60 lines
1.4 KiB
C
60 lines
1.4 KiB
C
#ifndef YALLOC_INTERNALS_H
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#define YALLOC_INTERNALS_H
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#include <stdint.h>
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typedef struct
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{
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uint16_t prev; // low bit set if free
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uint16_t next; // for used blocks: low bit set if unused header at the end
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} Header;
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// 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.
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#define NIL 0xFFFEu
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// return Header-address for a prev/next
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#define HDR_PTR(offset) ((Header*)((char*)pool + (((offset) & NIL)<<1)))
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// return a prev/next for a Header-address
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#define HDR_OFFSET(blockPtr) ((uint16_t)(((char*)blockPtr - (char*)pool) >> 1))
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#ifndef YALLOC_INTERNAL_VALIDATE
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# ifdef NDEBUG
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# define YALLOC_INTERNAL_VALIDATE 0
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# else
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# define YALLOC_INTERNAL_VALIDATE 1
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#endif
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#endif
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/*
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internal_assert() is used in some places to check internal expections.
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Activate this if you modify the code to detect problems as early as possible.
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In other cases this should be deactivated.
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*/
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#if 0
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#define internal_assert assert
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#else
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#define internal_assert(condition)((void) 0)
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#endif
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// detects offsets that point nowhere
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static inline int isNil(uint16_t offset)
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{
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return (offset | 1) == 0xFFFF;
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}
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static inline int isFree(Header * hdr)
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{
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return hdr->prev & 1;
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}
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static inline int isPadded(Header * hdr)
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{
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return hdr->next & 1;
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}
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#endif // YALLOC_INTERNALS_H
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