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-   -   need code to convert float format to internal java float format which is kept in 4 bytes integer (http://www.velocityreviews.com/forums/t133263-need-code-to-convert-float-format-to-internal-java-float-format-which-is-kept-in-4-bytes-integer.html)

Andy 05-07-2004 02:44 PM

need code to convert float format to internal java float format which is kept in 4 bytes integer
 
JVM structure CONSTANT_Float_info keeps float value
in 4 bytes integer type. I need code to convert float to 4 bytes
according to JVM spec
Thanks a lot

Thomas Fritsch 05-07-2004 03:23 PM

Re: need code to convert float format to internal java float formatwhich is kept in 4 bytes integer
 
Andy wrote:

>JVM structure CONSTANT_Float_info keeps float value
>in 4 bytes integer type. I need code to convert float to 4 bytes
>according to JVM spec
>Thanks a lot
>
>

float f = ...;
int i = Float.floatToIntBits(f);

See
http://java.sun.com/j2se/1.4.2/docs/...oIntBits(float)

--
Thomas<dot>Fritsch<squiggle>ops<dot>de


Roedy Green 05-07-2004 06:15 PM

Re: need code to convert float format to internal java float format which is kept in 4 bytes integer
 
On 7 May 2004 07:44:20 -0700, gmlvsk2@yahoo.com (Andy) wrote or quoted
:

>JVM structure CONSTANT_Float_info keeps float value
>in 4 bytes integer type. I need code to convert float to 4 bytes
>according to JVM spec


That question has nothing to do with softwaretools or the JVM, so I
have snipped those newsgroups.


See Float.intBitsToFloat and Float.floatToIntBits

--
Canadian Mind Products, Roedy Green.
Coaching, problem solving, economical contract programming.
See http://mindprod.com/jgloss/jgloss.html for The Java Glossary.

Roedy Green 05-07-2004 07:35 PM

Re: need code to convert float format to internal java float format which is kept in 4 bytes integer
 
On Fri, 07 May 2004 18:15:44 GMT, Roedy Green
<roedy-look-on-the-website@mindprod.com.invalid> wrote or quoted :

>
>>JVM structure CONSTANT_Float_info keeps float value
>>in 4 bytes integer type. I need code to convert float to 4 bytes
>>according to JVM spec

>
>That question has nothing to do with softwaretools or the JVM, so I
>have snipped those newsgroups.


see http://mindprod.com/jgloss/newsgroups.html to figure out which one
to pick.

--
Canadian Mind Products, Roedy Green.
Coaching, problem solving, economical contract programming.
See http://mindprod.com/jgloss/jgloss.html for The Java Glossary.

Andy 05-08-2004 03:00 PM

Re: need code to convert float format to internal java float format which is kept in 4 bytes integer
 
Thanks
But I need piece of code written in C.

>
> >JVM structure CONSTANT_Float_info keeps float value
> >in 4 bytes integer type. I need code to convert float to 4 bytes
> >according to JVM spec
> >Thanks a lot
> >
> >

> float f = ...;
> int i = Float.floatToIntBits(f);
>
> See
>

http://java.sun.com/j2se/1.4.2/docs/...loatToIntBits(
float)
>
> --
> Thomas<dot>Fritsch<squiggle>ops<dot>de
>




=?ISO-8859-1?Q?Daniel_Sj=F6blom?= 05-09-2004 12:08 AM

Re: need code to convert float format to internal java float formatwhich is kept in 4 bytes integer
 
Andy wrote:
> Thanks
> But I need piece of code written in C.


Why did you post here then? This is a java group. Anyway (assuming float
and int are both 4 bytes):

unsigned int f_to_ui(float f) { return *((unsigned int *) &f); }
float ui_to_f(unsigned int i) { return *((float *) &i); }

Remember that all of the class file format assumes big endian data,
while your platform might be little endian.

>>>JVM structure CONSTANT_Float_info keeps float value
>>>in 4 bytes integer type. I need code to convert float to 4 bytes
>>>according to JVM spec
>>>Thanks a lot
>>>
>>>

>>
>>float f = ...;
>>int i = Float.floatToIntBits(f);
>>
>>See
>>

>
> http://java.sun.com/j2se/1.4.2/docs/...loatToIntBits(
> float)
>
>>--
>>Thomas<dot>Fritsch<squiggle>ops<dot>de
>>

>
>
>



--
Daniel Sjöblom
Remove _NOSPAM to reply by mail


Andy 05-10-2004 01:26 PM

Re: need code to convert float format to internal java float format which is kept in 4 bytes integer
 
This is code to convert bytes to float.
I need the reverse of this

bytes
The bytes item of the CONSTANT_Integer_info structure represents
the value of the int constant. The bytes of the value are stored in
big-endian (high byte first) order.

The bytes item of the CONSTANT_Float_info structure represents the
value of the float constant in IEEE 754 floating-point single format
(§3.3.2). The bytes of the single format representation are stored in
big-endian (high byte first) order.

The value represented by the CONSTANT_Float_info structure is
determined as follows. The bytes of the value are first converted into
an int constant bits. Then:

* If bits is 0x7f800000, the float value will be positive
infinity.
* If bits is 0xff800000, the float value will be negative
infinity.
* If bits is in the range 0x7f800001 through 0x7fffffff or in
the range 0xff800001 through 0xffffffff, the float value will be NaN.
* In all other cases, let s, e, and m be three values that
might be computed from bits:

int s = ((bits >> 31) == 0) ? 1 : -1;
int e = ((bits >> 23) & 0xff);
int m = (e == 0) ?
(bits & 0x7fffff) << 1 :
(bits & 0x7fffff) | 0x800000;

Then the float value equals the result of the mathematical expression
s·m·2e-150.

Roedy Green 05-10-2004 09:26 PM

Re: need code to convert float format to internal java float format which is kept in 4 bytes integer
 
On 10 May 2004 06:26:11 -0700, gmlvsk2@yahoo.com (Andy) wrote or
quoted :

>This is code to convert bytes to float.
>I need the reverse of this

Please don't cross-post.

See http://mindprod.com/jgloss/converter.html
Version 3.9 now shows you this.

See http://mindprod.com/jgloss/floatingpoint.html
for more detail.
--
Canadian Mind Products, Roedy Green.
Coaching, problem solving, economical contract programming.
See http://mindprod.com/jgloss/jgloss.html for The Java Glossary.


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