I read 4 bytes from a binary file.
These bytes represent a floating point number (mantisse exponent form)
How can I get a float from these bytes ? 4 8276
Jean-Baptiste PERIN <jb******@yahoo.fr> wrote: I read 4 bytes from a binary file.
These bytes represent a floating point number (mantisse exponent form)
How can I get a float from these bytes ?
See the docs for module struct, specifically the struct.unpack function,
if the float is in the binary format your machine expects (or possibly
that but with the wrong endianity). If the float's binary format is
different from what your machine uses, you're in for a lot of painful
bit-twiddling.
Alex
Alex Martelli a écrit : Jean-Baptiste PERIN <jb******@yahoo.fr> wrote:
I read 4 bytes from a binary file.
These bytes represent a floating point number (mantisse exponent form)
How can I get a float from these bytes ?
See the docs for module struct, specifically the struct.unpack function, if the float is in the binary format your machine expects (or possibly that but with the wrong endianity). If the float's binary format is different from what your machine uses, you're in for a lot of painful bit-twiddling.
Alex
I'll have to handle Intel-PC, DEC-VAX and MIPS-SUN/SGI numbers
So I can't escape the painful bit-twiddling
Anyway, struct.unpack will undoubtedly be an incredibly valuable help
thank you very very very much ..
JiBé
Jean-Baptiste PERIN <jb******@yahoo.fr> wrote: I'll have to handle Intel-PC, DEC-VAX and MIPS-SUN/SGI numbers So I can't escape the painful bit-twiddling
I don't recall for sure (even though I did my thesis on a Vax, 25 years
ago!) but I think you _might_ be lucky -- VAX used the binary format
that became the IEEE standard, if I recall correctly.
Intel, MIPS, SUN and SGI surely did follow IEEE standards, endianity
apart, and you can correct for endianity with struct.unpack.
The problem would be there if you had, say, floats in old IBM 360/370
formats, or Cray's original formats, or the like...
Anyway, struct.unpack will undoubtedly be an incredibly valuable help
thank you very very very much ..
You're welcome!
Alex
Alex Martelli wrote: I don't recall for sure (even though I did my thesis on a Vax, 25 years ago!) but I think you _might_ be lucky -- VAX used the binary format that became the IEEE standard, if I recall correctly.
iirc, you have to swap bytes around. the code on this page might
be helpful: http://www.octave.org/octave-lists/a.../msg00033.html
The problem would be there if you had, say, floats in old IBM 360/370 formats, or Cray's original formats, or the like...
here's a IBM 360 converter (at least that's what I think it is; the code is taken
from a PIL format converter for a format that uses "IBM floats"):
def ibm_f32s(c):
a = ord(c[0]) & 127
b = ord(c[3]) + (ord(c[2])<<8) + (ord(c[1])<<16)
v = pow(2.0, -24) * b * pow(16.0, a-64)
if ord(c[0]) > 127:
return -v
return v
many floating point formats are trivial variations on this theme.
</F> This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics
by: Sam Smith |
last post by:
Hi,
I wan't a function to take a const char*, a start bit position and number of
bits and convert that bit-stream into a primitive of desired type.
I.e. something like:
char convert(const...
|
by: Cally |
last post by:
Hello,
I would like to convert a field from ntext field found in one database
table to float field found in another database table. The reason why I
want to do this is a long one.
I have...
|
by: GRoll35 |
last post by:
I get 4 of those errors. in the same spot. I'll show my parent class,
child class, and my driver.
All that is suppose to happen is the user enters data and it uses
parent/child class to display...
|
by: Michael Yanowitz |
last post by:
Hello:
For some reason I can't figure out how to split
a 4-byte (for instance) float number (such as 3.14159265359)
into its 4-bytes so I can send it via a socket to another
computer.
For...
|
by: SpreadTooThin |
last post by:
I have some code...
import array
a = array.array('d')
f = open('file.raw')
a.fromfile(f, 10)
now I need to convert them into floats (32 bit...) what do i do?
|
by: Mario M. Mueller |
last post by:
Hi,
I have a binary file containing 3 byte float values (big endian). How can I
read them into python? The struct module does not work, since it expects 4
byte floats.
Any hints?
Mario
|
by: Cross |
last post by:
I am building a client-server application. When the clients gets the data
from the server, the data is received as a byte array. The server works with
data in 2-dimentional arrays (recordsets...
|
by: Mason |
last post by:
I have tried and tried...
I'd like to read in a binary file, convert it's 4 byte values into
floats, and then save as a .txt file.
This works from the command line (import struct);
In : f =...
|
by: Peter |
last post by:
Does anyone know how to convert the following VB6 code to C# code?
Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (dest As
Any, Source As Any, ByVal bytes As Long)
Dim...
|
by: DolphinDB |
last post by:
Tired of spending countless mintues downsampling your data? Look no further!
In this article, you’ll learn how to efficiently downsample 6.48 billion high-frequency records to 61 million...
|
by: ryjfgjl |
last post by:
ExcelToDatabase: batch import excel into database automatically...
|
by: Vimpel783 |
last post by:
Hello!
Guys, I found this code on the Internet, but I need to modify it a little. It works well, the problem is this: Data is sent from only one cell, in this case B5, but it is necessary that data...
|
by: jfyes |
last post by:
As a hardware engineer, after seeing that CEIWEI recently released a new tool for Modbus RTU Over TCP/UDP filtering and monitoring, I actively went to its official website to take a look. It turned...
|
by: ArrayDB |
last post by:
The error message I've encountered is; ERROR:root:Error generating model response: exception: access violation writing 0x0000000000005140, which seems to be indicative of an access violation...
|
by: CloudSolutions |
last post by:
Introduction:
For many beginners and individual users, requiring a credit card and email registration may pose a barrier when starting to use cloud servers. However, some cloud server providers now...
|
by: Defcon1945 |
last post by:
I'm trying to learn Python using Pycharm but import shutil doesn't work
|
by: Shællîpôpï 09 |
last post by:
If u are using a keypad phone, how do u turn on JavaScript, to access features like WhatsApp, Facebook, Instagram....
|
by: isladogs |
last post by:
The next Access Europe User Group meeting will be on Wednesday 3 Apr 2024 starting at 18:00 UK time (6PM UTC+1) and finishing by 19:30 (7.30PM).
In this session, we are pleased to welcome former...
| |