1 /* 2 * Copyright 2008 The Android Open Source Project 3 * 4 * Use of this source code is governed by a BSD-style license that can be 5 * found in the LICENSE file. 6 */ 7 8 #include "SkMathPriv.h" 9 #include "SkFixed.h" 10 #include "SkFloatBits.h" 11 #include "SkFloatingPoint.h" 12 #include "SkScalar.h" 13 14 #define sub_shift(zeros, x, n) \ 15 zeros -= n; \ 16 x >>= n 17 18 int SkCLZ_portable(uint32_t x) { 19 if (x == 0) { 20 return 32; 21 } 22 23 int zeros = 31; 24 if (x & 0xFFFF0000) { 25 sub_shift(zeros, x, 16); 26 } 27 if (x & 0xFF00) { 28 sub_shift(zeros, x, 8); 29 } 30 if (x & 0xF0) { 31 sub_shift(zeros, x, 4); 32 } 33 if (x & 0xC) { 34 sub_shift(zeros, x, 2); 35 } 36 if (x & 0x2) { 37 sub_shift(zeros, x, 1); 38 } 39 40 return zeros; 41 } 42 43 /////////////////////////////////////////////////////////////////////////////// 44 45 /* www.worldserver.com/turk/computergraphics/FixedSqrt.pdf 46 */ 47 int32_t SkSqrtBits(int32_t x, int count) { 48 SkASSERT(x >= 0 && count > 0 && (unsigned)count <= 30); 49 50 uint32_t root = 0; 51 uint32_t remHi = 0; 52 uint32_t remLo = x; 53 54 do { 55 root <<= 1; 56 57 remHi = (remHi<<2) | (remLo>>30); 58 remLo <<= 2; 59 60 uint32_t testDiv = (root << 1) + 1; 61 if (remHi >= testDiv) { 62 remHi -= testDiv; 63 root++; 64 } 65 } while (--count >= 0); 66 67 return root; 68 } 69 70 /////////////////////////////////////////////////////////////////////////////// 71 72 float SkScalarSinCos(float radians, float* cosValue) { 73 float sinValue = sk_float_sin(radians); 74 75 if (cosValue) { 76 *cosValue = sk_float_cos(radians); 77 if (SkScalarNearlyZero(*cosValue)) { 78 *cosValue = 0; 79 } 80 } 81 82 if (SkScalarNearlyZero(sinValue)) { 83 sinValue = 0; 84 } 85 return sinValue; 86 } 87
