source: GTP/trunk/Lib/Geom/shared/GTGeometry/src/libs/ntl/uppalloc.cpp @ 1526

////////////////////////////////////////////////////////////////////////////////
// NTL Nonstandard Template Library for C++
// Copyright (c) 2003 by Miroslav Fidler, Tomas Rylek
//
// Created by Miroslav Fidler, Tomas Rylek, cxl@volny.cz
//
// Permission to use, copy, modify, distribute and sell this software for any 
//     purpose is hereby granted without fee, provided that the above copyright 
//     notice appear in all copies and that both that copyright notice and this 
//     permission notice appear in supporting documentation.
// The author makes no representations about the suitability of this software 
//     for any purpose. It is provided "as is" 
//     without express or implied warranty.
////////////////////////////////////////////////////////////////////////////////

#include <stddef.h>
#include <malloc.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>

#define LLOG(x)
#define LTIMING(x)
#define ASSERT(x) assert(x)

namespace upp
{

typedef unsigned char  byte;
typedef unsigned short word;
typedef unsigned int   dword;

struct BlockInfo {
        BlockInfo *link;
};

struct PageLink {
        PageLink  *bucket_next;
        PageLink  *bucket_prev;
        PageLink  *free_next;
        PageLink  *free_prev;

        void LinkSelf() {
                bucket_next = bucket_prev = free_next = free_prev = this;
        }
        void UnlinkBucket() {
                bucket_prev->bucket_next = bucket_next;
                bucket_next->bucket_prev = bucket_prev;
                bucket_next = bucket_prev = this;
        }
        void InsertBucket(PageLink *lnk) {
                lnk->bucket_prev = this;
                lnk->bucket_next = bucket_next;
                bucket_next->bucket_prev = lnk;
                bucket_next = lnk;
        }
        void UnlinkFree() {
                free_prev->free_next = free_next;
                free_next->free_prev = free_prev;
                free_next = free_prev = this;
        }
        void InsertFree(PageLink *lnk) {
                lnk->free_prev = this;
                lnk->free_next = free_next;
                free_next->free_prev = lnk;
                free_next = lnk;
        }
};

struct PageInfo : public PageLink {
        BlockInfo *freelist;
        byte      *memory;
        word       freecount;
        word       blockcount;
        word       magnitude;
        word       size;
        
        void Format(int m) {
                LTIMING("Format");
                ASSERT(m >= 0 && m <= 128);
                magnitude = word(m);
                size = word(4 * m);
                byte *p = memory;
                byte *e = memory + 2048 - size;
                blockcount = 0;
                freelist = NULL;
                while(p <= e) {
                        ((BlockInfo *)p)->link = freelist;
                        freelist = (BlockInfo *)p;
                        p += size;
                        blockcount++;
                }
                freecount = blockcount;
        }
};


typedef PageInfo *MemBook[512];

MemBook  nullbook[1];
MemBook *memmap[2048];

PageInfo *NewPage()
{
        LTIMING("NewPage");
        LLOG("Acquiring new page");
        static int ci = 32;
        static PageInfo *chunk;
        if(ci >= 32) {
                LLOG("**** Acquiring new 64KB block");
                dword ptr = (dword)malloc(33 * 2048);
                if(!ptr) return 0;
                dword a = (ptr + 2047) & ~2047;
                if(a - ptr >= 1024)
                        chunk = (PageInfo *)ptr;
                else
                        chunk = (PageInfo *)(a + 32 * 2048);
                byte *p = (byte *)a;
                for(int i = 0; i < 32; i++) {
                        chunk[i].LinkSelf();
                        chunk[i].memory = p;
                        p += 2048;
                }
                ci = 0;
        }
        PageInfo *p = chunk + ci++;
        int pgi = ((dword)p->memory >> 11);
        int bi = pgi >> 9;
        pgi &= 511;
        if(memmap[bi] == nullbook) {
                memmap[bi] = (MemBook *)malloc(sizeof(MemBook));
                memset(memmap[bi], 0, sizeof(MemBook));
        }
        (*memmap[bi])[pgi] = p;
        return p;
}


#define InitLink2(a, n)         { a + n, a + n, a + n, a + n }, \
                                { a + n + 1, a + n + 1, a + n + 1, a + n + 1 }
#define InitLink4(a, n)         InitLink2(a, n),   InitLink2(a,   n + 2)
#define InitLink8(a, n)         InitLink4(a, n),   InitLink4(a,   n + 4)
#define InitLink16(a, n)        InitLink8(a, n),   InitLink8(a,   n + 8)
#define InitLink32(a, n)        InitLink16(a, n),  InitLink16(a,  n + 16)
#define InitLink64(a, n)        InitLink32(a, n),  InitLink32(a,  n + 32)

PageLink bucket[129] = {
        InitLink64(bucket, 0),
        InitLink64(bucket, 64),
        { bucket + 128, bucket + 128, bucket + 128, bucket + 128 }
};

PageLink free_bucket[129] = {
        InitLink64(free_bucket, 0),
        InitLink64(free_bucket, 64),
        { free_bucket + 128, free_bucket + 128, free_bucket + 128, free_bucket + 128 }
};

PageLink emptylist[1] = {
        { emptylist, emptylist, emptylist, emptylist }
};

byte size_magnitude[513];


void GenerateMagnitudeTable(int *s)
{
        int size = 0;
        int magnitude = *s / 4;
        while(size <= 512) {
                ASSERT(*s);
                if(size > *s) {
                        s++;
                        magnitude = *s / 4;
                }
                size_magnitude[size] = byte(magnitude);
                size++;
        }
        ASSERT(*s == 512);
}


void *Alloc(size_t size)
{
        LTIMING("Alloc");
        LLOG("Alloc(" << size << ")");
        if(size <= 512) {
                int m = size_magnitude[size];
                PageLink& bm = bucket[m];
                PageInfo *page = (PageInfo *)bm.bucket_next;
                BlockInfo *q;
                if(page != &bm) {
                        ASSERT(page->freecount > 0 && page->freecount < page->blockcount);
                        LLOG("Allocating from page " << Dump(page));
                        q = page->freelist;
                        page->freelist = q->link;
                        if(--page->freecount == 0) {
                                LLOG("Page exhausted " << Dump(page));
                                page->UnlinkBucket();
                        }
                        return q;
                }
                page = (PageInfo *)free_bucket[m].bucket_next;  
                if(page != &free_bucket[m]) {
                        LLOG("Next empty bucket page " << Dump(page));
                        ASSERT(page->freecount == page->blockcount);
                        page->UnlinkFree();
                        page->UnlinkBucket();
                        bm.InsertBucket(page);
                        q = page->freelist;
                        page->freelist = q->link;
                        if(--page->freecount == 0)
                                page->UnlinkBucket();
                        return q;
                }
                page = (PageInfo *)emptylist->free_next;
                if(page != emptylist) {
                        ASSERT(page->freecount == page->blockcount);
                        LLOG("Recycling page " << Dump(page));
                        page->UnlinkFree();
                        page->UnlinkBucket();
                }
                else {
                        static bool init;
                        if(!init) {
                                init = true;
                                static int mtable1[] = { 4, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112,
                                                     128, 144, 168, 200, 256, 336, 408, 512 };
                                GenerateMagnitudeTable(mtable1);
                                for(int i = 0; i < 2048; i++)
                                        memmap[i] = nullbook;
                                m = size_magnitude[size];
                        }
                        page = NewPage();
                        if (page == 0) return 0;

                }
                page->Format(m);
                LLOG("Formated page " << Dump(page));
                bucket[m].InsertBucket(page);
                q = page->freelist;
                page->freelist = q->link;
                page->freecount--;
                return q;
        }
        void *q = malloc(size);
        return q;
}


void Free(void *ptr)
{
        int pgi = ((dword)ptr >> 11);
        PageInfo *page = (*memmap[pgi >> 9])[pgi & 511];
        if(page) {
                ASSERT(((dword)ptr & 2047) % page->size == 0);
                BlockInfo *b = (BlockInfo *)ptr;
                b->link = page->freelist;
                page->freelist = b;
                if(page->bucket_next == page) {
                        LLOG("Putting to bucket " << Dump(page));
                        bucket[page->magnitude].InsertBucket(page);
                }
                LLOG("Freeing in page " << Dump(page));
                if(++page->freecount == page->blockcount) {
                        page->UnlinkBucket();
                        free_bucket[page->magnitude].InsertBucket(page);
                        emptylist->InsertFree(page);
                        LLOG("Moving to empty " << Dump(page));
                }
                ASSERT(page->freecount <= page->blockcount);
        }
        else
                free(ptr);
}

}//namespace upp

#undef LLOG
#undef LTIMING