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// TITLE("Interlocked Increment and Decrement Support")//++//// Copyright (c) 1993 IBM Corporation//// Module Name://// critsect.c//// Abstract://// This module implements Win32 functions to support user mode// critical sections//// Author://// Curtis R. Fawcett 22-Sept-1993//// Environment://// Any mode.//// Revision History://// Curtis R. Fawcett 19-Jan-1994 Removed register names// as requested// Curtis R. Fawcett 04-Nov-1994 Cleaned up enter/leave// critical section functs//--
#include <ksppc.h>
//// Define local values// .struct 0 .space StackFrameHeaderLengthEcAddr: .space 4 // Saved critical section addressEcClient: .space 4 // Saved ClientIdEcLR: .space 4 // Saved Return address .align 3 // Ensure 8 byte alignmentEcFrameLength: // Frame length
//// Define external routines// .extern ..RtlpWaitForCriticalSection .extern ..RtlpNotOwnerCriticalSection .extern ..RtlpUnWaitCriticalSection// SBTTL("Interlocked Decrement")//++//// LONG// InterlockedDecrement(// IN PLONG Addend// )//// Routine Description://// This function performs an interlocked increment on the addend// variable.//// This function and its companion are assuming that the count will// never be incremented past 2**31 - 1.//// Arguments://// Addend (r.3) - Supplies a pointer to a variable whose value is to// be incremented.//// Return Value://// A negative value is returned if the updated value is less than// zero, a zero value is returned if the updated value is zero, and// a nonzero positive value is returned if the updated value is// greater than zero.////--
LEAF_ENTRY(InterlockedIncrement)//IntlckIncLp: lwarx r.5,0,r.3 // Get addend Value addi r.5,r.5,1 // Increment addend value stwcx. r.5,0,r.3 // Store conditionally bne- IntlckIncLp // Jump if store failed//// Exit the routine// mr r.3,r.5 // Set exit status LEAF_EXIT(InterlockedIncrement)// SBTTL("InterlockedDecrement")//++//// LONG// InterlockedDecrement(// IN PLONG Addend// )//// Routine Description://// This function performs an interlocked decrement on the addend// variable.//// This function and its companion are assuming that the count will// never be decremented past 2**31 - 1.//// Arguments://// Addend (r.3) - Supplies a pointer to a variable whose value is to// be decremented.//// Return Value://// A negative value is returned if the updated value is less than// zero, a zero value is returned if the updated value is zero, and// a nonzero positive value is returned if the updated value is// greater than zero.////--
LEAF_ENTRY(InterlockedDecrement)
IntlckDecLp: lwarx r.5,0,r.3 // Get addend Value subi r.5,r.5,1 // Decrement addend value stwcx. r.5,0,r.3 // Store conditionally bne- IntlckDecLp // Jump if store failed//// Exit the routine// mr r.3,r.5 // Set exit status LEAF_EXIT(InterlockedDecrement)
SBTTL("Interlocked Exchange Long")//++//// LONG// InterlockedExchangeUlong (// IN OUT LPLONG Target,// IN LONG Value// )//// Routine Description://// This function performs an interlocked exchange of a longword// value with a longword in memory and returns the memory value.//// Arguments://// Target (r.3) - Supplies a pointer to a variable whose value is// to be exchanged.//// Value (r.4) - Supplies the value to exchange with source value//// Return Value://// The target value is returned as the function value.////--
LEAF_ENTRY(InterlockedExchange)
IntlckExLp: lwarx r.5,0,r.3 // Get current source value stwcx. r.4,0,r.3 // Set new source value bne- IntlckExLp // Jump if store failed//// Exit the routine// mr r.3,r.5 // return old value LEAF_EXIT(InterlockedExchange)//
SBTTL("Interlocked Compare Exchange")//++//// PVOID// InterlockedCompareExchange (// IN OUT PVOID *Destination,// IN PVOID Exchange,// IN PVOID Comperand// )//// Routine Description://// This function performs an interlocked compare of the destination// value with the comperand value. If the destination value is equal// to the comperand value, then the exchange value is stored in the// destination. Otherwise, no opeation is performed.//// Arguments://// Destination (r3) - Supplies a pointer to the destination value.//// Exchange (r4) - Supplies the exchange.//// Comperand (r5) - Supplies the comperand value.//// Return Value://// The initial destination value is returned as the function value.////--
LEAF_ENTRY(InterlockedCompareExchange)
ice10: lwarx r6, 0, r3 // get current addend value cmpw r6, r5 // compare bne- ice20 // if ne, operands mismatch stwcx. r4, 0, r3 // store updated addend value bne- ice10 // loop if store failedice20: mr r3, r6 // return original value LEAF_EXIT(InterlockedCompareExchange) // return
// SBTTL("Interlocked Exchange Add")//++//// LONG// InterlockedExchangeAdd (// IN PLONG Addend,// IN LONG Increment// )//// Routine Description://// This function performs an interlocked add of an increment value to an// addend variable of type unsigned long. The initial value of the addend// variable is returned as the function value.//// Arguments://// Addend (r.3) - Supplies a pointer to a variable whose value is to be// adjusted by the increment value.//// Increment (r.4) - Supplies the increment value to be added to the// addend variable.//// Return Value://// The initial value of the addend variable.////--
LEAF_ENTRY(InterlockedExchangeAdd)
add1failed: lwarx r.5,0,r.3 // get current addend value add r.6,r.5,r.4 // increment addend value stwcx. r.6,0,r.3 // set new addend value bne- add1failed // if ne, store conditional failed
mr r.3,r.5 // return result
LEAF_EXIT(InterlockedExchangeAdd) // return
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