buddy.h

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#pragma once
 
#include <datatypes/array.h>
#include <datatypes/bitmap.h>
 
#include <assert.h>
#include <stddef.h>
#include <stdint.h>
 
#define B_TOTAL_EXP 17U
#define B_BLOCK_EXP 6U
#define B_LOG_INCREMENTAL_THRESHOLD 0.5
#define B_LOG_FREQUENCY 50
 
struct mm_state { // todo incremental checkpoints
        dyn_array(
                struct mm_log {
                        array_count_t ref_i;
                        struct mm_checkpoint *c;
                }
        ) logs;
        uint_fast32_t used_mem;
        uint_least8_t longest[(1U << (B_TOTAL_EXP - B_BLOCK_EXP + 1))]; // last char is actually unused
        unsigned char base_mem[1U << B_TOTAL_EXP];
#ifdef ROOTSIM_INCREMENTAL
        uint_fast32_t dirty_mem;
        block_bitmap dirty[
                bitmap_required_size(
                // this tracks writes to the allocation tree
                        (1 << (B_TOTAL_EXP - 2 * B_BLOCK_EXP + 1)) +
                // while this tracks writes to the actual memory buffer
                        (1 << (B_TOTAL_EXP - B_BLOCK_EXP))
 
                )
        ];
#endif
};
 
struct mm_checkpoint { // todo only log longest[] if changed, or incrementally
#ifdef ROOTSIM_INCREMENTAL
        bool is_incremental;
        block_bitmap dirty [
                bitmap_required_size(
                // this tracks writes to the allocation tree
                        (1 << (B_TOTAL_EXP - 2 * B_BLOCK_EXP + 1)) +
                // while this tracks writes to the actual memory buffer
                        (1 << (B_TOTAL_EXP - B_BLOCK_EXP))
                )
        ];
#endif
        uint_fast32_t used_mem;
        uint_least8_t longest[(1U << (B_TOTAL_EXP - B_BLOCK_EXP + 1))];
        unsigned char base_mem[];
};
 
static_assert(
        offsetof(struct mm_state, longest) ==
        offsetof(struct mm_state, base_mem) -
        sizeof(((struct mm_state *)0)->longest),
        "longest and base_mem are not contiguous, this will break incremental checkpointing");