C++ ATB_GET_KIND函数代码示例

// force the freeing of a piece of memory
void gc_free(void *ptr_in) {
    if (gc_lock_depth > 0) {
        // TODO how to deal with this error?
        return;
    }

    mp_uint_t ptr = (mp_uint_t)ptr_in;
    DEBUG_printf("gc_free(%p)\n", ptr);

    if (VERIFY_PTR(ptr)) {
        mp_uint_t block = BLOCK_FROM_PTR(ptr);
        if (ATB_GET_KIND(block) == AT_HEAD) {
            // set the last_free pointer to this block if it's earlier in the heap
            if (block / BLOCKS_PER_ATB < gc_last_free_atb_index) {
                gc_last_free_atb_index = block / BLOCKS_PER_ATB;
            }

            // free head and all of its tail blocks
            do {
                ATB_ANY_TO_FREE(block);
                block += 1;
            } while (ATB_GET_KIND(block) == AT_TAIL);

            #if EXTENSIVE_HEAP_PROFILING
            gc_dump_alloc_table();
            #endif
        }
    }
}

// force the freeing of a piece of memory
// TODO: freeing here does not call finaliser
void gc_free(void *ptr) {
    if (MP_STATE_MEM(gc_lock_depth) > 0) {
        // TODO how to deal with this error?
        return;
    }

    DEBUG_printf("gc_free(%p)\n", ptr);

    if (VERIFY_PTR(ptr)) {
        size_t block = BLOCK_FROM_PTR(ptr);
        if (ATB_GET_KIND(block) == AT_HEAD) {
            #if MICROPY_ENABLE_FINALISER
            FTB_CLEAR(block);
            #endif
            // set the last_free pointer to this block if it's earlier in the heap
            if (block / BLOCKS_PER_ATB < MP_STATE_MEM(gc_last_free_atb_index)) {
                MP_STATE_MEM(gc_last_free_atb_index) = block / BLOCKS_PER_ATB;
            }

            // free head and all of its tail blocks
            do {
                ATB_ANY_TO_FREE(block);
                block += 1;
            } while (ATB_GET_KIND(block) == AT_TAIL);

            #if EXTENSIVE_HEAP_PROFILING
            gc_dump_alloc_table();
            #endif
        } else {
            assert(!"bad free");
        }
    } else if (ptr != NULL) {
        assert(!"bad free");
    }
}

void gc_dump_alloc_table(void) {
    mp_uint_t bl;
    static const mp_uint_t DUMP_BYTES_PER_LINE = 64;
    #if !EXTENSIVE_HEAP_PROFILING
    // When comparing heap output we don't want to print the starting
    // pointer of the heap because it changes from run to run.
    printf("GC memory layout; from %p:", gc_pool_start);
    #endif
    for (bl = 0; bl < gc_alloc_table_byte_len * BLOCKS_PER_ATB; bl++) {
        if (bl % DUMP_BYTES_PER_LINE == 0) {
            // a new line of blocks
            #if EXTENSIVE_HEAP_PROFILING
            {
                // check if this line contains only free blocks
                bool only_free_blocks = true;
                for (mp_uint_t bl2 = bl; bl2 < gc_alloc_table_byte_len * BLOCKS_PER_ATB && bl2 < bl + DUMP_BYTES_PER_LINE; bl2++) {
                    if (ATB_GET_KIND(bl2) != AT_FREE) {

                        only_free_blocks = false;
                        break;
                    }
                }
                if (only_free_blocks) {
                    // line contains only free blocks, so skip printing it
                    bl += DUMP_BYTES_PER_LINE - 1;
                    continue;
                }
            }
            #endif
            // print header for new line of blocks
            printf("\n%04x: ", (uint)bl);
        }
        int c = ' ';
        switch (ATB_GET_KIND(bl)) {
            case AT_FREE: c = '.'; break;
            case AT_HEAD: c = 'h'; break;
            /* this prints the uPy object type of the head block
            case AT_HEAD: {
                mp_uint_t *ptr = gc_pool_start + bl * WORDS_PER_BLOCK;
                if (*ptr == (mp_uint_t)&mp_type_tuple) { c = 'T'; }
                else if (*ptr == (mp_uint_t)&mp_type_list) { c = 'L'; }
                else if (*ptr == (mp_uint_t)&mp_type_dict) { c = 'D'; }
                else if (*ptr == (mp_uint_t)&mp_type_float) { c = 'F'; }
                else if (*ptr == (mp_uint_t)&mp_type_fun_bc) { c = 'B'; }
                else { c = 'h'; }
                break;
            }
            */
            case AT_TAIL: c = 't'; break;
            case AT_MARK: c = 'm'; break;
        }
        printf("%c", c);
    }
    printf("\n");
}

// force the freeing of a piece of memory
void gc_free(void *ptr_in) {
    machine_uint_t ptr = (machine_uint_t)ptr_in;

    if (VERIFY_PTR(ptr)) {
        machine_uint_t block = BLOCK_FROM_PTR(ptr);
        if (ATB_GET_KIND(block) == AT_HEAD) {
            // free head and all of its tail blocks
            do {
                ATB_ANY_TO_FREE(block);
                block += 1;
            } while (ATB_GET_KIND(block) == AT_TAIL);
        }
    }
}

size_t gc_nbytes(const void *ptr) {
    if (VERIFY_PTR(ptr)) {
        size_t block = BLOCK_FROM_PTR(ptr);
        if (ATB_GET_KIND(block) == AT_HEAD) {
            // work out number of consecutive blocks in the chain starting with this on
            size_t n_blocks = 0;
            do {
                n_blocks += 1;
            } while (ATB_GET_KIND(block + n_blocks) == AT_TAIL);
            return n_blocks * BYTES_PER_BLOCK;
        }
    }

    // invalid pointer
    return 0;
}

void gc_dump_alloc_table(void) {
    printf("GC memory layout; from %p:", gc_pool_start);
    for (machine_uint_t bl = 0; bl < gc_alloc_table_byte_len * BLOCKS_PER_ATB; bl++) {
        if (bl % 64 == 0) {
            printf("\n%04x: ", (uint)bl);
        }
        int c = ' ';
        switch (ATB_GET_KIND(bl)) {
            case AT_FREE: c = '.'; break;
            case AT_HEAD: c = 'h'; break;
            /* this prints the uPy object type of the head block
            case AT_HEAD: {
                machine_uint_t *ptr = gc_pool_start + bl * WORDS_PER_BLOCK;
                if (*ptr == (machine_uint_t)&mp_type_tuple) { c = 'T'; }
                else if (*ptr == (machine_uint_t)&mp_type_list) { c = 'L'; }
                else if (*ptr == (machine_uint_t)&mp_type_dict) { c = 'D'; }
                else if (*ptr == (machine_uint_t)&mp_type_float) { c = 'F'; }
                else if (*ptr == (machine_uint_t)&mp_type_fun_bc) { c = 'B'; }
                else { c = 'h'; }
                break;
            }
            */
            case AT_TAIL: c = 't'; break;
            case AT_MARK: c = 'm'; break;
        }
        printf("%c", c);
    }
    printf("\n");
}

// force the freeing of a piece of memory
void gc_free(void *ptr_in) {
    if (gc_lock_depth > 0) {
        // TODO how to deal with this error?
        return;
    }

    machine_uint_t ptr = (machine_uint_t)ptr_in;

    if (VERIFY_PTR(ptr)) {
        machine_uint_t block = BLOCK_FROM_PTR(ptr);
        if (ATB_GET_KIND(block) == AT_HEAD) {
            // free head and all of its tail blocks
            do {
                ATB_ANY_TO_FREE(block);
                block += 1;
            } while (ATB_GET_KIND(block) == AT_TAIL);
        }
    }
}

STATIC void gc_sweep(void) {
    #if MICROPY_PY_GC_COLLECT_RETVAL
    MP_STATE_MEM(gc_collected) = 0;
    #endif
    // free unmarked heads and their tails
    int free_tail = 0;
    for (size_t block = 0; block < MP_STATE_MEM(gc_alloc_table_byte_len) * BLOCKS_PER_ATB; block++) {
        switch (ATB_GET_KIND(block)) {
            case AT_HEAD:
#if MICROPY_ENABLE_FINALISER
                if (FTB_GET(block)) {
                    mp_obj_base_t *obj = (mp_obj_base_t*)PTR_FROM_BLOCK(block);
                    if (obj->type != NULL) {
                        // if the object has a type then see if it has a __del__ method
                        mp_obj_t dest[2];
                        mp_load_method_maybe(MP_OBJ_FROM_PTR(obj), MP_QSTR___del__, dest);
                        if (dest[0] != MP_OBJ_NULL) {
                            // load_method returned a method, execute it in a protected environment
                            #if MICROPY_ENABLE_SCHEDULER
                            mp_sched_lock();
                            #endif
                            mp_call_function_1_protected(dest[0], dest[1]);
                            #if MICROPY_ENABLE_SCHEDULER
                            mp_sched_unlock();
                            #endif
                        }
                    }
                    // clear finaliser flag
                    FTB_CLEAR(block);
                }
#endif
                free_tail = 1;
                DEBUG_printf("gc_sweep(%p)\n", PTR_FROM_BLOCK(block));
                #if MICROPY_PY_GC_COLLECT_RETVAL
                MP_STATE_MEM(gc_collected)++;
                #endif
                // fall through to free the head

            case AT_TAIL:
                if (free_tail) {
                    ATB_ANY_TO_FREE(block);
                    #if CLEAR_ON_SWEEP
                    memset((void*)PTR_FROM_BLOCK(block), 0, BYTES_PER_BLOCK);
                    #endif
                }
                break;

            case AT_MARK:
                ATB_MARK_TO_HEAD(block);
                free_tail = 0;
                break;
        }
    }
}

STATIC void gc_dump_at(void) {
    for (machine_uint_t bl = 0; bl < gc_alloc_table_byte_len * BLOCKS_PER_ATB; bl++) {
        printf("block %06u ", bl);
        switch (ATB_GET_KIND(bl)) {
            case AT_FREE: printf("FREE"); break;
            case AT_HEAD: printf("HEAD"); break;
            case AT_TAIL: printf("TAIL"); break;
            default: printf("MARK"); break;
        }
        printf("\n");
    }
}

STATIC void gc_deal_with_stack_overflow(void) {
    while (MP_STATE_MEM(gc_stack_overflow)) {
        MP_STATE_MEM(gc_stack_overflow) = 0;

        // scan entire memory looking for blocks which have been marked but not their children
        for (size_t block = 0; block < MP_STATE_MEM(gc_alloc_table_byte_len) * BLOCKS_PER_ATB; block++) {
            // trace (again) if mark bit set
            if (ATB_GET_KIND(block) == AT_MARK) {
                gc_mark_subtree(block);
            }
        }
    }
}

// Take the given block as the topmost block on the stack. Check all it's
// children: mark the unmarked child blocks and put those newly marked
// blocks on the stack. When all children have been checked, pop off the
// topmost block on the stack and repeat with that one.
STATIC void gc_mark_subtree(size_t block) {
    // Start with the block passed in the argument.
    size_t sp = 0;
    for (;;) {
        // work out number of consecutive blocks in the chain starting with this one
        size_t n_blocks = 0;
        do {
            n_blocks += 1;
        } while (ATB_GET_KIND(block + n_blocks) == AT_TAIL);

        // check this block's children
        void **ptrs = (void**)PTR_FROM_BLOCK(block);
        for (size_t i = n_blocks * BYTES_PER_BLOCK / sizeof(void*); i > 0; i--, ptrs++) {
            void *ptr = *ptrs;
            if (VERIFY_PTR(ptr)) {
                // Mark and push this pointer
                size_t childblock = BLOCK_FROM_PTR(ptr);
                if (ATB_GET_KIND(childblock) == AT_HEAD) {
                    // an unmarked head, mark it, and push it on gc stack
                    TRACE_MARK(childblock, ptr);
                    ATB_HEAD_TO_MARK(childblock);
                    if (sp < MICROPY_ALLOC_GC_STACK_SIZE) {
                        MP_STATE_MEM(gc_stack)[sp++] = childblock;
                    } else {
                        MP_STATE_MEM(gc_stack_overflow) = 1;
                    }
                }
            }
        }

        // Are there any blocks on the stack?
        if (sp == 0) {
            break; // No, stack is empty, we're done.
        }

        // pop the next block off the stack
        block = MP_STATE_MEM(gc_stack)[--sp];
    }
}

void gc_collect_root(void **ptrs, size_t len) {
    for (size_t i = 0; i < len; i++) {
        void *ptr = ptrs[i];
        if (VERIFY_PTR(ptr)) {
            size_t block = BLOCK_FROM_PTR(ptr);
            if (ATB_GET_KIND(block) == AT_HEAD) {
                // An unmarked head: mark it, and mark all its children
                TRACE_MARK(block, ptr);
                ATB_HEAD_TO_MARK(block);
                gc_mark_subtree(block);
            }
        }
    }
}

STATIC void gc_deal_with_stack_overflow(void) {
    while (gc_stack_overflow) {
        gc_stack_overflow = 0;
        gc_sp = gc_stack;

        // scan entire memory looking for blocks which have been marked but not their children
        for (machine_uint_t block = 0; block < gc_alloc_table_byte_len * BLOCKS_PER_ATB; block++) {
            // trace (again) if mark bit set
            if (ATB_GET_KIND(block) == AT_MARK) {
                *gc_sp++ = block;
                gc_drain_stack();
            }
        }
    }
}

STATIC void gc_sweep(void) {
    mp_uint_t block;
    #if MICROPY_PY_GC_COLLECT_RETVAL
    gc_collected = 0;
    #endif
    // free unmarked heads and their tails
    int free_tail = 0;
    for (block = 0; block < gc_alloc_table_byte_len * BLOCKS_PER_ATB; block++) {
        switch (ATB_GET_KIND(block)) {
            case AT_HEAD:
#if MICROPY_ENABLE_FINALISER
                if (FTB_GET(block)) {
                    mp_obj_t obj = (mp_obj_t)PTR_FROM_BLOCK(block);
                    if (((mp_obj_base_t*)obj)->type != MP_OBJ_NULL) {
                        // if the object has a type then see if it has a __del__ method
                        mp_obj_t dest[2];
                        mp_load_method_maybe(obj, MP_QSTR___del__, dest);
                        if (dest[0] != MP_OBJ_NULL) {
                            // load_method returned a method
                            mp_call_method_n_kw(0, 0, dest);
                        }
                    }
                    // clear finaliser flag
                    FTB_CLEAR(block);
                }
#endif
                free_tail = 1;
                #if MICROPY_PY_GC_COLLECT_RETVAL
                gc_collected++;
                #endif
                // fall through to free the head
                // no break - disable eclipse static analyzer warning - intentional fall through

            case AT_TAIL:
                if (free_tail) {
                    DEBUG_printf("gc_sweep(%p)\n",PTR_FROM_BLOCK(block));
                    ATB_ANY_TO_FREE(block);
                }
                break;

            case AT_MARK:
                ATB_MARK_TO_HEAD(block);
                free_tail = 0;
                break;
        }
    }
}

void gc_info(gc_info_t *info) {
    mp_uint_t block, len;
    info->total = (gc_pool_end - gc_pool_start) * sizeof(mp_uint_t);
    info->used = 0;
    info->free = 0;
    info->num_1block = 0;
    info->num_2block = 0;
    info->max_block = 0;
    for (block = 0, len = 0; block < gc_alloc_table_byte_len * BLOCKS_PER_ATB; block++) {
        mp_uint_t kind = ATB_GET_KIND(block);
        if (kind == AT_FREE || kind == AT_HEAD) {
            if (len == 1) {
                info->num_1block += 1;
            } else if (len == 2) {
                info->num_2block += 1;
            }
            if (len > info->max_block) {
                info->max_block = len;
            }
        }
        switch (kind) {
            case AT_FREE:
                info->free += 1;
                len = 0;
                break;

            case AT_HEAD:
                info->used += 1;
                len = 1;
                break;

            case AT_TAIL:
                info->used += 1;
                len += 1;
                break;

            case AT_MARK:
                // shouldn't happen
                break;
        }
    }

    info->used *= BYTES_PER_BLOCK;
    info->free *= BYTES_PER_BLOCK;
}