libcore/luni/src/main/native/java_lang_Float.c

//
//  java_lang_Float.c
//  Android
//
//  Copyright 2005 The Android Open Source Project
//
#include "JNIHelp.h"

#include <math.h>
#include <stdlib.h>
#include <stdio.h>

typedef union {
    unsigned int    bits;
    float           f;
} Float;

#define NaN (0x7fc00000)

/*
 * Local helper function.
 */
static int IsNaN(unsigned bits)
{
    return ((bits >= 0x7f800001U && bits <= 0x7fffffffU)
        ||  (bits >= 0xff800001U && bits <= 0xffffffffU));
}

/*
 * public static native int floatToIntBits(float value)
 */
static jint floatToIntBits(JNIEnv* env, jclass clazz, jfloat val)
{
    Float   f;

    f.f = val;

    //  For this method all values in the NaN range are
    //  normalized to the canonical NaN value.

    if (IsNaN(f.bits))
        f.bits = NaN;

    return f.bits;
}

/*
 * public static native int floatToRawBits(float value)
 */
static jint floatToRawBits(JNIEnv* env, jclass clazz, jfloat val)
{
    Float   f;

    f.f = val;

    return f.bits;
}

/*
 * public static native float intBitsToFloat(int bits)
 */
static jfloat intBitsToFloat(JNIEnv* env, jclass clazz, jint val)
{
    Float   f;

    f.bits = val;

    return f.f;
}

/*
 * JNI registration
 */
static JNINativeMethod gMethods[] = {
    /* name, signature, funcPtr */
    { "floatToIntBits",         "(F)I",     floatToIntBits },
    { "floatToRawIntBits",      "(F)I",     floatToRawBits },
    { "intBitsToFloat",         "(I)F",     intBitsToFloat },
};
int register_java_lang_Float(JNIEnv* env)
{
    return jniRegisterNativeMethods(env, "java/lang/Float",
        gMethods, NELEM(gMethods));
}