JPH06250806A - Font cache system device - Google Patents

Abstract

PURPOSE:To quickly provide a font by setting up the threshold of the reregistered number of hits to a proper value. CONSTITUTION:A number of registered fonts recording part 18 for recording the number of fonts stored in a font cache RAM 8 and a total number of hits recording part 19 for recording the total number of hits in recorded fonts are newly added to a font cache system device 1. A number obtained by dividing the total number of hits by the number of registered fonts is multiplied by a prescribed value to use the multipied value as the threshold of the number of reregistered hits which is to be used for determining whether an already registered font is to be reregistered or not when a newly registered pointer is circulated by one round in the RAM 8. Since the threshold of the number of reregistered hits can be always changed in accordance with the numbr of used fonts or the total number of hits and characters occupying a prescribed rate of printing frequency out of total printing frequency are held so as to be supplied from the RAM 8, font suppy can be shortened as a whole.

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 device for providing fonts to a printer or the like at high speed.

[0002]

2. Description of the Related Art In order to provide fonts to a printer or the like at high speed, in addition to a large-capacity storage device that stores all fonts, a cache memory that has a small capacity but can be read at high speed is provided. A font cache system device is known in which bitmap data of high fonts is temporarily stored therein and provided from there.

FIG. 6 is a diagram showing the configuration of such a font cache system device. In FIG. 6, 1 is a printer controller which is the core of the font cache system device, 2 is a CPU (central processing unit), 3
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, and 10 is D.
MA controller (DMA ... Direct Memory Access),
Reference numeral 11 is a SCSI controller (SCSI ... scan line; interface for hard disk), 12 is a hard disk, 13 is a host computer, 14 is a printer engine, and 17 is an engine interface.

The ROM 5 is for storing various programs executed by the CPU 2, and is a work RAM 6
Provides a working memory area for executing the program. All fonts are stored in the hard disk 12, which is an external storage device, in the form of vector data. Printing information (eg, character code) such as characters to be printed by the printer engine 14 is given from the host computer 13 via the host interface 7.

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

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

Initially, the font cache RAM 8
Nothing is stored in. In response to a print request from the host computer 13, each time the font vector data is read from the hard disk 12 and bitmap data is generated, a record relating to the font is recorded in the font cache RAM 8.

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

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

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

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, not written (Nu
ll)).

In the cache area 8-2, the part with a dot is the record area used for registering the record relating to the font read from the hard disk 12, that is, the part of the used record. . The part without a dot is the part of the record area that is not used as such, that is, the part of the empty record. The straight line drawn horizontally indicates the record delimiter.

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

(Structure of Record) FIG. 8 is a diagram for explaining the structure of the used record and the 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 font, Gothic font), font code (character code, etc.),
Font size (length, width), hit count, data size, etc. In FIG. 8A, “A” is shown as an example of the bitmap data. The number of hits is the number of times that this font has been used while the newly registered pointer CP ₁ 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 the header is empty, an “empty size” indicating the data size of the bitmap data area of the empty record, and the like.

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

Step 2 ... If it is registered, the record (used record) is accessed. Then, the value of the number of hits written in the hit record is incremented by 1. Because it was a hit this time. Step 3: The requested font is the cache area 8
-2 if not present (no hit),
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 a predetermined value or less (eg, 2 kilobytes or less). This check is for deciding whether to register in the font cache RAM 8. If the data size is too large, it will occupy a large area of the font cache RAM 8 and will not be registered.

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

(Re-Registration of Font) By the way, when the number of font records registered in the cache area 8-2 becomes full and the fonts are full, the oldest registered ones are deleted and new ones are registered. FIFO
Many adopted the "algorithm". However, in this case, even if the font is frequently used, it will be automatically deleted when it becomes old, so that the font providing speed becomes slow.

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 re-registered at the position of the new registration pointer. Next, it will be explained.

FIG. 10 is a diagram for explaining re-registration of fonts in the cache area. CP is a new registration pointer, H is an arrow indicating the direction of registration, K is a predetermined range,
R _D and R _H are records. New registration pointer C
It is assumed that P has come to the position of the record R _D and proceeds in the direction of the arrow H. The predetermined range K is a range in which the new registration pointer CP is coming soon, and the records in this range are destined to be deleted in the near future.

However, when the record R _H within the predetermined range K in front of the new registration pointer CP is used (hit), font data is provided to the page memory 9 of FIG. 6 and the position of the record R _D is set. Register again. After that, the new registration pointer CP is advanced to the next record. As a result, the record R _H is stored in the cache area 8-- at least until the new registration pointer CP comes around.
It will be left in 2.

By the way, when a new font is to be registered in the area of the record designated by the new registration pointer CP, if the number of hits of the record is a predetermined value or more, it is also re-registered without being deleted. Is being done. The threshold value for determining whether to re-register or delete is referred to as a re-registration hit count threshold value here.

Conventionally, the re-registration hit count threshold value is set 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, when the size of the cache area 8-2 is large, the new registration pointer CP
Since it takes a long time to complete one round, the re-registration hit count threshold is set to a large value.

This is because, if the time is long, the number of times the same font is hit increases, so if the re-registration hit number threshold is set to a small value, all of them will be re-registered. This is inefficient because it provides valuable area for fonts that are unlikely to be used and takes time to re-register.

On the contrary, 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 becomes small. Therefore, when the next print request is made, many fonts are required to read out the outline data again and develop it into bitmap data. With this, it takes a long time to develop, and it is impossible to provide the font at high speed.

A conventional document relating to such a font cache control system is, for example, Japanese Patent Laid-Open No. 64-8.
There is an 8660 bulletin.

[0030]

[Problems to be Solved by the Invention]

(Problem) However, in the above-described conventional font cache system device, the threshold value of the re-registration hit count of the font record is fixedly set. 1
The number of hits for one font is reduced, and fewer are re-registered. Therefore, there is a problem that the font providing speed becomes slow.

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

[0032]

In order to solve the above problems, according to the present invention, a storage device for storing outline data, and bitmap data generated by reading out outline data of a font used for printing from the storage device are provided. In a font cache system device comprising a font cache memory for temporary storage, 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 re-registration hit count threshold for deciding whether to re-register or delete the registered font is set to a value obtained by dividing the total hit count by the number of registered fonts. The value is multiplied by the value.

[0033]

[Operation] The font cache system device is provided with a registered font number recording unit for recording the number of fonts stored in the font cache RAM and a total hit number recording unit for recording the total number of hits of the registered fonts. If 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-registration hits threshold value, the re-registration hits threshold value becomes the font cache RA.
Whenever the number of fonts registered in M changes or the total number of hits changes, the calculation is recalculated. As a result, the characters occupying a predetermined number of times of printing are kept 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 now be described in detail with reference to the drawings. FIG. 1 is a diagram showing the configuration of a font cache system device of the present invention. Reference numerals correspond to those of FIG. 6, 18 is a total hit number recording unit, and 19 is a registered font number recording unit. The parts having the same configurations as those of the font cache system device of FIG.

A structural difference from the conventional font cache system device of FIG. 6 is that a total hit number 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 fonts registered in the cache area 8-2. The registered font number recording unit 19 is provided to record the number of fonts registered in the cache area 8-2.

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

The total number of hits and the total number of registered records change every moment as printing proceeds. The changing values are substituted into the equation (1) to calculate the most appropriate value N at that time. This is used as the re-registration hit count threshold value. Next, why N is calculated by the above equation as a re-registration hit count threshold will be explained as to why it is appropriate.

FIG. 11 is a diagram showing an example of the relationship between the number of character types and the number of prints. A 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 prints 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 way of curve C is slightly different depending on the type of document, it is generally a curve having a long skirt on the horizontal axis.

The characters to be re-registered in the font cache RAM 8 must be characters that are not used very often. This is because if all the characters that are not frequently used are re-registered, the time required for re-registration itself will increase, and the printing speed will decrease. So, how many times can you re-register the characters,
As a result of investigating whether it is the most efficient in terms of time, it has been found that it is better to re-register characters that occupy about 95% of printing times.

The straight line L drawn in parallel with the vertical axis in FIG.
If the total number of prints on the right is summed up, the total number of prints will be 95
It is a straight line drawn in such a position that it occupies a percentage of%. Therefore, the height N of the vertical axis of the intersection P between the straight line L and the curve C
_The number ₉₅ indicates the number of times the character having the smallest number of prints is printed out of the character group that occupies 95% of the total number of prints.

[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 Figure 11
Is drawn based on the data that can be known after printing the entire document.

However, the average number of prints N _A (see FIG. 11) obtained by dividing the total number of prints by the number of used character types and the above N ₉₅
The ratio of and has been found to be approximately constant (T) for most documents. In the middle of printing, the average number of hits N _H obtained by dividing the number of prints up to that time by the number of used character types up to that time and 95% of the total number of prints up to that time
When the relation between the character and the minimum hit count N _M (corresponding to N ₉₅ in FIG. 11) of the character group that occupies the print count of
It was also found that when the newly registered pointer CP made a round of the cache area 8-2, a relationship of N _M = TN _H (T ... Constant) was established between them. The value of T is 0.
It is about 2.

Therefore, if the value of N _M is continuously adopted as the re-registration hit count threshold value N, a high-speed font can be always provided as a whole. Note that N _H is obtained by dividing the total number of hits of all fonts registered in the font cache RAM 8 by the number of registered fonts.
You can get it. Since N _H changes constantly, so does N _M. Therefore, the re-registration hit count threshold N also needs to be constantly updated. The present invention has been made by paying attention to the above relationship.

Next, the operation of the font cache system device of the present invention will be described with reference to the flow chart of FIG. The same operation as in FIG. 9 simplifies the description. Step 1 ... When the character code (font code) to be printed is received from the host computer 13, the character code is checked by checking the table division column defined corresponding to the character code in the font search table 8-1. It is checked whether or not the font of is registered in the cache area 8-2.

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

Step 5 ... When the requested font does not exist in the cache area 8-2 (when there is no hit), the outline data is read from the hard disk 12 to the work RAM 6. Step 6 ... Converts the read outline data into bitmap data.

Step 7 ... It is checked whether the data size of the converted bitmap data is a predetermined value or less (eg, 2 kilobytes or less). This check is for deciding whether to register in the font cache RAM 8. If the data size is too large, it will occupy a large area of the font cache RAM 8 and will not be registered.

Step 8 ... If the data size is less than a predetermined value, it is registered in the font cache RAM 8. Incidentally, a process which is incidental when registering a font will be described later with reference to FIGS. Step 9 ... Transfers the bitmap data of the hit font or the newly developed bitmap data to the page memory 9. This bitmap data is used for printing by the printer engine 14. .

FIG. 5 is a flow chart for explaining the process of updating the re-registration hit count threshold value N. As described above, if the re-registration hit count threshold N is kept in a fixed relationship with the average hit count, high-speed font provision can be performed. However, the total hit count recording unit 1 for approximately calculating the average hit count.
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 N as well.

Step 1 ... It is checked whether the value of the registered font number recording section 19 is not zero. If step 2 ... 0, the value of the re-registration hit number threshold N is an initial value that can be appropriately determined (for example, a value of “10”)
Set to. Step 3 ... If not 0, re-registration hit count threshold N
Is set to the value calculated by the following formula. The total hit count uses the value recorded in the total hit count recording unit 18, and the registered font count uses the value recorded in the registered font count recording unit 19.

Steps 4, 5 ... If N calculated by the above equation
If the value of is less than 2, ignore it and set N = 2. This is to set the minimum value of the re-registration hit count threshold value N so that the one that is used only once is deleted at least when the new registration pointer CP goes around next. Is.

FIG. 3 is a flow chart for explaining the processing such as the number of hits at the time of font registration. Step 1 ... Because a font is used for printing (that is, hit), font cache RAM
Since the record is registered in 8, the value of the total hit count recording unit 18 is incremented by 1.

Step 2 ... Since the number of registered fonts increases, the value of the registered font number recording section 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 by them changes to a new value (FIG. 5).

FIG. 4 is a flow chart for explaining the processing such as the number of hits when making an empty record and re-registering a font. First, the processing of the number of hits when making an empty record will be described with reference to FIG.

Step 1 ... When a certain record is made into an empty record, the number of hits possessed by that record disappears, and therefore the value of the total number of hits recording section 18 is subtracted by that amount. Step 2 ... Also, since one used record disappears due to making a blank record, 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 re-registering the font will be described with reference to FIG. Step 1 ... When re-registering the font, the number of hits held by the record of the font is once returned to 0, and accordingly, the total number of hits recording unit 18
Deduct more. However, since the font 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 unit 18 has changed, the value of the re-registration hit count threshold N is updated according to FIG.

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

The ratio of 95% is only one example, and this ratio may be slightly different. In short, if the character types that occupy this number of times of printing are cached in the font cache RAM 8, it is sufficient that the fonts can be provided in a short time as a whole.

[0059]

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

[Brief description of 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 when registering a font.

FIG. 4 is a flowchart for explaining processing such as the number of hits when making a blank record and re-registering a font.

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

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

FIG. 7 is a diagram illustrating the overall configuration of a font cache RAM.

FIG. 8 is a diagram for explaining the structure of used records and empty records.

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

FIG. 10 is a diagram for explaining re-registration of fonts.

FIG. 11 is a diagram showing an example of the relationship between the number of character types and the number of prints.

[Explanation 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 division column, 81 ... Used record, 82 ... Empty record, CP ... New registration pointer

Claims (1)

[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 out outline data of a font used for printing from the storage device. The device is provided with a registered font number recording unit for recording the number of fonts of the bitmap data stored in the font cache memory and a total hit number recording unit for recording the total number of hits of the registered fonts. A font cache system characterized in that the re-registration hit count threshold value for deciding whether to re-register the existing font is set to 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.