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    <p>For this purpose the best possible solution is to convert into bytes using IEEE754-1985 standard using SQL commands.</p> <p>First it is required to check for special cases defined by IEEE754-1985 standard. Then just follow the standard algorithm to convert if it is not in any special cases. Sample code is below.</p> <p>Inputs are <code>bytea_value bytea, is_little_endian boolean</code> then divide into 4 bytes as below: </p> <pre><code> byte_array[0]:= get_byte(bytea_value, 0); byte_array[1]:= get_byte(bytea_value, 1); byte_array[2]:= get_byte(bytea_value, 2); byte_array[3]:= get_byte(bytea_value, 3); </code></pre> <p>Then get the binary value by considering little endian or big endian</p> <pre><code>IF is_little_endian THEN binary_value:= byte_array[0]::bit(8) || byte_array[1]::bit(8) || byte_array[2]::bit(8) || byte_array[3]::bit(8); ELSE binary_value:= byte_array[3]::bit(8) || byte_array[2]::bit(8) || byte_array[1]::bit(8) || byte_array[0]::bit(8); END IF; </code></pre> <p>Now check for special cases:</p> <pre><code>IF binary_value = '00000000000000000000000000000000' OR binary_value = '10000000000000000000000000000000' THEN -- IEEE754-1985 Zero return 0.0; END IF; sign := substring(binary_value from 1 for 1); exponent := substring(binary_value from 2 for 8); mantissa := substring(binary_value from 10 for 23); IF exponent = '11111111' THEN IF mantissa = '00000000000000000000000' THEN -- IEEE754-1985 negative and positive infinity IF sign = '1' THEN return '-Infinity'; ELSE return 'Infinity'; END IF; ELSE return 'NaN'; -- IEEE754-1985 Not a number END IF; END IF; </code></pre> <p>If it does not belong to any special cases just convert it as below:</p> <pre><code>exp := exponent::int; IF exp &gt; 126 THEN exp := exp - 127; ELSE exp:= -exp; END IF; WHILE mantissa_index &lt; 24 LOOP IF substring(mantissa from mantissa_index for 1) = '1' THEN result := result + power(2, -(mantissa_index)); END IF; mantissa_index = mantissa_index + 1; END LOOP; result := result * power(2, exp); IF(sign = '1') THEN result = -result; END IF; return result; </code></pre>
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