Copyright (C) 1994, Digital Equipment Corp.
This interface defines platform (machine + OS) dependent types and constants.
INTERFACE--------------------------------------------------------- thread state ---RTMachine ; IMPORT Csetjmp;
TYPE
State = Csetjmp.jmp_buf;
(* The machine state is saved in a "State". This type is really
opaque to the client, i.e. it does not need to be an array. *)
<*EXTERNAL "_setjmp" *>
PROCEDURE SaveState (VAR s: State): INTEGER;
Capture the currently running thread's state
CONST
FramePadBottom = 2;
FramePadTop = 0;
(* Additional padding words from above and below an existing
thread's stack pointer to copy when creating a new thread *)
------------------------------------------------------------------ heap ---
The heap page size is machine-dependent, since it might depend on the architecture's VM page size (if VM is TRUE). Otherwise, 8192 bytes is a reasonable page size. The page size must be a power of two.
CONST BytesPerHeapPage = 8192; (* bytes per page *) LogBytesPerHeapPage = 13; AdrPerHeapPage = 8192; (* addresses per page *) LogAdrPerHeapPage = 13;The collector supports the use of VM protection to achieve incremental, generational collection. This is not possible on all architectures, and it may not be implemented in all cases where it is possible. The boolean constant
VMHeap is TRUE iff all necessary support is
present for this architecture. VMHeap is TRUE for the DS3100,
whose implementation you might use as a reference.
CONST VMHeap = TRUE;** hooks for the C wrapper functions **
<*EXTERNAL*> VAR RTHeapRep_Fault: ADDRESS; (* => RTHeapRep.Fault *) <*EXTERNAL*> VAR RTCSRC_FinishVM: ADDRESS; (* => RTCollectorSRC.FinishVM *)--------------------------------------------------------- thread stacks ---
CONST
PointerAlignment = 4;
(* The C compiler allocates all pointers on 'PointerAlignment'-byte
boundaries. The garbage collector scans thread stacks, but only
looks at these possible pointer locations. Setting this value
smaller than is needed will only make your system run slower.
Setting it too large will cause the collector to collect storage
that is not free. *)
CONST
StackFrameAlignment = 8;
(* Stack frames must be aligned to this constraint (in ADRSIZE units).
It's not a big deal if this value is too large, but it may break
the thread mechanism to make it too small. *)
----------------------------------------------- exception stack walking ---
The FrameInfo type must minimally include fields named pc and sp.
CONST
Has_stack_walker = TRUE;
(* Indicates whether this platform supports the stack walking functions
defined in the "RTStack" interface. *)
TYPE FrameInfo = RECORD pc, sp: ADDRESS END;
END RTMachine.