CN102147786B

CN102147786B - Method for dual-port virtual FIFO (first in first out) data exchange

Info

Publication number: CN102147786B
Application number: CN 201010612566
Authority: CN
Inventors: 韩嫚丽; 高杨; 张珏辉
Original assignee: AVIC No 631 Research Institute
Current assignee: AVIC No 631 Research Institute
Priority date: 2010-12-29
Filing date: 2010-12-29
Publication date: 2012-10-03
Anticipated expiration: 2030-12-29
Also published as: CN102147786A

Abstract

The invention proposes a method for dual-port virtual FIFO (first in first out) data exchange, which comprises the following steps: (1) obtaining FIFO semaphores; (2) judging the relationship between the length of a data block to be sent and the length of the FIFO; (3) obtaining a head pointer and a tail pointer of the FIFO (first in first out); judging whether the length of the data block is less than the length of the current space to be written in of the FIFO through the obtained head pointer and the obtained tail pointer; and if yes, carrying out the step (4); (4) calculating the check sum of the data block; (5) sequentially writing in the length of the data block, the data block and the check sum at a position pointed by the current head pointer and moving the head pointer; and (6) releasing the FIFO semaphores. The method for the dual-port virtual FIFO data exchange is suitable for data exchange among multiprocessor systems in an airborne computer.

Description

A kind of method of dual-port virtual fifo exchanges data

Technical field

The present invention relates to the method for interchanging data between the multicomputer system in a kind of airborne computer, relate in particular to a kind of data of dual-port virtual fifo that realize and write and reading method.

Background technology

In airborne computer, data are obtained and exchanged is the important component part of multicomputer system.Each Flexible Interface Card receives the various control commands of main processor modules, also in time data is offered main processor modules according to the real-time acquisition interface data of control command then.Traditional solution of multicomputer system exchanges data: design dual-ported memory circuit on interface module, solving the exchanges data between the multi-processor module for each functional module division list/double buffering data field on the dual-ported memory then.Along with the fast development of mobile system, the function that airborne computer is concentrated is more and more, and the function that Flexible Interface Card has is more and more, and the communication data amount that causes exchanges data to require is very big, and traditional solution is difficult to satisfy this a series of requirements.

Summary of the invention

In order to solve existing technical matters in the background technology, the present invention proposes a kind of method of dual-port virtual fifo exchanges data, be applicable to the exchanges data between the multicomputer system in the airborne computer.

Technical solution of the present invention is: the method that a kind of dual-port virtual fifo data write, and its special character is: said method comprising the steps of:

1) obtains the fifo signal amount;

2) judge the data block length to be sent and the relation of FIFO length;

3) obtain head pointer and the tail pointer of FIFO, whether the length through the head pointer that gets access to and tail pointer judgment data piece is less than the length in the current space to be written of FIFO; If then carry out step 4);

4) verification of computational data piece with;

5) in the position of current head pointer indication successively length, data block and the verification of writing data blocks and, and slip-on head pointer;

6) discharge the fifo signal amount.

Above-mentioned steps 2) concrete steps are:

2.1) whether the length of judgment data piece less than the length of FIFO, if then carry out step 2.2; If not, then directly carry out step 6);

2.2) whether the length of judgment data piece be 0, if not, then carries out step 3); If then directly carry out step 6);

2.3) judge whether queue full of FIFO, if not, then carry out step 3);

Above-mentioned steps 3) concrete steps are:

3.1) obtain head pointer (head) and the tail pointer (tail) of FIFO;

3.2) judge the magnitude relationship of head pointer and tail pointer: when head pointer during greater than tail pointer, head pointer is moved backward position after the length of data to be written greater than head pointer during perhaps less than tail pointer, this data block can write FIFO; When head pointer during less than tail pointer, when head pointer being moved backward position after the length of data to be written greater than head pointer and less than tail pointer, this data block can write FIFO.

The method that a kind of dual-port virtual fifo data are read, its special character is: said method comprising the steps of:

1) obtains the fifo signal amount;

2) obtain head pointer, the tail pointer of FIFO, judge according to the head pointer that gets access to, tail pointer whether FIFO has the new data block needs to receive;

3) read the length of the data block that need to receive, the data at promptly current head pointer place, then according to data block length sense data piece content successively and verification and;

4) discharge the fifo signal amount.

Above-mentioned steps 2) judge that the concrete steps whether FIFO has new data block to receive are in:

2.1) judge whether head pointer and tail pointer equate, if head pointer and tail pointer are unequal, then there are data to need to receive among the FIFO;

2.2) according to a preconcerted arrangement algorithm (for example calculating the XOR of all data) verification of calculating this data block with; Then with the verification of verification of reading and calculating with compare,, preserve this data block if identical then this data block is effective; Otherwise abandon this data block, and mobile tail pointer;

Advantage of the present invention is:

(1) dual-ported memory uses very generally in airborne computer, so physics realization is very convenient, and hardware circuit design technology maturation, Interface design are simple;

(2) adopt annular design, guarantee the high data volume of handling up, and the set condition message unit, guarantee the high efficiency of exchanges data;

(3) use Semaphore Mechanism to control the competition that double-port access brings, improved the reliability of data access;

(4) can be in a dual-ported memory according to a plurality of virtual fifos of user's requirement definition, and the reference position of each FIFO and length can be used flexibly by User Defined;

(5) mode of operation of virtual fifo (byte, word, double word) can be selected according to user's request, and can increase reliability of data transmission according to user's request definition of data block algorithm.

Description of drawings

Fig. 1 is that synoptic diagram is divided in the functional areas of dual-port virtual fifo;

Fig. 2 is that dual-port virtual fifo data write process flow diagram;

Fig. 3 is that dual-port virtual fifo data read goes out process flow diagram;

Embodiment

Referring to Fig. 1, the function zoning of dual-port virtual fifo is divided into (1) virtual fifo data management area, is used to preserve the duty of FIFO head pointer, FIFO tail pointer, FIFO, other relevant informations such as size of record FIFO; (2) virtual fifo data field is used to preserve data to be exchanged;

Referring to Fig. 2, a kind of method of dual-port virtual fifo exchanges data, the step of data fifo write operation is following:

1) obtains the fifo signal amount;

2) rationality of judgement data block to be sent:

2.1) whether the length (len) of judgment data piece (msg []) less than the length (fifo_size) of FIFO; If carry out step 2.2);

2.2) whether the length of judgment data piece be 0, if not, then carries out step 3);

2.3) judge whether fifo queue expires (if the next position of tail pointer equals head pointer, the expression queue full);

3) judge data block feasibility to be sent, whether the length of judgment data piece (len) is less than the length in the current space to be written of FIFO:

3.1) obtain head pointer (head) and the tail pointer (tail) of FIFO;

3.2) when head pointer during greater than tail pointer, tmp moves the position after the length of data to be written backward with head pointer, when tmp greater than head or tmp during less than tail, this data block can write FIFO; When head pointer during less than tail pointer, tmp moves the position after the length of data to be written backward with head pointer, when tmp greater than head and tmp during less than tail, this data block can write FIFO;

4) verification of good according to a preconcerted arrangement algorithm (for example calculating the XOR of all data) computational data piece with;

5) in the position of present head pointer indication successively length, data block and the verification of writing data blocks and, and slip-on head pointer;

6) discharge the fifo signal amount.

Referring to Fig. 3, a kind of switching method of dual-port virtual fifo exchanges data, the step of data fifo read operation is following:

1) obtains the fifo signal amount;

2) judge that FIFO has new data block: if head pointer and tail pointer are unequal, explaining has data to need to receive among the FIFO;

3) obtain data block: the length of read block is the data at current head pointer place; Then according to length sense data piece content successively and verification with, according to a preconcerted arrangement algorithm (for example calculating the XOR of all data) verification of calculating this data block with, then with the verification of verification of reading and calculating with compare; If this data block of identical explanation is effective; Preserve this data block so, otherwise abandon this data block, and mobile tail pointer;

4) discharge the fifo signal amount.

Claims

1. method that dual-port virtual fifo data write is characterized in that: said method comprising the steps of:

1) obtains the fifo signal amount;

2) judge the magnitude relationship of data block to be sent and the fifo signal amount that gets access to:

2.1) whether the length of judgment data piece less than the length of FIFO, if then carry out step 2.2); If not, then directly carry out step 6);

2.2) whether the length of judgment data piece be 0, if not, then carries out step 3); If then directly carry out step 2.3);

2.3) judge whether queue full of FIFO, if not, then carry out step 3); If then carry out step 6);

3) obtain head pointer and the tail pointer of FIFO, when head pointer during greater than tail pointer, when head pointer being moved backward position after the length of data to be written greater than head pointer or less than tail pointer, this data block writes FIFO; When head pointer during less than tail pointer, when head pointer being moved backward position after the length of data to be written greater than head pointer and less than tail pointer, this data block writes FIFO; Whether the length through the head pointer that gets access to and tail pointer judgment data piece is less than the length in the current space to be written of FIFO; If then carry out step 4); If not, then carry out step 6);

4) verification of computational data piece with;

6) discharge the fifo signal amount.

2. method that dual-port virtual fifo data are read is characterized in that: said method comprising the steps of:

1) obtains the fifo signal amount;

2) obtain head pointer, the tail pointer of FIFO, judge according to the head pointer that gets access to, tail pointer whether FIFO has the new data block needs to receive:

2.2) according to a preconcerted arrangement this data block of algorithm computation verification with, then with the verification of verification of reading and calculating with compare,, preserve this data block, otherwise abandon this data block, and mobile tail pointer if identical then this data block is effective;

4) discharge the fifo signal amount.

3. the method that dual-port virtual fifo data according to claim 2 are read is characterized in that: engagement arithmetic is the XOR that calculates all data said step 2.2).