42 lines
1.2 KiB
C
42 lines
1.2 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <stdint.h>
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#include "../lib/mem.h"
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typedef struct {
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int a;
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int b;
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int ref_count;
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uint8_t data[0];
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} test_struct;
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int main() {
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test_struct* entry = u_malloc(sizeof(test_struct) + 100);
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entry->a = 1;
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entry->b = 2;
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entry->ref_count = 3;
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void* data_ptr = entry->data; // or (void*)(entry + 1)
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printf("entry pointer: %p\n", entry);
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printf("data pointer: %p\n", data_ptr);
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printf("sizeof(test_struct): %zu\n", sizeof(test_struct));
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printf("difference in bytes: %ld\n", (char*)data_ptr - (char*)entry);
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// Test different ways to convert back
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test_struct* back1 = (test_struct*)((char*)data_ptr - sizeof(test_struct));
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test_struct* back2 = (test_struct*)data_ptr - 1;
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test_struct* back3 = (test_struct*)data_ptr - 0;
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printf("back1 (char* subtraction): %p\n", back1);
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printf("back2 (pointer - 1): %p\n", back2);
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printf("back3 (pointer - 0): %p\n", back3);
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printf("back1 ref_count: %d\n", back1->ref_count);
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printf("back2 ref_count: %d\n", back2->ref_count);
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printf("back3 ref_count: %d\n", back3->ref_count);
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u_free(entry);
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return 0;
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}
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