Please try to compile your code with all warnings and debug info (e.g. with g++ -Wall -g
on Linux) and to improve it till no warnings are given. Learn to use the debugger (i.e. gdb
on Linux)
I would guess that the fault is probably at
float rgbf = *reinterpret_cast<float*>(&rgb);
because this may trigger a fault if rgb
(i.e. uint32_t
) and float
don't have the same alignment or size constraints. Some systems (processors, ABIs, compilers) may have different & incompatible constraints for them.
BTW, your code works well with GCC 4.7 on Debian/GNU/Linux/x86-64 invoked as
g++-4.7 -std=c++11 -Wall -g ramji.cc -o ramji
when I have
#include <cstdint>
#include <iostream>
int main(int argc, char**argv)
{
uint32_t r,g,b;
r = (uint32_t)145;
g = (uint32_t)131;
b = (uint32_t)139;
std::cout << "r=" << r << " g=" << g << " b=" << b << std::endl;
uint32_t rgb = ((uint32_t)r << 16 | (uint32_t)g << 8 | (uint32_t)b);
std::cout << "rgb=" << rgb << std::endl;
float rgbf = *reinterpret_cast<float*>(&rgb);
std::cout << "rgbf=" << rgbf << std::endl;
uint32_t rgbnew = *(reinterpret_cast<uint32_t *>(&rgbf));
std::cout << "rgbnew=" << rgb << std::endl;
uint8_t rnew = (rgbnew >> 16) & 0x0000ff;
uint8_t gnew = (rgbnew >> 8) & 0x0000ff;
uint8_t bnew = (rgbnew) & 0x0000ff;
std::cout << "rnew=" << rnew << " gnew=" << gnew
<< " bnew=" << bnew << std::endl;
return 0;
}
No warnings, no crashes at execution.
Notice that <cstdint>
requires a C++11 conforming compiler.