1.6. Integer Intrinsics
This section describes integer intrinsic functions that are only supported in device code.
Functions
- __device__ unsigned int __brev ( unsigned int x )
- Reverse the bit order of a 32 bit unsigned integer.
- __device__ unsigned long long int __brevll ( unsigned long long int x )
- Reverse the bit order of a 64 bit unsigned integer.
- __device__ unsigned int __byte_perm ( unsigned int x, unsigned int y, unsigned int s )
- Return selected bytes from two 32 bit unsigned integers.
- __device__ int __clz ( int x )
- Return the number of consecutive high-order zero bits in a 32 bit integer.
- __device__ int __clzll ( long long int x )
- Count the number of consecutive high-order zero bits in a 64 bit integer.
- __device__ int __ffs ( int x )
- Find the position of the least significant bit set to 1 in a 32 bit integer.
- __device__ int __ffsll ( long long int x )
- Find the position of the least significant bit set to 1 in a 64 bit integer.
- __device__ int __hadd ( int , int )
- Compute average of signed input arguments, avoiding overflow in the intermediate sum.
- __device__ int __mul24 ( int x, int y )
- Calculate the least significant 32 bits of the product of the least significant 24 bits of two integers.
- __device__ long long int __mul64hi ( long long int x, long long int y )
- Calculate the most significant 64 bits of the product of the two 64 bit integers.
- __device__ int __mulhi ( int x, int y )
- Calculate the most significant 32 bits of the product of the two 32 bit integers.
- __device__ int __popc ( unsigned int x )
- Count the number of bits that are set to 1 in a 32 bit integer.
- __device__ int __popcll ( unsigned long long int x )
- Count the number of bits that are set to 1 in a 64 bit integer.
- __device__ int __rhadd ( int , int )
- Compute rounded average of signed input arguments, avoiding overflow in the intermediate sum.
- __device__ unsigned int __sad ( int x, int y, unsigned int z )
- Calculate , the sum of absolute difference.
- __device__ unsigned int __uhadd ( unsigned int, unsigned int )
- Compute average of unsigned input arguments, avoiding overflow in the intermediate sum.
- __device__ unsigned int __umul24 ( unsigned int x, unsigned int y )
- Calculate the least significant 32 bits of the product of the least significant 24 bits of two unsigned integers.
- __device__ unsigned long long int __umul64hi ( unsigned long long int x, unsigned long long int y )
- Calculate the most significant 64 bits of the product of the two 64 unsigned bit integers.
- __device__ unsigned int __umulhi ( unsigned int x, unsigned int y )
- Calculate the most significant 32 bits of the product of the two 32 bit unsigned integers.
- __device__ unsigned int __urhadd ( unsigned int, unsigned int )
- Compute rounded average of unsigned input arguments, avoiding overflow in the intermediate sum.
- __device__ unsigned int __usad ( unsigned int x, unsigned int y, unsigned int z )
- Calculate , the sum of absolute difference.
Functions
- __device__ unsigned int __brev ( unsigned int x )
-
Reverse the bit order of a 32 bit unsigned integer. Reverses the bit order of the 32 bit unsigned integer x.
Returns
Returns the bit-reversed value of x. i.e. bit N of the return value corresponds to bit 31-N of x.
- __device__ unsigned long long int __brevll ( unsigned long long int x )
-
Reverse the bit order of a 64 bit unsigned integer. Reverses the bit order of the 64 bit unsigned integer x.
Returns
Returns the bit-reversed value of x. i.e. bit N of the return value corresponds to bit 63-N of x.
- __device__ unsigned int __byte_perm ( unsigned int x, unsigned int y, unsigned int s )
-
Return selected bytes from two 32 bit unsigned integers. byte_perm(x,y,s) returns a 32-bit integer consisting of four bytes from eight input bytes provided in the two input integers x and y, as specified by a selector, s.
The input bytes are indexed as follows: input[0] = x<7:0> input[1] = x<15:8> input[2] = x<23:16> input[3] = x<31:24> input[4] = y<7:0> input[5] = y<15:8> input[6] = y<23:16> input[7] = y<31:24> The selector indices are as follows (the upper 16-bits of the selector are not used): selector[0] = s<2:0> selector[1] = s<6:4> selector[2] = s<10:8> selector[3] = s<14:12>
Returns
The returned value r is computed to be: result[n] := input[selector[n]] where result[n] is the nth byte of r.
- __device__ int __clz ( int x )
-
Return the number of consecutive high-order zero bits in a 32 bit integer. Count the number of consecutive leading zero bits, starting at the most significant bit (bit 31) of x.
Returns
Returns a value between 0 and 32 inclusive representing the number of zero bits.
- __device__ int __clzll ( long long int x )
-
Count the number of consecutive high-order zero bits in a 64 bit integer. Count the number of consecutive leading zero bits, starting at the most significant bit (bit 63) of x.
Returns
Returns a value between 0 and 64 inclusive representing the number of zero bits.
- __device__ int __ffs ( int x )
-
Find the position of the least significant bit set to 1 in a 32 bit integer. Find the position of the first (least significant) bit set to 1 in x, where the least significant bit position is 1.
Returns
Returns a value between 0 and 32 inclusive representing the position of the first bit set.
- __ffs(0) returns 0.
- __device__ int __ffsll ( long long int x )
-
Find the position of the least significant bit set to 1 in a 64 bit integer. Find the position of the first (least significant) bit set to 1 in x, where the least significant bit position is 1.
Returns
Returns a value between 0 and 64 inclusive representing the position of the first bit set.
- __ffsll(0) returns 0.
- __device__ int __hadd ( int , int )
-
Compute average of signed input arguments, avoiding overflow in the intermediate sum. Compute average of signed input arguments x and y as ( x + y ) >> 1, avoiding overflow in the intermediate sum.
Returns
Returns a signed integer value representing the signed average value of the two inputs.
- __device__ int __mul24 ( int x, int y )
-
Calculate the least significant 32 bits of the product of the least significant 24 bits of two integers. Calculate the least significant 32 bits of the product of the least significant 24 bits of x and y. The high order 8 bits of x and y are ignored.
Returns
Returns the least significant 32 bits of the product x * y.
- __device__ long long int __mul64hi ( long long int x, long long int y )
-
Calculate the most significant 64 bits of the product of the two 64 bit integers. Calculate the most significant 64 bits of the 128-bit product x * y, where x and y are 64-bit integers.
Returns
Returns the most significant 64 bits of the product x * y.
- __device__ int __mulhi ( int x, int y )
-
Calculate the most significant 32 bits of the product of the two 32 bit integers. Calculate the most significant 32 bits of the 64-bit product x * y, where x and y are 32-bit integers.
Returns
Returns the most significant 32 bits of the product x * y.
- __device__ int __popc ( unsigned int x )
-
Count the number of bits that are set to 1 in a 32 bit integer. Count the number of bits that are set to 1 in x.
Returns
Returns a value between 0 and 32 inclusive representing the number of set bits.
- __device__ int __popcll ( unsigned long long int x )
-
Count the number of bits that are set to 1 in a 64 bit integer. Count the number of bits that are set to 1 in x.
Returns
Returns a value between 0 and 64 inclusive representing the number of set bits.
- __device__ int __rhadd ( int , int )
-
Compute rounded average of signed input arguments, avoiding overflow in the intermediate sum. Compute average of signed input arguments x and y as ( x + y + 1 ) >> 1, avoiding overflow in the intermediate sum.
Returns
Returns a signed integer value representing the signed rounded average value of the two inputs.
- __device__ unsigned int __sad ( int x, int y, unsigned int z )
-
Calculate , the sum of absolute difference. Calculate , the 32-bit sum of the third argument z plus and the absolute value of the difference between the first argument, x, and second argument, y.
Inputs x and y are signed 32-bit integers, input z is a 32-bit unsigned integer.
Returns
Returns .
- __device__ unsigned int __uhadd ( unsigned int, unsigned int )
-
Compute average of unsigned input arguments, avoiding overflow in the intermediate sum. Compute average of unsigned input arguments x and y as ( x + y ) >> 1, avoiding overflow in the intermediate sum.
Returns
Returns an unsigned integer value representing the unsigned average value of the two inputs.
- __device__ unsigned int __umul24 ( unsigned int x, unsigned int y )
-
Calculate the least significant 32 bits of the product of the least significant 24 bits of two unsigned integers. Calculate the least significant 32 bits of the product of the least significant 24 bits of x and y. The high order 8 bits of x and y are ignored.
Returns
Returns the least significant 32 bits of the product x * y.
- __device__ unsigned long long int __umul64hi ( unsigned long long int x, unsigned long long int y )
-
Calculate the most significant 64 bits of the product of the two 64 unsigned bit integers. Calculate the most significant 64 bits of the 128-bit product x * y, where x and y are 64-bit unsigned integers.
Returns
Returns the most significant 64 bits of the product x * y.
- __device__ unsigned int __umulhi ( unsigned int x, unsigned int y )
-
Calculate the most significant 32 bits of the product of the two 32 bit unsigned integers. Calculate the most significant 32 bits of the 64-bit product x * y, where x and y are 32-bit unsigned integers.
Returns
Returns the most significant 32 bits of the product x * y.
- __device__ unsigned int __urhadd ( unsigned int, unsigned int )
-
Compute rounded average of unsigned input arguments, avoiding overflow in the intermediate sum. Compute average of unsigned input arguments x and y as ( x + y + 1 ) >> 1, avoiding overflow in the intermediate sum.
Returns
Returns an unsigned integer value representing the unsigned rounded average value of the two inputs.
- __device__ unsigned int __usad ( unsigned int x, unsigned int y, unsigned int z )
-
Calculate , the sum of absolute difference. Calculate , the 32-bit sum of the third argument z plus and the absolute value of the difference between the first argument, x, and second argument, y.
Inputs x, y, and z are unsigned 32-bit integers.
Returns
Returns .