But it is not -1.ffff it is -0.0001
In 16:16 fixed point:
0.5 is represented by 0x00008000; 1.0 is represented by 0x00010000; -1 is represented by 0xffff0000. -1.5 is represented by 0xffff8000.
This again highlights the issue:
#include <stdio.h>
void main( void )
{
int i = 0xffff8000;
printf( "%d\n", i >> 16 );
printf( "%d\n", i / 0x10000 );
}The shift gives the result of -1, the divide gives 0.
You can do it with a divide, but it's ugly and only really works for the 16:16 case: (short)((unsigned int)i / 0x10000). The problem with the divide method is you need to do an unsigned divide with a sign extended result.
Phill
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