Changing the most significant bit in a int16 - php

I want to encode an int16 value in 15 bits and leave the leftmost bit as a flag. Then I want to read the bytes and decode to decimal the rightmost 15 bits as the integer. Is this possible?
$value = 49;
$packed = pack('S', $value); // returns correct hex
$formatted = $packed ^ 0b1000000000000000; // returns too long number - 4 bytes instead of 2
How can I do this?


Use bitwise operators.
You have got your number in to $packed.
Let the $encoded be your target.
Save the $packed to the $encoded
$encoded = $packed;
$encoded = $encoded | 0b1000000000000000; //Set the MSB
Lets read it back
$encoded = $encoded $ 0b0111111111111111; //Clear the MSB first
$packed = $encoded; //The rest is automatically the value

Related

How to convert a large binary string to a binary value and back

I need to take a large binary string (whose length will always be divisible by 8) ...
// 96-digit binary string
$str = '000000000011110000000000000000001111111111111111111111111111111111111111000000000000000000001111';
... then convert it to a binary value (to store in a mysql db as type varbinary), and later convert it back again to recreate that string.
This is most likely NOT a duplicate question. Every posted stackoverflow answer I could find is either broken (PHP7 apparently changed how some of these functions work) or doesn't offer a solution to this specific problem. I've tried a few things, such as ...
// get binary value from binary string
$bin = pack('H*', base_convert($str, 2, 16));
// get binary string from binary value
$str2 = str_pad(base_convert(unpack('H*', $bin)[1], 16, 2), 96, 0, STR_PAD_LEFT);
... but this doesn't actually work.
My goal is to go back and forth between the given binary string and the smallest binary value. How is this best done?

These functions convert bit strings to binary character strings and back.
function binStr2charStr(string $binStr) : string
{
$rest8 = strlen($binStr)%8;
if($rest8) {
$binStr = str_repeat('0', 8 - $rest8).$binStr;
}
$strChar = "";
foreach(str_split($binStr,8) as $strBit8){
$strChar .= chr(bindec($strBit8));
}
return $strChar;
}
function charStr2binStr(string $charStr) : string
{
$strBin = "";
foreach(str_split($charStr,1) as $char){
$strBin .= str_pad(decbin(ord($char)),8,'0', STR_PAD_LEFT);
}
return $strBin;
}
usage:
// 96-digit binary string
$str = '000000000011110000000000000000001111111111111111111111111111111111111111000000000000000000001111';
$strChars = binStr2charStr($str);
// "\x00<\x00\x00\xff\xff\xff\xff\xff\x00\x00\x0f"
//back
$strBin = charStr2binStr($strChars);

Binary String to Array to HEX Color

Trying to import some color pallets from a program which stores them in binary format. I need them to be split and converted to hex. I didn't think it would be too difficult after seeing this tool: https://www.binaryhexconverter.com/binary-to-hex-converter, but I am not getting the results I expected.
$color = "[00001010,11101111,11000001,00000000,11111111,11111111,11111111,11111111,11111111,11111111,01100000,00000000,10010000,00000000,11111111,11111111,01100000,00000000,10010000,00000000,11111111,11111111,01100000,00000000,10010000,00000000,11111111,11111111,01100000,00000000,11111111,11111111,11111111,11111111,01100000,00000000,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,10001010,00000000,11000000,00000000,11111111,11111111,10001010,00000000,11000000,00000000,11111111,11111111,10001010,00000000,11000000,00000000,11111111,11111111,11000000,00000000,11111111,11111111,11111111,11111111,10010000,00000000,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,01110011,01110101,01110010,01100111,01100101,01110010,01111001,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,10101110,00000000,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,10101110,00000000,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11000000,00000000,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11000000,00000000,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,11000000,11000000,11000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000]";
$new_arr = array_map('trim', explode(',', trim($color, '[]')));
$arr = array_chunk($new_arr, 3);
foreach($arr as $bingroup){
print("<div style='position:absolute;height:20px;width:20px;background:#");
foreach($bingroup as $binitem){
$hex = bin2hex ($binitem);
print($hex);
}
print("'></div>");
}
So I import the string, trim, explode it to an array, group them into groups of 3 and then run over it with a couple foreach loops using bin2hex() -> simple right? Why then am I getting
<div style="position:absolute;height:20px;width:20px;background:#303030303130313031313130313131313131303030303031"></div>

See, this is happening as you want
<?php
$color = "[00001010,11101111,11000001,00000000,11111111,11111111,11111111,11111111,11111111,11111111,01100000,00000000,10010000,00000000,11111111,11111111,01100000,00000000,10010000,00000000,11111111,11111111,01100000,00000000,10010000,00000000,11111111,11111111,01100000,00000000,11111111,11111111,11111111,11111111,01100000,00000000,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,10001010,00000000,11000000,00000000,11111111,11111111,10001010,00000000,11000000,00000000,11111111,11111111,10001010,00000000,11000000,00000000,11111111,11111111,11000000,00000000,11111111,11111111,11111111,11111111,10010000,00000000,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,01110011,01110101,01110010,01100111,01100101,01110010,01111001,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,10101110,00000000,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,10101110,00000000,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11000000,00000000,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11000000,00000000,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,11111111,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,11000000,11000000,11000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000]";
$new_arr = array_map('trim', explode(',', trim($color, '[]')));
$arr = array_chunk($new_arr, 3);
foreach($arr as $bingroup){
print("<div style='position:absolute;height:20px;width:20px;background:#");
foreach($bingroup as $binitem){
$hex = base_convert($binitem, 2, 16);
if(strlen($hex) == 1){
$hex = '0'.$hex;
}
print($hex);
}
print("'></div>");
}

This happens because you're not actually converting a binary number to hexadecimal, which bin2hex() expects. You're trying to convert a string representation of a binary number to hexadecimal.
The ASCII character "0" is "30" in hexadecimal, character "1" is "31" in hexadecimal. So converting the string "00001010" to hexadecimal using binhex() will return the string "3030303031303130".
A workaround to get what you want is to first convert the string to decimal (funnily enough, bindec() does support strings) and then go from decimal to hexadecimal:
echo dechex(bindec("00001010"));
// "a"
// -> 00001010 in binary = 10 in decimal = "a" in hexadecimal
So you need to change this line:
// $hex = bin2hex ($binitem);
$hex = dechex(bindec($binitem));
CSS either supports single character color codes ("#abc") for all colors or double for all ("#aabbcc"), but not a mixture of the two so you might also need to add an extra check to make sure color codes < 16 will be output as "0a" instead of just "a".
You can use sprintf() for this. This formats the decimal (after conversion) as hexadecimal padded with a 0 to 2 characters.
$hex = sprintf('%02x', bindec($binitem));

php convert decimal to hexadecimal

I am extracting a serial from a digital certificate using the built-in OpenSSL library, however, I am having trouble converting this number to hex with precision.
The extracted number is originally in decimal but I need to have it in hex.
The number I am trying to convert is: 114483222461061018757513232564608398004
Here is what I've tried:
dechex() did not work, it returns: 7fffffffffffffff
The closest I could get was this function from the php.net page but it does not convert the whole number on part of it.
function dec2hex($dec) {
$hex = ($dec == 0 ? '0' : '');
while ($dec > 0) {
$hex = dechex($dec - floor($dec / 16) * 16) . $hex;
$dec = floor($dec / 16);
}
return $hex;
}
echo dec2hex('114483222461061018757513232564608398004');
//Result: 5620aaa80d50fc000000000000000000
Here is what I am expecting:
Decimal number: 114483222461061018757513232564608398004
Expected hex: 5620AAA80D50FD70496983E2A39972B4
I can see the correction conversion here:
https://www.mathsisfun.com/binary-decimal-hexadecimal-converter.html
I need a PHP solution.

The problem is that The largest number that can be converted is ... 4294967295 - hence why it's not working for you.
This answer worked for me during a quick test, assuming you have bcmath installed on your server, and you can obtain the number as a string to start with. If you can't, i.e. it begins life as numeric variable, you'll immediately reach PHP's float limit.
// Credit: joost at bingopaleis dot com
// Input: A decimal number as a String.
// Output: The equivalent hexadecimal number as a String.
function dec2hex($number)
{
$hexvalues = array('0','1','2','3','4','5','6','7',
'8','9','A','B','C','D','E','F');
$hexval = '';
while($number != '0')
{
$hexval = $hexvalues[bcmod($number,'16')].$hexval;
$number = bcdiv($number,'16',0);
}
return $hexval;
}
Example:
$number = '114483222461061018757513232564608398004'; // Important: already a string!
var_dump(dec2hex($number)); // string(32) "5620AAA80D50FD70496983E2A39972B4"
Ensure you pass a string into that function, not a numeric variable. In the example you provided in the question, it looks like you can obtain the number as a string initially, so should work if you have bc installed.

Answered by lafor.
How to convert a huge integer to hex in php?
function bcdechex($dec)
{
$hex = '';
do {
$last = bcmod($dec, 16);
$hex = dechex($last).$hex;
$dec = bcdiv(bcsub($dec, $last), 16);
} while($dec>0);
return $hex;
}
Example:
$decimal = '114483222461061018757513232564608398004';
echo "Hex decimal : ".bcdechex($decimal);

This is a big integer, so you need to use a big-integer library like GMP:
echo gmp_strval('114483222461061018757513232564608398004', 16);
// output: 5620aaa80d50fd70496983e2a39972b4

Try this 100% working for any number
<?php
$dec = '114483222461061018757513232564608398004';
// init hex array
$hex = array();
while ($dec)
{
// get modulus // based on docs both params are string
$modulus = bcmod($dec, '16');
// convert to hex and prepend to array
array_unshift($hex, dechex($modulus));
// update decimal number
$dec = bcdiv(bcsub($dec, $modulus), 16);
}
// array elements to string
echo implode('', $hex);
?>

Convert 64 bit Integer hex string to 64 bit decimal string on 32 bit system

What is a simple way to convert a 64 bit integer encoded as a hex string to a decimal string on a 32 bit system. It needs to be the full value, it can not be in scientific notation or truncated :/
"0c80000000000063" == "900719925474099299"
"0c80000000000063" != 9.007199254741E+17
PHP's base_convert() and hexdec() don't do the job right.

You need to use BC Math PHP extension (bundled).
First split your input string to get high and low bytes, next convert it to decimal and then do calculation via BC functions like this:
$input = "0C80000000000063";
$str_high = substr($input, 0, 8);
$str_low = substr($input, 8, 8);
$dec_high = hexdec($str_high);
$dec_low = hexdec($str_low);
//workaround for argument 0x100000000
$temp = bcmul ($dec_high, 0xffffffff);
$temp2 = bcadd ($temp, $dec_high);
$result = bcadd ($temp2, $dec_low);
echo $result;
/*
900719925474099299
*/

Have you seen the first comment to hexdec's help page on php.net?
When given large numbers, the hexdec function automatically converts
the value to scientific notation. So, "aa1233123124121241" as a
hexadecimal value will be converted to "3.13725790445E+21". If you're
converting a hexadecimal value that represents a hash value (md5 or
sha), then you need every single bit of that representation to make it
useful. By using the number_format function, you can do that
perfectly. For example :
<?php
// Author: holdoffhunger#gmail.com
// Example Hexadecimal
// ---------------------------------------------
$hexadecimal_string = "1234567890abcdef1234567890abcdef";
// Converted to Decimal
// ---------------------------------------------
$decimal_result = hexdec($hexadecimal_string);
// Print Pre-Formatted Results
// ---------------------------------------------
print($decimal_result);
// Output Here: "2.41978572002E+37"
// .....................................
// Format Results to View Whole All Digits in Integer
// ---------------------------------------------
// ( Note: All fractional value of the
// Hexadecimal variable are ignored
// in the conversion. )
$current_hashing_algorithm_decimal_result = number_format($decimal_result, 0, '', '');
// Print Formatted Results
// ---------------------------------------------
print($current_hashing_algorithm_decimal_result);
// Output Here: "24197857200151253041252346215207534592"
// .....................................
?>

Writing Hex data to a file

i am trying a piece of code.
<?php
$tmp = ord('F'); //gives the decimal value of character F (equals 70)
$tmp = $tmp - 55; //gives 15 - decimal equivalent of 0x0F
$tmp = dechex($tmp); // converts 15 to 0x0F
$fp = fopen("testing.data","wb+");
fwrite($fp,$tmp);
fclose($fp);
?>
When i open the file called testing.data in a hex editor, i see 2 bytes written. The 2 bytes are 0x36 and 0x33.
I am expecting that only 1 byte i.e. 0x0f will be written to the file. This doesn't happen.
Please help me out with this.

If you want to write the byte 0x0f to the file, simply write the character with that ASCII code. You effectively want to undo ord, and the reverse function is chr:
<?php
$tmp = ord('F'); //gives the decimal value of character F (equals 70)
$tmp = $tmp - 55; //gives 15 - decimal equivalent of 0x0F
$tmp = chr($tmp); // converts 15 to a character
$fp = fopen("testing.data","wb+");
fwrite($fp,$tmp);
fclose($fp);
?>

You are writing the string representation of the number 0x0F to the file (which will use 1 byte per character).
In PHP you would use the pack function to create binary strings.
$bindata = pack('n', 0x0F);
file_put_contents('testing.data', $bindata);

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