/
fmt.go
66 lines (48 loc) · 1.32 KB
/
fmt.go
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package period
import (
"errors"
"unsafe"
"github.com/akramarenkov/safe"
)
var (
ErrNumberBaseIsZero = errors.New("number base is zero")
)
func formatFractional(
number int64,
numberBase uint,
fractionalSize uint,
fractionalSeparator byte,
) (string, error) {
buffer := make([]byte, 1+fractionalSize)
digits := buffer[1:]
buffer[0] = fractionalSeparator
if numberBase == 0 {
return "", ErrNumberBaseIsZero
}
powered, err := safe.PowUnsigned(numberBase, fractionalSize)
if err != nil {
return "", ErrValueOverflow // For backward compatibility
}
divisor, err := safe.UnsignedToSigned[uint, int64](powered)
if err != nil {
return "", ErrValueOverflow // For backward compatibility
}
base, err := safe.UnsignedToSigned[uint, int64](numberBase)
if err != nil {
return "", ErrValueOverflow // For backward compatibility
}
// cut off an integer part of the number
integer := number / divisor
number -= integer * divisor
for id := range digits {
divisor /= base
digit := number / divisor
number -= digit * divisor
// we can't get this error because above we cut off integer part of the number
symbol, _ := digitToSymbol(digit)
digits[id] = symbol
}
formated := unsafe.String(unsafe.SliceData(buffer), len(buffer))
cleared := clearFractional(formated, fractionalSeparator)
return cleared, nil
}