Subj : IEEE-754 and Borland C5.2 issue
To   : borland.public.cpp.borlandcpp
From : schears@hotpop.com (GooglePoster)
Date : Thu Sep 04 2003 01:49 pm

Hello,
I wish to be able to use Borland C++5.2 to create a 16 bit DOS
application that reads IEEE-754 data in hex format and compares it to
a decimal value, and then convert the decimal value back into
IEEE-754.

I can do this under Microsoft VisualC++ 6.0 by creating a DOS app, but
find out that Borland has some restrictions that I can not seem to
work around.
In ConvertDataFrame() the right shift by 24 causes the ASCII value to
be placed into the buffer, versus the actual raw hex value.

Any suggestions?
Thank you,

A copy of the code appears:

#include <stdio.h>

unsigned char Buffer[] = {0,0,0x80,0x3f,0,0,0xc8,0x42};
unsigned char TestBuffer[9];
void ConvertData(void);
void ConvertDataFrame(void);
char MatchFound = 0;
long Min = 1, Max = 100;
float FloatMin, FloatMax;

union RANGE_CONVERT
{
    float RangeValue;
#ifdef __BORLANDC__
    long IntData;
#else
    int IntData;
#endif
} ;

//union RANGE_CONVERT var2;   // C declaration of a union variable
//RANGE_CONVERT var3;         // C++ declaration of a union variable
#ifdef __BORLANDC__
union RANGE_CONVERT RangeMin;
union RANGE_CONVERT RangeMax;
#else
RANGE_CONVERT RangeMin;
RANGE_CONVERT RangeMax;
#endif

int main()
{
	ConvertData();
	FloatMin = (float)Min;
	FloatMax = (float)Max;
    if ((RangeMin.RangeValue == FloatMin) && (RangeMax.RangeValue ==
FloatMax))
		MatchFound = 1;
    ConvertDataFrame();
	return(1);
}

void ConvertData()
{
    RangeMin.IntData = 0;
    RangeMin.IntData = ((long)Buffer[3] << 24);
    RangeMin.IntData |= ((long)Buffer[2] << 16);
    RangeMin.IntData |= ((long)Buffer[1] << 8);
    RangeMin.IntData |= ((long)Buffer[0]);
    //RangeMin.IntData = 3f800000
    RangeMax.IntData = 0;
    RangeMax.IntData = ((long)Buffer[7] << 24);
    RangeMax.IntData |= ((long)Buffer[6] << 16);
    RangeMax.IntData |= ((long)Buffer[5] << 8);
    RangeMax.IntData |= ((long)Buffer[4]);
    //RangeMax.IntData = 42c80000

return;
}

void ConvertDataFrame()
{
    TestBuffer[0] = (unsigned char)(RangeMin.IntData);
    TestBuffer[1] = (unsigned char)(RangeMin.IntData >> 8);
    TestBuffer[2] = (unsigned char)(RangeMin.IntData >> 16);
    // Borland causes this value to be placed as an ASCII
character(0x3f = '?') in to the buffer...WHY?
    TestBuffer[3] = (unsigned char)(RangeMin.IntData >> 24);
    TestBuffer[4] = (unsigned char)(RangeMax.IntData);
    TestBuffer[5] = (unsigned char)(RangeMax.IntData >> 8);
    TestBuffer[6] = (unsigned char)(RangeMax.IntData >> 16);
    // Borland causes this value to be placed as an ASCII
character(0x42 = 'B') in to the buffer...WHY?
    TestBuffer[7] = (unsigned char)(RangeMax.IntData >> 24);

return;
}

.