JPS59173865A - Idle space retrieving method - Google Patents

Abstract

PURPOSE:To retrieve an idle space at a high speed by using a conversion table and an interpretation test function. CONSTITUTION:A conversion table 2 includes the 1st conversion table 2-1 which displays the number of ''0'' showing the continuous idle regions at the side of the highest position in the bytes and the 2nd conversion table 2-2 which displays the continuous number of ''0'' from the highest bit of the bytes. A central processing unit 3 performs interpretation of details by means of the table 2 and stores an interpretation test instruction into a main memory 1 to prescribe the next action in accordance with the result of said interpretation. An instruction control part 5 executes the instruction and decides whether the value obtained from the table 2 is equal to ''0'' or ''1'' while referring to the table 2. If the value is equal to ''0'', the processing is continued; while the processing is discontinued with results other than ''0''.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a free space search method for managing the storage status of a direct access storage device connected to a processing device, particularly free space.

Direct access storage device (hereinafter referred to as DA) connected to the prior art and problem processing device
(written as SD) stores various information, and is also erased if unnecessary. Therefore, this DASD
It is necessary to manage the free space on the DAS
Free space on D is managed using a bitmap, and for this purpose a bitmap is created in units of bytes consisting of 8 bits, where free space is indicated as "0" and storage area is indicated as "1". It consists of Conventionally, in order to detect the number of consecutive empty spaces rO from this bitmap, the bitmap value was sequentially input into a register in 1-byte units, and this was shifted to the left to detect the values "0" and "1" that were shifted out. 7. Count the number of “0”s and find consecutive empty spaces. A method of detecting the base is used. However, the conventional method has the disadvantage that the processing speed is slow because the processing progresses only in byte units.

(C) Object of the Invention In view of the above-mentioned drawbacks of the prior art, it is an object of the present invention to provide a method for searching for free space that can be performed quickly and efficiently.

(d) Structure of the Invention Briefly stated, the present invention configures the storage state of a direct access storage device into a bitmap of 8-bit bytes, and sets "0" indicating continuous free space on the highest-order side of the bytes. A first conversion table that displays numbers and a second conversion table that displays consecutive numbers of "0" from the highest bit of a byte are attached to the processing device, and both conversion tables and a translation test function are used. The invention is characterized in that the vacant space is searched by using the search function.

(e) Examples of the invention Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the free space search method of the present invention, FIG. 2 is a schematic diagram showing the configuration of a conversion table of the present invention, and FIG. 6 is a flowchart of the free space search method of the present invention. be.

In the figure, 1 is the main memory, 2 is the conversion table, 3 is the central processing unit, 4 is the main memory control unit, 5 is the instruction control unit, 6 is the arithmetic processing unit, 6-1 is the register, and 7 is the file. . The central processing unit B uses a conversion table in the main memory device 1 to translate the details, and based on the result, the value determined by the translation test command table that specifies the next operation is ``
0” or “1”, and the result is “0”.
”, the process continues, and when the value is other than “0”, the process ends. “0”, which indicates free space, is used to manage how much free space the data stored in File/V7 has. 8 consisting of a bit and a “1” bit indicating storage
A search for "0" is performed using a bitmap that is displayed as one byte consisting of bits. i'1tiiooo o
ooooooooo ooooiitli 1ooo1oo+
Byte 0 By H Byte 2 If there is a bitmap consisting of byte 6, there are 12 consecutive "0"s, that is, empty spaces, between byte O and byte 2, and byte B has 6 consecutive "0s" on the high-order side. There is a vacancy. The feature of the present invention is to quickly find the number of empty "0"s,
FIG. 6 will be explained using FIG. 2. Figure 2 shows the conversion table. Figure 2 (a) 2-1 shows the number of consecutive "0"s on the leftmost side of the byte; Figure 2 (a)
The *16 display in 2-1 indicates that "0" continues in the next byte.

2-2 in FIG. 2 is a table that shows how many consecutive "0"s start from the highest bit and converts it to 8 when the highest bit is "1". No matter which table is used, if a translation test instruction is used, the conversion will continue if it is converted to "0". The instruction control unit 5 sets a byte pointer to the first byte of the file/L/7 bit map as shown in FIG.
) (Hereinafter, Figure 6 will be omitted and indicated by 0) For example, 11001
011 is OB when expressed in hexadecimal, and when the translation test command using the conversion table (a) is executed, it is shown in Figure 2 (a).
Q). This operation is executed for 256 bytes, and the value obtained each time is detected as "θ". If it is 0, repeat the next step and advance by 256 bytes. If the obtained value is "2" as in the above example, a check is performed to see if this obtained value is continuous with the next byte, that is, larger than 16 (5), and then If the value is "2", this 2 is input to the register 6-1 (6). The value of this register 6-1, ie, 2, indicates that there are two free areas near the left side of this byte. or greater than 16 in the test of 5), for example +111+
The 0[)O byte becomes “F8” in hexadecimal, as shown in Figure 2 (a).
When 6*16 is obtained, this value is divided by 16 and stored as 6 in register 6-1 as the number of 0°° (7).In other words, the value shown in *16 is as described above. Indicates that “O” continues in the next byte.

It is therefore necessary to examine the next byte and advance the byte pointer by one byte (8). At this time, Fig. 2(b)
The converted value ff: is determined using the tape) V shown in (9).

For example, if the above-mentioned F8'' is followed by a byte of 00011011, it is 1B in hexadecimal and the zero can be found as shown in Figure 2 (G). Check (10) whether it has been converted to "0".
If the result is B, it is detected in (11) that it is not 8, and the value obtained by adding 6 to the register value of V) is the number of empty bits. When converted to 256 bytes "0" (10), all bits are "0", that is, 256 x 8 bits are "0", and 256 x 8 bits are added to the register value in step (7), resulting in 4 (12). This indicates the number of free bits. Next, advance the byte pointer by 256 bytes and check as soon as it continues to the next 256 bytes (12). In (11) above, if the converted value is 8, it is 0.
Then, the value 6 of register 6-1 is added to the free bit. In addition, if all 256 bytes are not converted to "0", add the converted value at that time and the value of register 6-1, and then subtract the value of the byte pointer from the address of the byte where conversion was interrupted, and multiply by 8. Add what you added. It goes without saying that the above calculations are performed by the calculation processing section 6.

(f) Effects of the Invention As explained in detail above, the free space search method of the present invention uses Chive μ to search for free space at high speed, and has many advantages in managing magnetic areas. Become.・

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the free space search method of the present invention, FIG. 2 is a schematic diagram showing the configuration of a conversion table of the present invention, and FIG. 3 is a flowchart of the free space search method of the present invention. be. In the figure, 2', 2-1.2-2 are conversion tables, RO is a central processing unit, and 7 is a file, respectively. Figure 1 (Ω) Figure 2 0 123456789ABCDEF Lower A 1 [0,
811676655'S S 44444441a7
111111111111111 0 1 23456789ABCDEF Dingi Rainbow 61
1111+l+l+IMIII 7 +MIIllllIl+1III

Claims (1)

[Claims] A method for searching for free space in a direct access storage device in a processing device having a function of performing a translation test using a conversion table, the method comprising: configuring the storage state of the direct access storage device into a bitmap of 8-bit bytes; A first conversion table that displays the number of consecutive "0"s indicating the highest-order free space in the byte, and a second conversion table that displays the number of consecutive "0"s starting from the highest-order bit of the byte.
A method for searching for an empty space, characterized in that a conversion table is attached to the processing device, and the empty space is searched using both conversion tables and the translation test function.