JP3082504B2 - Font cache system device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a font cache system for providing fonts to a printer or the like at a high speed.

[0002]

2. Description of the Related Art In order to provide fonts to printers and the like at high speed, a small-capacity but high-speed cache memory is provided in addition to a large-capacity storage device for storing all fonts. Font cache system devices are known that temporarily store high font bitmap data therein and provide it therefrom.

FIG. 6 is a diagram showing a configuration of such a font cache system device. In FIG. 6, reference numeral 1 denotes a printer controller which is a core of a font cache system device, 2 denotes a CPU (central processing unit),
Is an address bus, 4 is a data bus, 5 is a ROM (read only memory), 6 is a work RAM (RAM ... random access memory), 7 is a host interface, 8 is a font cache RAM, 9 is a page memory, 10 is a D memory.
MA controller (DMA: Direct Memory Access),
Numeral 11 denotes a SCSI controller (SCSI ... Skudge; interface for hard disk), numeral 12 denotes a hard disk, numeral 13 denotes a host computer, numeral 14 denotes a printer engine, and numeral 17 denotes an engine interface.

[0004] The ROM 5 is for storing various programs to be executed by the CPU 2.
Provides a working memory area when executing a program. All fonts are stored in the form of vector data on a hard disk 12 which is an external storage device. Printing information (eg, character codes) such as characters to be printed by the printer engine 14 is provided from the host computer 13 via the host interface 7.

A font corresponding to the character code is first searched in the font cache RAM 8, and if there is, read out therefrom and expanded in the page memory 9. If not, the vector data is read from the hard disk 12, bitmap data of a desired size is generated based on the vector data, and is expanded in the page memory 9. At the same time, it is stored in the font cache RAM 8.

When the font for one page is developed in the page memory 9, a print start command is transmitted through the engine interface 17 of the printer engine 14, and
The print data (bitmap data) is serially transmitted to the printer engine 14 via the DMA controller 10, and the printing is executed.

At first, the font cache RAM 8
Does not contain anything. In response to a print request from the host computer 13, every time font vector data is read from the hard disk 12 and bitmap data is generated, a record related to the font is recorded in the font cache RAM 8.

[Structure of Font Cache RAM] First, the structure of the font cache RAM 8 will be described. FIG. 7 is a diagram illustrating the overall configuration of the font cache RAM 8. 7, 8-1 is a font search table, 8-2 is a cache area, 80 is a table section column, 81 is a used record, 82 is an empty record,
CP is a newly registered pointer.

The font cache RAM 8 includes a font search table 8-1 and a cache area 8-2. Records related to fonts such as bitmap data are registered in the cache area 8-2, and information indicating the location where the records are registered is recorded in the font search table 8-1.

The font search table 8-1 is divided into the same number of sections as the number of font codes, and one specific section is associated with one font code. For example, a section called a table section column 80 is assigned to a font code representing the character A.

If the font A is registered in the cache area 8-2, information indicating the registered location (address) is written in the table section column 80. When a plurality of fonts having the same font code are registered, one of the registered locations is written. If not registered, it is not written (Nu
ll)

In the cache area 8-2, a portion with a dot is a record area used for registering a record related to a font read from the hard disk 12, that is, a used record portion. . The portion without dots is a record area that is not so used, that is, a portion of an empty record. A straight line drawn horizontally indicates a record break.

The new registration pointer CP is a pointer indicating a position when a record relating to a font is newly registered, and is advanced in a fixed direction in the cache area 8-2 in a ring shape. If the certain direction is a direction from top to bottom in FIG. 7, the lowermost end is advanced to the uppermost end.

(Structure of Record) FIG. 8 is a diagram for explaining the structure of a used record and an empty record. These are composed of a bitmap data area and an area for recording header information.

FIG. 8A shows the structure of the usage record 81. The header information includes font type (eg, Mincho, Gothic), font code (character code, etc.)
There are font size (vertical and horizontal length), number of hits, data size, and the like. FIG. 8A shows “A” as an example of the bitmap data. The hit count is a count indicating how many times this font has been used while the newly registered pointer CP1 circulating in the cache area 8-2 in a certain direction makes _one round.

FIG. 8B shows the structure of the empty record 82. The header information includes an “empty flag” indicating that it is empty, an “empty size” indicating the data size of the bitmap data area of an empty record, and the like.

[Operation] Next, the control operation of the font cache system configured as described above will be described with reference to the flowchart of FIG. Step 1: When a character code (font code) to be printed is received from the host computer 13, the character code is checked by examining a table section column defined corresponding to the character code in the font search table 8-1. It is determined whether or not the font is registered in the cache area 8-2.

Step 2: If registered, access the record (use record). Then, the value of the number of hits described in the hit record is increased by one. Because it was hit this time. Step 3: The font being sought is cache area 8
-2 if not present (if not hit),
The outline data is read from the hard disk 12 to the work RAM 6. Step 4: Convert the read outline data into bitmap data.

Step 5: It is checked whether the data size of the converted bitmap data is smaller than a predetermined value (for example, smaller than 2 kilobytes). This check is for determining whether or not to register in the font cache RAM 8. If the data size is too large, it is not registered because it occupies a large area of the font cache RAM 8.

Step 6: If the data size is equal to or smaller than the predetermined value, the data size is registered in the font cache RAM 8. Step 7: The bitmap data of the hit record or the newly developed bitmap data is transferred to the page memory 9. This bitmap data is used for printing by the printer engine 14.

(Re-registration of Fonts) By the way, when the number of fonts registered in the cache area 8-2 increases and becomes full, so-called "registering" is performed by deleting oldest ones and registering new ones. FIFO
Algorithms "were often used. However, in this case, even a frequently used font is automatically deleted when it becomes old, so that the font providing speed is reduced.

Therefore, when a record which is in the order of being deleted from the font cache RAM 8 in the near future (which can be known by the fact that the newly registered pointer CP has come close to a predetermined range) is hit, It is being re-registered at the position of the new registration pointer. Next, it will be described.

FIG. 10 is a diagram for explaining re-registration of fonts in the cache area. CP is a newly registered pointer, H is an arrow indicating the direction of registration, K is a predetermined range,
_RD and _RH are records. Now, newly registered pointer C
It is assumed that P has come to the position of the record _RD and proceeds sequentially in the direction of the arrow H. The predetermined range K is a range in which the newly registered pointer CP is coming soon, and records in this range are destined to be deleted soon.

[0024] However, when the record R _H, which is in the front of the predetermined range K of the new registration pointer CP is used (hit) is configured to provide the font data in the page memory 9 in FIG. 6, the position of the record R _D Register again. Thereafter, the newly registered pointer CP is advanced to the next record. As a result, the record _RH is stored in the cache area 8-at least until the next newly registered pointer CP comes around.
2 will be left.

When a new font is to be registered in the area of the record indicated by the new registration pointer CP, if the number of hits of the record is equal to or more than a predetermined value, this is also re-registered without being deleted. That is being done. Here, the threshold for determining whether to re-register or delete is referred to as a re-registration hit count threshold.

Conventionally, the re-registration hit count threshold value is determined as a fixed value. Since the appropriate value is related to the size of the cache area 8-2, it is appropriately determined in consideration of the size and the like. For example, if the size of the cache area 8-2 is large, the newly registered pointer CP
Since the time required for one round to be made becomes longer, the threshold value of the number of re-registration hits is also set to a large value.

The reason is that if the time is long, the number of hits of the same font increases, and if the re-registration hit frequency threshold value is set small, all of them will be re-registered. This provides valuable areas for fonts that are unlikely to be used, and wastes time working on re-registration, which is inefficient.

Conversely, if the value is set to a value larger than the value considered appropriate in view of the size of the cache area 8-2, the number of fonts to be re-registered decreases. For this reason, there are many fonts that require an effort to read the outline data again and develop it into bitmap data when the next print request is made. In this case, it takes time to develop the font, and it is not possible to provide fonts at high speed.

As a conventional document relating to such a font cache control system, for example, Japanese Unexamined Patent Publication No.
There is 8660 publication.

[0030]

[Problems to be solved by the invention]

(Problem) However, in the conventional font cache system described above, the threshold value of the number of re-registration hits of the font record is fixedly set. 1
The number of hits for one font decreases, and the number of re-registers decreases. Therefore, there was a problem that the provision speed of the font became slow.

(Explanation of Problems) As the number of types of fonts used increases, the number of hits within the time that the newly registered pointer CP makes a round in the cache area 8-2 becomes smaller. Therefore, if the re-registration hit count threshold is fixedly set, the number of fonts whose hit count exceeds the value decreases. Since those fonts are deleted from the cache area 8-2, the next time the same font is requested, the outline data must be read from the hard disk 12 and developed into bitmap data. Therefore, the font providing speed is reduced. An object of the present invention is to solve such a problem.

[0032]

According to the present invention, a storage device for storing outline data and bitmap data generated by reading outline data of a font used for printing from the storage device are provided. In a font cache system device having a font cache memory for temporarily storing, a registered font number recording unit for recording the number of fonts of bitmap data stored in the font cache memory, and a total hit of registered fonts It has a total hit count recording unit that records the number of times, and the threshold value for re-registering hit count for determining whether to re-register or delete registered fonts is set to a value obtained by dividing the total hit count by the number of registered fonts. The value was multiplied.

[0033]

[Operation] A font cache system device includes a registered font number recording unit for recording the number of fonts stored in a font cache RAM, and a total hit number recording unit for recording the total hit number of registered fonts. When a value obtained by multiplying a value obtained by dividing the total number of hits by the number of registered fonts by a predetermined value is used as the re-registered hit number threshold, the re-registered hit number threshold becomes the font cache RA.
Each time the number of fonts registered in M changes or the total number of hits changes, the calculation is performed again. As a result, characters that occupy a predetermined number of times of printing the number of times of printing are maintained so as to be supplied from the font cache RAM, so that it is possible to supply the font as a whole in a short time.

[0034]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing a configuration of a font cache system device of the present invention. The reference numerals correspond to those in FIG. 6, reference numeral 18 denotes a total hit count recording unit, and reference numeral 19 denotes a registered font number recording unit. Parts having the same configuration as the font cache system device of FIG. 6 operate in the same manner, and a description thereof will be omitted.

The configuration differs from the conventional font cache system shown in FIG. 6 in that a total hit count recording unit 18 and a registered font number recording unit 19 are provided. These are configured by a storage device such as a RAM. The total hit count recording unit 18 is provided to record the total hit count of the font registered in the cache area 8-2. The registered font number recording unit 19 is provided for recording the number of fonts registered in the cache area 8-2.

In the present invention, the re-registration hit count threshold is not a fixed value, but a floating value according to the font usage. Specifically, the value N _A is calculated by the following equation. Here, T is a constant.

Although the total number of hits and the total number of registered records change every moment as printing progresses, the values that change are substituted into equation (1), and the most appropriate value N at that time is calculated. This is used as the re-registration hit count threshold. Next, the reason why the N calculated by the above equation is appropriate when used as the re-registration hit count threshold will be described.

FIG. 11 is a diagram showing an example of the relationship between the number of character types and the number of times of printing. The curve C is obtained by arranging the character types appearing in the document in the horizontal axis direction in descending order of the number of times of printing, and connecting the plotted points. Therefore, the area enclosed by the curve C, the vertical axis, and the horizontal axis indicates the total number of times of printing. Although the manner of curve C is slightly different depending on the type of document, the curve C is generally a curve having a long tail on the horizontal axis.

The characters to be reregistered in the font cache RAM 8 must be characters whose use frequency is not very small. This is because if all the characters that are used less frequently are re-registered, the time required for the re-registration itself increases, and the printing speed is rather lowered. Therefore, if you re-register characters up to how many times
Investigation into the most efficient in terms of time revealed that it would be better to re-register characters that account for about 95% of the number of times of printing.

A straight line L drawn in parallel with the vertical axis in FIG.
The total number of prints to the right is 95
It is a straight line drawn at a position that occupies the percentage of%. Therefore, the height N of the vertical axis of the intersection P between the straight line L and the curve C
₉₅ indicates the number of times of printing of a character having the least number of times of printing in a character group occupying 95% of the total number of times of printing.

[0041] Therefore, in order to re-register the character, which accounts for 95% of the total printing number of times, but not may be employed N ₉₅ as the re-registration hit threshold of the number of times, in the middle of printing a document of N ₉₅ I don't know the value. Because, FIG.
This is because the drawing is based on the data that is known after the printing of the entire document is completed.

However, the average number of prints N _A (see FIG. 11) obtained by dividing the total number of prints by the number of character types used and the above N ₉₅
Was found to be nearly constant (T) for most documents. In the middle of printing, the average number of hits N _H obtained by dividing the number of printings up to that time by the number of character types used up to that time is 95% of the total number of printings up to that point.
When examining the relationship with the minimum number of hits N _M (corresponding to N ₉₅ in FIG. 11) of the characters in the character group occupying the number of times of printing,
When the newly registered pointer CP makes one round of the cache area 8-2, it has been found that a relationship of approximately N _M = TN _H (T... Constant) is established between the two. The value of T is 0.
About 2.

Therefore, if this value of N _M is continuously adopted as the re-registration hit count threshold value N, fonts can always be provided at high speed as a whole. N _H is calculated by dividing the total number of hits of all fonts registered in the font cache RAM 8 by the number of registered fonts.
Can be obtained. Since N _H changes constantly, N _M will also change constantly. Therefore, it is necessary to constantly update the re-registration hit count threshold value N. The present invention has been made by focusing on the above-described relationship.

Next, the operation of the font cache system of the present invention will be described with reference to the flowchart of FIG. Operations similar to those in FIG. 9 simplify the description. Step 1: When a character code (font code) to be printed is received from the host computer 13, the character code is checked by examining a table section column defined corresponding to the character code in the font search table 8-1. It is determined whether or not the font is registered in the cache area 8-2.

Step 2: If registered, access the record of the font. Then, the value of the number of hits described in the record of the hit font is set to 1
To increase. Step 3: The value of the total hit count recording unit 18 is incremented by one. Step 4: Since the value of the total number of hits has changed, the value of the re-registration hit number threshold N is recalculated and updated. The details will be described later with reference to FIG.

Step 5: If the desired font does not exist in the cache area 8-2 (if no hit is found), the outline data is read from the hard disk 12 to the work RAM 6. Step 6: The read outline data is converted into bitmap data.

Step 7: It is checked whether the data size of the converted bitmap data is smaller than a predetermined value (for example, whether it is smaller than 2 kilobytes). This check is for determining whether or not to register in the font cache RAM 8. If the data size is too large, it is not registered because it occupies a large area of the font cache RAM 8.

Step 8: If the data size is equal to or smaller than the predetermined value, the data size is registered in the font cache RAM 8. The processing that accompanies the registration of the font will be described later with reference to FIGS. Step 9: The bitmap data of the hit font or the newly developed bitmap data is transferred to the page memory 9. This bitmap data is used for printing by the printer engine 14. .

FIG. 5 is a flowchart for explaining the process of updating the re-registration hit count threshold value N. It has already been described that if the re-registration hit number threshold N is maintained in a fixed relationship with the average number of hits, a high-speed font can be provided. However, the total hit number recording unit 1 for approximately calculating the average number of hits
The value of 8 and the value of the registered font number recording unit 19 constantly change. Therefore, it is necessary to constantly update the re-registration hit count threshold value N.

Step 1: Check whether the value of the registered font number recording unit 19 is not 0 or not. If step 2... 0, an initial value (for example, a value of “10”) from which the value of the re-registration hit count threshold N can be determined as appropriate
Set to. Step 3: If not 0, re-registration hit count threshold N
Is set to the value calculated by the following equation. The total number of hits uses the value recorded in the total number of hits recording unit 18, and the number of registered fonts uses the value recorded in the number of registered fonts recording unit 19.

Steps 4, 5... N
Is smaller than 2, it is ignored and N = 2 is set. This is to determine the minimum value of the re-registration hit count threshold value N, and the one that has been used only once is to be deleted at least when the newly registered pointer CP comes next. It is.

FIG. 3 is a flowchart for explaining processing such as the number of hits at the time of font registration. Step 1: A font is used for printing (that is, a hit), and the font cache RAM is used.
8, the value of the total hit count recording unit 18 is incremented by one.

Step 2: Since the number of registered fonts increases, the value of the registered font number recording unit 19 is also incremented by one. Step 3: Since the value of the total hit count recording unit 18 and the value of the registered font count recording unit 19 change, the re-registration hit count threshold N calculated thereby is also updated to a new value (FIG. 5).

FIG. 4 is a flow chart for explaining processing such as the number of hits when making a free record and when reregistering a font. First, the processing of the number of hits at the time of empty record conversion will be described with reference to FIG.

Step 1... When a record becomes an empty record, the number of hits possessed by the record disappears. Step 2: Since one used record disappears due to the empty record conversion, 1 is subtracted from the value of the registered font number recording unit 19. Step 3: Since the value of the total hit count recording unit 18 and the value of the registered font count recording unit 19 have changed, the value of the re-registration hit count threshold N is updated according to FIG.

Next, the processing of the number of hits when reregistering a font will be described with reference to FIG. Step 1: When the font is re-registered, the number of hits of the record of the font is once returned to 0, so that the total number of hits recording unit 18
Subtract more. However, fonts will be re-registered,
The value of the registered font number recording unit 19 does not change. Step 2: Since the value of the total hit count recording section 18 has changed, the value of the re-registration hit count threshold N is updated according to FIG.

In this manner, the re-registration hit count threshold N is always kept at T times the average hit count N (T = about 0.2), which is the fastest font providing speed. Printing can be performed at high speed as a whole.

Note that the ratio of 95% is up to one example, and this ratio may be slightly different. In short, if the character type occupying this ratio of the number of times of printing is cached in the font cache RAM 8, it is sufficient if the font can be provided in a short time as a whole.

[0059]

As described above, according to the font cache system of the present invention, the registered font number recording unit and the total hit number recording unit are provided, and the total number of hits is divided by the registered font number. The value multiplied by the value is used as the re-registration hit count threshold. Therefore, it can be constantly changed according to the number of fonts used and the total number of hits,
Characters that always occupy a predetermined percentage of the number of prints
Since the font is kept supplied from the font cache RAM, the font can be supplied in a short time as a whole.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a font cache system device of the present invention.

FIG. 2 is a flowchart for explaining the operation of the font cache system device of the present invention.

FIG. 3 is a flowchart illustrating processing such as the number of hits at the time of font registration.

FIG. 4 is a flowchart for explaining processing such as the number of hits when making an empty record and when reregistering a font.

FIG. 5 is a flowchart illustrating an update process of a re-registration hit count threshold value N;

FIG. 6 is a diagram showing a configuration of a conventional font cache system device.

FIG. 7 is a view for explaining the overall configuration of a font cache RAM;

FIG. 8 is a view for explaining the configuration of a used record and an empty record;

FIG. 9 is a flowchart illustrating the operation of a conventional font cache system device.

FIG. 10 is a view for explaining re-registration of a font.

FIG. 11 is a diagram illustrating an example of a relationship between the number of character types and the number of times of printing.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Printer controller, 2 ... CPU, 3 ... Address bus, 4 ... Data bus, 5 ... ROM, 6 ... Work RA
M, 7 host interface, 8 font cache RAM, 8-1 font search table, 8-2 cache area, 9 page memory, 10 DMA controller, 11 SCSI controller, 12 hard disk, 13 host Computer, 14: Printer engine, 17: Engine interface, 18: Total hit count recording unit, 19: Registered font number recording unit, 80:
Table partition column, 81: used record, 82: empty record, CP: new registration pointer

Claims (1)

(57) [Claims] 1. A font cache system comprising: a storage device for storing outline data; and a font cache memory for temporarily storing bitmap data generated by reading outline data of a font used for printing from the storage device. The apparatus includes a registered font number recording unit that records the number of fonts of the bitmap data stored in the font cache memory, and a total hit number recording unit that records the total number of hits of the registered font. A font cache system characterized in that a re-registration hit count threshold value for determining whether to re-register or delete a font is a value obtained by multiplying a value obtained by dividing the total hit count by the number of registered fonts by a predetermined value. apparatus.