SkMathPriv.cpp File Reference

#include "src/base/SkMathPriv.h"
#include "include/private/base/SkAssert.h"
#include <cstdint>

Go to the source code of this file.

Functions
int32_t	SkSqrtBits (int32_t x, int count)
int	SkPopCount_portable (uint32_t n)
int	SkNthSet (uint32_t target, int n)

Function Documentation

SkNthSet()

int SkNthSet	(	uint32_t	target,
		int	n
	)

Definition at line 53 of file SkMathPriv.cpp.

                                     {
    SkASSERT(n < SkPopCount(target));
 
    for (int i = 0; i < n; ++i) {
        target &= (target - 1); // Remove the lowest bit in the integer.
    }
 
    return SkCTZ(target);
}

SkPopCount_portable()

int SkPopCount_portable

(

uint32_t

n

)

Definition at line 42 of file SkMathPriv.cpp.

                                    {
    int count = 0;
 
    while (n) {
        n &= (n - 1); // Remove the lowest bit in the integer.
        count++;
    }
    return count;
}

SkSqrtBits()

int32_t SkSqrtBits	(	int32_t	value,
		int	bitBias
	)

Return the integer square root of value, with a bias of bitBias

Definition at line 18 of file SkMathPriv.cpp.

                                         {
    SkASSERT(x >= 0 && count > 0 && (unsigned)count <= 30);
 
    uint32_t    root = 0;
    uint32_t    remHi = 0;
    uint32_t    remLo = x;
 
    do {
        root <<= 1;
 
        remHi = (remHi<<2) | (remLo>>30);
        remLo <<= 2;
 
        uint32_t testDiv = (root << 1) + 1;
        if (remHi >= testDiv) {
            remHi -= testDiv;
            root++;
        }
    } while (--count >= 0);
 
    return root;
}