CN1532727A - Improving method and system for changing binary data sequence into printable character - Google Patents

Abstract

The present invention relates to improved method and system for converting 8-bit byte data flow into ASCII characters. The method includes the following steps: dividing each input byte into one 2-bit prefix and one 6-bit part one byte by one byte; expressing each input byte with one character of one group of special printable characters; converting the 6-bit part of each byte into one printable character one byte by one byte in preset mode; and output the special character and the printable characters.

Description

Binary data sequence is converted to the improved method and system of printable character

Invention field

The present invention relates to a kind ofly convert binary data sequence the method and system of printable character to, more particularly, relate to a kind of improved method and system that one eight (8 bit) data stream is converted to ascii character.

Background technology

In many applications, file uses their " nature " form to represent usually, as eight bit character or binary data.Such data may not be transmitted on some transmission protocol, and may have to convert to the transformat that can receive, i.e. an ASCII fromat.

Converting an eight bit data sequence to printable character is generally used for e-mail, e-mail annex, the mail that passes to the CGI server, Cookie data and is not suitable for the application scenario that binary data is used and transmitted.

The most frequently used method that converts such eight bit data to printable character is BASE64, it adopts the 3-in-4 of binary sequence to represent mode, be it by three continuous gulp being divided into per 6 bits be four groups of one group, the ASCII byte sequence of encoding.

We know, eight-digit binary number are being converted in the coding of ASCII character, and the efficient of stipulations contradicts with the character probability of interference of communication channel.That is to say that the efficient of stipulations increases along with the increase of number of characters used in the expression, and on the other hand, used character is many more, the jammer that may appear on the communication channel can be just big more.

Because BASE64 has used the set of 64 printable characters to convert eight bit data to printable character, be lowercase a to z, capitalization A is to Z, arabic numeral 0 to 9, "+" and "/" is so it has reduced the chance disturbed between used character and communication channel.

Yet, in the BASE64 coding method, the 3-in-4 of famous binary sequence represents that mode make to be difficult to individually byte ground of a byte and to handle data sequence, and causes output data quantity to increase by 33%, and the character that occurs in this increase and the input data is irrelevant.This causes wanting the increase of deal with data amount, and therefore the required processing time also increases.

Summary of the invention

The object of the present invention is to provide a kind of data stream to convert the improved method and system of ascii character to one eight.

Method according to an aspect of the present invention comprises the following steps: described data sequence of being made up of eight bit byte of byte ground input of a byte; One byte, one byte is divided into the prefix of 2 bits and the part of 6 bits with the byte of each input; The byte of from one group of special printable character, representing each input with a special printable character; According to predetermined way,, a byte one byte partly converts 6 bits of each byte in one group of printable character a printable character; Export described special printable character and printable character.

Method according to another aspect of the present invention comprises the following steps: described data sequence of being made up of eight bit byte of byte ground input of a byte; Represent one group of each byte of importing continuously in the byte with a special printable character in one group of special printable character; According to predetermined mode, byte ground of a byte partly converts 6 bits of each byte in described group in one group of printable character a printable character; Export described printable character.

System according to an aspect of the present invention comprises: the device of importing the described data sequence of being made up of eight bit byte; Byte device divided into two parts with input; Generate the device of a printable prefix designates; Generate the device of a printable character and an ascii character of generation; Each byte that byte ground of byte of wherein said tripping device will be imported is divided into the prefix of one 2 bit and the part of 6 bits; Described prefix designates generating apparatus generates a prefix designates to the byte of each input; Described printable character generating apparatus partly generates a printable character based on predetermined way to each described 6 bit, this printable character is from one group of printable character, and prefix designates that is produced and printable character form an ascii character and represent so that export in described ascii character generating apparatus.

System according to a further aspect in the invention comprises: the device of importing the described data sequence of being made up of eight bit byte; To import byte device divided into two parts; Generate the device of a printable prefix designates; Generate the device of a printable character and generate the device of an ascii character; Each byte that wherein said tripping device will be imported to byte of a byte adaptively is divided into the prefix of one 2 bit and the part of 6 bits; Described prefix designates generating apparatus generates a special prefix designates to each byte in one group of byte of importing continuously; Described printable character generating apparatus is based on predetermined way, and to the printable character of each generation in the described continuous input gulp, this character is from one group of character; Described printable character is exported as ascii character by the ascii character generating apparatus.

Description of drawings

Fig. 1 is the process flow diagram that shows the inventive method.

Fig. 2 is the process flow diagram that shows the another kind of mode of the inventive method.

Fig. 3 is the schematic block diagram that shows the embodiment of a system of the present invention.

Fig. 4 shows that a present invention improves the schematic block diagram of the embodiment of system.

Embodiment

The present inventor notices that one eight byte has 256 kinds of variations at most, it can be divided into 4 groups, form by 64 kinds of variations for every group, and every group can be by a special character representation, in addition, preceding two bits in any one byte must be one of following four kinds: 00,01,10,11.Therefore, if with a byte separated into two parts, just, a part is made up of preceding two bits, and a part is made up of 6 remaining bits, and then this byte can be made up of the prefix (00,01,10,11) of one 2 bit and the part of one 6 bit.

Because the byte of one 6 bit can convert a printable character to the BASE64 coded system, if give prefix with a special printable character, then any one eight bit byte can be by a special printable character and a BASE64 character representation.Encoding scheme of the present invention adopts BASE64 character set and eight bit byte of four special character representations, these special characters can be printable characters arbitrarily, the value that they concentrate corresponding to 128 ascii characters of standard is 32 to 126 character, except those characters of having been used by the BASE64 character set.These special characters can comprise, @ for example, #, $, % ， ﹠amp; , *, (), ^,! ,-,?,＜, 〉, ", ' ,-: and; , [,], {, },, | etc.

Because each byte of eight can be made up of the part of a prefix and one 6 bit, according to method of the present invention, can one byte ground of byte handle the input data, and not used in BASE64, one group of ground of per three bytes is handled and is imported data.

Because eight bit byte has 256 kinds of variations.These 256 kinds of variations are mapped to 64 characters in one of 4 groups of BASE64 character set.Every group from character @, #, $, % ， ﹠amp; , *, (), ^,! ,-,?,＜, 〉, ", ' ,-: and; , [,], {, },, | the expression of one of 4 special characters of middle selection.For example, 00=@, 01=#, 10=$, 11=%, therefore a byte can convert one to by for example @, #, $, prefix and a BASE64 character of the expression of one of four characters of %.

Mapping relations between byte and the printable character (special character and BASE64 character) can be provided with as follows:

Mapping example 1:

Perhaps mapping can be represented by ' prefix '+BASE64.That is to say,,, can be expressed as the prefix of one 2 bit and corresponding to 6 bits of decimal numeral 0-63 no matter this byte is 0-63 or 192-255 for any one byte of eight.For 2 bit prefix, @ represents 00, and # represents 01, and $ represents 10, and % represents 11.

Yet, importantly because special character is selected from character group @, #, $, % ， ﹠amp; , *, (), ^,! ,,?,＜, 〉, ", ' ,-: and; , [,], {, },, |, also can use other mapping, as:

Mapping example 2

Represent 00 at this %, $ represents 01, and # represents 10, and @ represents 11.

In fact, except @, #, other special characters beyond the $, % also can be used for representing respectively 00,01,10,11.

Because have only 4 special characters, the prefix of two successive bytes in a binary data stream may be identical, in other words, they may represent same group of BASE64 character set, have only when it with back to back last byte not when same group (identical prefix is arranged), prefix just is used or exports.

Now, by example explanation the present invention.

Fig. 1 is a process flow diagram that shows the inventive method.At first, according to change and as: mapping example 1 is referred to one of four groups (steps 102) with an input byte.

Then, according to the classification of mapping example 1 definite coding, that is: the prefix designates (step 103) of this byte.

Then, the prefix with this prefix and last byte compares (step 104a).If the group of the prefix TYP of it and last byte, or in other words is if the prefix of it and last byte is represented this prefix be left in the basket (step 104b) by same special character.

Simultaneously, byte is divided into one 2 bit prefix and one 6 bit part (step 104).According to the matching way of routine, partly convert 6 bits to BASE64 character (step 105).That is to say, in a BASE64 character set, find out a BASE64 character that partly is complementary with 6 bits and finish matching process.For example, one 6 bit partly is 011001, the capital Z in its expression BASE64 character set.

At last, with BASE64 character and prefix (for example: Z) together output so that for example: transmission (step 106), if the prefix of previous byte is not represent Z to organize.Yet,, only export the BASE64 character and ignore prefix if this prefix is identical with the prefix of previous byte.

As shown in Figure 2, can also be not first with byte packet, but it directly is divided into the part (step 202) of one 2 bit prefix and one 6 bit.Then, according to the corresponding special character of prefix search (step 203a).If prefix is 00, then represent with @, if prefix is 01, then represent with #, if prefix is 10, then represent with $, if prefix is 11, then represent with %.

Then, the prefix of represented prefix and last byte is compared (step 204), if the same group of byte representation of it and front, perhaps in other words, if it uses the special character the same with the prefix of back to back previous byte to represent, then omit represented prefix (step 205).

If the group that this prefix that is expressed representative is different or different with the expression of front byte prefix, this prefix is about to be output so.

Simultaneously,, partly convert 6 bits to a BASE64 character (step 203b), promptly in the BASE64 character set, find out a BASE64 character that partly is complementary with this 6 bit and mate according to the matching way of routine.For example, if 6 bits partly are 011001, it is represented by ' Z ' in the BASE64 character set.

At last, this BASE64 character with represented prefix (for example: Z) export, if the prefix of last byte is not to represent Z group (step 206).Yet,, only export the BASE64 character, and prefix is omitted if represented prefix is the same with the prefix of last byte.

For a hexadecimal data sequence 0x14fb9c03d9, its eight-digit binary number is expressed as 00,010,100 11,111,011 10,011,100 00,000,011 11011001.

According to the present invention, in the scale-of-two-text-converted of these data, at first get first byte, and be divided into a prefix 00 and one 6 bit part 010100, if adopt mapping example 1, special character @ of prefix 00 usefulness represents.

Prefix with this prefix and tight last byte compares then, in this case, because in this data stream, the 00010100th, first byte, prefix are saved so that export.

This 6 bit part 010100 is converted into a BASE64 character T, and the form of Yi @T is exported with prefix @ then.

Handle second byte 11111011 then.It is divided into a prefix 11 and one 6 bit part 111011, prefix 11 corresponding special character %, with the prefix of it and the byte 00010100 in front relatively, just the special character @ with expression 00 compares, because two prefixes are not at same group, prefix % will be output so that transmit so.

6 bit parts 111011 are converted into a BASE64 character 7, export with prefix % with the form of %7 then.

Handle the 3rd byte 10011100 similarly, it is divided into a prefix 10 and one 6 bit part 011100, prefix 10 corresponding special character $, with the prefix of the byte 11111011 of it and its front relatively, just the special character % with expression 11 compares, because two prefixes are not at same group, prefix $ will be output so that transmit so.

6 bit parts 011100 are converted into a BASE64 character c, and the form of Yi $c is exported with prefix $ then.

Also handle nybble 00000011 similarly, it is divided into a prefix 00 and one 6 bit part 000011, prefix 00 corresponding special character @, 6 bit parts 000011 are converted into a BASE64 character D.

Although prefix @ is identical with the prefix of first byte, the byte in it and tight front, that is: 10011100 prefix difference, prefix @ exports with the BASE64 character of expression 000011.

Similarly, the 5th byte 11011001 also is divided into a prefix 11 and one 6 bit part 011001, and prefix 11 usefulness character % represent that 6 bit parts 011001 are converted into zed.

Although the prefix of the prefix % and second byte is at same group, the byte in it and tight front, that is: 00000011 at same group, and prefix % exports with the zed of expression 011001.

Byte ground of byte of cataloged procedure carries out.

In decode procedure, process is carried out on the contrary.Just use mapping relations and BASE64 mode, printable ascii character is changed back the eight-digit binary number data, for example, at first be divided into and T, be converted into 00, T is converted into 010100, therefore, is converted into 00010100.

Similarly, %7 ， $c ， @D, %Z is changed back 11111011,10011100,00000011 and 11011001 respectively, and table 1 and table 2 have shown the result who data (sexadecimal) 0x14fb9c03d9 is converted to ascii character.

Table 1

The input data:	????0x14fb9c03d9
						HEX：	????1??????4	??f??????b	??9??????c	??0??????3	??d??????9
Eight:	????00010100	??11111011	??10011100	??00000011	??11011001
						The decimal system:	????20	??251	??156	??3	??217
Output:	????@T	??％7	??$c	??@D	??％Z

Table 2

The input data:	??0x14fb9c03d9
						HEX：	??1??????4	????f??????b	????9??????c	????0??????3	????d??????9
Eight:	??00010100	????11111011	????10011100	????00000011	????11011001
						Prefix:	??@	????％	????$	????@	????％
6-bit	??20	????59	????28	????3	????25
						Output:	??@T	????％7	????$c	????@D	????％Z

In cataloged procedure, those characters in the BASE64 character set not, as: carriage return and other blank character, may indicate an error of transmission.

In decode procedure, if the character in decoded character and the BASE64 character set does not match or beyond the BASE64 character set, these characters are left in the basket or are not decoded.The carriage return or other character that do not have in BASE64 character set and special prefix character list also are left in the basket.

With reference now to Fig. 3,, Fig. 3 is the block diagram that embodies an embodiment of the present invention system.

System according to the present invention comprises: an impact damper (301), a byte separation vessel (302) links to each other with above-mentioned impact damper, a prefix generator (303) links to each other with described byte separation vessel respectively with a BASE64 generator (304), and an ASCII character generator (305) links to each other with the output of above-mentioned prefix generator (303) with BASE64 generator (304) respectively.

At first, binary data stream is imported into a byte separation vessel or a mechanism that realizes identity function.If data are hexadecimal, must convert it to eight bit byte.Utilize separating mechanism with this byte separated into two parts, i.e. 2 bit prefix and remaining 6 bit parts.

One of this 2 bit prefix and predetermined four special printable characters are complementary, and represent with a special printable character, and this is at a device of finishing such function, as: in the prefix generator.

According to the BASE64 mode of routine, 6 bits partly are converted into a BASE64 character, and this is at a device of finishing such function, as: carry out in the BASE64 generator.

Then, produce ASCII character character device at one, as: the prefix with the byte of prefix and tight front that produced in the ASCII generator compares, and whether belongs to same group to determine byte of current byte and tight front.If they belong to same group, just the prefix of a byte of prefix that is produced and tight front is identical, then has only the BASE64 character to produce and be output as ascii character.If different, prefix that is produced and BASE64 character export with the form of ascii character so that transmission or further use.

Should be noted that those skilled in the art can be in every way or method realize the present invention, and be not only mode described above or method.For example, some function can not only be passed through an independent device, but passes through, and for example: the combination of two kinds of devices realizes.

Fig. 4 is a schematic block diagram that shows another embodiment of system of the present invention.In Fig. 4, the byte tripping device is finished self-adaptation " dynamically " mapping rather than " static state " mapping, and the mapping in " static state " mapping between eight bit byte and the printable character is reserved as mentioned above in advance.

In the embodiment shown in fig. 3, the byte separation vessel carries out so-called " static state " mapping, because the mapping between eight system bytes and 4 BASE64 group is that reserve in advance or fixing.Yet mapping also can realize that for example, the byte in a data stream can followingly be divided into groups based on the frequency that byte value occurs:

Mapping example 3 (dynamically shining upon 1):

In this case, 64 bytes in the data stream are by expression, and 64 follow-up bytes are represented by #, or the like, that is to say, with the sequential packet of byte transmission, and no matter their value.Mapping relations between byte and the BASE64 character can be set up with a following mapping table:

Byte 1	Byte 2	Byte 3	Byte 4	Byte 5	Byte 6	Byte 7	Byte ..	Byte 64
									??A	??B	??C	??D	??B	??F	??G	??...	??/

The byte that has with sample value will be mapped to a character, and for example, because byte 2 has identical value with byte 5, they are mapped to identical symbol, for example: capital B.

Be the example of one " dynamically " mapping below.For an input string: " I ' m glad to seeyou.... ", if use the dynamic mapping mode of mapping example 3, then conversion will be:

Text:	I	‘	?m	?sp	?g	?l	?a	?d	?sp	?t	?o	?sp	?s	...
															The decimal system	73	?39	?109	?32	?103	?108	?97	?100	?32	?116	?111	?32	?115	...
16 systems	49	?27	?6D	?20	?67	?6C	?61	?64	?20	?74	?6F	?20	?73	...
															Scale-of-two	01 001 001	?00 ?100 ?111	?01 ?101 ?101	?00 ?100 ?000	?01 ?100 ?111	?01 ?101 ?100	?01 ?100 ?001	?01 ?100 ?100	?00 ?100 ?000	?01 ?110 ?100	?01 ?101 ?111	?00 ?100 ?000	?01 ?110 ?011	...
Static 1	#J	?@n	?#t	?@g	?#n	?#s	?#h	?#k	?@g	?#0	?#v	?@g	?#z	...
															Dynamic 1	A	?B	?C	?D	?E	?F	?G	?H	?D	?I	?J	?D	?K

The output of above-described usefulness " static state " mapping is: J@n#t@g#nshk@g#0v@g#z...

For " dynamically " mapping is because first 64 byte is that @ is omitted and exports and is: ABCDEFGHDIJDK... among this group of Zai @+BASE64

In this case, the mapping table of " dynamically " is:

16 systems	49	??27	??6D	??20	??67	??6C	??61	??64	??74	??6F	??73	...
													Dynamically	A	??B	??C	??D	??E	??F	??G	??H	??I	??J	??K

In some applications, as the e_mail text, its used byte is less than 64, and " dynamically " of ASCII mapping at this moment arranges with respect to " static state " arrangement its superiority.Therefore, will be between group less than conversion, output is less.

The present invention has below been described by way of example.Importantly the invention is not restricted to described example, those skilled in the art can carry out various modifications to it under the situation that does not break away from spirit of the present invention.

Claims (26)

1. a method that converts an octet of data sequence to printable character comprises the following steps:

The described octet of data sequence that byte ground input of a byte is made up of eight bit byte;

Byte ground of a byte is divided into one 2 bit prefix and one 6 bit part with the byte of each input;

The byte of representing each input with a special printable character in one group of special printable character;

According to a predetermined mode, byte ground of byte partly converts 6 bits of each byte in one group of printable character a printable character;

Export described special printable character and described printable character.

2. according to the process of claim 1 wherein that described special printable character group is made up of 4 special printable characters.

3. according to the method for claim 2, wherein said special printable character be from one group by #, $, % ， ﹠amp; , *, (), ^,! , ^-,?,＜, 〉, ", ' ,-: and; , [,], {, },, | select in the character of composition.

4. according to the method for claim 3, wherein said special printable character is @, #, $, %.

5. according to the process of claim 1 wherein that described printable character group comprises A, B, C, D, E, F, G, H, I, J, K, L, M, NO, P, Q, R, S, T, U, V, W, X, Y, Z, a, b, c, d, e, f, g, h, I, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, z, 0,1,2,3,4,5,6,7,8,9 ,+,/, they represent decimal number 0-63 respectively.

6. according to the method for claim 1 and 5, wherein said predetermined way is BASE64.

7. according to the process of claim 1 wherein that special printable character of described usefulness represents described byte, be to realize according to a predetermined mapping mode between byte variable and the described special character.

8. according to the method for claim 7, wherein said byte variable is classified into four groups, and every group has 64 variablees.

9. according to the process of claim 1 wherein that special printable character of described usefulness represents that described byte is by representing that with a special printable character described byte prefix realizes.

10. the method according to claim 1 further comprises this step: the special printable character of a byte of described special printable character and the tight front of described byte is represented to compare.

11. according to the method for claim 1 and 10, if same group an of byte representation of wherein described special printable character and tight front, this character is omitted.

12. a system that converts an octet of data sequence to printable character comprises: the device of importing the described data sequence of forming by eight bit byte; Byte device divided into two parts with input; Generate the device of a printable prefix designates; Generate the device of a printable character; With the device that generates an ascii character,

Each byte that byte ground of byte of wherein said tripping device will be imported is separated into one 2 bit prefix and one 6 bit part; Described prefix designates generating apparatus generates a prefix designates to the byte of each input; Described printable character generating apparatus is to each described 6 bit part, based on predetermined way, generate a printable character from one group of printable character, the prefix designates of generation and printable character are combined to form an ascii character and represent for output in described ascii character generating apparatus.

13. according to the system of claim 12, wherein said 2 bit prefix have 4 kinds of variations, described prefix designates be from one group by #, $, % ， ﹠amp; , *, (), ^,! , ^-,?,＜, 〉, ", ' ,-: and; , [,], {, },, | a special printable character of selecting in the character of composition.

14. according to the system of claim 13, wherein said prefix designates is one of following character: @, #, $, %.

15. according to the system of claim 12, wherein said printable character group comprises A, B, C, D, E, F, G, H, I, J, K, L, M, NO, P, Q, R, S, T, U, V, W, X, Y, Z, a, b, c, d, e, f, g, h, I, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, z, 0,1,2,3,4,5,6,7,8,9 ,+,/, they represent decimal number 0-63 respectively.

16. according to the system of claim 12 and 15, wherein said predetermined way is BASE64.

17. the method that converts an octet of data sequence to printable character may further comprise the steps:

Described octet of data sequence of forming by eight bit byte of byte ground input of a byte;

Represent one group of each byte of importing continuously in the byte with a special printable character in one group of special printable character;

According to predefined procedure, byte ground of byte partly converts 6 bits of each byte in described group in one group of printable character a printable character;

Export this printable character.

18. according to the method for claim 17, wherein said printable character group comprises A, B, C, D, E, F, G, H, I, J, K, L, M, NO, P, Q, R, S, T, U, V, W, X, Y, Z, a, b, c, d, e, f, g, h, I, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, z, 0,1,2,3,4,5,6,7,8,9 ,+,/.

19. according to the method for claim 17, wherein said predefined procedure is A, B, C, D, E, F, G, H, I, J, K, L, M, NO, P, Q, R, S, T, U, V, W, X, Y, Z, a, b, c, d, e, f, g, h, I, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, z, 0,1,2,3,4,5,6,7,8,9 ,+,/.

20. according to the method for claim 17, a wherein said special prefix represents it is a printable character, it is selected from one group and comprises #, $, % ， ﹠amp; , *, (), ^,! , ^-,?,＜, 〉, ", ' ,-: and; , [,], {, },, | character.

21. according to the method for claim 17, the gulp of wherein said continuous input is made up of 64 bytes of importing continuously.

22. the system that the data sequence with an eight bit byte converts printable character to comprises: the device of the described data sequence of forming by eight bit byte of byte ground input of a byte; Byte device divided into two parts with input; Generate the device of printable prefix designates; Generate the device of printable character and the device of generation ascii character,

Each byte that byte ground of byte of wherein said tripping device will be imported adaptively is separated into one 2 bit prefix and one 6 bit part; Described prefix designates generating apparatus generates a special prefix designates to one group of each byte of importing continuously in the byte; Described printable character generating apparatus generates a printable character to each byte in the described continuous input gulp based on predetermined way from one group of printable character; Printable character is exported as ascii character by described ascii character generating apparatus.

23. according to the system of claim 22, wherein said printable character group comprises: A, B, C, D, E, F, G, H, I, J, K, L, M, NO, P, Q, R, S, T, U, V, W, X, Y, Z, a, b, c, d, e, f, g, h, I, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, z, 0,1,2,3,4,5,6,7,8,9 ,+,/.

24. according to the system of claim 22, wherein said predefined procedure is: A, B, C, D, E, F, G, H, I, J, K, L, M, NO, P, Q, R, S, T, U, V, W, X, Y, Z, a, b, c, d, e, f, g, h, I, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, z, 0,1,2,3,4,5,6,7,8,9 ,+,/.

25. according to the system of claim 22, a wherein said special prefix designates is a printable character, it is selected from one group and comprises #, $, % ， ﹠amp; , *, (), ^,! , ^-,?,＜, 〉, ", ' ,-: and; , [,], {, },, | character.

26. according to the system of claim 22, the gulp of wherein said continuous input is imported byte continuously by 64 and is formed.

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