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#ifndef YALLOC_INTERNALS_H
#define YALLOC_INTERNALS_H
#include <stdint.h>
typedef struct
{
uint32_t prev; // low bit set if free
uint32_t next; // for used blocks: low bit set if unused header at the end
/* We need user data to be 32-byte aligned, so the header needs
* to be 32 bytes in size (as user data follows the header) */
uint8_t padding[32 - (sizeof(uint32_t) * 2)];
} Header;
// NOTE: We have 32bit aligned data and 16bit offsets where the lowest bit is used as flag. So we remove the low bit and shift by 1 to address 128k bytes with the 15bit significant offset bits.
#define NIL 0xFFFFFFFEu
// return Header-address for a prev/next
#define HDR_PTR(offset) ((Header*)((char*)pool + (((offset) & NIL)<<1)))
// return a prev/next for a Header-address
#define HDR_OFFSET(blockPtr) ((uint32_t)(((char*)blockPtr - (char*)pool) >> 1))
#ifndef YALLOC_INTERNAL_VALIDATE
# ifdef NDEBUG
# define YALLOC_INTERNAL_VALIDATE 0
# else
# define YALLOC_INTERNAL_VALIDATE 1
#endif
#endif
/*
internal_assert() is used in some places to check internal expections.
Activate this if you modify the code to detect problems as early as possible.
In other cases this should be deactivated.
*/
#if 0
#define internal_assert assert
#else
#define internal_assert(condition)((void) 0)
#endif
// detects offsets that point nowhere
static inline int isNil(uint32_t offset)
{
return (offset | 1) == 0xFFFFFFFF;
}
static inline int isFree(Header * hdr)
{
return hdr->prev & 1;
}
static inline int isPadded(Header * hdr)
{
return hdr->next & 1;
}
#endif // YALLOC_INTERNALS_H
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