JP2806535B2 - Microcomputer development support equipment - Google Patents

Description

The present invention relates to a microcomputer development support device,
In particular, the present invention relates to a data access process of an apparatus for emulating a microcomputer having a plurality of accessible data lengths.

[Conventional technology]

The data access processing of the microcomputer development support apparatus is used, for example, for a target memory read / write function. Usually, when a user obtains information for access from an input device, a target data access is performed using a data access address and data length of the input information. FIGS. 3 and 4 show flowcharts of memory reading and memory writing as conventional data access processing.

In the conventional memory read, as shown in FIG. 3, a read address and a display data length are obtained from the input device as information required for the memory read (step 31), and the display data length is obtained from the read address. Access the target and read the data as if reading with (Step 3
2) The data is displayed on the output device as data having a display data length (step 33).

In the conventional memory write, as shown in FIG. 4, a write address, a write data input data length, and write data are obtained from an input device as information required for the memory write (step 41), and the write data is input data length. The target is accessed so as to write from the write address, and data is written (step 42).

[Problems to be solved by the invention]

For a target of a microcomputer having a plurality of accessible data lengths, an access data length is set to a data bus width of a development support target microcomputer, for example, 4 bytes (32 bits) in order to reduce hardware and increase processing speed. ) Is designed to always access data buses having valid data on all 4-byte data buses.

When a target such as described above is performed by the conventional access processing method, the display format and the input format must always be adjusted to the data length of the target, for example, a word. Even in this case, the disadvantage is that the user has to input and display data as word string data,
There is a disadvantage in that data cannot be accessed correctly unless a user inputs an address that always causes valid data to appear on all data buses (undefined data does not appear).

[Means for solving the problem]

The microcomputer development support device of the present invention includes a step of rounding an input data access address to an address at a boundary of a data length unit, and reading data of a data length unit including data of the rounded portion during writing, and It has a data access processing function including a step of embedding data to be written in the read data and a step of accessing a target from a rounded address in units of data length.

〔Example〕

Next, the present invention will be described with reference to the drawings. In the present embodiment, a description will be given by taking as an example a memory read and a memory write of a 32-bit CPU as a microcomputer to be supported for development.

FIG. 1 is a flowchart of memory reading. First, a read address and a display data length are obtained from an input device as information required for memory read in the past (step 11). Next, the read address is rounded to a 4-byte boundary which is the bus width of the 32-bit CPU (step 12). The rounding method can be obtained by dividing the read address by the remainder of the read address and 4 which is the number of bytes of the CPU bus width. Specify the CPU bus width value in advance as data or
May be obtained from the input device so that it can be changed. In this embodiment, 4 is given in advance. Next, the CPU accesses the target from the rounded read address using the instruction of the CPU for reading the memory with a 4-byte length (hereinafter referred to as a word) which is the bus width of the CPU, and stores the target in the buffer (step 13). If the read data spans a word unit boundary and the data read has not yet been completed (step 14), change the address to the next word boundary (step 16) and access the target in the same manner. It is stored in the buffer. When reading of all data is completed (step 14), data display is performed according to the address and data length at the time of inputting the reading condition from the buffer data (step 15).

FIG. 2 is a flow chart of the memory writing. First, a write address, a write data input data length, and write data are obtained from an input device as information conventionally required for writing to a memory (step 21). Round write address as well as memory read (step
twenty two). For data correction, data read is performed from the rounded write address by performing a target access by a word access instruction, and the read data is stored in a buffer (step 23). Next, the write data is corrected for the buffer (step 24). ), Target access is performed by a word access instruction as write data having a word data length, and data is written (step 25). If the write data straddles the word unit boundary and the write data still remains (step 26), change the address to the next word boundary (step 27), read the data similarly (step 23), and buffer The data is written to the target (step 24), and the target is accessed by word (step 25) to write the data. When all the write data has been written (step 26), the process ends.

〔The invention's effect〕

As described above, the step of rounding the data access address by the data length of the data bus width of the microcomputer to be supported, the step of supplementing the rounded part data at the time of writing, and the step of rounding the target to the target. By having a data access processing function consisting of a step of accessing from the address with the data length of the data bus width of the development support target microcomputer, the development support target microcomputer Since the access is performed using the data length of the data bus width, there is an effect that the user can access the target without being conscious of the data length of the input format or the display format.

[Brief description of the drawings]

FIG. 1 is a flowchart of a memory read process of the present invention, FIG. 2 is a flowchart of a memory write process of the present invention, FIG. 3 is a flowchart of a conventional memory read process, and FIG. It is a flowchart. 1 and 2 show a 32-bit CPU as an example. 12,22 ... Rounding the data access address by the data length of the data bus width of the microcomputer, 28 ...
Step of supplementing the data in the rounded portion, 23 ... Reading data to supplement the data, 24 ... Write data to the buffer to supplement the data, 13,25 ... , Access from the address with the data length of the data bus width of the microcomputer, 14, 26... Determination of the presence or absence of access data, 16, 27... Change of access data, 11, 21, 31, 41. Input process, 15,33 …… Read data display process, 32,42
... A step of accessing the access information input to the target.

Claims (1)

(57) [Claims] 1. A microcomputer development support device having a function of performing data access to a device (hereinafter, referred to as a target) including a microcomputer as a constituent element, wherein an input data access address is an address at a boundary of a data length unit. A step of rounding, and at the time of writing, reading the data of the data length unit including the data of the rounded portion, and filling the data to be written in the read data, and A microcomputer development support device having a data access processing function comprising a step of accessing in data length units.