JPH0451327A - Character string processing method - Google Patents

Abstract

PURPOSE:To recognize the terminal of a one-word unit character-string, to simplify the processing, and also, to execute it at a high speed by adding a zero bit string to the terminal of the character string so that the data of at least one word in which all bits are always zero is present thereon. CONSTITUTION:A character string 11 is generated by a character string generating part 1, on the other hand, to the terminal of its character string 11, a prescribed number of zero bit trains 13 are always added from a zero bit train generating part 12. In the case of processing such a character string, the processing of a copy, etc., is executed by a word unit, that is, in this example, by a 4-byte unit. Subsequently, whether data which is read at the time when the processing such as a copy is executed is zero every time by a 1-word unit or not is decided. In such a manner, the terminal of the character string is recognized.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a character string processing method that facilitates recognition of the end of character data used in an information processing device.

(Prior Art) When character data is used in an information processing device, there are cases in which character strings are processed with a predetermined fixed length, and cases where character strings are processed with an arbitrary arbitrary length. In the latter case, a special code of about 1 byte is added to the end of the character string in order to recognize the end of the character data. A typical example of this code is a code in which all bits have a value of zero. In this case, the end of character data is recognized and processed as follows.

FIG. 2 is an explanatory diagram of the operation of the conventional character string processing method.

In the figure, character data to be recognized is a - f
A character string 11 consisting of six characters up to 1, and a zero bit string 12 consisting of one byte in which all bits have a value of zero. Note that this zero bit string 12 is represented as ¥O in the figure.

In this example, each character is represented by 1 or 2 bytes of data, and the information processing device processes character data in units of 4 bytes per word. in this case,
The information processing device extracts 4 bytes of character data per word and performs processing such as copying.

On the other hand, in parallel with this copying process, it is determined whether each byte of character data is a zero bit string 12 of ¥0, and if a zero bit string 12 of ¥O is found, it is assumed that the end of the character string has been recognized. Copy processing ends.

(Problem to be Solved by the Invention) By the way, in the conventional method as described above, although the processor itself combines several bytes into one word and processes character data in units of words, it is difficult to recognize the end of a character string. 1
This is done in bytes. Therefore, in order to find the end of a character string, each word must be partially compared, which is time-consuming and labor-intensive, resulting in poor processing efficiency.

The present invention has been made with attention to the above points, and provides a character string processing method that can efficiently recognize the end of a character string according to the length of one word handled by an information processing device. The purpose is to

(Means for Solving the Problem) The character string processing method of the present invention provides at least one word of data in which all bits are zero at the end of the character string when a character string of indefinite length is divided into one word units. A certain number of zero bit strings are added so that the character string exists, and if one word near the end of the character string is all zero, it is recognized as the end of an indefinite long string. .

(Operation) According to the character string processing method of the present invention, a constant number of zero bit strings, which are set in advance with consideration to the word length, etc., are always added to the end of the character string. In other words, when reading a character string word by word, if you add a zero bit string so that there is always one word of data where all bits have a value of zero, you can recognize the end of the string by finding that word. .

(Example) Hereinafter, the present invention will be explained in detail using embodiments shown in the drawings.

FIG. 1 is an explanatory diagram of the operation of the method of the present invention.

According to the method of the present invention shown in the figure, first, a character string 11 is generated by a character string generator 1, and at the end of the character string 11, a constant number of zero bit strings 13 are always added by a zero bit string generator 12. will be added.

Here, for example, consider an information processing apparatus that processes data in units of I words, with 4 bytes and 32 bits as one word. In this case, one character can be represented by one byte, and two
There are cases where a single character can be represented by a byte. In the example shown,
Character string 11 consisting of only 1-byte characters was displayed. That is,
This character string 11 is a, b, c, d, e, f, g, h,
It consists of a 12-character code called ij. On the other hand, the zero-pi] column 13 added to the second character string 11 has a configuration in which 7 consecutive bytes of 1-byte data ¥0 in which all bits have a value of zero are arranged.

When processing such a character string, processing such as copying is performed in word units, that is, in this example, in 4-byte units.

Then, when processing such as copying is performed, it is determined whether or not the data read is the upper limit each time in units of one word. This allows the end of the string to be recognized.

That is, in the example shown in the figure, 1. After one word including j is copied, one word of data consisting of 4 bytes containing ¥0 is read. If it is determined that these are all zeros, the copying process ends.

A specific operational flowchart of the method of the present invention is shown using FIG.

This example describes the operation of copying a character string of arbitrary length having the structure shown in FIG. 1, and adding a zero bit string as shown in FIG. 1 after copying is completed.

First, in step S1, the start address of a character string to be copied is loaded into a first register (not shown). Note that this first register is a register that specifies an address for reading out the copy source character string in units of words.

Next, in step S2, the copy destination address is loaded into a second register (not shown).

The copy destination is a memory (not shown), and the second register is for specifying the write address.

Next, in step S3, a one-word character string is loaded into a third register (not shown) from the address indicated in the first register. This third register is used as a buffer for string copying.

Here, in step S4, it is determined whether the contents of the third register are all zeros.

If the contents of the third register are not all zeros, it is considered that the word contains a string that needs to be copied. Therefore, in step S5, the word in the third register is copied to the address indicated in the second register. Then, 4°' is added to the contents of the first register and the second register (step S6). by this,
The address is incremented by one word, and the process moves on to reading and copying a new word.

Copying data composed of a large number of character strings is executed by repeating steps S3 to S6.

Here, if it is determined in step S4 that the contents of the third register are all zero, the process moves to step S7.

In step S7, ¥ is added to the end of the copy destination character string.
Add 7 bytes of O data. That is, in step S4, the data to be copied is monitored word by word,
If it is a zero bit string with all zeros, it is recognized as the end of the character string and post-processing is executed. In this case, in the post-processing, 7 bytes of data of \O are added.

In the method of the present invention, a constant number of zero bit strings are always added to the end of a character string.

Any sufficiently long string of zero bits may be appended to implement the above method. However, this would make the data length unnecessarily long and waste memory.

Therefore, in the present invention, a fixed minimum number of zero bit strings are added to the memory.

FIG. 4 shows various operation explanatory diagrams of the method of the present invention.

In the method of the present invention, when recognizing the end of a character string of undefined length, it is recognized not in units of bytes but in units of words. Therefore, in the case of the present invention, when a character string is divided into 1 word length units, all bits at the end of the character string have a value, regardless of the length of the character string. A certain number of zero bit strings are added to ensure that at least one word of zero data exists.

In the case of the above embodiment, one word is 32 bits, and since 1-byte characters and 2-byte characters are mixed, the cello bit string at the end of the character string requires 7 bytes or more.

FIG. 4 shows various operation explanatory diagrams of the method of the present invention to show the reason for this.

FIGS. 4(a) to 4(d) show the state near the end of the character string when copying the character string is started from an arbitrary position in the character string shown in FIG.

In Figure 4(a), the last word of the character string is g, h, i.
, j, followed by 7 bytes of ¥0 data. In this case, the letter J
The end of the character string is recognized by the ¥0 zero bit string of 4 bytes and one word that follows , and the remaining 3 bytes of ¥0 zero bit string are ignored.

Next, in FIG. 4(b), the last character j of the character string and the 3-byte zero bit string of ¥0 are combined to form one word, and then the 4-byte cello bit string of ¥0 is added. Indicates the state in which In this situation, the last ¥○4
The end of the string is recognized by a string of zero bits in one byte word.

Therefore, when compared with the case of FIG. 4(a),
), the zero bit string of ¥O that is wasted is the maximum of 3 bytes, whereas in the case of FIG. 4(b), there is no waste.

In the cases of FIGS. 4(c) and (d), the intermediate states are shown. In FIG. 4(c), 1 byte of ¥0 zero bit string is wasted, and in FIG. 4(d), 2 The zero bit string of ¥○ for bytes is wasted. However, in either case, the existence of a zero bit string of \0 for one word and four hides is guaranteed, and the end of the character string can always be recognized.

Therefore, it can be seen that in the above embodiment, it is necessary to add at least 7 bytes of the zero bit string of ¥0 to the end of the character string. The number of zero bit strings to be added differs depending on the word length handled by the information processing device.

When one word is 2 bytes, or when one word is 6 bytes, 8 bytes, etc., the lengths of the zero bit strings will be different.

Note that depending on the hardware configuration of the information processing device, etc., it may be freely selected whether the bit having the value of zero corresponds to a high level signal or a low level signal.

(Effects of the Invention) According to the character string processing method of the present invention described above, in an information processing device that handles character strings in units of one word, all bits at the end of a character string are always set to at least one value of zero.
Since the cello bit string is added so that word data exists, it is possible to process the data word by word, check the contents of the data word by word, and recognize the end of the character string. Therefore, compared to the conventional end recognition method based on 1-byte units, processing can be simplified and faster. This makes it possible to perform processes such as copying and comparing character strings in word units at higher speed.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the operation of the method of the present invention, FIG. 2 is an explanatory diagram of the operation of the conventional method, FIG. 3 is a flowchart of the method of the present invention, and FIG. 4 is an explanatory diagram of various operations of the method of the present invention. . 11...Character string, 13...Zero bit string. ] 2

Claims (1)

[Claims] When a character string of indefinite length is divided into 1 word units, all bits have a value of zero at least 1 at the end of the character string.
A certain number of zero bit strings are added so that word data exists, and if one word near the end of the character string is all zeros, it is recognized as the end of an indefinite long string. String processing method.