*
* This component provides the Resource, ArbiterInfo, and Resource
* Controller interfaces and uses the ResourceConfigure interface as
- * described in TEP 108. It provides arbitration to a shared resource in a
- * round robin fashion. An array is used to keep track of which users have
- * put in requests for the resource. Upon the release of the resource by
- * one of these users, the array is checked and the next user (in round
- * robin order) that has a pending request will ge granted control of the
- * resource. If there are no pending requests, then the resource becomes
- * idle and any user can put in a request and immediately receive access to
- * the round robin order * Resource.
+ * described in TEP 108. It provides arbitration to a shared resource in
+ * an FCFS fashion. An array is used to keep track of which users have put
+ * in requests for the resource. Upon the release of the resource by one
+ * of these users, the array is checked and the next user (in FCFS order)
+ * that has a pending request will ge granted control of the resource. If
+ * there are no pending requests, then the resource becomes idle and any
+ * user can put in a request and immediately receive access to the
+ * Resource.
*
* @param <b>resourceName</b> -- The name of the Resource being shared
*
* @author Kevin Klues (klues@tkn.tu-berlin.de)
- * @author Philip Levis
*/
-generic module RoundRobinArbiterC(char resourceName[]) {
+generic configuration RoundRobinArbiterC(char resourceName[]) {
provides {
- interface Init @atleastonce();
interface Resource[uint8_t id];
- interface ResourceController;
+ interface ResourceRequested[uint8_t id];
+ interface ResourceDefaultOwner;
interface ArbiterInfo;
}
- uses {
- interface ResourceConfigure[uint8_t id];
- }
+ uses interface ResourceConfigure[uint8_t id];
}
implementation {
- enum {RES_IDLE, RES_GRANTING, RES_BUSY};
- enum {NO_RES = 0xFF};
- enum {CONTROLLER_ID = uniqueCount(resourceName) + 1};
-
- uint8_t state = RES_IDLE;
- uint8_t resId = NO_RES;
- uint8_t reqResId;
- uint8_t request[(uniqueCount(resourceName)-1)/8 + 1];
- bool irp = FALSE;
-
- task void grantedTask();
- task void requestedTask();
- void grantNextRequest();
-
- /**
- Initialize the Arbiter to the idle state
- */
- command error_t Init.init() {
- return SUCCESS;
- }
-
- uint8_t requested(uint8_t id) {
- return request[id / 8] & (1 << (id % 8));
- }
-
- void clearRequest(uint8_t id) {
- request[id / 8] &= ~(1 << (id % 8));
- }
-
- error_t queueRequest(uint8_t id) {
- if (!requested(id)){
- request[id / 8] |= 1 << (id % 8);
- return SUCCESS;
- }
- return EBUSY;
- }
-
- /**
- Request the use of the shared resource
-
- If the user has not already requested access to the
- resource, the request will be either served immediately
- or queued for later service in a round robin fashion.
- A SUCCESS value will be returned and the user will receive
- the granted() event in synchronous context once it has
- been given access to the resource.
-
- Whenever requests are queued, the current owner of the bus
- will receive a requested() event, notifying him that another
- user would like to have access to the resource.
-
- If the user has already requested access to the resource and
- is waiting on a pending granted() event, an EBUSY value will
- be returned to the caller.
- */
- async command error_t Resource.request[uint8_t id]() {
- atomic {
- if( state == RES_IDLE ) {
- state = RES_GRANTING;
- reqResId = id;
- post grantedTask();
- return SUCCESS;
- }
- if(resId == CONTROLLER_ID)
- post requestedTask();
- return queueRequest( id );
- }
- }
-
- async command error_t ResourceController.request() {
- return call Resource.request[CONTROLLER_ID]();
- }
-
- /**
- * Request immediate access to the shared resource. Requests are
- * not queued, and no granted event is returned. A return value
- * of SUCCESS signifies that the resource has been granted to you,
- * while a return value of EBUSY signifies that the resource is
- * currently being used.
- */
- uint8_t tryImmediateRequest(uint8_t id) {
- atomic {
- if( state == RES_IDLE ) {
- state = RES_BUSY;
- resId = id;
- return id;
- }
- return resId;
- }
- }
- async command error_t Resource.immediateRequest[uint8_t id]() {
- uint8_t ownerId = tryImmediateRequest(id);
-
- if(ownerId == id) {
- call ResourceConfigure.configure[id]();
- return SUCCESS;
- }
- else if(ownerId == CONTROLLER_ID){
- atomic {
- irp = TRUE; //indicate that immediateRequest is pending
- reqResId = id; //Id to grant resource to if can
- }
- signal ResourceController.requested();
- atomic {
- ownerId = resId; //See if I have been granted the resource
- irp = FALSE; //Indicate that immediate request no longer pending
- }
- if(ownerId == id) {
- call ResourceConfigure.configure[id]();
- return SUCCESS;
- }
- return EBUSY;
- }
- else return EBUSY;
- }
-
- async command error_t ResourceController.immediateRequest() {
- return call Resource.immediateRequest[CONTROLLER_ID]();
- }
-
- /**
- Release the use of the shared resource
-
- The resource will only actually be released if
- there are no pending requests for the resource.
- If requests are pending, then the next pending request
- will be serviced, according to a round robin arbitration
- scheme. If no requests are currently pending, then the
- resource is released, and any users can put in a request
- for immediate access to the resource.
- */
- async command void Resource.release[uint8_t id]() {
- uint8_t currentState;
- atomic {
- if (state == RES_BUSY && resId == id) {
- if(irp)
- resId = reqResId;
- else grantNextRequest();
- call ResourceConfigure.unconfigure[id]();
- }
- currentState = state;
- }
- if(currentState == RES_IDLE)
- signal ResourceController.idle();
- }
+ components MainC;
+ components new RoundRobinResourceQueueC(uniqueCount(resourceName)) as Queue;
+ components new ArbiterP(uniqueCount(resourceName)) as Arbiter;
- async command void ResourceController.release() {
- call Resource.release[CONTROLLER_ID]();
- }
-
- /**
- Check if the Resource is currently in use
- */
- async command bool ArbiterInfo.inUse() {
- atomic {
- if ( state == RES_IDLE )
- return FALSE;
- }
- return TRUE;
- }
-
- /**
- Returns the current user of the Resource.
- If there is no current user, the return value
- will be 0xFF
- */
- async command uint8_t ArbiterInfo.userId() {
- atomic return resId;
- }
+ MainC.SoftwareInit -> Queue;
- /**
- * Returns my user id.
- */
- async command uint8_t Resource.isOwner[uint8_t id]() {
- atomic {
- if(resId == id) return TRUE;
- else return FALSE;
- }
- }
- async command uint8_t ResourceController.isOwner() {
- return call Resource.isOwner[CONTROLLER_ID]();
- }
-
- //Grant a request to the next Pending user
- //in Round-Robin order
- void grantNextRequest() {
- int i;
-
- for (i = resId + 1; ; i++) {
- if (i >= (uniqueCount(resourceName) + 1))
- i = 0;
- if (i == resId)
- break;
- if (requested(i)) {
- reqResId = i;
- clearRequest(i);
- resId = NO_RES;
- state = RES_GRANTING;
- post grantedTask();
- return;
- }
- }
- resId = NO_RES;
- state = RES_IDLE;
- }
-
- //Task for pulling the Resource.granted() signal
- //into synchronous context
- task void grantedTask() {
- uint8_t tmpId;
- atomic {
- tmpId = resId = reqResId;
- state = RES_BUSY;
- }
- call ResourceConfigure.configure[tmpId]();
- signal Resource.granted[tmpId]();
- }
+ Resource = Arbiter;
+ ResourceRequested = Arbiter;
+ ResourceDefaultOwner = Arbiter;
+ ArbiterInfo = Arbiter;
+ ResourceConfigure = Arbiter;
- //Task for pulling the ResourceController.requested() signal
- //into synchronous context
- task void requestedTask() {
- uint8_t tmpId;
- atomic {
- tmpId = resId;
- }
- if(tmpId == CONTROLLER_ID)
- signal ResourceController.requested();
- }
-
- //Default event/command handlers for all of the other
- //potential users/providers of the parameterized interfaces
- //that have not been connected to.
- default event void Resource.granted[uint8_t id]() {
- signal ResourceController.granted();
- }
- default event void ResourceController.granted() {
- }
- default async event void ResourceController.requested() {
- }
- default async event void ResourceController.idle() {
- }
- default async command void ResourceConfigure.configure[uint8_t id]() {
- }
- default async command void ResourceConfigure.unconfigure[uint8_t id]() {
- }
+ Arbiter.Queue -> Queue;
}
projects / tinyos-2.x.git / blobdiff