82 lines
1.6 KiB
C++
82 lines
1.6 KiB
C++
namespace factor
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{
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static const cell context_object_count = 10;
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enum context_object {
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OBJ_NAMESTACK,
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OBJ_CATCHSTACK,
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OBJ_CONTEXT_ID,
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};
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/* Assembly code makes assumptions about the layout of this struct */
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struct context {
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/* C stack pointer on entry */
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stack_frame *callstack_top;
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stack_frame *callstack_bottom;
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/* current datastack top pointer */
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cell datastack;
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/* current retain stack top pointer */
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cell retainstack;
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/* memory region holding current datastack */
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segment *datastack_region;
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/* memory region holding current retain stack */
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segment *retainstack_region;
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/* context-specific special objects, accessed by context-object and
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set-context-object primitives */
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cell context_objects[context_object_count];
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context *next;
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context(cell ds_size, cell rs_size);
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void reset_datastack();
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void reset_retainstack();
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void reset_context_objects();
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cell peek()
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{
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return *(cell *)datastack;
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}
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void replace(cell tagged)
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{
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*(cell *)datastack = tagged;
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}
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cell pop()
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{
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cell value = peek();
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datastack -= sizeof(cell);
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return value;
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}
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void push(cell tagged)
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{
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datastack += sizeof(cell);
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replace(tagged);
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}
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static const cell stack_reserved = (64 * sizeof(cell));
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void fix_stacks()
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{
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if(datastack + sizeof(cell) < datastack_region->start
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|| datastack + stack_reserved >= datastack_region->end)
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reset_datastack();
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if(retainstack + sizeof(cell) < retainstack_region->start
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|| retainstack + stack_reserved >= retainstack_region->end)
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reset_retainstack();
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}
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};
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VM_C_API void nest_stacks(factor_vm *vm);
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VM_C_API void unnest_stacks(factor_vm *vm);
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}
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