#include <stdlib.h>
#include <string.h>
#include "memoryPool.h"

/* ストア */
typedef struct _store* store;
struct _store {
	store next;	/* 次ストア */
	void* data;	/* データ */
};

/* プールハンドル */
struct _poolHandle {
	long providableByte;	/* 提供可能なサイズ */
	void* candi;	/* 提供候補 */
	store first;
	store last;
};


poolHandle memoryPool_Create() {
	void* p = NULL;
	p = malloc( sizeof( struct _poolHandle ) );
	if( p ) {
		memset( p, 0x00, sizeof( struct _poolHandle ) );
	}
	return p;
}


void* memoryPool_Alloc( poolHandle handle, long byte ) {
	if( !handle || byte == 0 ) {
		return NULL;
	}
	if( ALLOC_BYTE < byte ) {
		return NULL;
	}

	if( byte <= handle->providableByte ) {
		/* 提供可能 */
		handle->providableByte -= byte;
		void* ret = handle->candi;
		(long)handle->candi += byte + 1;
		return ret;
	}
	else {
		/* 提供不可 */
		store s = ( store )malloc( sizeof( struct _store ) );
		if( !s ) {
			return NULL;
		}
		memset( s, 0x00, sizeof( struct _store ) );
		s->data = malloc( ALLOC_BYTE );
		if( !( s->data ) ) {
			return NULL;
		}
		memset( s->data, 0x00, ALLOC_BYTE );

		if( !( handle->first ) ) {
			/* 既存ストア無し */
			handle->first = handle->last = s;
		}
		else {
			/* 既存ストアあり */
			handle->last->next = s;
			handle->last = s;
		}

		handle->providableByte = ALLOC_BYTE - byte;
		//void* ret = handle->candi;
		handle->candi = (long)s->data + byte + 1;
		return ( long )s->data;
	}
}


void memoryPool_Release( poolHandle handle ) {
	if( !handle ) {
		return;
	}

	store s = handle->first;
	if( !s ) return;

	do {
		store t = s;
		s = s->next;

		free( t->data );
		free( t );
	} while( s );

	free( handle );
}