JP5757097B2 - Bitmap font display device - Google Patents

Description

  The present invention relates to a bitmap font display device that develops a bitmap font stored in a flash memory by a command from a CPU into a VRAM, transfers it to a display by a graphic controller, and displays the bitmap font. An effective bitmap font display device is provided.

  FIG. 11 is a functional block diagram showing a configuration example of a conventional bitmap font display device. On the system bus, a flash memory 101, a system memory 102, an external storage interface 103, an external communication interface 104, a graphic controller 105, a display 106, a VRAM 107, and a CPU 108 which is a processor of the device main body are connected.

  The conventional bitmap font display device of the present invention and the bitmap font display device according to the present invention will be described by exemplifying a multilingual bitmap font having a large memory size. However, the present invention is not limited to this. This can be effectively applied to bitmap fonts with a large amount of. Further, the notation of “character string” includes a symbol.

  The flash memory 101 includes a boot program, a measurement / control program, initial data, a character string code, and a bitmap font of all characters (full set).

  In the system memory 102, the measurement / control program and the initial data are expanded by the boot program. In addition, after execution shifts to the measurement / control program, the character font of the language stored in the flash memory 101 is developed in accordance with a preset language mode.

  A hard disk, CDROM drive, USB memory, SD memory, etc. are connected to the external storage interface 103. The external communication interface 104 is an interface with Ethernet (registered trademark), a field bus, a wireless line, and the like, and exchanges data with the distributed control system and the handy terminal through these lines.

  The graphic controller 105 displays a fixed screen display, a message, data, and the like on the display 106 in accordance with a command from the CPU 108. The bitmap font of characters and symbols necessary for display is searched by the character code from the bitmap font of all characters developed in the system memory 102 by the CPU 108, and the bitmap font of the characters and symbols is developed in the VRAM 107.

  The display 106 is a general color liquid crystal display. The VRAM 107 expands and stores a bitmap font displayed on the display 106, and the whole and a part thereof are DMA-transferred to the display 106 by the graphic controller 105.

JP-A-4-318894

The conventional apparatus has the following problems.
(1) In a bitmap font display device applied to an industrial embedded device, it is impossible to incorporate a large-capacity multilingual bitmap font (several tens of MBs) due to the cost constraints of the flash memory 101 and the system memory 102. there were.

(2) Industrial embedded devices usually have a fixed display, and arbitrary character codes such as mobile phones and car navigation systems do not come in from communication, but bitmap fonts of characters that are not actually used (full set) Was incorporated. Also, when using a large bitmap font of 24 dots or more, a hard disk may be required.

(3) The bitmap font table search overhead by character code is large, and the burden on the CPU is large. In addition, characters may be garbled when an arbitrary character code is input from a keyboard or communication interface.

  An object of the present invention is to realize a bitmap font display device in which only a bitmap font of characters necessary for display is incorporated in a flash memory and the required memory size is minimized.

In order to achieve such a subject, the present invention has the following configuration.
(1) In a bitmap font display device that develops a bitmap font held in a flash memory by a command from a CPU into a VRAM, transfers it to a display by a graphic controller, and displays it.
Master font data holding means for holding a master bitmap font data or master vector font data acquired via a font management unit activated by an instruction of the CPU and an external interface ,
The font management unit is
At system initialization, the previously stored in the flash memory, a character string code table for outputting a code string defined by the string ID and language ID, the master bitmap provided via the external interface Based on the font data or the master vector font data ,
A string index table that outputs the index of the string to be displayed by address input ;
A character string index table management table for outputting an address to the character string index table by the character string ID and the language ID ;
A character code / index correspondence table for inputting a character code and outputting an index corresponding to the character code;
A bitmap font table that inputs an index output from the character code / index correspondence table and outputs pattern data of a bitmap font of a character code corresponding to the index ;
Is generated and stored in the flash memory.

(2) The font management unit
When one character code is read from the character string code table or the external input character code at the time of system initialization or acquisition of the external input character code, the bitmap font corresponding to this character code is the character code index. If it is in the correspondence table, the bitmap font table is extracted from this index with reference to the bitmap font and displayed, and the display processing of all character strings is executed. Map font display device.

(3) The font management unit
When one character code is read from the character string code table or the external input character code at the time of system initialization or acquisition of the external input character code, the bitmap font corresponding to this character code is the character code index. When not in the correspondence table and the system supports bitmap font, the master bitmap font data is searched with the character code, and a combination with the index corresponding to the character code is associated with the character code / index. registered in the table, registers a bitmap fonts matching the search to the free index slots in the bit map font table, retrieves the bitmap fonts by referring to the bit map font table from the index The drives the graphic controller to display the bitmap font display device according to and executes the display processing of all character strings (1).

(4) The font management unit
When one character code is read from the character string code table or the external input character code at the time of system initialization or acquisition of the external input character code, the bitmap font corresponding to this character code is the character code index. If not in the correspondence table and the system supports vector fonts , the master vector font data is converted into bitmap data, the master font data bitmap-converted by the character code is searched, and the character code A pair with an index corresponding to is registered in the character code / index correspondence table, and a bitmap font matched by the search is registered in an empty index slot of the bitmap font table. Remove the bit map font by referring to the bit map font table is displayed by driving the graphic controller, the bit map font display device according to and executes the display processing of all character strings (1).

(5) The font management unit
In the normal operation of the system, the address of the character string index table is acquired from the character string index table management table based on the parameters of the display request message including the designated coordinates and character string ID passed from the CPU, and the bit is calculated from the address. A bitmap font is retrieved by accessing a map font table, written into the VRAM using the designated coordinates as a base point, driven to display the graphic controller, and a display process for all character strings is executed (1). The bitmap font display device according to any one of (4) to (4).

According to the present invention, the following effects can be expected.
(1) Memory cost reduction:
Master bitmap font data, which is a full set of original font data, is provided from the external storage interface 103 at the time of system initialization (initialization processing only needs to be performed once) and is not required during operation. This is effective for cost reduction of the system memory 101 and system memory 102.

  Incidentally, the memory size necessary for storing the multilingual bitmap font data for the 12 languages illustrated in FIG. 2 is 12 dots, 14 dots, and 16 dots, and about 20 MB when the typeface is regular, italic, or bold. Need. By applying the present invention, this can be reduced to about 1 MB, and the required capacity is reduced to 1/20.

(2) Speeding up of liquid crystal display:
Since access to the various tables of the present invention is performed by index (element number of array), there is no overhead of normal “character code search”. Therefore, the display speed is almost constant except for the difference in the number of characters in the character string, font size, and type of font, and the speed can be increased.

(3) CPU load reduction:
By newly providing a display-only font management unit 109, the CPU 108 can reduce the display load and concentrate on the original processing.

(4) Dynamic character code identification:
Character codes entered from communication can be stored in the flash memory while dynamically identifying whether the character codes are new or already registered. Even when an arbitrary character code is dynamically input from a keyboard or a communication interface, it can be displayed without being garbled.

(5) Font update:
By making multilingual character bitmap font data externally attached, update management of bitmap fonts becomes easy.

It is a functional block diagram which shows one Example of the bitmap font display apparatus to which this invention is applied. It is an image figure of a character string code table. It is an image figure of a character string index table. It is an image figure of a character string index table management table. It is an image figure of a multilingual bitmap font table. It is an image figure of multilingual bitmap font data. It is an image figure of a character code index management table. It is a flowchart explaining the initialization operation | movement sequence of a font management unit. It is a flowchart explaining the sequence at the time of normal operation | movement of a font management unit. It is a flowchart explaining the online character code conversion operation | movement sequence of a font management unit. It is a functional block diagram which shows the structural example of the conventional bitmap font display apparatus.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a functional block diagram showing an embodiment of a bitmap font display device to which the present invention is applied. The same elements as those of the conventional configuration described with reference to FIG.

  The structural features of the present invention added to the conventional configuration shown in FIG. 11 are the new installation of a font management unit 109 and multilingual master font data holding means 114 connected to the system bus.

  The font management unit 109 is supplied from the multilingual master font data holding unit 114 via the character string code table 110 stored in advance in the flash memory 101 and the external storage interface 103 in accordance with an instruction from the CPU 108 at the time of system initialization. A character string index table 111, a character string index table management table 112, a minimum necessary multilingual bitmap font table 113, and a character code / index correspondence table 115 necessary for character display are generated from the original master bitmap font data. And stored in the flash memory 101.

  FIG. 2 is an image diagram of a character string code table. The character string code table 110 is a table that is pre-installed in the flash memory 101 of the embedded device, and character strings used in the device are defined by a two-dimensional array of language IDs and character string IDs. The string code is defined in Unicode or local code.

  FIG. 3A is an image diagram of the character string index table. The character string index table 111 is a table that is automatically generated from the character string code table 110 and the master bitmap font data of the multilingual master font data holding unit 114 when the system is initialized. FIG. 3B shows a data format.

  FIG. 4A is an image diagram of the character string index table management table. The character string index table management table 112 is a table automatically generated from the character string code table 110 and the master bitmap font data of the multilingual master font data holding unit 114 at the time of system initialization.

  FIG. 4B shows a data format. It consists of a two-dimensional array of language IDs and character string IDs, and addresses to the character string index table 111 are registered.

  FIG. 5A is an image diagram of a multilingual bitmap font table. The multilingual bitmap font table 113 is a table automatically generated from the character string code table 110 and the master bitmap data of the multilingual master font data holding unit 114 at the time of system initialization.

  FIG. 5B shows a data format. Bitmap fonts corresponding to the characters in the character string code table 110 are registered in the order in which they appear without duplication. Bitmap fonts for all languages defined in the character string code table 110 are registered in a batch.

  FIG. 6A is an image diagram of master bitmap font data held by the multilingual master font data holding means 114. The master bitmap font data is an example of a full 12 × 12 dot original font data table provided from the multilingual master font data holding unit 114 via the external storage interface 103 at the time of system initialization. . FIG. 6B shows a data format.

  FIG. 7 is an image diagram of the character code / index management table. The character code index management table 115 is a table automatically generated from the character string code table 110 and master bitmap font data of the multilingual master font data holding means 114 at the time of initialization of the system. , Characters are defined.

  FIG. 8 is a flowchart for explaining an initialization operation sequence of the font management unit. If the string is not changed, it only needs to be initialized once. When the initialization operation starts in step S1, one character code is read from the character string code table 110 in step S2.

  If it is determined in step S3 that the bitmap font corresponding to the read character code is in the character code / index correspondence table 115, the bitmap is referred to the multilingual bitmap font table 113 from this index value in step S4. The font is taken out and the initial screen is displayed by driving the graphic controller 105.

  If the check of step S5 confirms the end of the process for all the character strings, and the next check of step S6 confirms the end of the process for all the character strings, the process of the initialization operation ends in step S7.

  If it is determined in step S3 that the bitmap font corresponding to the read character code is not in the character code / index correspondence table 115 and the system is bitmap font compatible in step S8, the process proceeds to step S9.

  In step S9, the master bitmap font data (full set bitmap font data) of the multilingual master font data holding means 114 given through the external storage interface 103 is searched by the character code.

  In step S10, a combination with the index value corresponding to the character code is registered in the character code / index correspondence table 115. Further, in step S11, the bitmap font matched by the search is registered in the empty index slot of the multilingual bitmap font table 113, the processing in steps S4 to S7 described above is executed, and the initialization operation processing is completed. .

  If it is determined in step S3 that the bitmap font corresponding to the read character code is not in the character code / index correspondence table 115 and the system is compatible with the vector font in step S8, the process proceeds to step S12.

  In step S12, the master vector font data of the multilingual master font data holding means 114 given through the external storage interface 103 is converted into bitmap data, and the converted bitmap font is searched by the character code.

  Thereafter, the process proceeds to the processes of step S10 and step S11 described above, and the processes of steps S4 to S7 described above are further executed to complete the initialization operation process.

  FIG. 9 is a flowchart for explaining a sequence during normal operation of the font management unit 109. When the normal operation in units of one character string is started in step S1, the parameters of the display request message including the designated coordinates, language ID, and character string ID delivered from the CPU 108 are sent to the font management unit 109 in step S2.

  In step S3, the address of the character string index table 111 is acquired from the character string index table management table 112 based on the parameters (designated coordinates, language ID, character string ID) sent from the CPU.

  In step S4, the bitmap font table 113 is accessed from this address, a bitmap font corresponding to the index number is extracted, and written in the VRAM 107 using the designated coordinates as a base point.

  In step S5, the processing of all characters in one character string is confirmed. In step S6, the graphic controller 105 is driven and displayed. In step S7, the display operation of one character string is terminated.

  FIG. 10 is a flowchart for explaining the online character code conversion operation sequence of the font management unit. The operation of this flow is a dynamic character code identification operation input from the external communication interface 104. In order to enable this operation, it is necessary to connect the master bitmap font data of the multilingual master font data holding unit 114 so that the master bitmap font data can always be read.

  This processing flow is close to the initialization processing flow described in FIG. When the character code conversion operation starts in step S1, one character code is read from the external communication interface 104 in step S2.

  If it is determined in step S3 that the bitmap font corresponding to the read character code is in the character code / index correspondence table 115, the bitmap is referred to the multilingual bitmap font table 113 from this index value in step S4. The font is taken out and the graphic controller 105 is driven to be displayed.

  If it is confirmed in the check in step S5 that the processing of all input character strings has been completed, the processing of the character code conversion operation is ended in step S6.

  If it is determined in step S3 that the bitmap font corresponding to the read character code is not in the character code / index correspondence table 115 and the system is bitmap font compatible in step S8, the process proceeds to step S9.

  In step S9, the master bitmap font data (full set bitmap font data) of the multilingual master font data holding means 114 given through the external storage interface 103 is searched by the character code.

  In step S10, a combination with the index value corresponding to the character code is registered in the character code / index correspondence table 115. Furthermore, in step S11, the bitmap font matched by the search is registered in the empty index slot of the bitmap font table 113, the processing of steps S4 to S6 is executed, and the processing of the conversion operation is completed.

  If it is determined in step S3 that the bitmap font corresponding to the read character code is not in the character code / index correspondence table 115 and the system is compatible with the vector font in step S8, the process proceeds to step S12.

  In step S12, the multilingual master vector font data of the master font data holding means 114 given through the external storage interface 103 is converted into bitmap data, and the converted bitmap font is searched by the character code.

  Thereafter, the process proceeds to the above-described steps S10 and S11, and the above-described steps S4 to S6 are further executed to complete the conversion operation.

  In the present invention, a bitmap font has been described as an example, but the same applies to a vector font. In particular, the rasterization load of the vector font can be limited at the initial initialization.

  The present invention can be effectively applied to all embedded device products mounted with ITRON base or non-OS, such as field products, communication / measuring instruments, and PLCs.

101 Flash memory 102 System memory 103 External storage interface 104 External communication interface 105 Graphic controller 106 Display 107 VRAM
108 CPU
109 Font management unit 110 Character string code table 111 Character string index table 112 Character string index table management table 113 Multilingual bitmap font table 114 Multilingual master font data holding means 115 Character code / index correspondence table

Claims (5)

In a bitmap font display device that develops a bitmap font stored in a flash memory in accordance with a command from a CPU into a VRAM, transfers it to a display by a graphic controller, and displays it.
Master font data holding means for holding a master bitmap font data or master vector font data acquired via a font management unit activated by an instruction of the CPU and an external interface,
The font management unit is
A character string code table for outputting a character string code defined by a character string ID and a language ID, which is stored in advance in the flash memory at the time of system initialization, and the master bit map given via the external interface Based on the font data or the master vector font data,
A string index table that outputs the index of the string to be displayed by address input;
A character string index table management table for outputting an address to the character string index table by the character string ID and the language ID;
A character code / index correspondence table for inputting a character code and outputting an index corresponding to the character code;
A bitmap font table that inputs an index output from the character code / index correspondence table and outputs pattern data of a bitmap font of a character code corresponding to the index;
Is generated and stored in the flash memory. The font management unit is
When one character code is read from the character string code table or the external input character code at the time of system initialization or acquisition of the external input character code, the bitmap font corresponding to this character code is the character code index. 2. The bit according to claim 1, wherein, if it is in the correspondence table, a bitmap font is extracted from the index by referring to the bitmap font table and displayed, and display processing of all character strings is executed. Map font display device. The font management unit is
When one character code is read from the character string code table or the external input character code at the time of system initialization or acquisition of the external input character code, the bitmap font corresponding to this character code is the character code index. When not in the correspondence table and the system supports bitmap font, the master bitmap font data is searched with the character code, and a combination with the index corresponding to the character code is associated with the character code / index. The bitmap font registered in the table and registered in the search is registered in an empty index slot of the bitmap font table, and the bitmap font is retrieved from the index by referring to the bitmap font table. Wherein it is displayed by driving the graphic controller, the bit map font display device according to claim 1, wherein the display processing is executed for all strings. The font management unit is
When one character code is read from the character string code table or the external input character code at the time of system initialization or acquisition of the external input character code, the bitmap font corresponding to this character code is the character code index. If not in the correspondence table and the system supports vector fonts , the master vector font data is converted into bitmap data, the master font data bitmap-converted by the character code is searched, and the character code A pair with an index corresponding to is registered in the character code / index correspondence table, and a bitmap font matched by the search is registered in an empty index slot of the bitmap font table. Remove the bit map font by referring to the bit map font table is displayed by driving the graphic controller, the bit map font display device according to claim 1, wherein the display processing is executed for all strings. The font management unit is
In the normal operation of the system, the address of the character string index table is acquired from the character string index table management table based on the parameters of the display request message including the designated coordinates and character string ID passed from the CPU, and the bit is calculated from the address. The bitmap font is retrieved by accessing a map font table, written into the VRAM using the designated coordinates as a base point, the graphic controller is driven to display, and display processing of all character strings is executed. The bitmap font display device according to any one of 1 to 4.