no bug
the comparison is being done correctly. the type is Char - this means signed.
#defines are replaced by value at preprocessing time. integer constant
type is assumed to be int
comparing into to char, of course causes char to be extended, as you see
however if the char is 0xFF, it gets extended to 0xFFFF, meaning it
will not be equal to 0xFF
if you want this comparaison to work, change the define to be "-1",
change the type to be "unsigned Char", or change the comparaison to
cast it to unsigned char
On 4/10/08, Luc Le Blanc <[EMAIL PROTECTED]> wrote:
> I have a position union:
>
> typedef struct
> {
> UInt8 type;
> UInt8 datum;
>
> union
> {
> struct
> {
> Int16 altitude;
> UInt32 northing;
> UInt32 easting;
> Char zone;
> UInt8 gore;
>
> } grid;
>
> struct
> {
> Int16 altitude;
> UInt32 latitude;
> UInt32 longitude;
> Boolean south;
> Boolean east;
>
> } latLon;
>
> Int16 altitude;
>
> Int16 depth;
>
> struct
> {
> float x, y, z;
>
> } absolute;
>
> struct
> {
> Int16 altitude;
> UInt16 unused;
> float x, y;
>
> } spot;
> };
> } Position;
>
> I use the grid case. Both zone and gore contain 0xff (as seen in debugger).
>
> I have a symbol:
>
> #define Undefined 0xff
>
> yet, when I hit
>
> if ( position->grid.zone == Undefined )
> StrPrintF( string, "X %ld%sY %ld",
> ( position->grid.easting + 50 ) / 100, separator,
> ( position->grid.northing + 50 ) / 100 );
>
> the StrPrintF is skipped. Here's the assembler:
>
> 00000214: 102A 000C move.b 12(a2),d0
> 00000218: 4880 ext.w d0
> 0000021A: 0C40 00FF cmpi.w #255,d0
> 0000021E: 6632 bne.s *+52 ; 0x00000252
>
> Go figure.
>
>
> Luc Le Blanc
>
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--
Best Regards,
Dmitry Grinberg
(847) 226 9295
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