct 15 10:23:09 CDT 2007
On Mon, 2007-10-15 at 15:15 +0200, Juergen Zeller wrote:
> try things like this:
> typedef signed char int8;
> typedef unsigned char uint8;
> typedef signed short int16;
> typedef unsigned short uint16;
> typedef signed int int32;
> typedef unsigned int uint32;
> typedef signed long long int64;
> typedef unsigned long long uint64;
These are (POSIX, ANSII, ISO, C99) standardized types you are not
supposed to define/typedef.
As Joel already wrote: #include <stdint.h>
> typedef unsigned char byte;
> typedef unsigned short int word;
> typedef unsigned int dword;
If you really need fixed size types, use uint8_t, uint16_t etc.
If you need a "byte" (in the sense of "minimal addressable machine
unit") use "signed char" or "unsigned char".
If you need 8-bit types, use uint8_t rsp. int8_t.
Though on most modern architectures the assumptions of "char == byte ==
8bit" etc. apply, there is no guarantee that they really are.
Esp. on embedded targets these occasionally do NOT apply.
E.g. in RTEMS, we have several architectures for which "int == 16bit"
applies, and we have one architecture for which
"char == short == int == 32bit" applies.
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