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https://github.com/nunuhara/xsystem4.git
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kichikuou
12ddb585fb
Delegates "weakly" reference objects, meaning that referenced objects can be deleted. Delegate invocations must not invoke on deleted objects. This is achieved as follows: * Each heap object has a sequential number. * Each delegate object is backed by a page storing (object, function, seq) triples. * Deleted objects can be detected by comparing the sequential number stored in the delegate with the sequential number of the object currently on the heap. This is consistent with the AliceSoft's implementation (presumed from the contents of resume save). This implementation removes dead objects from the delegate in DG_CALL and DG_NUMOF instructions. (We could do that more often, e.g. when an object is added to a delegate.) This breaks existing resume saves that contain delegates. For games that predate delegate support, this does not affect the save format.
98 lines
2.5 KiB
C
98 lines
2.5 KiB
C
/* Copyright (C) 2019 Nunuhara Cabbage <nunuhara@haniwa.technology>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, see <http://gnu.org/licenses/>.
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*/
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#ifndef SYSTEM4_HEAP_H
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#define SYSTEM4_HEAP_H
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#include <stdbool.h>
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#include <stddef.h>
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#include <stdint.h>
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struct string;
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struct page;
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enum vm_pointer_type {
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VM_PAGE,
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VM_STRING
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};
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#define NR_VM_POINTER_TYPES (VM_STRING+1)
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// Heap-backed objects. Reference counted.
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struct vm_pointer {
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int ref;
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uint32_t seq;
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enum vm_pointer_type type;
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union {
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struct string *s;
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struct page *page;
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};
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#ifdef DEBUG_HEAP
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size_t alloc_addr;
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size_t ref_addr[16];
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size_t ref_nr;
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size_t deref_addr[16];
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size_t deref_nr;
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size_t free_addr;
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#endif
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};
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extern struct vm_pointer *heap;
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extern size_t heap_size;
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void heap_init(void);
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void heap_delete(void);
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void heap_grow(size_t new_size);
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int32_t heap_alloc_slot(enum vm_pointer_type type);
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void heap_ref(int slot);
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void heap_unref(int slot);
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void exit_unref(int slot);
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uint32_t heap_get_seq(int slot);
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bool heap_index_valid(int index);
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bool page_index_valid(int index);
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bool string_index_valid(int index);
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struct page *heap_get_page(int index);
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struct page *heap_get_delegate_page(int index);
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struct string *heap_get_string(int index);
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void heap_set_page(int slot, struct page *page);
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void heap_string_assign(int slot, struct string *string);
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void heap_struct_assign(int lval, int rval);
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int32_t heap_alloc_page(struct page *page);
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int32_t heap_alloc_string(struct string *s);
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void heap_describe_slot(int slot);
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/*
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* Guarantee `headroom` free slots are available on the heap.
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*
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* XXX: this is a hack to fix an issue with HLL calls where a pointer into the
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* heap can be made invalid by a heap reallocation triggered within the
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* body of the HLL function.
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*/
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void heap_guarantee(unsigned headroom);
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#ifdef VM_PRIVATE
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extern uint32_t heap_next_seq;
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extern int32_t *heap_free_stack;
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extern size_t heap_free_ptr;
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#endif /* VM_PRIVATE */
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#endif /* SYSTEM4_HEAP_H */
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