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/// @ref gtx_integer
namespace glm
{
// pow
GLM_FUNC_QUALIFIER int pow(int x, uint y)
{
if(y == 0)
return x >= 0 ? 1 : -1;
int result = x;
for(uint i = 1; i < y; ++i)
result *= x;
return result;
}
// sqrt: From Christopher J. Musial, An integer square root, Graphics Gems, 1990, page 387
GLM_FUNC_QUALIFIER int sqrt(int x)
{
if(x <= 1) return x;
int NextTrial = x >> 1;
int CurrentAnswer;
do
{
CurrentAnswer = NextTrial;
NextTrial = (NextTrial + x / NextTrial) >> 1;
} while(NextTrial < CurrentAnswer);
return CurrentAnswer;
}
// Henry Gordon Dietz: http://aggregate.org/MAGIC/
namespace detail
{
GLM_FUNC_QUALIFIER unsigned int ones32(unsigned int x)
{
/* 32-bit recursive reduction using SWAR...
but first step is mapping 2-bit values
into sum of 2 1-bit values in sneaky way
*/
x -= ((x >> 1) & 0x55555555);
x = (((x >> 2) & 0x33333333) + (x & 0x33333333));
x = (((x >> 4) + x) & 0x0f0f0f0f);
x += (x >> 8);
x += (x >> 16);
return(x & 0x0000003f);
}
}//namespace detail
// Henry Gordon Dietz: http://aggregate.org/MAGIC/
/*
GLM_FUNC_QUALIFIER unsigned int floor_log2(unsigned int x)
{
x |= (x >> 1);
x |= (x >> 2);
x |= (x >> 4);
x |= (x >> 8);
x |= (x >> 16);
return _detail::ones32(x) >> 1;
}
*/
// mod
GLM_FUNC_QUALIFIER int mod(int x, int y)
{
return ((x % y) + y) % y;
}
// factorial (!12 max, integer only)
template<typename genType>
GLM_FUNC_QUALIFIER genType factorial(genType const& x)
{
genType Temp = x;
genType Result;
for(Result = 1; Temp > 1; --Temp)
Result *= Temp;
return Result;
}
template<typename T, qualifier Q>
GLM_FUNC_QUALIFIER vec<2, T, Q> factorial(
vec<2, T, Q> const& x)
{
return vec<2, T, Q>(
factorial(x.x),
factorial(x.y));
}
template<typename T, qualifier Q>
GLM_FUNC_QUALIFIER vec<3, T, Q> factorial(
vec<3, T, Q> const& x)
{
return vec<3, T, Q>(
factorial(x.x),
factorial(x.y),
factorial(x.z));
}
template<typename T, qualifier Q>
GLM_FUNC_QUALIFIER vec<4, T, Q> factorial(
vec<4, T, Q> const& x)
{
return vec<4, T, Q>(
factorial(x.x),
factorial(x.y),
factorial(x.z),
factorial(x.w));
}
GLM_FUNC_QUALIFIER uint pow(uint x, uint y)
{
if (y == 0)
return 1u;
uint result = x;
for(uint i = 1; i < y; ++i)
result *= x;
return result;
}
GLM_FUNC_QUALIFIER uint sqrt(uint x)
{
if(x <= 1) return x;
uint NextTrial = x >> 1;
uint CurrentAnswer;
do
{
CurrentAnswer = NextTrial;
NextTrial = (NextTrial + x / NextTrial) >> 1;
} while(NextTrial < CurrentAnswer);
return CurrentAnswer;
}
GLM_FUNC_QUALIFIER uint mod(uint x, uint y)
{
return x - y * (x / y);
}
#if(GLM_COMPILER & (GLM_COMPILER_VC | GLM_COMPILER_GCC))
GLM_FUNC_QUALIFIER unsigned int nlz(unsigned int x)
{
return 31u - findMSB(x);
}
#else
// Hackers Delight: http://www.hackersdelight.org/HDcode/nlz.c.txt
GLM_FUNC_QUALIFIER unsigned int nlz(unsigned int x)
{
int y, m, n;
y = -int(x >> 16); // If left half of x is 0,
m = (y >> 16) & 16; // set n = 16. If left half
n = 16 - m; // is nonzero, set n = 0 and
x = x >> m; // shift x right 16.
// Now x is of the form 0000xxxx.
y = x - 0x100; // If positions 8-15 are 0,
m = (y >> 16) & 8; // add 8 to n and shift x left 8.
n = n + m;
x = x << m;
y = x - 0x1000; // If positions 12-15 are 0,
m = (y >> 16) & 4; // add 4 to n and shift x left 4.
n = n + m;
x = x << m;
y = x - 0x4000; // If positions 14-15 are 0,
m = (y >> 16) & 2; // add 2 to n and shift x left 2.
n = n + m;
x = x << m;
y = x >> 14; // Set y = 0, 1, 2, or 3.
m = y & ~(y >> 1); // Set m = 0, 1, 2, or 2 resp.
return unsigned(n + 2 - m);
}
#endif//(GLM_COMPILER)
}//namespace glm
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