Table containing values for the exponent of 900. This is used in the numeric compaction decode algorithm.
Byte Compaction mode (see 5.4.3) permits all 256 possible 8-bit byte values to be encoded. This includes all ASCII characters value 0 to 127 inclusive and provides for international character set support.
The byte compaction mode i.e. 901 or 924
The array of codewords (data + error)
Currently active character encoding
The current index into the codeword array.
The decoded data is appended to the result.
The next index into the codeword array.
Convert a list of Numeric Compacted codewords from Base 900 to Base 10.
The array of codewords
The number of codewords
The decoded string representing the Numeric data.
EXAMPLE Encode the fifteen digit numeric string 000213298174000 Prefix the numeric string with a 1 and set the initial value of t = 1 000 213 298 174 000 Calculate codeword 0 d0 = 1 000 213 298 174 000 mod 900 = 200
t = 1 000 213 298 174 000 div 900 = 1 111 348 109 082 Calculate codeword 1 d1 = 1 111 348 109 082 mod 900 = 282
t = 1 111 348 109 082 div 900 = 1 234 831 232 Calculate codeword 2 d2 = 1 234 831 232 mod 900 = 632
t = 1 234 831 232 div 900 = 1 372 034 Calculate codeword 3 d3 = 1 372 034 mod 900 = 434
t = 1 372 034 div 900 = 1 524 Calculate codeword 4 d4 = 1 524 mod 900 = 624
t = 1 524 div 900 = 1 Calculate codeword 5 d5 = 1 mod 900 = 1 t = 1 div 900 = 0 Codeword sequence is: 1, 624, 434, 632, 282, 200
Decode the above codewords involves 1 x 900 power of 5 + 624 x 900 power of 4 + 434 x 900 power of 3 + 632 x 900 power of 2 + 282 x 900 power of 1 + 200 x 900 power of 0 = 1000213298174000
Remove leading 1 => Result is 000213298174000
The Text Compaction mode includes all the printable ASCII characters (i.e. values from 32 to 126) and three ASCII control characters: HT or tab (9: e), LF or line feed (10: e), and CR or carriage return (13: e). The Text Compaction mode also includes various latch and shift characters which are used exclusively within the mode. The Text Compaction mode encodes up to 2 characters per codeword. The compaction rules for converting data into PDF417 codewords are defined in 5.4.2.2. The sub-mode switches are defined in 5.4.2.3.
The text compaction data.
The byte compaction data if there was a mode shift.
The size of the text compaction and byte compaction data.
The decoded data is appended to the result.
Numeric Compaction mode (see 5.4.4) permits efficient encoding of numeric data strings.
The array of codewords (data + error)
The current index into the codeword array.
The decoded data is appended to the result.
The next index into the codeword array.
Text Compaction mode (see 5.4.1.5) permits all printable ASCII characters to be encoded, i.e. values 32 - 126 inclusive in accordance with ISO/IEC 646 (IRV), as well as selected control characters.
The array of codewords (data + error)
The current index into the codeword array.
The decoded data is appended to the result.
The next index into the codeword array.
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This class contains the methods for decoding the PDF417 codewords.
SITA Lab (kevin.osullivan@sita.aero)
Guenther Grau