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// TITLE("Interlocked Support")
//++
//
// Copyright (c) 1990 Microsoft Corporation
// Copyright (c) 1992 Digital Equipment Corporation
//
// Module Name:
//
// intrlock.s
//
// Abstract:
//
// This module implements functions to support interlocked operations.
// Interlocked operations can only operate on nonpaged data and the
// specified spinlock cannot be used for any other purpose.
//
// Author:
//
// David N. Cutler (davec) 26-Mar-1990
//
// Environment:
//
// Kernel mode.
//
// Revision History:
//
// Thomas Van Baak (tvb) 18-May-1992
//
// Adapted for Alpha AXP.
//
//--
#include "ksalpha.h"
SBTTL("Interlocked Add Large Integer")
//++
//
// LARGE_INTEGER
// ExInterlockedAddLargeInteger (
// IN PLARGE_INTEGER Addend,
// IN LARGE_INTEGER Increment,
// IN PKSPIN_LOCK Lock
// )
//
// Routine Description:
//
// This function performs an interlocked add of an increment value to an
// addend variable of type large integer. The initial value of the addend
// variable is returned as the function value.
//
// Arguments:
//
// Addend (a0) - Supplies a pointer to a variable whose value is to be
// adjusted by the increment value.
//
// Increment (a1) - Supplies the increment value to be added to the
// addend variable.
//
// Lock (a2) - Supplies a pointer to a spin lock to be used to synchronize
// access to the addend variable.
//
// Return Value:
//
// The result of the interlocked large integer add.
//
// Implementation Note:
//
// The specification of this function requires that the given lock must be
// used to synchronize the update even though on Alpha the operation can
// actually done atomically without using the specified lock.
//
//--
LEAF_ENTRY(ExInterlockedAddLargeInteger)
10: DISABLE_INTERRUPTS // disable interrupts
#if !defined(NT_UP)
LDP_L t0, 0(a2) // get current lock value - locked
bne t0, 20f // if ne, spin lock owned
mov a2, t0 // set ownership value (lock address)
STP_C t0, 0(a2) // set spin lock owned - conditionally
beq t0, 20f // if eq, conditional store failed
mb // synchronize memory access
#endif
ldq t0, 0(a0) // get addend
addq t0, a1, v0 // do the add
stq v0, 0(a0) // store result
#if !defined(NT_UP)
mb // synchronize memory access
STP zero, 0(a2) // set spin lock not owned
#endif
ENABLE_INTERRUPTS // enable interrupts
ret zero, (ra) // return
//
// We expect the store conditional will usually succeed the first time so it
// is faster to branch forward (predicted not taken) to here and then branch
// backward (predicted taken) to where we wanted to go.
//
#if !defined(NT_UP)
20: ENABLE_INTERRUPTS // enable interrupts
22: LDP t0, 0(a2) // read current lock value
beq t0, 10b // if eq, lock not owned
br zero, 22b // spin in cache until available
#endif
.end ExInterlockedAddLargeInteger
SBTTL("Interlocked Add Large Statistic")
//++
//
// VOID
// ExInterlockedAddLargeStatistic (
// IN PLARGE_INTEGER Addend,
// IN ULONG Increment
// )
//
// Routine Description:
//
// This function performs an interlocked add of an increment value to an
// addend variable of type large integer.
//
// Arguments:
//
// Addend (a0) - Supplies a pointer to a variable whose value is to be
// adjusted by the increment value.
//
// Increment (a1) - Supplies the increment value to be added to the
// addend variable.
//
// Return Value:
//
// None.
//
// Implementation Note:
//
// The specification of this function requires that the given lock must be
// used to synchronize the update even though on Alpha the operation can
// actually done atomically without using the specified lock.
//
//--
LEAF_ENTRY(ExInterlockedAddLargeStatistic)
zap a1, 0xf0, a1 // zero extend increment value
10: ldq_l t0, 0(a0) // get addend
addq t0, a1, t0 // do the add
stq_c t0, 0(a0) // store result
beq t0, 20f // if eq, store conditional failed
ret zero, (ra) // return
//
// We expect the store conditional will usually succeed the first time so it
// is faster to branch forward (predicted not taken) to here and then branch
// backward (predicted taken) to where we wanted to go.
//
20: br zero, 10b // try again
.end ExInterlockedAddLargeStatistic
SBTTL("Interlocked Add Unsigned Long")
//++
//
// ULONG
// ExInterlockedAddUlong (
// IN PULONG Addend,
// IN ULONG Increment,
// IN PKSPIN_LOCK Lock
// )
//
// 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 (a0) - Supplies a pointer to a variable whose value is to be
// adjusted by the increment value.
//
// Increment (a1) - Supplies the increment value to be added to the
// addend variable.
//
// Lock (a2) - Supplies a pointer to a spin lock to be used to synchronize
// access to the addend variable.
//
// Return Value:
//
// The initial value of the addend variable.
//
// Implementation Note:
//
// The specification of this function requires that the given lock must be
// used to synchronize the update even though on Alpha the operation can
// actually done atomically without using the specified lock.
//
//--
LEAF_ENTRY(ExInterlockedAddUlong)
10: DISABLE_INTERRUPTS // (PALcode) v0 is clobbered
#if !defined(NT_UP)
LDP_L t0, 0(a2) // get current lock value - locked
bne t0, 20f // if ne, spin lock still owned
mov a2, t0 // set ownership value (lock address)
STP_C t0, 0(a2) // set spin lock owned - conditionally
beq t0, 20f // if eq, conditional store failed
mb // synchronize memory access
#endif
//
// Set the return value in t0 for now since PALcode may use v0.
//
ldl t0, 0(a0) // get addend value (return value also)
addl t0, a1, t1 // compute adjusted value
stl t1, 0(a0) // store updated value
#if !defined(NT_UP)
mb // synchronize memory access
STP zero, 0(a2) // set spin lock not owned
#endif
ENABLE_INTERRUPTS // (PALcode) v0 is clobbered
mov t0, v0 // set return value
ret zero, (ra) // return
//
// We expect the store conditional will usually succeed the first time so it
// is faster to branch forward (predicted not taken) to here and then branch
// backward (predicted taken) to where we wanted to go.
//
#if !defined(NT_UP)
20: ENABLE_INTERRUPTS // (PALcode) v0 is clobbered
22: LDP t0, 0(a2) // read current lock value
beq t0, 10b // try spinlock again if available
br zero, 22b // spin in cache until available
#endif
.end ExInterlockedAddUlong
SBTTL("Interlocked Exchange Unsigned Long")
//++
//
// ULONG
// ExInterlockedExchangeUlong (
// IN PULONG Source,
// IN ULONG Value,
// IN PKSPIN_LOCK Lock
// )
//
// Routine Description:
//
// This function performs an interlocked exchange of a longword value with
// a longword in memory and returns the memory value.
//
// N.B. There is an alternate entry point provided for this routine which
// is ALPHA target specific and whose prototype does not include the
// spinlock parameter. Since the routine never refers to the spinlock
// parameter, no additional code is required.
//
// Arguments:
//
// Source (a0) - Supplies a pointer to a variable whose value is to be
// exchanged.
//
// Value (a1) - Supplies the value to exchange with the source value.
//
// Lock (a2) - Supplies a pointer to a spin lock to be used to synchronize
// access to the source variable.
//
// Return Value:
//
// The source value is returned as the function value.
//
//--
LEAF_ENTRY(ExInterlockedExchangeUlong)
ALTERNATE_ENTRY(ExAlphaInterlockedExchangeUlong)
10: ldl_l v0, 0(a0) // get current source value
bis a1, zero, t0 // set exchange value
stl_c t0, 0(a0) // replace source value
beq t0, 20f // if eq, conditional store failed
ret zero, (ra) // return old value to caller
//
// We expect the store conditional will usually succeed the first time so it
// is faster to branch forward (predicted not taken) to here and then branch
// backward (predicted taken) to where we wanted to go.
//
20: br zero,10b // go try spin lock again
.end ExInterlockedExchangeUlong
SBTTL("Interlocked Decrement Long")
//++
//
// INTERLOCKED_RESULT
// ExInterlockedDecrementLong (
// IN PLONG Addend,
// IN PKSPIN_LOCK Lock
// )
//
// Routine Description:
//
// This function performs an interlocked decrement on an addend variable
// of type signed long. The sign and whether the result is zero is returned
// as the function value.
//
// N.B. There is an alternate entry point provided for this routine which
// is ALPHA target specific and whose prototype does not include the
// spinlock parameter. Since the routine never refers to the spinlock
// parameter, no additional code is required.
//
// Arguments:
//
// Addend (a0) - Supplies a pointer to a variable whose value is to be
// decremented.
//
// Lock (a1) - Supplies a pointer to a spin lock to be used to synchronize
// access to the addend variable.
//
// Return Value:
//
// RESULT_NEGATIVE is returned if the resultant addend value is negative.
// RESULT_ZERO is returned if the resultant addend value is zero.
// RESULT_POSITIVE is returned if the resultant addend value is positive.
//
// Implementation Note:
//
// The specification of this function does not require that the given lock
// be used to synchronize the update as long as the update is synchronized
// somehow. On Alpha a single load locked-store conditional does the job.
//
//--
LEAF_ENTRY(ExInterlockedDecrementLong)
ALTERNATE_ENTRY(ExAlphaInterlockedDecrementLong)
10: ldl_l v0, 0(a0) // get current addend value - locked
subl v0, 1, v0 // decrement addend value
mov v0, t0 // copy updated value to t0 for store
stl_c t0, 0(a0) // store updated value - conditionally
beq t0, 20f // if eq, conditional store failed
//
// Determine the INTERLOCKED_RESULT value based on the updated addend value.
// N.B. RESULT_ZERO = 0, RESULT_NEGATIVE = 1, RESULT_POSITIVE = 2.
//
sra v0, 63, t0 // replicate the sign bit to every bit
addl t0, 2, t0 // if t0 = 0 return 2, if -1 return 1
cmovne v0, t0, v0 // if v0 = 0 return 0
ret zero, (ra) // return
//
// We expect the store conditional will usually succeed the first time so it
// is faster to branch forward (predicted not taken) to here and then branch
// backward (predicted taken) to where we wanted to go.
//
20: br zero, 10b // go try spin lock again
.end ExInterlockedDecrementLong
SBTTL("Interlocked Increment Long")
//++
//
// INTERLOCKED_RESULT
// ExInterlockedIncrementLong (
// IN PLONG Addend,
// IN PKSPIN_LOCK Lock
// )
//
// Routine Description:
//
// This function performs an interlocked increment on an addend variable
// of type signed long. The sign and whether the result is zero is returned
// as the function value.
//
// N.B. There is an alternate entry point provided for this routine which
// is ALPHA target specific and whose prototype does not include the
// spinlock parameter. Since the routine never refers to the spinlock
// parameter, no additional code is required.
//
// Arguments:
//
// Addend (a0) - Supplies a pointer to a variable whose value is to be
// incremented.
//
// Lock (a1) - Supplies a pointer to a spin lock to be used to synchronize
// access to the addend variable.
//
// Return Value:
//
// RESULT_NEGATIVE is returned if the resultant addend value is negative.
// RESULT_ZERO is returned if the resultant addend value is zero.
// RESULT_POSITIVE is returned if the resultant addend value is positive.
//
// Implementation Note:
//
// The specification of this function does not require that the given lock
// be used to synchronize the update as long as the update is synchronized
// somehow. On Alpha a single load locked-store conditional does the job.
//
//--
LEAF_ENTRY(ExInterlockedIncrementLong)
ALTERNATE_ENTRY(ExAlphaInterlockedIncrementLong)
10: ldl_l v0, 0(a0) // get current addend value - locked
addl v0, 1, v0 // increment addend value
mov v0, t0 // copy updated value to t0 for store
stl_c t0, 0(a0) // store updated value - conditionally
beq t0, 20f // if eq, conditional store failed
//
// Determine the INTERLOCKED_RESULT value based on the updated addend value.
// N.B. RESULT_ZERO = 0, RESULT_NEGATIVE = 1, RESULT_POSITIVE = 2.
//
sra v0, 63, t0 // replicate the sign bit to every bit
addl t0, 2, t0 // if t0 = 0 return 2, if -1 return 1
cmovne v0, t0, v0 // if v0 = 0 return 0
ret zero, (ra) // return
//
// We expect the store conditional will usually succeed the first time so it
// is faster to branch forward (predicted not taken) to here and then branch
// backward (predicted taken) to where we wanted to go.
//
20: br zero, 10b // go try spin lock again
.end ExInterlockedIncrementLong
SBTTL("Interlocked Insert Head List")
//++
//
// PLIST_ENTRY
// ExInterlockedInsertHeadList (
// IN PLIST_ENTRY ListHead,
// IN PLIST_ENTRY ListEntry,
// IN PKSPIN_LOCK Lock
// )
//
// Routine Description:
//
// This function inserts an entry at the head of a doubly linked list
// so that access to the list is synchronized in a multiprocessor system.
//
// Arguments:
//
// ListHead (a0) - Supplies a pointer to the head of the doubly linked
// list into which an entry is to be inserted.
//
// ListEntry (a1) - Supplies a pointer to the entry to be inserted at the
// head of the list.
//
// Lock (a2) - Supplies a pointer to a spin lock to be used to synchronize
// access to the list.
//
// Return Value:
//
// Pointer to entry that was at the head of the list or NULL if the list
// was empty.
//
//--
LEAF_ENTRY(ExInterlockedInsertHeadList)
10: DISABLE_INTERRUPTS // (PALcode) v0 is clobbered
#if !defined(NT_UP)
LDP_L t0, 0(a2) // get current lock value - locked
bne t0, 20f // if ne, spin lock still owned
mov a2, t0 // set ownership value (lock address)
STP_C t0, 0(a2) // set spin lock owned - conditionally
beq t0, 20f // if eq, conditional store failed
mb // synchronize memory access
#endif
//
// Set the return value in t0 for now since PALcode may use v0.
//
LDP t0, LsFlink(a0) // get address of next entry (return value also)
STP t0, LsFlink(a1) // store next link in entry
STP a0, LsBlink(a1) // store previous link in entry
STP a1, LsBlink(t0) // store previous link in next
STP a1, LsFlink(a0) // store next link in head
#if !defined(NT_UP)
mb // sychronize memory access
STP zero, 0(a2) // set spin lock not owned
#endif
ENABLE_INTERRUPTS // (PALcode) v0 is clobbered
xor t0, a0, v0 // if t0=a0, list empty, set v0 to NULL
cmovne v0, t0, v0 // else return previous entry at head
ret zero, (ra) // return
//
// We expect the store conditional will usually succeed the first time so it
// is faster to branch forward (predicted not taken) to here and then branch
// backward (predicted taken) to where we wanted to go.
//
#if !defined(NT_UP)
20: ENABLE_INTERRUPTS // (PALcode) v0 is clobbered
22: LDP t0, 0(a2) // read current lock value
beq t0, 10b // try spinlock again if available
br zero, 22b // spin in cache until available
#endif
.end ExInterlockedInsertHeadList
SBTTL("Interlocked Insert Tail List")
//++
//
// PLIST_ENTRY
// ExInterlockedInsertTailList (
// IN PLIST_ENTRY ListHead,
// IN PLIST_ENTRY ListEntry,
// IN PKSPIN_LOCK Lock
// )
//
// Routine Description:
//
// This function inserts an entry at the tail of a doubly linked list
// so that access to the list is synchronized in a multiprocessor system.
//
// Arguments:
//
// ListHead (a0) - Supplies a pointer to the head of the doubly linked
// list into which an entry is to be inserted.
//
// ListEntry (a1) - Supplies a pointer to the entry to be inserted at the
// tail of the list.
//
// Lock (a2) - Supplies a pointer to a spin lock to be used to synchronize
// access to the list.
//
// Return Value:
//
// Pointer to entry that was at the tail of the list or NULL if the list
// was empty.
//
//--
LEAF_ENTRY(ExInterlockedInsertTailList)
10: DISABLE_INTERRUPTS // (PALcode) v0 is clobbered
#if !defined(NT_UP)
LDP_L t0, 0(a2) // get current lock value - locked
bne t0, 20f // if ne, spin lock still owned
mov a2, t0 // set ownership value (lock address)
STP_C t0, 0(a2) // set spin lock owned - conditionally
beq t0, 20f // if eq, conditional store failed
mb // sychronize memory access
#endif
//
// Set the return value in t0 for now since PALcode may use v0.
//
LDP t0, LsBlink(a0) // get address of previous entry (return value also)
STP a0, LsFlink(a1) // store next link in entry
STP t0, LsBlink(a1) // store previous link in entry
STP a1, LsBlink(a0) // store previous link in next
STP a1, LsFlink(t0) // store next link in head
#if !defined(NT_UP)
mb // sychronize memory access
STP zero, 0(a2) // set spin lock not owned
#endif
ENABLE_INTERRUPTS // (PALcode) v0 is clobbered
xor t0, a0, v0 // if t0=a0, list empty, set v0 to NULL
cmovne v0, t0, v0 // else return previous entry at tail
ret zero, (ra) // return
//
// We expect the store conditional will usually succeed the first time so it
// is faster to branch forward (predicted not taken) to here and then branch
// backward (predicted taken) to where we wanted to go.
//
#if !defined(NT_UP)
20: ENABLE_INTERRUPTS // (PALcode) v0 is clobbered
22: LDP t0, 0(a2) // read current lock value
beq t0, 10b // try spinlock again if available
br zero, 22b // spin in cache until available
#endif
.end ExInterlockedInsertTailList
SBTTL("Interlocked Remove Head List")
//++
//
// PLIST_ENTRY
// ExInterlockedRemoveHeadList (
// IN PLIST_ENTRY ListHead,
// IN PKSPIN_LOCK Lock
// )
//
// Routine Description:
//
// This function removes an entry from the head of a doubly linked list
// so that access to the list is synchronized in a multiprocessor system.
// If there are no entries in the list, then a value of NULL is returned.
// Otherwise, the address of the entry that is removed is returned as the
// function value.
//
// Arguments:
//
// ListHead (a0) - Supplies a pointer to the head of the doubly linked
// list from which an entry is to be removed.
//
// Lock (a1) - Supplies a pointer to a spin lock to be used to synchronize
// access to the list.
//
// Return Value:
//
// The address of the entry removed from the list, or NULL if the list is
// empty.
//
//--
LEAF_ENTRY(ExInterlockedRemoveHeadList)
10: DISABLE_INTERRUPTS // (PALcode) v0 is clobbered
#if !defined(NT_UP)
LDP_L t0, 0(a1) // get current lock value - locked
bne t0, 30f // if ne, spin lock still owned
mov a1, t0 // set ownership value (lock address)
STP_C t0, 0(a1) // set spin lock owned - conditionally
beq t0, 30f // if eq, conditional store failed
mb // synchronize memory access
#endif
//
// Set the return value in t0 for now since PALcode may use v0.
//
LDP t2, LsFlink(a0) // get address of next entry
xor t2, a0, t0 // if t2=a0, list empty, set t0 to NULL
beq t0, 20f // if eq, list is empty
LDP t1, LsFlink(t2) // get address of next entry
STP t1, LsFlink(a0) // store address of next in head
STP a0, LsBlink(t1) // store address of previous in next
mov t2, t0 // return the address of entry removed
20: //
#if !defined(NT_UP)
mb // synchronize memory access
STP zero, 0(a1) // set spin lock not owned
#endif
ENABLE_INTERRUPTS // (PALcode) v0 is clobbered
mov t0, v0 // set return value
ret zero, (ra) // return
//
// We expect the store conditional will usually succeed the first time so it
// is faster to branch forward (predicted not taken) to here and then branch
// backward (predicted taken) to where we wanted to go.
//
#if !defined(NT_UP)
30: ENABLE_INTERRUPTS // (PALcode) v0 is clobbered
32: LDP t0, 0(a1) // read current lock value
beq t0, 10b // try spinlock again if available
br zero, 32b // spin in cache until available
#endif
.end ExInterlockedRemoveHeadList
SBTTL("Interlocked Pop Entry List")
//++
//
// PSINGLE_LIST_ENTRY
// ExInterlockedPopEntryList (
// IN PSINGLE_LIST_ENTRY ListHead,
// IN PKSPIN_LOCK Lock
// )
//
// Routine Description:
//
// This function removes an entry from the head of a singly linked list
// so that access to the list is synchronized in a multiprocessor system.
// If there are no entries in the list, then a value of NULL is returned.
// Otherwise, the address of the entry that is removed is returned as the
// function value.
//
// Arguments:
//
// ListHead (a0) - Supplies a pointer to the head of the singly linked
// list from which an entry is to be removed.
//
// Lock (a1) - Supplies a pointer to a spin lock to be used to synchronize
// access to the list.
//
// Return Value:
//
// The address of the entry removed from the list, or NULL if the list is
// empty.
//
//--
LEAF_ENTRY(ExInterlockedPopEntryList)
10: DISABLE_INTERRUPTS // (PALcode) v0 is clobbered
#if !defined(NT_UP)
LDP_L t0, 0(a1) // get current lock value - locked
bne t0, 30f // if ne, spin lock still owned
mov a1, t0 // set ownership value (lock address)
STP_C t0, 0(a1) // set spin lock owned - conditionally
beq t0, 30f // if eq, conditional store failed
mb // synchronize memory access
#endif
//
// Set the return value in t0 for now since PALcode may use v0.
//
LDP t0, 0(a0) // get address of next entry (return value also)
beq t0, 20f // if eq [NULL], list is empty
LDP t1, 0(t0) // get address of next entry
STP t1, 0(a0) // store address of next in head
20: //
#if !defined(NT_UP)
mb // synchronize memory access
STP zero, 0(a1) // set spin lock not owned
#endif
ENABLE_INTERRUPTS // (PALcode) v0 is clobbered
mov t0, v0 // set return value
ret zero, (ra) // return
//
// We expect the store conditional will usually succeed the first time so it
// is faster to branch forward (predicted not taken) to here and then branch
// backward (predicted taken) to where we wanted to go.
//
#if !defined(NT_UP)
30: ENABLE_INTERRUPTS // (PALcode) v0 is clobbered
32: LDP t0, 0(a1) // read current lock value
beq t0, 10b // try spinlock again if available
br zero, 32b // spin in cache until available
#endif
.end ExInterlockedPopEntryList
SBTTL("Interlocked Push Entry List")
//++
//
// PSINGLE_LIST_ENTRY
// ExInterlockedPushEntryList (
// IN PSINGLE_LIST_ENTRY ListHead,
// IN PSINGLE_LIST_ENTRY ListEntry,
// IN PKSPIN_LOCK Lock
// )
//
// Routine Description:
//
// This function inserts an entry at the head of a singly linked list
// so that access to the list is synchronized in a multiprocessor system.
//
// Arguments:
//
// ListHead (a0) - Supplies a pointer to the head of the singly linked
// list into which an entry is to be inserted.
//
// ListEntry (a1) - Supplies a pointer to the entry to be inserted at the
// head of the list.
//
// Lock (a2) - Supplies a pointer to a spin lock to be used to synchronize
// access to the list.
//
// Return Value:
//
// Previous contents of ListHead. NULL implies list went from empty
// to not empty.
//
//--
LEAF_ENTRY(ExInterlockedPushEntryList)
10: DISABLE_INTERRUPTS // (PALcode) v0 is clobbered
#if !defined(NT_UP)
LDP_L t0, 0(a2) // get current lock value - locked
bne t0, 20f // if ne, spin lock still owned
mov a2, t0 // set ownership value (lock address)
STP_C t0, 0(a2) // set spin lock owned - conditionally
beq t0, 20f // if eq, conditional store failed
mb // synchronize memory access
#endif
//
// Set the return value in t0 for now since PALcode may use v0.
//
LDP t0, 0(a0) // get address of first entry (return value also)
STP t0, 0(a1) // set address of next in new entry
STP a1, 0(a0) // set address of first entry
#if !defined(NT_UP)
mb // synchronize memory access
STP zero, 0(a2) // set spin lock not owned
#endif
ENABLE_INTERRUPTS // (PALcode) v0 is clobbered
mov t0, v0 // set return value
ret zero, (ra) // return
//
// We expect the store conditional will usually succeed the first time so it
// is faster to branch forward (predicted not taken) to here and then branch
// backward (predicted taken) to where we wanted to go.
//
#if !defined(NT_UP)
20: ENABLE_INTERRUPTS // (PALcode) v0 is clobbered
22: LDP t0, 0(a2) // read current lock value
beq t0, 10b // try spinlock again if available
br zero, 22b // spin in cache until available
#endif
.end ExInterlockedPushEntryList
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 (a0) - Supplies a pointer to the destination value.
//
// Exchange (a1) - Supplies the exchange.
//
// Comperand (a2) - Supplies the comperand value.
//
// Return Value:
//
// The initial destination value is returned as the function value.
//
//--
LEAF_ENTRY(InterlockedCompareExchange)
10: //
#if !defined(NT_UP)
mb // synchronize memory access
#endif
ldl_l v0, 0(a0) // get current value
bis a1, zero, t0 // copy exchange value for store
cmpeq v0, a2, t1 // check if operands match
beq t1, 20f // if eq, operands mismatch
stl_c t0, 0(a0) // store updated addend value
beq t0,25f // if eq, store conditional failed
#if !defined(NT_UP)
mb // synchronize memory access
#endif
20: ret zero, (ra) // return
//
// We expect the store conditional will usually succeed the first time so it
// is faster to branch forward (predicted not taken) to here and then branch
// backward (predicted taken) to where we wanted to go.
//
25: br zero, 10b // go try spin lock again
.end InterlockedCompareExchange
SBTTL("Interlocked Exchange Add")
//++
//
// LONG
// ExInterlockedAdd (
// IN PLONG Addend,
// IN ULONG 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 (a0) - Supplies a pointer to a variable whose value is to be
// adjusted by the increment value.
//
// Increment (a1) - Supplies the increment value to be added to the
// addend variable.
//
// Return Value:
//
// The initial value of the addend variable.
//
//--
LEAF_ENTRY(InterlockedExchangeAdd)
10: //
#if !defined(NT_UP)
mb // synchronize memory access
#endif
ldl_l v0, 0(a0) // get current addend value - locked
addl v0, a1, t0 // increment addend value
stl_c t0, 0(a0) // store updated value - conditionally
beq t0, 20f // if eq, conditonal store failed
#if !defined(NT_UP)
mb // synchronize memory access
#endif
ret zero, (ra) // return
//
// We expect the store conditional will usually succeed the first time so it
// is faster to branch forward (predicted not taken) to here and then branch
// backward (predicted taken) to where we wanted to go.
//
20: br zero, 10b // go try spin lock again
.end InterlockedExchangeAdd
SBTTL("Interlocked Pop Entry Sequenced List")
//++
//
// PSINGLE_LIST_ENTRY
// ExpInterlockedPopEntrySList (
// IN PSLIST_HEADER ListHead
// )
//
// Routine Description:
//
// This function removes an entry from the front of a sequenced singly
// linked list so that access to the list is synchronized in a MP system.
// If there are no entries in the list, then a value of NULL is returned.
// Otherwise, the address of the entry that is removed is returned as the
// function value.
//
// Arguments:
//
// ListHead (a0) - Supplies a pointer to the sequenced listhead from which
// an entry is to be removed.
//
// Return Value:
//
// The address of the entry removed from the list, or NULL if the list is
// empty.
//
//--
LEAF_ENTRY(ExpInterlockedPopEntrySList)
//
// N.B. The following code is the continuation address should a fault
// occur in the rare case described below.
//
ALTERNATE_ENTRY(ExpInterlockedPopEntrySListResume)
10: ldq t0, 0(a0) // get next entry address and sequence
#if defined(_AXP64_)
sra t0, 63 - 42, v0 // extract next entry address
bic v0, 7, v0 //
beq v0, 30f // if eq, list is empty
bis t0, zero, t1 // copy depth and sequence
#else
addl t0, zero, v0 // sign extend next entry address
beq v0, 30f // if eq, list is empty
srl t0, 32, t1 // shift sequence to low 32-bits
#endif
#if !defined(NT_UP)
mb // synchronize memory access
#endif
//
// N.B. It is possible for the following instruction to fault in the rare
// case where the first entry in the list is allocated on another
// processor and freed between the time the free pointer is read above
// and the following instruction. When this happens, the access fault
// code continues execution above at the resumption address and the
// entire operation is retried.
//
ALTERNATE_ENTRY(ExpInterlockedPopEntrySListFault)
LDP t5, 0(v0) // get address of successor entry
#if defined(_AXP64_)
sll t5, 63 - 42, t2 // shift address into position
#else
zapnot t5, 0xf ,t2 // clear high 32-bits for merge
#endif
ldq_l t3, 0(a0) // reload next entry address and sequence
ldil t5, 0xffff // decrement list depth and
addl t1, t5, t1 // increment sequence number
#if defined(_AXP64_)
zapnot t1, 0x7, t1 // clear upper five bytes
#else
sll t1, 32, t1 // shift depth and sequence into position
#endif
cmpeq t0, t3, t4 // check if listhead has changed
beq t4, 15f // if eq, listhead changed
bis t1, t2, t1 // merge address, depth, and sequence
stq_c t1, 0(a0) // store next entry address and sequence
beq t1, 15f // if eq, store conditional failed
#if !defined(NT_UP)
mb // synchronize memory access
#endif
30: ret zero, (ra) //
//
// Conditional store attempt failed or listhead changed.
//
15: br zero, 10b // retry
.end ExpInterlockedPopEntrySList
SBTTL("Interlocked Push Entry Sequenced List")
//++
//
// PSINGLE_LIST_ENTRY
// ExpInterlockedPushEntrySList (
// IN PSLIST_HEADER ListHead,
// IN PSINGLE_LIST_ENTRY ListEntry
// )
//
// Routine Description:
//
// This function inserts an entry at the head of a sequenced singly linked
// list so that access to the list is synchronized in an MP system.
//
// Arguments:
//
// ListHead (a0) - Supplies a pointer to the sequenced listhead into which
// an entry is to be inserted.
//
// ListEntry (a1) - Supplies a pointer to the entry to be inserted at the
// head of the list.
//
// Return Value:
//
// Previous contents of ListHead. NULL implies list went from empty
// to not empty.
//
//--
LEAF_ENTRY(ExpInterlockedPushEntrySList)
10: ldq t0, 0(a0) // get next entry address and sequence
#if defined(_AXP64_)
sra t0, 63 - 42, v0 // extract next entry address
bic v0, 7, v0 //
bis t0, zero, t1 // copy depth and sequence number
#else
addl t0, zero, v0 // sign extend next entry address
srl t0, 32, t1 // shift sequence to low 32-bits
#endif
STP v0, 0(a1) // set next link in new first entry
#if !defined(NT_UP)
mb // synchronize memory access
#endif
#if defined(_AXP64_)
sll a1, 63 - 42, t2 // shift address into position
#else
zapnot a1, 0xf, t2 // zero extend new first entry
#endif
ldq_l t3, 0(a0) // reload next entry address and sequence
ldah t5, 1(zero) // get sequence adjustment value
addl t1, 1, t1 // increment list depth
addl t1, t5, t1 // increment sequence number
#if defined(_AXP64_)
zapnot t1, 0x7, t1 // clear upper five bytes
#else
sll t1, 32, t1 // merge new first entry address and sequence
#endif
cmpeq t0, t3, t4 // check if listhead changed
beq t4, 15f // if eq, listhead changed
bis t1, t2, t2 // merge address, depth, and sequence
stq_c t2, 0(a0) // store next entry address and sequence
beq t2, 15f // if eq, store conditional failed
ret zero, (ra) // return
//
// Conditional store attempt failed or listhead changed.
//
15: br zero, 10b // retry
.end ExpInterlockedPushEntrySList
SBTTL("Interlocked Flush Sequenced List")
//++
//
// PSINGLE_LIST_ENTRY
// ExpInterlockedFlushSList (
// IN PSLIST_HEADER ListHead
// )
//
// Routine Description:
//
// This function flushes the entire list of entries on a sequenced singly
// linked list so that access to the list is synchronized in a MP system.
// If there are no entries in the list, then a value of NULL is returned.
// Otherwise, the address of the 1st entry on the list is returned as the
// function value.
//
// Arguments:
//
// ListHead (a0) - Supplies a pointer to the sequenced listhead from which
// an entry is to be removed.
//
// Return Value:
//
// The address of the entry removed from the list, or NULL if the list is
// empty.
//
//--
LEAF_ENTRY(ExpInterlockedFlushSList)
and t1, zero, t1 // set new listhead value
10: ldq_l t0, 0(a0) // get next entry address and sequence
stq_c t1, 0(a0) // store new listhead value
beq t1, 15f // if eq, store conditional failed
#if defined(_AXP64_)
sra t0, 63 - 42, v0 // extract next entry address
bic v0, 7, v0 //
#else
addl t0, zero, v0 // sign extend next entry address
#endif
ret zero, (ra) // return
//
// Conditional store attempt failed or listhead changed.
//
15: br zero, 10b // retry, store conditional failed
.end ExpInterlockedFlushSList
SBTTL("Interlocked Compare Exchange 64-bits")
//++
//
// LONGLONG
// ExpInterlockedCompareExchange64 (
// IN PLONGLONG Destination,
// IN PLONGLONG Exchange,
// IN PLONGLONG Comperand
// )
//
// Routine Description:
//
// This function performs an interlocked compare and exchange of 64-bits.
//
// Arguments:
//
// Destination (a0) - Supplies a pointer to the destination variable.
//
// Exchange (a1) - Supplies a pointer to the exchange value.
//
// Comperand (a2) - Supplies a pointer to the comperand value.
//
// Return Value:
//
// The current destination value are returned as the function value.
//
//--
LEAF_ENTRY(ExpInterlockedCompareExchange64)
ldq t0, 0(a1) // get exchange value
ldq t1, 0(a2) // get comperand value
10: ldq_l v0, 0(a0) // get current destination value
bis t0, zero, t2 // set exchange value
cmpeq v0, t1, t3 // check if current and comperand match
beq t3, 20f // if eq, current and comperand mismatch
stq_c t2, 0(a0) // store exchange value
beq t2, 30f // if eq, store conditional failed
20: ret zero, (ra)
//
// Conditional store attempt failed.
//
30: br zero, 10b // retry
.end ExpInterlockedCompareExchange64
SBTTL("Interlocked Compare Exchange 64-bits")
//++
//
// LONGLONG
// InterlockedCompareExchange64 (
// IN PLONGLONG Destination,
// IN LONGLONG Exchange,
// IN LONGLONG Comperand
// )
//
// Routine Description:
//
// This function performs an interlocked compare and exchange of 64-bits.
//
// Arguments:
//
// Destination (a0) - Supplies a pointer to the destination variable.
//
// Exchange (a1) - Supplies the exchange value.
//
// Comperand (a2) - Supplies the comperand value.
//
// Return Value:
//
// The current destination value are returned as the function value.
//
//--
#if !defined(_AXP64_)
LEAF_ENTRY(InterlockedCompareExchange64)
10: ldq_l v0, 0(a0) // get current destination value
bis a1, zero, t2 // set exchange value
cmpeq v0, a2, t3 // check if current and comperand match
beq t3, 20f // if eq, current and comperand mismatch
stq_c t2, 0(a0) // store exchange value
beq t2, 10b // if eq, store conditional failed
20: ret zero, (ra)
.end InterlockedCompareExchange64
#endif
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