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Hi,
My problem is that I have integer constants coded as compile-time constant floating equations to avoid having to use the floating point library... let me explain...
Take some code that does not use floating point operations - say:
void main(void) { unsigned int i = 1000; for (; i; i--) ; }
Under Projects / Options / C/C++ / Misc Controls: add the directive:
--fpu=none
since we don't need FPU support.
Like this, the program will compile.
Now, ask the compiler to do some compile-time floating-point calculation that results in an integer - insert at head of file:
unsigned int j = (unsigned int)(1.0*3.0);
The RealView compiler refuses to compile the line, even though we don't need FP support at run-time.
Is there a way round this?
#define DAC_const (15.0/255) #define VPP_5V (BYTE)((5.0/DAC_const)+0.5) #define VPP_12V (BYTE)((12.0/DAC_const)+0.5) #define VPP_OFF (BYTE)((0.0/DAC_const)+0.5
Because of this limitation, the code has to be written:
#define VPP_5V (BYTE)(85U) #define VPP_12V (BYTE)(204U) #define VPP_OFF (BYTE)(0U)
which is not as good.
If you changed the definitions to the following they would be the same as the floating point versions
#define VPP_5V (BYTE)(86U) //(BYTE)((5.0/DAC_const)+0.5) evaluates to 86 not 85 #define VPP_12V (BYTE) (205U) #define VPP_OFF (BYTE) (1U) #define ONE_OVER_DAC_CONSTANT (17U) // Because 1 / DAC_const is an exact integer (17) , you could do 5 * 17 and just add 1 because you are rounding up.
Sorry I believe I got my "rounding" (or truncating) wrong. But these numbers do come out to be EXACT integers. There should be no need to use floating point.