CN105404599B - A kind of bus access error protection method - Google Patents
A kind of bus access error protection method Download PDFInfo
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- CN105404599B CN105404599B CN201510718453.2A CN201510718453A CN105404599B CN 105404599 B CN105404599 B CN 105404599B CN 201510718453 A CN201510718453 A CN 201510718453A CN 105404599 B CN105404599 B CN 105404599B
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- access
- user
- delay
- visitor
- cycle
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F13/00—Interconnection of, or transfer of information or other signals between, memories, input/output devices or central processing units
- G06F13/14—Handling requests for interconnection or transfer
- G06F13/36—Handling requests for interconnection or transfer for access to common bus or bus system
Abstract
The invention discloses a kind of bus access error protection methods, the described method comprises the following steps：Obtain the access cycle of the multiple visitors to access；Access conflict is judged whether in the flag of Accessor Access's data block；When access cycle, there are change one or more visitors during the access conflict to the time point accessed of the flag next time to avoid access generates the access conflict next time described in multiple visitors each other by identical multiple visitors.Compared with prior art, the method according to the invention can effectively reduce the number of bus access error；Meanwhile method of the invention need not increase hardware cost, have higher promotional value.
Description
Technical field
The present invention relates to field of computer technology, in particular relate to a kind of bus access error protection method.
Background technology
The number for accessing error is the key factor for weighing bus communication degree of stability.Currently for the protection of bus error
There are two types of methods, and one kind is designed in itself by hardware, to reduce or avoid the probability of error.But this mode is to correlation
Hardware device has special requirement, and designs relative complex.It is another a kind of, it is to be gone out by the design of software itself
Error protection.
Currently used software mode is logically by the deblocking of access, and corresponding each data block sets a mark
Position is known, for the data block is marked to be in the either idle state of reading and writing.Then, which is shared to visit
The person of asking accesses access identities position first before data block.If flag is read/write status, wait until flag is idle.
If flag is the free time, flag is performed into read/write operation labeled as read/write and further to data block.Finally read/
Flag is reverted into idle state after write operation.
Above-mentioned setting also generates a problem simultaneously.In multiple visitors state of one flag of reading simultaneously,
If the flag is the free time, multiple visitors can be caused to change same flag simultaneously and access a data block simultaneously
Happen, so as to generate access errors.Further, if the access cycle of multiple visitors is identical, then Duo Gefang
The person of asking goes the probability for accessing or operating the flag that can increase simultaneously, increases so as to cause to access the number to malfunction.
Therefore, in order to reduce bus access error number, it is necessary to a kind of bus access error protection method.
The content of the invention
In order to reduce the number for accessing error, the present invention provides a kind of bus access error protection method, the methods
Comprise the following steps：
Obtain the access cycle of the multiple visitors to access；
Access conflict is judged whether in the flag of Accessor Access's data block；
When the access cycle identical multiple visitors each other there are change during the access conflict one or
Multiple visitors are to the time point accessed of the flag next time to avoid the described next of multiple visitors
Secondary access generates the access conflict.
In one embodiment, described in when two or more visitors access the same flag simultaneously
There are the access conflicts each other by visitor.
In one embodiment, during the time point accessed described in changing next time it is respectively each visitor
Set the delay of different durations so that accessed next time described in being carried out after each corresponding delay of visitor's wait.
In one embodiment, the delay is not equal to the integral multiple of the access cycle.
In one embodiment, the delay is less than the access cycle.
In one embodiment, wait and accessed again afterwards still the time of the access conflict occurs in the visitor
Point performs the access operation after the visitor for start time point according to the access cycle.
In one embodiment, the time point for being waited using the visitor and being accessed again is start time point according to the visit
Ask that the cycle performs the access operation after the visitor.
In one embodiment, the delay of different durations is set according to the access privileges of the different visitors,
The visitor higher to the access privileges sets the delay of smaller duration.
In one embodiment, the visitor includes main side and one or more from side, is visited next time described in change
The access cycle that the main side is kept during the time point asked is constant, respectively will be each described different from being just set as waiting
It is accessed again after the delay of duration, wherein, the arbitrary delay from side is not equal to the access cycle.
In one embodiment, the arbitrary delay from side is more than the access cycle.
Compared with prior art, the method according to the invention can effectively reduce the number of bus access error；Meanwhile this
The method of invention need not increase hardware cost, have higher promotional value.
The other feature or advantage of the present invention will illustrate in the following description.Also, the present invention Partial Feature or
Advantage will be become apparent or be appreciated that by implementing the present invention by specification.The purpose of the present invention and part
Advantage can be realized or obtained by specifically noted step in specification, claims and attached drawing.
Description of the drawings
Attached drawing is used for providing a further understanding of the present invention, and a part for constitution instruction, the reality with the present invention
It applies example to be provided commonly for explaining the present invention, not be construed as limiting the invention.In the accompanying drawings：
Fig. 1 is execution flow chart according to an embodiment of the invention；
Fig. 2 is that data block identifier position sets schematic diagram in the prior art.
Specific embodiment
Carry out the embodiment that the present invention will be described in detail below with reference to accompanying drawings and embodiments, whereby implementation personnel of the invention
Can fully understand how application technology means solve technical problem to the present invention, and reach the realization process of technique effect and according to
The present invention is embodied according to above-mentioned realization process.If it should be noted that do not form conflict, each embodiment in the present invention
And each feature in each embodiment can be combined with each other, the technical solution formed protection scope of the present invention it
It is interior.
In order to reduce the number of bus access error, the present invention proposes a kind of bus access error protection method.It connects down
To be described in detail the execution flow of method according to an embodiment of the invention based on attached drawing.The step of being shown in the flow chart of attached drawing
It can be performed in the computer system comprising such as a group of computer-executable instructions.Although each step is shown in flow charts
Rapid logical order, but in some cases, it can be with the steps shown or described are performed in an order that is different from the one herein.
As shown in Figure 1, in the method for the invention, initially performing step S100, start step, start bus access.With
Exemplified by core bus accesses, in core bus communication, mainly to avoid because of mainboard and operate the same area simultaneously from plate causing
Access error.Existing scheme is that the region that entire core bus is able to access that is first divided into several pieces, is connected on and distributes several
Identification byte corresponds to each piece of data area, which identifies the current state of the data block.
As shown in Fig. 2, 1 flag of data block, 2 flag of data block, 3 flag ... data block N flags of data block
Corresponding data block 1, data block 2, data block 3 ... data block N respectively.Whenever mainboard or to go from plate to access a certain data block
When (data block 1, data block 2, data block 3 ... or data block N), it is necessary to the state for reading the data block first be gone (to access data
1 flag of block, 2 flag of data block, 3 flag ... of data block or data block N mark), so that it is determined that this time operation whether
It has permission.After the side for obtaining permission has operated corresponding data block, the value of set identifier, represents this operation again
It has been completed that, so as to discharge operating right.The side for not obtaining permission again accesses to the data block in next cycle.
According to above-mentioned logic flow, in the present embodiment, when bus access starts (step S100), if necessary to access
A certain data block first has to perform step S101, and identification marking position step judges whether this visit operation has permission.If
Flag is busy state, then illustrates have other users (visitor) accessing the data block at this time.Step is performed at this time
S102, waiting step wait access identities position again after an access cycle.
If flag is idle state, illustrate accessing the data block without other users at this time.But at this time again
There will be two kinds of situations, and a kind of situation, which is that only there are one users at this time, to access the flag, and such the user was based in the free time
Flag further can normally access data block.Another situation is that there are multiple (two or more) at this time
User access the flag simultaneously.Since the user that current time each accesses the flag can the free time based on flag
State goes further to access data block, this has resulted in multiple users while has accessed a data block, and punching is accessed so as to generate
It is prominent.
For the above situation, in the present embodiment, after step slol, when flag is idle state, it is necessary to hold
Row step S110 judges whether that access conflict occurs.I.e. whether current time has multiple users access identities position simultaneously.If work as
The preceding moment, there are one user's access identities positions (not generating access conflict), then the user can continue to execute step
S103 marks flag, and (access rights are obtained, and other users is prevented to obtain access right flag labeled as busy
Limit).Then step S104 is further performed, accesses data block, read/write operation is carried out to data block.
When the read/write operation is completed, step S105 is performed, recovers flag, flag is reverted into idle state (release
Access rights).Step S106 is finally performed, data access terminates, and terminates this access to data block.
In step s 110, i.e., ought sometime if access conflict currently has occurred, multiple users will in synchronization
Operate this data block.Since multiple users go to read flag before operation, it is to have permission that multiple users, which have been found that, at this time
The data block is operated, as a result multiple users go to operate the data block, are missed so as to cause data write error.
Generally, when the above-mentioned data write error mistake (access conflict) of generation, it is necessary to when each user's wait one is specific
Data block access is carried out after length again.But in the design of many access mechanisms, multiple users are with a fixed cycle
A certain data block is operated.Due to being all the access cycle of multiple users fixed, so that this while operation
Probability greatly increases, and the probability of error also increases, so as to affect the reliability of communication.
Specifically, such as data write error occurs for data block 1 in moment T1 user A and user B to miss.User A and user B
Respectively wait one access cycle T2Access data block 1 again afterwards.Since user A and the access cycle of the wait of user B are
T2, at this time data write error by mistake will occur again.
To avoid the occurrence of upper one, in the present embodiment, (step 110 judging result is after access conflict occurs
It is), step S111 is first carried out, judges whether the access cycle that each side user of access conflict occurs is consistent.In the event of access
The access cycle of each side user of conflict is inconsistent, then can perform step S112, and each side waits a respective access respectively
Performing step S101 after cycle again, (since access cycle is inconsistent, each side waits after a respective access cycle again respectively
The time point of secondary access will not overlap).
When the access cycle for each side user that access conflict occurs is consistent, then step S113 is performed, respectively delaying step,
The delay of different durations is set respectively for each user (access cycle is identical and access conflict occurs).Then step is performed
S114 makes each user be waited according to the delay set.It waits and performs step S101 again later.Since each user uses
It is different in the duration of the delay of wait, therefore after step S114, each user again identifies that the time point of flag (S101)
Also would not overlap.
Summarize the above process, exactly when access cycle identical multiple visitors there are change one during access conflict each other
A or multiple visitors generate visit to the time point accessed of flag next time to avoid the access next time of multiple visitors
Ask conflict.It is noted herein that the premise of step 111 is to obtain the access cycle of visitor.The access cycle of visitor
It can be obtained when accessing (the step S100) at the beginning of operation, that is, obtain the access week of the multiple visitors to access
Phase can also obtain after step silo, that is, obtain the access cycle for multiple visitors that access conflict occurs.
Further, in step S113, the premise for setting delay is the access next time in order to enable multiple visitors
Time point it is misaligned.Based on above-mentioned premise, a variety of different schemes may be employed in the duration setting of delay.First, in order to drop
There is the probability of access conflict after low multiple access, in one embodiment of the invention, delay is whole not equal to access cycle
Several times (not equal to the multiple of access cycle or access cycle).Further, in another embodiment of the present invention, it is delayed
Less than access cycle.In addition, in order to reduce the setting of delay, for multiple users, the delay of one of user is made to access
Cycle (does not do delay process), and other users set the delay not equal to access cycle.
Specifically, in an embodiment of the present invention.A time-delayed sequence is set for each user.Each time-delayed sequence is
One array, all numerical value in whole arrays are different (each numerical value represents a duration) each other.Into line delay
During setting, duration of the numerical value as delay in respective time-delayed sequence (array) is respectively adopted in each user, can thus protect
Demonstrate,prove the difference of the stand-by period of each user.
By taking user A and user B as an example, the time-delayed sequence of user A is (A1、A2、A3、A4), the time-delayed sequence of user B is (B1、
B2、B3、B4), A1、A2、A3、A4、B1、B2、B3、B4It is 8 different numbers, is not mutually equal between them.
It is assumed that T1 moment user A and user B are conflicted, A is respectively adopted in user A and user B1And B2As delay, then
User A and user B is respectively in moment T1+A1And T+B2It accesses again.Due to A1Not equal to B2, therefore moment T1+A1And T1+B2No
Together.
In order to further reduce the probability of access conflict appearance, in an embodiment of the present invention, can be read when setting and being delayed
The last delay used is taken, then (is occurred using the delay for being different from last delay using last delay currently
Access conflict, then the probability that access conflicts occur again using other delays is relatively small).
Continue by taking user A and user B as an example, it is assumed that T2 moment (a certain moment after the T1 moment) user A and user B occurs
Conflict.The delay that last time (T1 moment) user A is used is A1, the delay that user B is used is B2.The last time is read respectively (during T1
Carve) delay, then according to the order of array carry out this delay setting.Namely according to array order this (T2 moment)
User A uses A2, user B use B3。
After the completion of step S113 and S114, user is again introduced into browsing process.In order to avoid the confusion of browsing process,
It reduces and performs step, in an embodiment of the present invention, still access conflict occurs after being accessed again after visitor is delayed
Time point performs the access operation after visitor for start time point according to access cycle.
Continue by taking user A and user B as an example, it is assumed that the access cycle of user A and user B are all T.It is assumed that T2 moment users
A and user B are conflicted, and A is respectively adopted in user A and user B2And B3As delay, then user A and user B are respectively at the moment
T2+A2And T2+B3It accesses again.After this, user A and user B is still using T as access cycle, in timing node T2+nT (T2
+ nT is moment T2+A2And T2+B3Timing node afterwards) it accesses.
In said program, due to performing visit according to access cycle as start time point using the time point that access conflict occurs
Access operation after the person of asking, therefore the probability that access conflict occurs again is still higher, in order to further reduce access conflict
The probability of generation, in one embodiment of this invention, the time point accessed again after being delayed using visitor are pressed as initial time
The access operation after visitor is performed according to access cycle.
Continue by taking user A and user B as an example, it is assumed that T2 moment user A and user B are conflicted, user A and user B
A is respectively adopted2And B3As delay, then user A and user B is respectively in moment T2+A2And T2+B3It accesses again.After this,
User A and user B is still using T as access cycle, respectively in timing node T2+A2+ nT and T2+B3+ nT accesses.Due to
A2Not equal to B3, therefore moment T2+A2+ nT and T2+B3+ nT is misaligned (to also need to A herein2And B3Not for T's access cycle
Integral multiple).The access time point that this is allowed for after user A and user B is completely misaligned, thus greatly reduces access conflict
The probability of generation.
In a practical situation, each user's is specifically different.In some specific cases, different user may
With different access privileges., it is necessary to which the high user of priority preferentially accesses i.e. when there is access conflict.Therefore in this hair
In a bright embodiment, different delays, the visit higher to access privileges are set according to the access privileges of different visitors
The person of asking sets smaller delay.
Continue by taking user A and user B as an example, it is assumed that T2 moment user A and user B are conflicted, user A and user B
A is respectively adopted2And B3As delay, then user A and user B is respectively in moment T2+A2And T2+B3It accesses again.Herein, it is false
The access privileges of user A is determined higher than user B, then sets delay A2Less than B3(all numerical value is small in the time-delayed sequence of user A
Any value in the time-delayed sequence of user B).So user A can just be accessed prior to user B.
In addition, in some specific cases, different user may have different stability requirements.Such as in some systems
In (core bus), user be divided into main side and from side (one master one from or one master and multiple slaves).It in some cases, be as far as possible
The accessing time sequence flow of main side is not upset.For this case, in an embodiment of the present invention, when change accesses next time
Between put during kept for the access cycle of main side constant, respectively by it is each from side be set as visiting again after waiting different delays
It asks, wherein, arbitrarily it is not equal to access cycle from the delay of side.
Continue by taking user A and user B as an example, it is assumed that T2 moment user A and user B are conflicted, user A and user B
A is respectively adopted2And B3As delay, then user A and user B is respectively in moment T2+A2And T2+B3It accesses again.Herein, it is false
Determine side based on user A, user B is from side.Setting delay A2For T access cycle the accessing time sequence of main side (do not change set), if
It is B to determine user B delays3(B3Not equal to T).
Further, in master-slave system, the access privileges of main side is ensured, even being arbitrarily more than from the delay of side described
Access cycle.It is B to set user B delays3More than T).The accessing time sequence for so neither changing main side is set, and can guarantee master
The preferential access of side.
Explanation is needed exist for, the setting of above-mentioned principal and subordinate is only to facilitate the life of description embodiment of the present invention
Name.The user not fully represented in actual conditions names setting.In a practical situation, it is possible that needing as far as possible not
Upset from square accessing time sequence flow and/or ensure the situation of the access privileges from side.
To sum up, compared with prior art, the method according to the invention can effectively reduce the number of bus access error；Together
When, method of the invention need not increase hardware cost, have higher promotional value.
While it is disclosed that embodiment as above, but the content only to facilitate understand the present invention and adopt
Embodiment is not limited to the present invention.Method of the present invention can also have other various embodiments.Without departing substantially from
In the case of essence of the present invention, those skilled in the art make various corresponding changes or change in accordance with the present invention
Shape, but these corresponding changes or deformation should all belong to the scope of the claims of the present invention.
Claims (8)
1. a kind of bus access error protection method, which is characterized in that the described method comprises the following steps：
Obtain the access cycle of the multiple visitors to access；
Access conflict is judged whether in the flag of Accessor Access's data block；
After access conflict occurs, judge whether the access cycle that each side user of access conflict occurs is consistent；
Inconsistent in the event of the access cycle of each side user of access conflict, then each visitor waits a respective visit respectively
Ask the cycle；
When the access cycle for each side user that access conflict occurs is consistent, then different durations are set respectively for each visitor
Delay so that accessed next time described in being carried out after each corresponding delay of visitor's wait, the delay is not equal to
The integral multiple of the access cycle.
2. according to the method described in claim 1, it is characterized in that, when two or more visitors access simultaneously
There are the access conflicts each other by the visitor during the same flag.
3. according to the method described in claim 1, it is characterized in that, the delay is less than the access cycle.
4. according to the method described in claim 1, which is characterized in that the visitor wait and again access afterwards still with
The time point that the access conflict occurs is start time point according to the access after the access cycle execution visitor
Operation.
5. according to the method described in claim 1, which is characterized in that the time point for being waited with the visitor and being accessed again
It is operated for start time point according to the access after the access cycle execution visitor.
6. according to the method described in claim 1, which is characterized in that set according to the access privileges of the different visitors
The delay of fixed different durations, the visitor higher to the access privileges set the delay of smaller duration.
7. according to the method described in claim 1, it is characterized in that, the visitor include main side and it is one or more from
Side is kept for the access cycle of the main side constant during the time point accessed described in changing next time, respectively will be each
It is described to be accessed again after the delay for being just set as waiting different durations, wherein, the arbitrary delay from side is not
Equal to the access cycle.
8. the method according to the description of claim 7 is characterized in that the arbitrary delay from side is more than the access week
Phase.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4467418A (en) * | 1980-09-12 | 1984-08-21 | Quinquis Jean Paul | Data transmission system resolving access conflicts between transmitters-receivers to a common bus |
| CN101510181A (en) * | 2009-03-19 | 2009-08-19 | 北京中星微电子有限公司 | Bus arbitration method and bus arbitration apparatus |
| CN101626334A (en) * | 2009-08-10 | 2010-01-13 | 中兴通讯股份有限公司 | Method and device for controlling communication bus |
| CN103580976A (en) * | 2012-07-20 | 2014-02-12 | 中兴通讯股份有限公司 | Method and device for avoiding carrier sensing conflicts |
-
2015
- 2015-10-29 CN CN201510718453.2A patent/CN105404599B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4467418A (en) * | 1980-09-12 | 1984-08-21 | Quinquis Jean Paul | Data transmission system resolving access conflicts between transmitters-receivers to a common bus |
| CN101510181A (en) * | 2009-03-19 | 2009-08-19 | 北京中星微电子有限公司 | Bus arbitration method and bus arbitration apparatus |
| CN101626334A (en) * | 2009-08-10 | 2010-01-13 | 中兴通讯股份有限公司 | Method and device for controlling communication bus |
| CN103580976A (en) * | 2012-07-20 | 2014-02-12 | 中兴通讯股份有限公司 | Method and device for avoiding carrier sensing conflicts |
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| CN105404599A (en) | 2016-03-16 |
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