Unit PlatformARMv8

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OldStack	The address to save the stack pointer to for the current thread (Passed in r0)
NewStack	The address to restore the stack pointer from for the new thread (Passed in r1)
NewThread	The handle of the new thread to switch to (Passed in r2)
Note	At the point of the actual context switch (str sp / ldr sp) the thread stacks will look like this: (See: ARMv8ThreadSetupStack for additional information) (Base "Highest Address" of Stack) . . . . cpsr <- The current program status register value to load on return from the context switch lr/pc <- The address to return to from the context switch lr <- The lr value prior to the context switch r12 <- r11 <- r10 <- r9 <- r8 <- r7 <- r6 <- The value of these registers prior to the context switch r5 <- r4 <- r3 <- r2 <- r1 <- r0 <- d15 <- d14 <- d13 <- d12 <- d11 <- d10 <- d9 <- d8 <- The value of these floating point registers prior to the context switch d7 <- d6 <- d5 <- d4 <- d3 <- d2 <- d1 <- d0 <- fpscr <- The floating point FPSCR register fpexc <- The floating point FPEXC register (Current StackPointer points to here) . . . . (Top "Lowest Address" of Stack) This form of context switch uses r12 to save the cpsr value (and RFE to restore it). Because this context switch is called from a routine which will have saved the value of r12 (which is caller save in the ARM ABI) then we do not need to save the original value of r12. The context switch will be performed from SYS mode to SYS mode, the cpsr value will include the control bits (Mode and IRQ/FIQ state) but not the flags values. Again the ARM ABI does not require that the flags be saved by the callee and so the caller would have accounted for any needed flags before calling. If the thread to be resumed was interrupted by an IRQ or FIQ then the cpsr will also contain the flags etc as they were at the point of interrupt. We do not need to account for the state bits in the cpsr since all operations are performed in ARM mode at present. The main requirement of this routine is to ensure that the context record on the stack matches exactly that which is created on an interrupt and also that created by ThreadSetupStack for a new thread. If this is correct then the next context switch for any given thread can be either by a call to reschedule or by an interrupt. Equally a new thread can be first run from a context switch that resulted from either a call to reschedule or an interrupt. Note that this routine could use: pop (lr) pop (r12) msr cpsr_c, r12 mov pc, lr To return but that would mess up the value of r12, lr and the cpsr flags etc if the thread being resumed was interrupted by an IRQ,FIQ or SWI. The use of RFE here allows for exactly the same behaviour no matter which way the context record is saved and restored.

procedure ARMv8ContextSwitchIRQ(OldStack,NewStack:Pointer; NewThread:TThreadHandle);  assembler; nostackframe;

Description: Perform a context switch from one thread to another as a result of an interrupt request (IRQ)

OldStack	The address to save the stack pointer to for the current thread (Passed in r0)
NewStack	The address to restore the stack pointer from for the new thread (Passed in r1)
NewThread	The handle of the new thread to switch to (Passed in r2)
Note	At the point of the actual context switch (str sp / ldr sp) the thread stacks will look like this: (See: ARMv8ThreadSetupStack for additional information) (Base "Highest Address" of Stack) . . . . cpsr <- The current program status register value to load on return from the context switch lr/pc <- The address to return to from the context switch lr <- The lr value prior to the context switch r12 <- r11 <- r10 <- r9 <- r8 <- r7 <- r6 <- The value of these registers prior to the context switch r5 <- r4 <- r3 <- r2 <- r1 <- r0 <- d15 <- d14 <- d13 <- d12 <- d11 <- d10 <- d9 <- d8 <- The value of these floating point registers prior to the context switch d7 <- d6 <- d5 <- d4 <- d3 <- d2 <- d1 <- d0 <- fpscr <- The floating point FPSCR register fpexc <- The floating point FPEXC register (Current StackPointer points to here) . . . . (Top "Lowest Address" of Stack) This form of context switch relies on the IRQ handler to save the necessary registers including the lr, cpsr and other general registers from the point at which the thread was interrupted. The thread to be resumed may have been saved by a previous IRQ or by a call to the standard context switch from SchedulerReschule or it may be a new thread to be run for the first time. All of these result in the same context record on the stack and therefore can be resumed the same way. The context switch will be performed by switching to SYS mode, exchanging the stack pointers and then returning to IRQ mode.

procedure ARMv8ContextSwitchFIQ(OldStack,NewStack:Pointer; NewThread:TThreadHandle); assembler; nostackframe;

Description: Perform a context switch from one thread to another as a result of a fast interrupt request (FIQ)

OldStack	The address to save the stack pointer to for the current thread (Passed in r0)
NewStack	The address to restore the stack pointer from for the new thread (Passed in r1)
NewThread	The handle of the new thread to switch to (Passed in r2)
Note	At the point of the actual context switch (str sp / ldr sp) the thread stacks will look like this: (See: ARMv8ThreadSetupStack for additional information) (Base "Highest Address" of Stack) . . . . cpsr <- The current program status register value to load on return from the context switch lr/pc <- The address to return to from the context switch lr <- The lr value prior to the context switch r12 <- r11 <- r10 <- r9 <- r8 <- r7 <- r6 <- The value of these registers prior to the context switch r5 <- r4 <- r3 <- r2 <- r1 <- r0 <- d15 <- d14 <- d13 <- d12 <- d11 <- d10 <- d9 <- d8 <- The value of these floating point registers prior to the context switch d7 <- d6 <- d5 <- d4 <- d3 <- d2 <- d1 <- d0 <- fpscr <- The floating point FPSCR register fpexc <- The floating point FPEXC register (Current StackPointer points to here) . . . . (Top "Lowest Address" of Stack) This form of context switch relies on the FIQ handler to save the necessary registers including the lr, cpsr and other general registers from the point at which the thread was interrupted. The thread to be resumed may have been saved by a previous FIQ or by a call to the standard context switch from SchedulerReschule or it may be a new thread to be run for the first time. All of these result in the same context record on the stack and therefore can be resumed the same way. The context switch will be performed by switching to SYS mode, exchanging the stack pointers and then returning to FIQ mode.

procedure ARMv8ContextSwitchSWI(OldStack,NewStack:Pointer; NewThread:TThreadHandle); assembler; nostackframe;

Description: Perform a context switch from one thread to another as a result of a software interrupt (SWI)

OldStack	The address to save the stack pointer to for the current thread (Passed in r0)
NewStack	The address to restore the stack pointer from for the new thread (Passed in r1)
NewThread	The handle of the new thread to switch to (Passed in r2)
Note	At the point of the actual context switch (str sp / ldr sp) the thread stacks will look like this: (See: ARMv8ThreadSetupStack for additional information) (Base "Highest Address" of Stack) . . . . cpsr <- The current program status register value to load on return from the context switch lr/pc <- The address to return to from the context switch lr <- The lr value prior to the context switch r12 <- r11 <- r10 <- r9 <- r8 <- r7 <- r6 <- The value of these registers prior to the context switch r5 <- r4 <- r3 <- r2 <- r1 <- r0 <- d15 <- d14 <- d13 <- d12 <- d11 <- d10 <- d9 <- d8 <- The value of these floating point registers prior to the context switch d7 <- d6 <- d5 <- d4 <- d3 <- d2 <- d1 <- d0 <- fpscr <- The floating point FPSCR register fpexc <- The floating point FPEXC register (Current StackPointer points to here) . . . . (Top "Lowest Address" of Stack) This form of context switch relies on the SWI handler to save the necessary registers including the lr, cpsr and other general registers from the point at which the thread was interrupted. The thread to be resumed may have been saved by a previous SWI or by a call to the standard context switch from SchedulerReschule or it may be a new thread to be run for the first time. All of these result in the same context record on the stack and therefore can be resumed the same way. The context switch will be performed by switching to SYS mode, exchanging the stack pointers and then returning to SWI (SVC) mode.

function ARMv8InterlockedOr(var Target:LongInt; Value:LongInt):LongInt; assembler; nostackframe;

Description: Perform an atomic OR operation using LDREX/STREX

Note	See page ???

function ARMv8InterlockedXor(var Target:LongInt; Value:LongInt):LongInt; assembler; nostackframe;

Description: Perform an atomic XOR operation using LDREX/STREX

Note	See page ???

function ARMv8InterlockedAnd(var Target:LongInt; Value:LongInt):LongInt; assembler; nostackframe;

Description: Perform an atomic AND operation using LDREX/STREX

Note	See page ???

function ARMv8InterlockedDecrement(var Target:LongInt):LongInt; assembler; nostackframe;

Description: Perform an atomic decrement operation using LDREX/STREX

Note	See page ???

function ARMv8InterlockedIncrement(var Target:LongInt):LongInt; assembler; nostackframe;

Description: Perform an atomic increment operation using LDREX/STREX

Note	See page ???

function ARMv8InterlockedExchange(var Target:LongInt; Source:LongInt):LongInt; assembler; nostackframe;

Description: Perform an atomic exchange operation using LDREX/STREX

Note	See page ???

function ARMv8InterlockedAddExchange(var Target:LongInt; Source:LongInt):LongInt; assembler; nostackframe;

Description: Perform an atomic add and exchange operation using LDREX/STREX

Note	See page ???

function ARMv8InterlockedCompareExchange(var Target:LongInt; Source,Compare:LongInt):LongInt; assembler; nostackframe;

Description: Perform an atomic compare and exchange operation using LDREX/STREX

Note	See page ???

function ARMv8PageTableGetEntry(Address:PtrUInt):TPageTableEntry;

Description: Get and Decode the entry in the Page Table that corresponds to the supplied virtual address

Note	None documented

function ARMv8PageTableSetEntry(const Entry:TPageTableEntry):LongWord;

Description: Encode and Set an entry in the Page Table that corresponds to the supplied virtual address

Note	None documented

function ARMv8VectorTableGetEntry(Number:LongWord):PtrUInt;

Description: Return the address of the specified vector table entry number

Note	None documented

function ARMv8VectorTableSetEntry(Number:LongWord; Address:PtrUInt):LongWord;

Description: Set the supplied address as the value of the specified vector table entry number

Note	None documented

function ARMv8FirstBitSet(Value:LongWord):LongWord; assembler; nostackframe;

Description: To be documented

Note	ARM arm states that CLZ is supported for ARMv5 and above

function ARMv8CountLeadingZeros(Value:LongWord):LongWord; assembler; nostackframe;

Description: Equivalent of the GCC Builtin function __builtin_clz

Note	ARM arm states that CLZ is supported for ARMv5 and above

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SetWay	Set/Way/Level will be passed in r0
Note	See page B3-127 of the ARMv7 Architecture Reference Manual

SetWay	Set/Way/Level will be passed in r0
Note	See page B3-127 of the ARMv7 Architecture Reference Manual

SetWay	Set/Way/Level will be passed in r0
Note	See page B3-127 of the ARMv7 Architecture Reference Manual

Unit PlatformARMv8

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