Decimal -> HexaDecimal -> Character Encoding in XSLT

Question

(1) My requirement is to convert a DECIMAL INPUT to hexadecimal notation with fixed 8 digits

(2) Convert/Map HEXADECIMAL RESULT to character set by picking 2 HEXADECIMAL characters at a time and append the respective character codes. Please refer to below link for character encoding
https://learn.microsoft.com/en-us/office/vba/language/reference/user-interface-help/character-set-0127
https://learn.microsoft.com/en-us/office/vba/language/reference/user-interface-help/character-set-128255

(3) The final character encoding is showcased as OUTPUT

(4) Can XSLT handle all the special encoding character sets?

DECIMAL INPUT

 <decimal> 
   <input>2<input>
   <input>100<input>
   <input>819<input>
   <input>60<input>
 </decimal>

HEXADECIMAL RESULT

 <input>
   <hex>00000002</hex>
   <hex>00000064</hex>
   <hex>00000333</hex>
   <hex>0000003C</hex>
 </input>

OUTPUT - CHARACTER ENCODING

 <output>
   <charset>    </charset>
   <charset>   d</charset>
   <charset>   3</charset>
   <charset>   <</charset>
 </output>

Answer 1

EDIT: this is an answer to the original question which asked how to convert a hex number into a character using XSLT.

I'm leaving my answer here in case it's helpful to someone with that problem, though it's not a very helpful answer to the question as it's subsequently been edited.

Here's an alternative using XSLT 2.0, which I think is supported by IBM DataPower.

XSLT 2.0 includes the codepoints-to-string function which can convert a Unicode codepoint (number) into a string. But the conversion of hex digits to integers is still a long-winded affair (at least, I don't know of an easy way to do it).

<xsl:stylesheet version="2.0" 
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform" 
  xmlns:hex="http://example.com/hex"
  xmlns:xs="http://www.w3.org/2001/XMLSchema">

  <xsl:output method="xml" version="1.1"/>
  
  <xsl:function name="hex:to-integer" as="xs:integer">
    <xsl:param name="hex" as="xs:string"/>
    <xsl:variable name="least-significant-digit"
      select="substring($hex, string-length($hex))"/>
    <xsl:variable name="most-significant-digits" 
      select="substring($hex, 1, string-length($hex) - 1)"/>
    <xsl:variable name="hex-digit-value" select="
      string-length(
        substring-before('0123456789ABCDEF', $least-significant-digit)
      )
    "/>
    <xsl:choose>
      <xsl:when test="$most-significant-digits">
        <xsl:sequence 
          select="$hex-digit-value + 16 * hex:to-integer($most-significant-digits)"/>
      </xsl:when>
      <xsl:otherwise>
        <xsl:sequence select="$hex-digit-value"/>
      </xsl:otherwise>
    </xsl:choose>
  </xsl:function>
  
  <xsl:template match="input">
    <output>
      <xsl:apply-templates/>
    </output>
  </xsl:template>
  
  <xsl:template match="hex">
    <xsl:value-of select="codepoints-to-string(hex:to-integer(.))"/>
  </xsl:template>
  
</xsl:stylesheet>

Answer 2

I am going to take a guess here and assume that your input values are decimal numbers, each representing a string of up to 4 characters, so that for example the string "Char" (which in hexadecimal notation would be represented as 43 68 61 72) is calculated as the decimal value of the combined hexadecimal number 43686172 = 1130914162.

Now, to decode such number back to the original string it is sufficient to do:

XML

<input>
    <decimal>67</decimal>
    <decimal>17256</decimal>
    <decimal>4417633</decimal>
    <decimal>1130914162</decimal>
    <decimal>100</decimal>
    <decimal>51</decimal>
    <decimal>60</decimal>
</input>

XSLT 2.0

<xsl:stylesheet version="2.0" 
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:math="http://www.w3.org/2005/xpath-functions/math"
exclude-result-prefixes="math">
<xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes"/>

<xsl:template match="/input">
    <output>
        <xsl:for-each select="decimal">
            <xsl:variable name="codes" select="for $i in 0 to 3 return . idiv math:pow(256, $i) mod 256"/>    
            <charset>
                <xsl:value-of select="codepoints-to-string(reverse($codes[. > 0]))"/>
            </charset>
        </xsl:for-each>
    </output>
</xsl:template>

</xsl:stylesheet>

Result

<?xml version="1.0" encoding="UTF-8"?>
<output>
   <charset>C</charset>
   <charset>Ch</charset>
   <charset>Cha</charset>
   <charset>Char</charset>
   <charset>d</charset>
   <charset>3</charset>
   <charset>&lt;</charset>
</output>

Answer 3

Some of these codes are outside the ASCII range, but if by ASCII you mean Unicode, you could try

<xsl:value-of select="concat('&amp;#x', hex, ';')"
  disable-output-escaping="yes"/>