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GUI: Handle standard/scientific notation. Exponents > 308 are bugged. 

Replacement for Float128 pending.
This commit is contained in:
Nukem 2016-01-12 23:28:55 -05:00
parent d550d3e264
commit c3b6c470ee
1 changed files with 41 additions and 9 deletions
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50
src/gui/Src/Utils/StringUtil.cpp
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@ -13,8 +13,11 @@ QString ToLongDoubleString(void* buffer)
const uint64_t HIGHBIT = (uint64_t)1 << 63;
const uint64_t QUIETBIT = (uint64_t)1 << 62;
// Convert to pointer of array of bytes
uint8_t* bytes = (uint8_t*)buffer;
// Swap endianness (buffer is an array of bytes; not a true variable)
uint8_t bytes[10];
for(size_t k = 0; k < 10; k++)
bytes[k] = ((uint8_t*)buffer)[10 - k - 1];
// Extract exponent and mantissa
uint16_t exponent = *(uint16_t*)&bytes[8];
@ -26,17 +29,13 @@ QString ToLongDoubleString(void* buffer)
switch(exponent)
{
// Default: exponent is ignored
default:
break;
// If exponent zero
case 0:
{
if((mantissa & HIGHBIT) == 0)
{
if((mantissa & QUIETBIT) == 0)
return (sign) ? "-0.0" : "0.0";
return (sign) ? "-0.000000000000000000" : "0.000000000000000000";
}
// Everything else psuedo denormal
@ -75,6 +74,19 @@ QString ToLongDoubleString(void* buffer)
return "NAN";
}
break;
// Default: exponent has maximum ranges
default:
{
// e+4932
if((exponent - EXP_BIAS) > 4932)
return "INF";
// e-4931
if((exponent - EXP_BIAS) < -4931)
return "-INF";
}
break;
}
// Convert both numbers to 128 bit types
@ -87,12 +99,32 @@ QString ToLongDoubleString(void* buffer)
dd_real significand = dd_mantissa / dd_divisor;
dd_real exp = pown(2, exponent - EXP_BIAS);
// Calculate final result with sign
if(std::isnan(exp))
return "NAN";
significand *= exp;
// Determine flags for rounding between scientific notation and standard notation (billions)
std::ios_base::fmtflags fmt = 0;
int digits = 19;
int leadingDigits = 0;
// Determine number of leading zeroes with log (log(0) is undefined)
if(significand == dd_real(0))
leadingDigits = 0;
else
leadingDigits = std::floor(std::log10(significand)).toInt() + 1;
if(leadingDigits <= 10 && leadingDigits >= -4)
{
fmt = std::ios_base::fixed;
digits = 20 - leadingDigits;
}
// Signed-ness
if(sign)
significand *= -1;
// Print result
return QString::fromStdString(significand.to_string(16));
return QString::fromStdString(significand.to_string(digits, 0, fmt));
}