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/*
* Copyright 2008 The Android Open Source Project
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "src/base/SkMathPriv.h"
#include "include/private/base/SkAssert.h"
#include "include/private/base/SkFloatingPoint.h"
#include <cstddef>
#include <cstdint>
///////////////////////////////////////////////////////////////////////////////
/* www.worldserver.com/turk/computergraphics/FixedSqrt.pdf
*/
int32_t SkSqrtBits(int32_t x, int count) {
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;
}
// Kernighan's method
int SkPopCount_portable(uint32_t n) {
int count = 0;
while (n) {
n &= (n - 1); // Remove the lowest bit in the integer.
count++;
}
return count;
}
// Here we strip off the unwanted bits and then return the number of trailing zero bits
int SkNthSet(uint32_t target, int n) {
SkASSERT(n < SkPopCount(target));
for (int i = 0; i < n; ++i) {
target &= (target - 1); // Remove the lowest bit in the integer.
}
return SkCTZ(target);
}
///////////////////////////////////////////////////////////////////////////////////////////////////
bool sk_floats_are_unit(const float array[], size_t count) {
bool is_unit = true;
for (size_t i = 0; i < count; ++i) {
is_unit &= (array[i] >= 0) & (array[i] <= 1);
}
return is_unit;
}