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/* libs/opengles/fp.h
**
** Copyright 2006, The Android Open Source Project
**
** Licensed under the Apache License, Version 2.0 (the "License");
** you may not use this file except in compliance with the License.
** You may obtain a copy of the License at
**
** http://www.apache.org/licenses/LICENSE-2.0
**
** Unless required by applicable law or agreed to in writing, software
** distributed under the License is distributed on an "AS IS" BASIS,
** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
** See the License for the specific language governing permissions and
** limitations under the License.
*/
#ifndef ANDROID_OPENGLES_FP_H
#define ANDROID_OPENGLES_FP_H
#include <stdint.h>
#include <stddef.h>
#include <sys/types.h>
#include <math.h>
#include <private/pixelflinger/ggl_context.h>
#include <GLES/gl.h>
#define DEBUG_USE_FLOATS 0
// ----------------------------------------------------------------------------
extern "C" GLfixed gglFloatToFixed(float f) __attribute__((const));
// ----------------------------------------------------------------------------
namespace android {
namespace gl {
GLfloat fixedToFloat(GLfixed) CONST;
void sincosf(GLfloat angle, GLfloat* s, GLfloat* c);
float sinef(GLfloat x) CONST;
float cosinef(GLfloat x) CONST;
inline bool cmpf(GLfloat a, GLfloat b) CONST;
inline bool isZerof(GLfloat) CONST;
inline bool isOnef(GLfloat) CONST;
inline int isZeroOrNegativef(GLfloat) CONST;
inline int exponent(GLfloat) CONST;
inline int32_t mantissa(GLfloat) CONST;
inline GLfloat clampToZerof(GLfloat) CONST;
inline GLfloat reciprocalf(GLfloat) CONST;
inline GLfloat rsqrtf(GLfloat) CONST;
inline GLfloat sqrf(GLfloat) CONST;
inline GLfloat addExpf(GLfloat v, int e) CONST;
inline GLfloat mul2f(GLfloat v) CONST;
inline GLfloat div2f(GLfloat v) CONST;
inline GLfloat absf(GLfloat v) CONST;
/*
* float fastexpf(float) : a fast approximation of expf(x)
* give somewhat accurate results for -88 <= x <= 88
*
* exp(x) = 2^(x/ln(2))
* we use the properties of float encoding
* to get a fast 2^ and linear interpolation
*
*/
inline float fastexpf(float y) __attribute__((const));
inline float fastexpf(float y)
{
union {
float r;
int32_t i;
} u;
// 127*ln(2) = 88
if (y < -88.0f) {
u.r = 0.0f;
} else if (y > 88.0f) {
u.r = INFINITY;
} else {
const float kOneOverLogTwo = (1L<<23) / M_LN2;
const int32_t kExponentBias = 127L<<23;
const int32_t e = int32_t(y*kOneOverLogTwo);
u.i = e + kExponentBias;
}
return u.r;
}
bool cmpf(GLfloat a, GLfloat b) {
#if DEBUG_USE_FLOATS
return a == b;
#else
union {
float f;
uint32_t i;
} ua, ub;
ua.f = a;
ub.f = b;
return ua.i == ub.i;
#endif
}
bool isZerof(GLfloat v) {
#if DEBUG_USE_FLOATS
return v == 0;
#else
union {
float f;
int32_t i;
};
f = v;
return (i<<1) == 0;
#endif
}
bool isOnef(GLfloat v) {
return cmpf(v, 1.0f);
}
int isZeroOrNegativef(GLfloat v) {
#if DEBUG_USE_FLOATS
return v <= 0;
#else
union {
float f;
int32_t i;
};
f = v;
return isZerof(v) | (i>>31);
#endif
}
int exponent(GLfloat v) {
union {
float f;
uint32_t i;
};
f = v;
return ((i << 1) >> 24) - 127;
}
int32_t mantissa(GLfloat v) {
union {
float f;
uint32_t i;
};
f = v;
if (!(i&0x7F800000)) return 0;
const int s = i >> 31;
i |= (1L<<23);
i &= ~0xFF000000;
return s ? -i : i;
}
GLfloat clampToZerof(GLfloat v) {
#if DEBUG_USE_FLOATS
return v<0 ? 0 : (v>1 ? 1 : v);
#else
union {
float f;
int32_t i;
};
f = v;
i &= ~(i>>31);
return f;
#endif
}
GLfloat reciprocalf(GLfloat v) {
// XXX: do better
return 1.0f / v;
}
GLfloat rsqrtf(GLfloat v) {
// XXX: do better
return 1.0f / sqrtf(v);
}
GLfloat sqrf(GLfloat v) {
// XXX: do better
return v*v;
}
GLfloat addExpf(GLfloat v, int e) {
union {
float f;
int32_t i;
};
f = v;
if (i<<1) { // XXX: deal with over/underflow
i += int32_t(e)<<23;
}
return f;
}
GLfloat mul2f(GLfloat v) {
#if DEBUG_USE_FLOATS
return v*2;
#else
return addExpf(v, 1);
#endif
}
GLfloat div2f(GLfloat v) {
#if DEBUG_USE_FLOATS
return v*0.5f;
#else
return addExpf(v, -1);
#endif
}
GLfloat absf(GLfloat v) {
#if DEBUG_USE_FLOATS
return v<0 ? -v : v;
#else
union {
float f;
int32_t i;
};
f = v;
i &= ~0x80000000;
return f;
#endif
}
}; // namespace gl
// ----------------------------------------------------------------------------
}; // namespace android
#endif // ANDROID_OPENGLES_FP_H
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