зеркало из https://github.com/mozilla/gecko-dev.git
262 строки
9.4 KiB
C++
262 строки
9.4 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* ***** BEGIN LICENSE BLOCK *****
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* Version: NPL 1.1/GPL 2.0/LGPL 2.1
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*
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* The contents of this file are subject to the Netscape Public License
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* Version 1.1 (the "License"); you may not use this file except in
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* compliance with the License. You may obtain a copy of the License at
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* http://www.mozilla.org/NPL/
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*
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* Software distributed under the License is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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* for the specific language governing rights and limitations under the
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* License.
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*
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* The Original Code is Mozilla Communicator client code.
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*
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* The Initial Developer of the Original Code is
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* Netscape Communications Corporation.
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* Portions created by the Initial Developer are Copyright (C) 2001
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* the Initial Developer. All Rights Reserved.
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*
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* Contributor(s):
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* Brian Stell <bstell@netscape.com>
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*
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*
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* Alternatively, the contents of this file may be used under the terms of
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* either the GNU General Public License Version 2 or later (the "GPL"), or
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* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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* in which case the provisions of the GPL or the LGPL are applicable instead
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* of those above. If you wish to allow use of your version of this file only
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* under the terms of either the GPL or the LGPL, and not to allow others to
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* use your version of this file under the terms of the NPL, indicate your
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* decision by deleting the provisions above and replace them with the notice
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* and other provisions required by the GPL or the LGPL. If you do not delete
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* the provisions above, a recipient may use your version of this file under
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* the terms of any one of the NPL, the GPL or the LGPL.
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*
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* ***** END LICENSE BLOCK ***** */
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#ifndef NSCOMPRESSEDCHARMAP_H
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#define NSCOMPRESSEDCHARMAP_H
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#include "prtypes.h"
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#define ALU_SIZE PR_BITS_PER_LONG
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//#define ALU_SIZE 16
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//#define ALU_SIZE 32
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//#define ALU_SIZE 64
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#if (ALU_SIZE==32)
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# define ALU_TYPE PRUint32
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# define CCMAP_POW2(n) (1L<<(n))
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# define CCMAP_BITS_PER_ALU_LOG2 5
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#elif (ALU_SIZE==64)
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# define ALU_TYPE PRUint64
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# define CCMAP_POW2(n) (1LL<<(n))
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# define CCMAP_BITS_PER_ALU_LOG2 6
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#else
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# define ALU_TYPE PRUint16
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# define CCMAP_POW2(n) (1<<(n))
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# define CCMAP_BITS_PER_ALU_LOG2 4
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#endif
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class nsICharRepresentable;
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extern PRUint16* MapToCCMap(PRUint32* aMap);
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extern PRUint16* MapperToCCMap(nsICharRepresentable *aMapper);
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extern void FreeCCMap(PRUint16* &aMap);
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//
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// nsCompressedCharMap
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//
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// A Compressed Char Map (CCMap) saves memory by folding all
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// the empty portions of the map on top of each other.
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//
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// Building a Compressed Char Map (CCMap) is more complex than
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// accessing it. We use the nsCompressedCharMap object to
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// build the CCMap. Once nsCompressedCharMap has built the CCMap
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// we get a copy of the CCMap and discard the nsCompressedCharMap
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// object. The CCMap is an array of PRUint16 and is accessed by
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// a macro.
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//
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// See "Character Map Compression" below for a discussion of
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// what the array looks like.
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//
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// The maximum size a CCMap:
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// (16 upper pointers) + (16 empty mid pointers) +
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// (16 empty page) + (16*16 max mid pointers) +
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// (256*16 max pages) = 4400 PRUint16
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#define CCMAP_MAX_LEN (16+16+16+256+4096)
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class nsCompressedCharMap {
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public:
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nsCompressedCharMap();
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PRUint16* NewCCMap();
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void FreeCCMap(PRUint16*);
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void SetChar(PRUint16);
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void SetChars(PRUint16*);
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void SetChars(PRUint16, ALU_TYPE*);
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void SetChars(PRUint32*);
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protected:
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PRUint16 mUsedLen; // in PRUint16
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PRUint16 mAllOnesPage;
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PRUint16 mCCMap[CCMAP_MAX_LEN];
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};
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//
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// Character Map Compression
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//
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// Each font requires its own 8k charmap. On a system with 200
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// fonts this would take: 200 * 8K = 1600K memory.
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//
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// Since most char maps are mostly empty a significant amount
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// of memory can be saved by not allocating the unused sections.
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//
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// If the map has one or more levels of indirection then the
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// the empty sections of the map can all be folded to a single
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// common empty element. In this way only the non-empty sections
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// need space. Because the empty sections actually point to a
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// common empty section every entry in the map can be valid
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// without requiring actually allocating space.
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// Some larger CJK fonts have large sections where every bit
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// is set. In the same way that the empty sections are folded
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// onto one "empty page", the sections where all bits are set are
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// folded on to one "all bits set page" .
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//
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// Break up the Unicode range bits 0x0000 - 0xFFFF
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// into 3 bit ranges:
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//
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// upper bits: bit15 - bit12
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// mid bits: bit11 - bit8
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// page bits: bit7 - bit0
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//
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// within a page, (assumming a 4 byte ALU)
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// bits 7-5 select one of the 8 longs
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// bits 4-0 select one of the 32 bits within the long
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//
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// There is exactly one upper "pointers" array.
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//
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// The upper pointers each point to a mid array. If there are no chars
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// in an upper pointer's block that pointer points to the empty mid.
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// Thus all upper pointers are "valid" even if they do not have space
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// allocated; eg: the accessor macro does not need to test if the
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// pointer is zero.
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//
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// Each mid pointer in the mid array points to a page. If there are no
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// chars in a mid pointer's page that pointer points to the empty page.
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// Thus all mid pointers are "valid" even if they do not have space
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// allocated; eg: the accessor macro does not need to test if the
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// pointer is zero.
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//
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// Since the array will be less than 5K PRUint16 the "pointers" can
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// be implemented as 2 byte offsets from the base instead of
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// real pointers.
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//
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// the format of the CCMap is
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// the upper pointers (16 PRUint16)
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// the empty mid pointers (16 PRUint16)
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// the empty page (16 PRUint16)
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// non-empty mid pointers and pages as needed
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// One minor note: for a completely empty map it is actually
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// possible to fold the upper, empty mid, and empty page
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// on top of each other and make a map of only 32 bytes.
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// offsets to the empty mid and empty page
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#define CCMAP_EMPTY_MID CCMAP_NUM_UPPER_POINTERS
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#define CCMAP_EMPTY_PAGE CCMAP_EMPTY_MID+CCMAP_NUM_MID_POINTERS
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//
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// Because the table is offset based the code can build the table in a
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// temp space (max table size on the stack) and then do one alloc of
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// the actual needed size and simply copy over the data.
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//
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//
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// Page bits
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//
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#define CCMAP_BITS_PER_PAGE_LOG2 8
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#define CCMAP_BITS_PER_PAGE CCMAP_POW2(CCMAP_BITS_PER_PAGE_LOG2)
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#define CCMAP_BIT_INDEX(c) ((c) & PR_BITMASK(CCMAP_BITS_PER_ALU_LOG2))
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#define CCMAP_ALU_INDEX(c) (((c)>>CCMAP_BITS_PER_ALU_LOG2) \
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& PR_BITMASK(CCMAP_BITS_PER_PAGE_LOG2 - CCMAP_BITS_PER_ALU_LOG2))
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#define CCMAP_PAGE_MASK PR_BITMASK(CCMAP_BITS_PER_PAGE_LOG2)
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#define CCMAP_NUM_PRUINT16S_PER_PAGE \
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(CCMAP_BITS_PER_PAGE/CCMAP_BITS_PER_PRUINT16)
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// one bit per char
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#define CCMAP_NUM_ALUS_PER_PAGE (CCMAP_BITS_PER_PAGE/CCMAP_BITS_PER_ALU)
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#define CCMAP_NUM_UCHARS_PER_PAGE CCMAP_BITS_PER_PAGE
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//
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// Mid bits
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//
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#define CCMAP_BITS_PER_MID_LOG2 4
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#define CCMAP_MID_INDEX(c) \
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(((c)>>CCMAP_BITS_PER_PAGE_LOG2) & PR_BITMASK(CCMAP_BITS_PER_MID_LOG2))
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#define CCMAP_NUM_MID_POINTERS CCMAP_POW2(CCMAP_BITS_PER_MID_LOG2)
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#define CCMAP_NUM_UCHARS_PER_MID \
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CCMAP_POW2(CCMAP_BITS_PER_MID_LOG2+CCMAP_BITS_PER_PAGE_LOG2)
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//
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// Upper bits
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//
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#define CCMAP_BITS_PER_UPPER_LOG2 4
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#define CCMAP_UPPER_INDEX(c) \
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(((c)>>(CCMAP_BITS_PER_MID_LOG2+CCMAP_BITS_PER_PAGE_LOG2)) \
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& PR_BITMASK(CCMAP_BITS_PER_UPPER_LOG2))
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#define CCMAP_NUM_UPPER_POINTERS CCMAP_POW2(CCMAP_BITS_PER_UPPER_LOG2)
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//
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// Misc
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//
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#define CCMAP_BITS_PER_PRUINT16_LOG2 4
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#define CCMAP_BITS_PER_PRUINT32_LOG2 5
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#define CCMAP_BITS_PER_PRUINT16 CCMAP_POW2(CCMAP_BITS_PER_PRUINT16_LOG2)
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#define CCMAP_BITS_PER_PRUINT32 CCMAP_POW2(CCMAP_BITS_PER_PRUINT32_LOG2)
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#define CCMAP_BITS_PER_ALU CCMAP_POW2(CCMAP_BITS_PER_ALU_LOG2)
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#define CCMAP_ALUS_PER_PRUINT32 (CCMAP_BITS_PER_PRUINT32/CCMAP_BITS_PER_ALU)
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#define CCMAP_PRUINT32S_PER_ALU (CCMAP_BITS_PER_ALU/CCMAP_BITS_PER_PRUINT32)
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#define CCMAP_PRUINT32S_PER_PAGE (CCMAP_BITS_PER_PAGE/CCMAP_BITS_PER_PRUINT32)
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#define CCMAP_ALU_MASK PR_BITMASK(CCMAP_BITS_PER_ALU)
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#define CCMAP_ALUS_PER_PAGE CCMAP_POW2(CCMAP_BITS_PER_PAGE_LOG2 \
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- CCMAP_BITS_PER_ALU_LOG2)
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#define NUM_UNICODE_CHARS CCMAP_POW2(CCMAP_BITS_PER_UPPER_LOG2 \
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+CCMAP_BITS_PER_MID_LOG2 \
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+CCMAP_BITS_PER_PAGE_LOG2)
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#define CCMAP_TOTAL_PAGES CCMAP_POW2(CCMAP_BITS_PER_UPPER_LOG2 \
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+CCMAP_BITS_PER_MID_LOG2)
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//
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// Finally, build up the macro to test the bit for a given char
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//
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// offset from base to mid array
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#define CCMAP_TO_MID(m,c) ((m)[CCMAP_UPPER_INDEX(c)])
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// offset from base to page
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#define CCMAP_TO_PAGE(m,c) ((m)[CCMAP_TO_MID((m),(c)) + CCMAP_MID_INDEX(c)])
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// offset from base to alu
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#define CCMAP_TO_ALU(m,c) \
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(*((ALU_TYPE*)(&((m)[CCMAP_TO_PAGE((m),(c))])) + CCMAP_ALU_INDEX(c)))
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// test the bit
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#define CCMAP_HAS_CHAR(m,c) (((CCMAP_TO_ALU(m,c))>>CCMAP_BIT_INDEX(c)) & 1)
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// unset the bit
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#define CCMAP_UNSET_CHAR(m,c) (CCMAP_TO_ALU(m,c) &= ~(CCMAP_POW2(CCMAP_BIT_INDEX(c))))
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#endif // NSCOMPRESSEDCHARMAP_H
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