Source code of Windows XP (NT5)
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3.9 KiB

//
// Scheduler
//
#ifndef _H_SCH
#define _H_SCH
//
//
// CONSTANTS
//
//
#define SCH_MODE_ASLEEP 0
#define SCH_MODE_NORMAL 1
#define SCH_MODE_TURBO 2
//
// All of the following values are times in milliseconds.
//
#define SCH_PERIOD_NORMAL 200
#define SCH_PERIOD_TURBO 100
#define SCH_TURBO_MODE_DURATION 1000
#define SCH_EVENT_NAME "DCS_SCHEDULE_EVENT"
//
//
// PROTOTYPES
//
//
// Name: SCH_Init
//
// Purpose: Scheduler initialization function.
//
// Params: None.
//
BOOL SCH_Init(void);
// Name: SCH_Term
//
// Purpose: Scheduler termination function.
//
// Returns: Nothing.
//
// Params: None.
//
void SCH_Term(void);
// Name: SCH_ContinueScheduling
//
// Purpose: Called by components when they want periodic scheduling to
// continue. They are guaranteed to get at least one more
// periodic callback following a call to this function.
// If they want further callbacks then they must call this
// function again during their periodic processing.
//
// Returns: Nothing.
//
// Params: schedulingMode - either SCH_MODE_NORMAL or SCH_MODE_TURBO
//
// Operation:
// SCH_MODE_NORMAL triggers periodic processing at 200ms
// intervals (5 times a second)
//
// SCH_MODE_TURBO triggers periodic processing at 100ms
// intervals (10 times a second)
//
// The scheduler automatically drops from SCH_MODE_TURBO back
// to SCH_MODE_NORMAL after 1 second of turbo mode processing.
//
// SCH_MODE_TURBO overrides SCH_MODE_NORMAL, so if calls to
// this function are made with SCH_MODE_NORMAL when the
// scheduler is in TURBO mode, TURBO mode continues.
//
// If this function is not called during processing of a
// scheduler callback message then the scheduler enters
// SLEEP mode - and will not generate any more periodic
// callbacks until it is woken by another call to
// this function, or until the output accumulation code
// signals the scheduler's event.
//
void SCH_ContinueScheduling(UINT schedulingMode);
// Name: SCH_SchedulingMessageProcessed
//
// Purpose: A feedback function called by the Share Core to signal that
// a scheduler message has been received. This ensures that
// that the scheduler only ever has one scheduler message
// outstanding at a time.
//
// Returns: Nothing.
//
// Params: None.
//
void SCH_SchedulingMessageProcessed(void);
// Name: SCH_PacingProcessor
//
// Purpose: The main function executed by the scheduling thread.
//
// Returns: Zero.
//
// Params: syncObject - object to pass back to COM_SignalThreadStarted
//
// Operation: The thread enters a main loop which continues while the
// scheduler is initialized.
//
// The thread sets its priority to TIME_CRITICAL in order
// that it runs as soon as possible when ready.
//
// The thread waits on an event (schEvent) with a timeout that
// is set according to the current scheduler mode.
//
// The thread runs due to either:
// - the timeout expiring, which is the normal periodic
// scheduler behavior, or
// - schEvent being signalled, which is how the scheduler is
// woken from ASLEEP mode.
//
// The thread then posts a scheduler message the the Share Core
// (if there is not one already outstanding) and loops back
// to wait on schEvent.
//
// Changes in the scheduler mode are caused by calls to
// SCH_ContinueScheduling updating variables accessed in this
// routine, or by calculations made within the main loop of
// this routine (e.g. TURBO mode timeout).
//
DWORD WINAPI SCH_PacingProcessor(LPVOID lpParam);
void SCHSetMode(UINT newMode);
void SCHPostSchedulingMessage(void);
#endif // _H_SCH