What is the fastest way to convert a vector of size 4 into a 32 bit float?
My failed attempt:
static bool vec2float32(std::vector<uint8_t> bytes, float &result)
{
if(bytes.size() != 4) return false;
uint8_t sign = (bytes.at(0) & 0x10000000); //will be 1 or 0
uint8_t exponent = (bytes.at(0) & 0x01111111);
uint16_t mantissa = (bytes.at(1) << (2*8)) + (bytes.at(2) << (1*8)) + (bytes.at(3) << (0*8));
result = (2^(exponent - 127)) * mantissa;
if(sign == 1) result = result * -1;
return true;
}
I believe this should be the fastest:
return *reinterpret_cast<float*>(&bytes[0]);
I think its technically undefined behavior. But most compilers should output what you expect here. The &bytes[0] is guaranteed to work because std::vector is guaranteed to be contiguous.
From the vector you can get a pointer to the first byte. If the bytes are already in the correct order, then you can copy the bytes directly into a float
variable.
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