| /* |
| * 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 "SkMathPriv.h" |
| #include "SkFloatBits.h" |
| #include "SkFloatingPoint.h" |
| #include "SkScalar.h" |
| |
| const uint32_t gIEEENotANumber = 0x7FFFFFFF; |
| const uint32_t gIEEEInfinity = 0x7F800000; |
| const uint32_t gIEEENegativeInfinity = 0xFF800000; |
| |
| #define sub_shift(zeros, x, n) \ |
| zeros -= n; \ |
| x >>= n |
| |
| int SkCLZ_portable(uint32_t x) { |
| if (x == 0) { |
| return 32; |
| } |
| |
| int zeros = 31; |
| if (x & 0xFFFF0000) { |
| sub_shift(zeros, x, 16); |
| } |
| if (x & 0xFF00) { |
| sub_shift(zeros, x, 8); |
| } |
| if (x & 0xF0) { |
| sub_shift(zeros, x, 4); |
| } |
| if (x & 0xC) { |
| sub_shift(zeros, x, 2); |
| } |
| if (x & 0x2) { |
| sub_shift(zeros, x, 1); |
| } |
| |
| return zeros; |
| } |
| |
| SkFixed SkFixedMul_portable(SkFixed a, SkFixed b) { |
| #if defined(SkLONGLONG) |
| return static_cast<SkFixed>((int64_t)a * b >> 16); |
| #else |
| int sa = SkExtractSign(a); |
| int sb = SkExtractSign(b); |
| // now make them positive |
| a = SkApplySign(a, sa); |
| b = SkApplySign(b, sb); |
| |
| uint32_t ah = a >> 16; |
| uint32_t al = a & 0xFFFF; |
| uint32_t bh = b >> 16; |
| uint32_t bl = b & 0xFFFF; |
| |
| uint32_t R = ah * b + al * bh + (al * bl >> 16); |
| |
| return SkApplySign(R, sa ^ sb); |
| #endif |
| } |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| |
| #define DIVBITS_ITER(n) \ |
| case n: \ |
| if ((numer = (numer << 1) - denom) >= 0) \ |
| result |= 1 << (n - 1); else numer += denom |
| |
| int32_t SkDivBits(int32_t numer, int32_t denom, int shift_bias) { |
| SkASSERT(denom != 0); |
| if (numer == 0) { |
| return 0; |
| } |
| |
| // make numer and denom positive, and sign hold the resulting sign |
| int32_t sign = SkExtractSign(numer ^ denom); |
| numer = SkAbs32(numer); |
| denom = SkAbs32(denom); |
| |
| int nbits = SkCLZ(numer) - 1; |
| int dbits = SkCLZ(denom) - 1; |
| int bits = shift_bias - nbits + dbits; |
| |
| if (bits < 0) { // answer will underflow |
| return 0; |
| } |
| if (bits > 31) { // answer will overflow |
| return SkApplySign(SK_MaxS32, sign); |
| } |
| |
| denom <<= dbits; |
| numer <<= nbits; |
| |
| SkFixed result = 0; |
| |
| // do the first one |
| if ((numer -= denom) >= 0) { |
| result = 1; |
| } else { |
| numer += denom; |
| } |
| |
| // Now fall into our switch statement if there are more bits to compute |
| if (bits > 0) { |
| // make room for the rest of the answer bits |
| result <<= bits; |
| switch (bits) { |
| DIVBITS_ITER(31); DIVBITS_ITER(30); DIVBITS_ITER(29); |
| DIVBITS_ITER(28); DIVBITS_ITER(27); DIVBITS_ITER(26); |
| DIVBITS_ITER(25); DIVBITS_ITER(24); DIVBITS_ITER(23); |
| DIVBITS_ITER(22); DIVBITS_ITER(21); DIVBITS_ITER(20); |
| DIVBITS_ITER(19); DIVBITS_ITER(18); DIVBITS_ITER(17); |
| DIVBITS_ITER(16); DIVBITS_ITER(15); DIVBITS_ITER(14); |
| DIVBITS_ITER(13); DIVBITS_ITER(12); DIVBITS_ITER(11); |
| DIVBITS_ITER(10); DIVBITS_ITER( 9); DIVBITS_ITER( 8); |
| DIVBITS_ITER( 7); DIVBITS_ITER( 6); DIVBITS_ITER( 5); |
| DIVBITS_ITER( 4); DIVBITS_ITER( 3); DIVBITS_ITER( 2); |
| // we merge these last two together, makes GCC make better ARM |
| default: |
| DIVBITS_ITER( 1); |
| } |
| } |
| |
| if (result < 0) { |
| result = SK_MaxS32; |
| } |
| return SkApplySign(result, sign); |
| } |
| |
| /* 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; |
| } |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| |
| float SkScalarSinCos(float radians, float* cosValue) { |
| float sinValue = sk_float_sin(radians); |
| |
| if (cosValue) { |
| *cosValue = sk_float_cos(radians); |
| if (SkScalarNearlyZero(*cosValue)) { |
| *cosValue = 0; |
| } |
| } |
| |
| if (SkScalarNearlyZero(sinValue)) { |
| sinValue = 0; |
| } |
| return sinValue; |
| } |