The Tor Browser: intl/icu/source/common/ubidiln.c@129ffea94266 (annotated)

intl/icu/source/common/ubidiln.c@129ffea94266 (annotated)

intl/icu/source/common/ubidiln.c

Sat, 03 Jan 2015 20:18:00 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Sat, 03 Jan 2015 20:18:00 +0100
branch: TOR_BUG_3246
changeset 7: 129ffea94266
permissions: -rw-r--r--

Conditionally enable double key logic according to:
private browsing mode or privacy.thirdparty.isolate preference and
implement in GetCookieStringCommon and FindCookie where it counts...
With some reservations of how to convince FindCookie users to test
condition and pass a nullptr when disabling double key logic.

 /*
 ******************************************************************************
 *
 *   Copyright (C) 1999-2013, International Business Machines
 *   Corporation and others.  All Rights Reserved.
 *
 ******************************************************************************
 *   file name:  ubidiln.c
 *   encoding:   US-ASCII
 *   tab size:   8 (not used)
 *   indentation:4
 *
 *   created on: 1999aug06
 *   created by: Markus W. Scherer, updated by Matitiahu Allouche
 */
 #include "cmemory.h"
 #include "unicode/utypes.h"
 #include "unicode/ustring.h"
 #include "unicode/uchar.h"
 #include "unicode/ubidi.h"
 #include "ubidiimp.h"
 #include "uassert.h"
 #ifndef U_COMMON_IMPLEMENTATION
 #error U_COMMON_IMPLEMENTATION not set - must be set for all ICU source files in common/ - see http://userguide.icu-project.org/howtouseicu
 #endif
 /*
  * General remarks about the functions in this file:
  *
  * These functions deal with the aspects of potentially mixed-directional
  * text in a single paragraph or in a line of a single paragraph
  * which has already been processed according to
  * the Unicode 6.3 BiDi algorithm as defined in
  * http://www.unicode.org/unicode/reports/tr9/ , version 28,
  * also described in The Unicode Standard, Version 6.3.0 .
  *
  * This means that there is a UBiDi object with a levels
  * and a dirProps array.
  * paraLevel and direction are also set.
  * Only if the length of the text is zero, then levels==dirProps==NULL.
  *
  * The overall directionality of the paragraph
  * or line is used to bypass the reordering steps if possible.
  * Even purely RTL text does not need reordering there because
  * the ubidi_getLogical/VisualIndex() functions can compute the
  * index on the fly in such a case.
  *
  * The implementation of the access to same-level-runs and of the reordering
  * do attempt to provide better performance and less memory usage compared to
  * a direct implementation of especially rule (L2) with an array of
  * one (32-bit) integer per text character.
  *
  * Here, the levels array is scanned as soon as necessary, and a vector of
  * same-level-runs is created. Reordering then is done on this vector.
  * For each run of text positions that were resolved to the same level,
  * only 8 bytes are stored: the first text position of the run and the visual
  * position behind the run after reordering.
  * One sign bit is used to hold the directionality of the run.
  * This is inefficient if there are many very short runs. If the average run
  * length is <2, then this uses more memory.
  *
  * In a further attempt to save memory, the levels array is never changed
  * after all the resolution rules (Xn, Wn, Nn, In).
  * Many functions have to consider the field trailingWSStart:
  * if it is less than length, then there is an implicit trailing run
  * at the paraLevel,
  * which is not reflected in the levels array.
  * This allows a line UBiDi object to use the same levels array as
  * its paragraph parent object.
  *
  * When a UBiDi object is created for a line of a paragraph, then the
  * paragraph's levels and dirProps arrays are reused by way of setting
  * a pointer into them, not by copying. This again saves memory and forbids to
  * change the now shared levels for (L1).
  */
 /* handle trailing WS (L1) -------------------------------------------------- */
 /*
  * setTrailingWSStart() sets the start index for a trailing
  * run of WS in the line. This is necessary because we do not modify
  * the paragraph's levels array that we just point into.
  * Using trailingWSStart is another form of performing (L1).
  *
  * To make subsequent operations easier, we also include the run
  * before the WS if it is at the paraLevel - we merge the two here.
  *
  * This function is called only from ubidi_setLine(), so pBiDi->paraLevel is
  * set correctly for the line even when contextual multiple paragraphs.
  */
 static void
 setTrailingWSStart(UBiDi *pBiDi) {
     /* pBiDi->direction!=UBIDI_MIXED */
     const DirProp *dirProps=pBiDi->dirProps;
     UBiDiLevel *levels=pBiDi->levels;
     int32_t start=pBiDi->length;
     UBiDiLevel paraLevel=pBiDi->paraLevel;
     /* If the line is terminated by a block separator, all preceding WS etc...
        are already set to paragraph level.
        Setting trailingWSStart to pBidi->length will avoid changing the
        level of B chars from 0 to paraLevel in ubidi_getLevels when
        orderParagraphsLTR==TRUE.
      */
     if(dirProps[start-1]==B) {
         pBiDi->trailingWSStart=start;   /* currently == pBiDi->length */
         return;
     }
     /* go backwards across all WS, BN, explicit codes */
     while(start>0 && DIRPROP_FLAG(PURE_DIRPROP(dirProps[start-1]))&MASK_WS) {
         --start;
     }
     /* if the WS run can be merged with the previous run then do so here */
     while(start>0 && levels[start-1]==paraLevel) {
         --start;
     }
     pBiDi->trailingWSStart=start;
 }
 /* ubidi_setLine ------------------------------------------------------------ */
 U_CAPI void U_EXPORT2
 ubidi_setLine(const UBiDi *pParaBiDi,
               int32_t start, int32_t limit,
               UBiDi *pLineBiDi,
               UErrorCode *pErrorCode) {
     int32_t length;
     /* check the argument values */
     RETURN_VOID_IF_NULL_OR_FAILING_ERRCODE(pErrorCode);
     RETURN_VOID_IF_NOT_VALID_PARA(pParaBiDi, *pErrorCode);
     RETURN_VOID_IF_BAD_RANGE(start, 0, limit, *pErrorCode);
     RETURN_VOID_IF_BAD_RANGE(limit, 0, pParaBiDi->length+1, *pErrorCode);
     if(pLineBiDi==NULL) {
         *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
         return;
     }
     if(ubidi_getParagraph(pParaBiDi, start, NULL, NULL, NULL, pErrorCode) !=
        ubidi_getParagraph(pParaBiDi, limit-1, NULL, NULL, NULL, pErrorCode)) {
         /* the line crosses a paragraph boundary */
         *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
         return;
     }
     /* set the values in pLineBiDi from its pParaBiDi parent */
     pLineBiDi->pParaBiDi=NULL;          /* mark unfinished setLine */
     pLineBiDi->text=pParaBiDi->text+start;
     length=pLineBiDi->length=limit-start;
     pLineBiDi->resultLength=pLineBiDi->originalLength=length;
     pLineBiDi->paraLevel=GET_PARALEVEL(pParaBiDi, start);
     pLineBiDi->paraCount=pParaBiDi->paraCount;
     pLineBiDi->runs=NULL;
     pLineBiDi->flags=0;
     pLineBiDi->reorderingMode=pParaBiDi->reorderingMode;
     pLineBiDi->reorderingOptions=pParaBiDi->reorderingOptions;
     pLineBiDi->controlCount=0;
     if(pParaBiDi->controlCount>0) {
         int32_t j;
         for(j=start; j<limit; j++) {
             if(IS_BIDI_CONTROL_CHAR(pParaBiDi->text[j])) {
                 pLineBiDi->controlCount++;
             }
         }
         pLineBiDi->resultLength-=pLineBiDi->controlCount;
     }
     pLineBiDi->dirProps=pParaBiDi->dirProps+start;
     pLineBiDi->levels=pParaBiDi->levels+start;
     pLineBiDi->runCount=-1;
     if(pParaBiDi->direction!=UBIDI_MIXED) {
         /* the parent is already trivial */
         pLineBiDi->direction=pParaBiDi->direction;
         /*
          * The parent's levels are all either
          * implicitly or explicitly ==paraLevel;
          * do the same here.
          */
         if(pParaBiDi->trailingWSStart<=start) {
             pLineBiDi->trailingWSStart=0;
         } else if(pParaBiDi->trailingWSStart<limit) {
             pLineBiDi->trailingWSStart=pParaBiDi->trailingWSStart-start;
         } else {
             pLineBiDi->trailingWSStart=length;
         }
     } else {
         const UBiDiLevel *levels=pLineBiDi->levels;
         int32_t i, trailingWSStart;
         UBiDiLevel level;
         setTrailingWSStart(pLineBiDi);
         trailingWSStart=pLineBiDi->trailingWSStart;
         /* recalculate pLineBiDi->direction */
         if(trailingWSStart==0) {
             /* all levels are at paraLevel */
             pLineBiDi->direction=(UBiDiDirection)(pLineBiDi->paraLevel&1);
         } else {
             /* get the level of the first character */
             level=(UBiDiLevel)(levels[0]&1);
             /* if there is anything of a different level, then the line is mixed */
             if(trailingWSStart<length && (pLineBiDi->paraLevel&1)!=level) {
                 /* the trailing WS is at paraLevel, which differs from levels[0] */
                 pLineBiDi->direction=UBIDI_MIXED;
             } else {
                 /* see if levels[1..trailingWSStart-1] have the same direction as levels[0] and paraLevel */
                 i=1;
                 for(;;) {
                     if(i==trailingWSStart) {
                         /* the direction values match those in level */
                         pLineBiDi->direction=(UBiDiDirection)level;
                         break;
                     } else if((levels[i]&1)!=level) {
                         pLineBiDi->direction=UBIDI_MIXED;
                         break;
                     }
                     ++i;
                 }
             }
         }
         switch(pLineBiDi->direction) {
         case UBIDI_LTR:
             /* make sure paraLevel is even */
             pLineBiDi->paraLevel=(UBiDiLevel)((pLineBiDi->paraLevel+1)&~1);
             /* all levels are implicitly at paraLevel (important for ubidi_getLevels()) */
             pLineBiDi->trailingWSStart=0;
             break;
         case UBIDI_RTL:
             /* make sure paraLevel is odd */
             pLineBiDi->paraLevel|=1;
             /* all levels are implicitly at paraLevel (important for ubidi_getLevels()) */
             pLineBiDi->trailingWSStart=0;
             break;
         default:
             break;
         }
     }
     pLineBiDi->pParaBiDi=pParaBiDi;     /* mark successful setLine */
     return;
 }
 U_CAPI UBiDiLevel U_EXPORT2
 ubidi_getLevelAt(const UBiDi *pBiDi, int32_t charIndex) {
     /* return paraLevel if in the trailing WS run, otherwise the real level */
     if(!IS_VALID_PARA_OR_LINE(pBiDi) || charIndex<0 || pBiDi->length<=charIndex) {
         return 0;
     } else if(pBiDi->direction!=UBIDI_MIXED || charIndex>=pBiDi->trailingWSStart) {
         return GET_PARALEVEL(pBiDi, charIndex);
     } else {
         return pBiDi->levels[charIndex];
     }
 }
 U_CAPI const UBiDiLevel * U_EXPORT2
 ubidi_getLevels(UBiDi *pBiDi, UErrorCode *pErrorCode) {
     int32_t start, length;
     RETURN_IF_NULL_OR_FAILING_ERRCODE(pErrorCode, NULL);
     RETURN_IF_NOT_VALID_PARA_OR_LINE(pBiDi, *pErrorCode, NULL);
     if((length=pBiDi->length)<=0) {
         *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
         return NULL;
     }
     if((start=pBiDi->trailingWSStart)==length) {
         /* the current levels array reflects the WS run */
         return pBiDi->levels;
     }
     /*
      * After the previous if(), we know that the levels array
      * has an implicit trailing WS run and therefore does not fully
      * reflect itself all the levels.
      * This must be a UBiDi object for a line, and
      * we need to create a new levels array.
      */
     if(getLevelsMemory(pBiDi, length)) {
         UBiDiLevel *levels=pBiDi->levelsMemory;
         if(start>0 && levels!=pBiDi->levels) {
             uprv_memcpy(levels, pBiDi->levels, start);
         }
         /* pBiDi->paraLevel is ok even if contextual multiple paragraphs,
            since pBidi is a line object                                     */
         uprv_memset(levels+start, pBiDi->paraLevel, length-start);
         /* this new levels array is set for the line and reflects the WS run */
         pBiDi->trailingWSStart=length;
         return pBiDi->levels=levels;
     } else {
         /* out of memory */
         *pErrorCode=U_MEMORY_ALLOCATION_ERROR;
         return NULL;
     }
 }
 U_CAPI void U_EXPORT2
 ubidi_getLogicalRun(const UBiDi *pBiDi, int32_t logicalPosition,
                     int32_t *pLogicalLimit, UBiDiLevel *pLevel) {
     UErrorCode errorCode;
     int32_t runCount, visualStart, logicalLimit, logicalFirst, i;
     Run iRun;
     errorCode=U_ZERO_ERROR;
     RETURN_VOID_IF_BAD_RANGE(logicalPosition, 0, pBiDi->length, errorCode);
     /* ubidi_countRuns will check VALID_PARA_OR_LINE */
     runCount=ubidi_countRuns((UBiDi *)pBiDi, &errorCode);
     if(U_FAILURE(errorCode)) {
         return;
     }
     /* this is done based on runs rather than on levels since levels have
        a special interpretation when UBIDI_REORDER_RUNS_ONLY
      */
     visualStart=logicalLimit=0;
     iRun=pBiDi->runs[0];
     for(i=0; i<runCount; i++) {
         iRun = pBiDi->runs[i];
         logicalFirst=GET_INDEX(iRun.logicalStart);
         logicalLimit=logicalFirst+iRun.visualLimit-visualStart;
         if((logicalPosition>=logicalFirst) &&
            (logicalPosition<logicalLimit)) {
             break;
         }
         visualStart = iRun.visualLimit;
     }
     if(pLogicalLimit) {
         *pLogicalLimit=logicalLimit;
     }
     if(pLevel) {
         if(pBiDi->reorderingMode==UBIDI_REORDER_RUNS_ONLY) {
             *pLevel=(UBiDiLevel)GET_ODD_BIT(iRun.logicalStart);
         }
         else if(pBiDi->direction!=UBIDI_MIXED || logicalPosition>=pBiDi->trailingWSStart) {
             *pLevel=GET_PARALEVEL(pBiDi, logicalPosition);
         } else {
         *pLevel=pBiDi->levels[logicalPosition];
         }
     }
 }
 /* runs API functions ------------------------------------------------------- */
 U_CAPI int32_t U_EXPORT2
 ubidi_countRuns(UBiDi *pBiDi, UErrorCode *pErrorCode) {
     RETURN_IF_NULL_OR_FAILING_ERRCODE(pErrorCode, -1);
     RETURN_IF_NOT_VALID_PARA_OR_LINE(pBiDi, *pErrorCode, -1);
     ubidi_getRuns(pBiDi, pErrorCode);
     if(U_FAILURE(*pErrorCode)) {
         return -1;
     }
     return pBiDi->runCount;
 }
 U_CAPI UBiDiDirection U_EXPORT2
 ubidi_getVisualRun(UBiDi *pBiDi, int32_t runIndex,
                    int32_t *pLogicalStart, int32_t *pLength)
 {
     int32_t start;
     UErrorCode errorCode = U_ZERO_ERROR;
     RETURN_IF_NOT_VALID_PARA_OR_LINE(pBiDi, errorCode, UBIDI_LTR);
     ubidi_getRuns(pBiDi, &errorCode);
     if(U_FAILURE(errorCode)) {
         return UBIDI_LTR;
     }
     RETURN_IF_BAD_RANGE(runIndex, 0, pBiDi->runCount, errorCode, UBIDI_LTR);
     start=pBiDi->runs[runIndex].logicalStart;
     if(pLogicalStart!=NULL) {
         *pLogicalStart=GET_INDEX(start);
     }
     if(pLength!=NULL) {
         if(runIndex>0) {
             *pLength=pBiDi->runs[runIndex].visualLimit-
                      pBiDi->runs[runIndex-1].visualLimit;
         } else {
             *pLength=pBiDi->runs[0].visualLimit;
         }
     }
     return (UBiDiDirection)GET_ODD_BIT(start);
 }
 /* in trivial cases there is only one trivial run; called by ubidi_getRuns() */
 static void
 getSingleRun(UBiDi *pBiDi, UBiDiLevel level) {
     /* simple, single-run case */
     pBiDi->runs=pBiDi->simpleRuns;
     pBiDi->runCount=1;
     /* fill and reorder the single run */
     pBiDi->runs[0].logicalStart=MAKE_INDEX_ODD_PAIR(0, level);
     pBiDi->runs[0].visualLimit=pBiDi->length;
     pBiDi->runs[0].insertRemove=0;
 }
 /* reorder the runs array (L2) ---------------------------------------------- */
 /*
  * Reorder the same-level runs in the runs array.
  * Here, runCount>1 and maxLevel>=minLevel>=paraLevel.
  * All the visualStart fields=logical start before reordering.
  * The "odd" bits are not set yet.
  *
  * Reordering with this data structure lends itself to some handy shortcuts:
  *
  * Since each run is moved but not modified, and since at the initial maxLevel
  * each sequence of same-level runs consists of only one run each, we
  * don't need to do anything there and can predecrement maxLevel.
  * In many simple cases, the reordering is thus done entirely in the
  * index mapping.
  * Also, reordering occurs only down to the lowest odd level that occurs,
  * which is minLevel|1. However, if the lowest level itself is odd, then
  * in the last reordering the sequence of the runs at this level or higher
  * will be all runs, and we don't need the elaborate loop to search for them.
  * This is covered by ++minLevel instead of minLevel|=1 followed
  * by an extra reorder-all after the reorder-some loop.
  * About a trailing WS run:
  * Such a run would need special treatment because its level is not
  * reflected in levels[] if this is not a paragraph object.
  * Instead, all characters from trailingWSStart on are implicitly at
  * paraLevel.
  * However, for all maxLevel>paraLevel, this run will never be reordered
  * and does not need to be taken into account. maxLevel==paraLevel is only reordered
  * if minLevel==paraLevel is odd, which is done in the extra segment.
  * This means that for the main reordering loop we don't need to consider
  * this run and can --runCount. If it is later part of the all-runs
  * reordering, then runCount is adjusted accordingly.
  */
 static void
 reorderLine(UBiDi *pBiDi, UBiDiLevel minLevel, UBiDiLevel maxLevel) {
     Run *runs, tempRun;
     UBiDiLevel *levels;
     int32_t firstRun, endRun, limitRun, runCount;
     /* nothing to do? */
     if(maxLevel<=(minLevel|1)) {
         return;
     }
     /*
      * Reorder only down to the lowest odd level
      * and reorder at an odd minLevel in a separate, simpler loop.
      * See comments above for why minLevel is always incremented.
      */
     ++minLevel;
     runs=pBiDi->runs;
     levels=pBiDi->levels;
     runCount=pBiDi->runCount;
     /* do not include the WS run at paraLevel<=old minLevel except in the simple loop */
     if(pBiDi->trailingWSStart<pBiDi->length) {
         --runCount;
     }
     while(--maxLevel>=minLevel) {
         firstRun=0;
         /* loop for all sequences of runs */
         for(;;) {
             /* look for a sequence of runs that are all at >=maxLevel */
             /* look for the first run of such a sequence */
             while(firstRun<runCount && levels[runs[firstRun].logicalStart]<maxLevel) {
                 ++firstRun;
             }
             if(firstRun>=runCount) {
                 break;  /* no more such runs */
             }
             /* look for the limit run of such a sequence (the run behind it) */
             for(limitRun=firstRun; ++limitRun<runCount && levels[runs[limitRun].logicalStart]>=maxLevel;) {}
             /* Swap the entire sequence of runs from firstRun to limitRun-1. */
             endRun=limitRun-1;
             while(firstRun<endRun) {
                 tempRun = runs[firstRun];
                 runs[firstRun]=runs[endRun];
                 runs[endRun]=tempRun;
                 ++firstRun;
                 --endRun;
             }
             if(limitRun==runCount) {
                 break;  /* no more such runs */
             } else {
                 firstRun=limitRun+1;
             }
         }
     }
     /* now do maxLevel==old minLevel (==odd!), see above */
     if(!(minLevel&1)) {
         firstRun=0;
         /* include the trailing WS run in this complete reordering */
         if(pBiDi->trailingWSStart==pBiDi->length) {
             --runCount;
         }
         /* Swap the entire sequence of all runs. (endRun==runCount) */
         while(firstRun<runCount) {
             tempRun=runs[firstRun];
             runs[firstRun]=runs[runCount];
             runs[runCount]=tempRun;
             ++firstRun;
             --runCount;
         }
     }
 }
 /* compute the runs array --------------------------------------------------- */
 static int32_t getRunFromLogicalIndex(UBiDi *pBiDi, int32_t logicalIndex, UErrorCode *pErrorCode) {
     Run *runs=pBiDi->runs;
     int32_t runCount=pBiDi->runCount, visualStart=0, i, length, logicalStart;
     for(i=0; i<runCount; i++) {
         length=runs[i].visualLimit-visualStart;
         logicalStart=GET_INDEX(runs[i].logicalStart);
         if((logicalIndex>=logicalStart) && (logicalIndex<(logicalStart+length))) {
             return i;
         }
         visualStart+=length;
     }
     /* we should never get here */
     U_ASSERT(FALSE);
     *pErrorCode = U_INVALID_STATE_ERROR;
     return 0;
 }
 /*
  * Compute the runs array from the levels array.
  * After ubidi_getRuns() returns TRUE, runCount is guaranteed to be >0
  * and the runs are reordered.
  * Odd-level runs have visualStart on their visual right edge and
  * they progress visually to the left.
  * If option UBIDI_OPTION_INSERT_MARKS is set, insertRemove will contain the
  * sum of appropriate LRM/RLM_BEFORE/AFTER flags.
  * If option UBIDI_OPTION_REMOVE_CONTROLS is set, insertRemove will contain the
  * negative number of BiDi control characters within this run.
  */
 U_CFUNC UBool
 ubidi_getRuns(UBiDi *pBiDi, UErrorCode *pErrorCode) {
     /*
      * This method returns immediately if the runs are already set. This
      * includes the case of length==0 (handled in setPara)..
      */
     if (pBiDi->runCount>=0) {
         return TRUE;
     }
     if(pBiDi->direction!=UBIDI_MIXED) {
         /* simple, single-run case - this covers length==0 */
         /* pBiDi->paraLevel is ok even for contextual multiple paragraphs */
         getSingleRun(pBiDi, pBiDi->paraLevel);
     } else /* UBIDI_MIXED, length>0 */ {
         /* mixed directionality */
         int32_t length=pBiDi->length, limit;
         UBiDiLevel *levels=pBiDi->levels;
         int32_t i, runCount;
         UBiDiLevel level=UBIDI_DEFAULT_LTR;   /* initialize with no valid level */
         /*
          * If there are WS characters at the end of the line
          * and the run preceding them has a level different from
          * paraLevel, then they will form their own run at paraLevel (L1).
          * Count them separately.
          * We need some special treatment for this in order to not
          * modify the levels array which a line UBiDi object shares
          * with its paragraph parent and its other line siblings.
          * In other words, for the trailing WS, it may be
          * levels[]!=paraLevel but we have to treat it like it were so.
          */
         limit=pBiDi->trailingWSStart;
         /* count the runs, there is at least one non-WS run, and limit>0 */
         runCount=0;
         for(i=0; i<limit; ++i) {
             /* increment runCount at the start of each run */
             if(levels[i]!=level) {
                 ++runCount;
                 level=levels[i];
             }
         }
         /*
          * We don't need to see if the last run can be merged with a trailing
          * WS run because setTrailingWSStart() would have done that.
          */
         if(runCount==1 && limit==length) {
             /* There is only one non-WS run and no trailing WS-run. */
             getSingleRun(pBiDi, levels[0]);
         } else /* runCount>1 || limit<length */ {
             /* allocate and set the runs */
             Run *runs;
             int32_t runIndex, start;
             UBiDiLevel minLevel=UBIDI_MAX_EXPLICIT_LEVEL+1, maxLevel=0;
             /* now, count a (non-mergeable) WS run */
             if(limit<length) {
                 ++runCount;
             }
             /* runCount>1 */
             if(getRunsMemory(pBiDi, runCount)) {
                 runs=pBiDi->runsMemory;
             } else {
                 return FALSE;
             }
             /* set the runs */
             /* FOOD FOR THOUGHT: this could be optimized, e.g.:
              * 464->444, 484->444, 575->555, 595->555
              * However, that would take longer. Check also how it would
              * interact with BiDi control removal and inserting Marks.
              */
             runIndex=0;
             /* search for the run limits and initialize visualLimit values with the run lengths */
             i=0;
             do {
                 /* prepare this run */
                 start=i;
                 level=levels[i];
                 if(level<minLevel) {
                     minLevel=level;
                 }
                 if(level>maxLevel) {
                     maxLevel=level;
                 }
                 /* look for the run limit */
                 while(++i<limit && levels[i]==level) {}
                 /* i is another run limit */
                 runs[runIndex].logicalStart=start;
                 runs[runIndex].visualLimit=i-start;
                 runs[runIndex].insertRemove=0;
                 ++runIndex;
             } while(i<limit);
             if(limit<length) {
                 /* there is a separate WS run */
                 runs[runIndex].logicalStart=limit;
                 runs[runIndex].visualLimit=length-limit;
                 /* For the trailing WS run, pBiDi->paraLevel is ok even
                    if contextual multiple paragraphs.                   */
                 if(pBiDi->paraLevel<minLevel) {
                     minLevel=pBiDi->paraLevel;
                 }
             }
             /* set the object fields */
             pBiDi->runs=runs;
             pBiDi->runCount=runCount;
             reorderLine(pBiDi, minLevel, maxLevel);
             /* now add the direction flags and adjust the visualLimit's to be just that */
             /* this loop will also handle the trailing WS run */
             limit=0;
             for(i=0; i<runCount; ++i) {
                 ADD_ODD_BIT_FROM_LEVEL(runs[i].logicalStart, levels[runs[i].logicalStart]);
                 limit+=runs[i].visualLimit;
                 runs[i].visualLimit=limit;
             }
             /* Set the "odd" bit for the trailing WS run. */
             /* For a RTL paragraph, it will be the *first* run in visual order. */
             /* For the trailing WS run, pBiDi->paraLevel is ok even if
                contextual multiple paragraphs.                          */
             if(runIndex<runCount) {
                 int32_t trailingRun = ((pBiDi->paraLevel & 1) != 0)? 0 : runIndex;
                 ADD_ODD_BIT_FROM_LEVEL(runs[trailingRun].logicalStart, pBiDi->paraLevel);
             }
         }
     }
     /* handle insert LRM/RLM BEFORE/AFTER run */
     if(pBiDi->insertPoints.size>0) {
         Point *point, *start=pBiDi->insertPoints.points,
                       *limit=start+pBiDi->insertPoints.size;
         int32_t runIndex;
         for(point=start; point<limit; point++) {
             runIndex=getRunFromLogicalIndex(pBiDi, point->pos, pErrorCode);
             pBiDi->runs[runIndex].insertRemove|=point->flag;
         }
     }
     /* handle remove BiDi control characters */
     if(pBiDi->controlCount>0) {
         int32_t runIndex;
         const UChar *start=pBiDi->text, *limit=start+pBiDi->length, *pu;
         for(pu=start; pu<limit; pu++) {
             if(IS_BIDI_CONTROL_CHAR(*pu)) {
                 runIndex=getRunFromLogicalIndex(pBiDi, (int32_t)(pu-start), pErrorCode);
                 pBiDi->runs[runIndex].insertRemove--;
             }
         }
     }
     return TRUE;
 }
 static UBool
 prepareReorder(const UBiDiLevel *levels, int32_t length,
                int32_t *indexMap,
                UBiDiLevel *pMinLevel, UBiDiLevel *pMaxLevel) {
     int32_t start;
     UBiDiLevel level, minLevel, maxLevel;
     if(levels==NULL || length<=0) {
         return FALSE;
     }
     /* determine minLevel and maxLevel */
     minLevel=UBIDI_MAX_EXPLICIT_LEVEL+1;
     maxLevel=0;
     for(start=length; start>0;) {
         level=levels[--start];
         if(level>UBIDI_MAX_EXPLICIT_LEVEL+1) {
             return FALSE;
         }
         if(level<minLevel) {
             minLevel=level;
         }
         if(level>maxLevel) {
             maxLevel=level;
         }
     }
     *pMinLevel=minLevel;
     *pMaxLevel=maxLevel;
     /* initialize the index map */
     for(start=length; start>0;) {
         --start;
         indexMap[start]=start;
     }
     return TRUE;
 }
 /* reorder a line based on a levels array (L2) ------------------------------ */
 U_CAPI void U_EXPORT2
 ubidi_reorderLogical(const UBiDiLevel *levels, int32_t length, int32_t *indexMap) {
     int32_t start, limit, sumOfSosEos;
     UBiDiLevel minLevel = 0, maxLevel = 0;
     if(indexMap==NULL || !prepareReorder(levels, length, indexMap, &minLevel, &maxLevel)) {
         return;
     }
     /* nothing to do? */
     if(minLevel==maxLevel && (minLevel&1)==0) {
         return;
     }
     /* reorder only down to the lowest odd level */
     minLevel|=1;
     /* loop maxLevel..minLevel */
     do {
         start=0;
         /* loop for all sequences of levels to reorder at the current maxLevel */
         for(;;) {
             /* look for a sequence of levels that are all at >=maxLevel */
             /* look for the first index of such a sequence */
             while(start<length && levels[start]<maxLevel) {
                 ++start;
             }
             if(start>=length) {
                 break;  /* no more such sequences */
             }
             /* look for the limit of such a sequence (the index behind it) */
             for(limit=start; ++limit<length && levels[limit]>=maxLevel;) {}
             /*
              * sos=start of sequence, eos=end of sequence
              *
              * The closed (inclusive) interval from sos to eos includes all the logical
              * and visual indexes within this sequence. They are logically and
              * visually contiguous and in the same range.
              *
              * For each run, the new visual index=sos+eos-old visual index;
              * we pre-add sos+eos into sumOfSosEos ->
              * new visual index=sumOfSosEos-old visual index;
              */
             sumOfSosEos=start+limit-1;
             /* reorder each index in the sequence */
             do {
                 indexMap[start]=sumOfSosEos-indexMap[start];
             } while(++start<limit);
             /* start==limit */
             if(limit==length) {
                 break;  /* no more such sequences */
             } else {
                 start=limit+1;
             }
         }
     } while(--maxLevel>=minLevel);
 }
 U_CAPI void U_EXPORT2
 ubidi_reorderVisual(const UBiDiLevel *levels, int32_t length, int32_t *indexMap) {
     int32_t start, end, limit, temp;
     UBiDiLevel minLevel = 0, maxLevel = 0;
     if(indexMap==NULL || !prepareReorder(levels, length, indexMap, &minLevel, &maxLevel)) {
         return;
     }
     /* nothing to do? */
     if(minLevel==maxLevel && (minLevel&1)==0) {
         return;
     }
     /* reorder only down to the lowest odd level */
     minLevel|=1;
     /* loop maxLevel..minLevel */
     do {
         start=0;
         /* loop for all sequences of levels to reorder at the current maxLevel */
         for(;;) {
             /* look for a sequence of levels that are all at >=maxLevel */
             /* look for the first index of such a sequence */
             while(start<length && levels[start]<maxLevel) {
                 ++start;
             }
             if(start>=length) {
                 break;  /* no more such runs */
             }
             /* look for the limit of such a sequence (the index behind it) */
             for(limit=start; ++limit<length && levels[limit]>=maxLevel;) {}
             /*
              * Swap the entire interval of indexes from start to limit-1.
              * We don't need to swap the levels for the purpose of this
              * algorithm: the sequence of levels that we look at does not
              * move anyway.
              */
             end=limit-1;
             while(start<end) {
                 temp=indexMap[start];
                 indexMap[start]=indexMap[end];
                 indexMap[end]=temp;
                 ++start;
                 --end;
             }
             if(limit==length) {
                 break;  /* no more such sequences */
             } else {
                 start=limit+1;
             }
         }
     } while(--maxLevel>=minLevel);
 }
 /* API functions for logical<->visual mapping ------------------------------- */
 U_CAPI int32_t U_EXPORT2
 ubidi_getVisualIndex(UBiDi *pBiDi, int32_t logicalIndex, UErrorCode *pErrorCode) {
     int32_t visualIndex=UBIDI_MAP_NOWHERE;
     RETURN_IF_NULL_OR_FAILING_ERRCODE(pErrorCode, -1);
     RETURN_IF_NOT_VALID_PARA_OR_LINE(pBiDi, *pErrorCode, -1);
     RETURN_IF_BAD_RANGE(logicalIndex, 0, pBiDi->length, *pErrorCode, -1);
     /* we can do the trivial cases without the runs array */
     switch(pBiDi->direction) {
     case UBIDI_LTR:
         visualIndex=logicalIndex;
         break;
     case UBIDI_RTL:
         visualIndex=pBiDi->length-logicalIndex-1;
         break;
     default:
         if(!ubidi_getRuns(pBiDi, pErrorCode)) {
             *pErrorCode=U_MEMORY_ALLOCATION_ERROR;
             return -1;
         } else {
             Run *runs=pBiDi->runs;
             int32_t i, visualStart=0, offset, length;
             /* linear search for the run, search on the visual runs */
             for(i=0; i<pBiDi->runCount; ++i) {
                 length=runs[i].visualLimit-visualStart;
                 offset=logicalIndex-GET_INDEX(runs[i].logicalStart);
                 if(offset>=0 && offset<length) {
                     if(IS_EVEN_RUN(runs[i].logicalStart)) {
                         /* LTR */
                         visualIndex=visualStart+offset;
                     } else {
                         /* RTL */
                         visualIndex=visualStart+length-offset-1;
                     }
                     break;          /* exit for loop */
                 }
                 visualStart+=length;
             }
             if(i>=pBiDi->runCount) {
                 return UBIDI_MAP_NOWHERE;
             }
         }
     }
     if(pBiDi->insertPoints.size>0) {
         /* add the number of added marks until the calculated visual index */
         Run *runs=pBiDi->runs;
         int32_t i, length, insertRemove;
         int32_t visualStart=0, markFound=0;
         for(i=0; ; i++, visualStart+=length) {
             length=runs[i].visualLimit-visualStart;
             insertRemove=runs[i].insertRemove;
             if(insertRemove & (LRM_BEFORE|RLM_BEFORE)) {
                 markFound++;
             }
             /* is it the run containing the visual index? */
             if(visualIndex<runs[i].visualLimit) {
                 return visualIndex+markFound;
             }
             if(insertRemove & (LRM_AFTER|RLM_AFTER)) {
                 markFound++;
             }
         }
     }
     else if(pBiDi->controlCount>0) {
         /* subtract the number of controls until the calculated visual index */
         Run *runs=pBiDi->runs;
         int32_t i, j, start, limit, length, insertRemove;
         int32_t visualStart=0, controlFound=0;
         UChar uchar=pBiDi->text[logicalIndex];
         /* is the logical index pointing to a control ? */
         if(IS_BIDI_CONTROL_CHAR(uchar)) {
             return UBIDI_MAP_NOWHERE;
         }
         /* loop on runs */
         for(i=0; ; i++, visualStart+=length) {
             length=runs[i].visualLimit-visualStart;
             insertRemove=runs[i].insertRemove;
             /* calculated visual index is beyond this run? */
             if(visualIndex>=runs[i].visualLimit) {
                 controlFound-=insertRemove;
                 continue;
             }
             /* calculated visual index must be within current run */
             if(insertRemove==0) {
                 return visualIndex-controlFound;
             }
             if(IS_EVEN_RUN(runs[i].logicalStart)) {
                 /* LTR: check from run start to logical index */
                 start=runs[i].logicalStart;
                 limit=logicalIndex;
             } else {
                 /* RTL: check from logical index to run end */
                 start=logicalIndex+1;
                 limit=GET_INDEX(runs[i].logicalStart)+length;
             }
             for(j=start; j<limit; j++) {
                 uchar=pBiDi->text[j];
                 if(IS_BIDI_CONTROL_CHAR(uchar)) {
                     controlFound++;
                 }
             }
             return visualIndex-controlFound;
         }
     }
     return visualIndex;
 }
 U_CAPI int32_t U_EXPORT2
 ubidi_getLogicalIndex(UBiDi *pBiDi, int32_t visualIndex, UErrorCode *pErrorCode) {
     Run *runs;
     int32_t i, runCount, start;
     RETURN_IF_NULL_OR_FAILING_ERRCODE(pErrorCode, -1);
     RETURN_IF_NOT_VALID_PARA_OR_LINE(pBiDi, *pErrorCode, -1);
     RETURN_IF_BAD_RANGE(visualIndex, 0, pBiDi->resultLength, *pErrorCode, -1);
     /* we can do the trivial cases without the runs array */
     if(pBiDi->insertPoints.size==0 && pBiDi->controlCount==0) {
         if(pBiDi->direction==UBIDI_LTR) {
             return visualIndex;
         }
         else if(pBiDi->direction==UBIDI_RTL) {
             return pBiDi->length-visualIndex-1;
         }
     }
     if(!ubidi_getRuns(pBiDi, pErrorCode)) {
         *pErrorCode=U_MEMORY_ALLOCATION_ERROR;
         return -1;
     }
     runs=pBiDi->runs;
     runCount=pBiDi->runCount;
     if(pBiDi->insertPoints.size>0) {
         /* handle inserted LRM/RLM */
         int32_t markFound=0, insertRemove;
         int32_t visualStart=0, length;
         runs=pBiDi->runs;
         /* subtract number of marks until visual index */
         for(i=0; ; i++, visualStart+=length) {
             length=runs[i].visualLimit-visualStart;
             insertRemove=runs[i].insertRemove;
             if(insertRemove&(LRM_BEFORE|RLM_BEFORE)) {
                 if(visualIndex<=(visualStart+markFound)) {
                     return UBIDI_MAP_NOWHERE;
                 }
                 markFound++;
             }
             /* is adjusted visual index within this run? */
             if(visualIndex<(runs[i].visualLimit+markFound)) {
                 visualIndex-=markFound;
                 break;
             }
             if(insertRemove&(LRM_AFTER|RLM_AFTER)) {
                 if(visualIndex==(visualStart+length+markFound)) {
                     return UBIDI_MAP_NOWHERE;
                 }
                 markFound++;
             }
         }
     }
     else if(pBiDi->controlCount>0) {
         /* handle removed BiDi control characters */
         int32_t controlFound=0, insertRemove, length;
         int32_t logicalStart, logicalEnd, visualStart=0, j, k;
         UChar uchar;
         UBool evenRun;
         /* add number of controls until visual index */
         for(i=0; ; i++, visualStart+=length) {
             length=runs[i].visualLimit-visualStart;
             insertRemove=runs[i].insertRemove;
             /* is adjusted visual index beyond current run? */
             if(visualIndex>=(runs[i].visualLimit-controlFound+insertRemove)) {
                 controlFound-=insertRemove;
                 continue;
             }
             /* adjusted visual index is within current run */
             if(insertRemove==0) {
                 visualIndex+=controlFound;
                 break;
             }
             /* count non-control chars until visualIndex */
             logicalStart=runs[i].logicalStart;
             evenRun=IS_EVEN_RUN(logicalStart);
             REMOVE_ODD_BIT(logicalStart);
             logicalEnd=logicalStart+length-1;
             for(j=0; j<length; j++) {
                 k= evenRun ? logicalStart+j : logicalEnd-j;
                 uchar=pBiDi->text[k];
                 if(IS_BIDI_CONTROL_CHAR(uchar)) {
                     controlFound++;
                 }
                 if((visualIndex+controlFound)==(visualStart+j)) {
                     break;
                 }
             }
             visualIndex+=controlFound;
             break;
         }
     }
     /* handle all cases */
     if(runCount<=10) {
         /* linear search for the run */
         for(i=0; visualIndex>=runs[i].visualLimit; ++i) {}
     } else {
         /* binary search for the run */
         int32_t begin=0, limit=runCount;
         /* the middle if() is guaranteed to find the run, we don't need a loop limit */
         for(;;) {
             i=(begin+limit)/2;
             if(visualIndex>=runs[i].visualLimit) {
                 begin=i+1;
             } else if(i==0 || visualIndex>=runs[i-1].visualLimit) {
                 break;
             } else {
                 limit=i;
             }
         }
     }
     start=runs[i].logicalStart;
     if(IS_EVEN_RUN(start)) {
         /* LTR */
         /* the offset in runs[i] is visualIndex-runs[i-1].visualLimit */
         if(i>0) {
             visualIndex-=runs[i-1].visualLimit;
         }
         return start+visualIndex;
     } else {
         /* RTL */
         return GET_INDEX(start)+runs[i].visualLimit-visualIndex-1;
     }
 }
 U_CAPI void U_EXPORT2
 ubidi_getLogicalMap(UBiDi *pBiDi, int32_t *indexMap, UErrorCode *pErrorCode) {
     RETURN_VOID_IF_NULL_OR_FAILING_ERRCODE(pErrorCode);
     /* ubidi_countRuns() checks for VALID_PARA_OR_LINE */
     ubidi_countRuns(pBiDi, pErrorCode);
     if(U_FAILURE(*pErrorCode)) {
         /* no op */
     } else if(indexMap==NULL) {
         *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
     } else {
         /* fill a logical-to-visual index map using the runs[] */
         int32_t visualStart, visualLimit, i, j, k;
         int32_t logicalStart, logicalLimit;
         Run *runs=pBiDi->runs;
         if (pBiDi->length<=0) {
             return;
         }
         if (pBiDi->length>pBiDi->resultLength) {
             uprv_memset(indexMap, 0xFF, pBiDi->length*sizeof(int32_t));
         }
         visualStart=0;
         for(j=0; j<pBiDi->runCount; ++j) {
             logicalStart=GET_INDEX(runs[j].logicalStart);
             visualLimit=runs[j].visualLimit;
             if(IS_EVEN_RUN(runs[j].logicalStart)) {
                 do { /* LTR */
                     indexMap[logicalStart++]=visualStart++;
                 } while(visualStart<visualLimit);
             } else {
                 logicalStart+=visualLimit-visualStart;  /* logicalLimit */
                 do { /* RTL */
                     indexMap[--logicalStart]=visualStart++;
                 } while(visualStart<visualLimit);
             }
             /* visualStart==visualLimit; */
         }
         if(pBiDi->insertPoints.size>0) {
             int32_t markFound=0, runCount=pBiDi->runCount;
             int32_t length, insertRemove;
             visualStart=0;
             /* add number of marks found until each index */
             for(i=0; i<runCount; i++, visualStart+=length) {
                 length=runs[i].visualLimit-visualStart;
                 insertRemove=runs[i].insertRemove;
                 if(insertRemove&(LRM_BEFORE|RLM_BEFORE)) {
                     markFound++;
                 }
                 if(markFound>0) {
                     logicalStart=GET_INDEX(runs[i].logicalStart);
                     logicalLimit=logicalStart+length;
                     for(j=logicalStart; j<logicalLimit; j++) {
                         indexMap[j]+=markFound;
                     }
                 }
                 if(insertRemove&(LRM_AFTER|RLM_AFTER)) {
                     markFound++;
                 }
             }
         }
         else if(pBiDi->controlCount>0) {
             int32_t controlFound=0, runCount=pBiDi->runCount;
             int32_t length, insertRemove;
             UBool evenRun;
             UChar uchar;
             visualStart=0;
             /* subtract number of controls found until each index */
             for(i=0; i<runCount; i++, visualStart+=length) {
                 length=runs[i].visualLimit-visualStart;
                 insertRemove=runs[i].insertRemove;
                 /* no control found within previous runs nor within this run */
                 if((controlFound-insertRemove)==0) {
                     continue;
                 }
                 logicalStart=runs[i].logicalStart;
                 evenRun=IS_EVEN_RUN(logicalStart);
                 REMOVE_ODD_BIT(logicalStart);
                 logicalLimit=logicalStart+length;
                 /* if no control within this run */
                 if(insertRemove==0) {
                     for(j=logicalStart; j<logicalLimit; j++) {
                         indexMap[j]-=controlFound;
                     }
                     continue;
                 }
                 for(j=0; j<length; j++) {
                     k= evenRun ? logicalStart+j : logicalLimit-j-1;
                     uchar=pBiDi->text[k];
                     if(IS_BIDI_CONTROL_CHAR(uchar)) {
                         controlFound++;
                         indexMap[k]=UBIDI_MAP_NOWHERE;
                         continue;
                     }
                     indexMap[k]-=controlFound;
                 }
             }
         }
     }
 }
 U_CAPI void U_EXPORT2
 ubidi_getVisualMap(UBiDi *pBiDi, int32_t *indexMap, UErrorCode *pErrorCode) {
     RETURN_VOID_IF_NULL_OR_FAILING_ERRCODE(pErrorCode);
     if(indexMap==NULL) {
         *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
         return;
     }
     /* ubidi_countRuns() checks for VALID_PARA_OR_LINE */
     ubidi_countRuns(pBiDi, pErrorCode);
     if(U_SUCCESS(*pErrorCode)) {
         /* fill a visual-to-logical index map using the runs[] */
         Run *runs=pBiDi->runs, *runsLimit=runs+pBiDi->runCount;
         int32_t logicalStart, visualStart, visualLimit, *pi=indexMap;
         if (pBiDi->resultLength<=0) {
             return;
         }
         visualStart=0;
         for(; runs<runsLimit; ++runs) {
             logicalStart=runs->logicalStart;
             visualLimit=runs->visualLimit;
             if(IS_EVEN_RUN(logicalStart)) {
                 do { /* LTR */
                     *pi++ = logicalStart++;
                 } while(++visualStart<visualLimit);
             } else {
                 REMOVE_ODD_BIT(logicalStart);
                 logicalStart+=visualLimit-visualStart;  /* logicalLimit */
                 do { /* RTL */
                     *pi++ = --logicalStart;
                 } while(++visualStart<visualLimit);
             }
             /* visualStart==visualLimit; */
         }
         if(pBiDi->insertPoints.size>0) {
             int32_t markFound=0, runCount=pBiDi->runCount;
             int32_t insertRemove, i, j, k;
             runs=pBiDi->runs;
             /* count all inserted marks */
             for(i=0; i<runCount; i++) {
                 insertRemove=runs[i].insertRemove;
                 if(insertRemove&(LRM_BEFORE|RLM_BEFORE)) {
                     markFound++;
                 }
                 if(insertRemove&(LRM_AFTER|RLM_AFTER)) {
                     markFound++;
                 }
             }
             /* move back indexes by number of preceding marks */
             k=pBiDi->resultLength;
             for(i=runCount-1; i>=0 && markFound>0; i--) {
                 insertRemove=runs[i].insertRemove;
                 if(insertRemove&(LRM_AFTER|RLM_AFTER)) {
                     indexMap[--k]= UBIDI_MAP_NOWHERE;
                     markFound--;
                 }
                 visualStart= i>0 ? runs[i-1].visualLimit : 0;
                 for(j=runs[i].visualLimit-1; j>=visualStart && markFound>0; j--) {
                     indexMap[--k]=indexMap[j];
                 }
                 if(insertRemove&(LRM_BEFORE|RLM_BEFORE)) {
                     indexMap[--k]= UBIDI_MAP_NOWHERE;
                     markFound--;
                 }
             }
         }
         else if(pBiDi->controlCount>0) {
             int32_t runCount=pBiDi->runCount, logicalEnd;
             int32_t insertRemove, length, i, j, k, m;
             UChar uchar;
             UBool evenRun;
             runs=pBiDi->runs;
             visualStart=0;
             /* move forward indexes by number of preceding controls */
             k=0;
             for(i=0; i<runCount; i++, visualStart+=length) {
                 length=runs[i].visualLimit-visualStart;
                 insertRemove=runs[i].insertRemove;
                 /* if no control found yet, nothing to do in this run */
                 if((insertRemove==0)&&(k==visualStart)) {
                     k+=length;
                     continue;
                 }
                 /* if no control in this run */
                 if(insertRemove==0) {
                     visualLimit=runs[i].visualLimit;
                     for(j=visualStart; j<visualLimit; j++) {
                         indexMap[k++]=indexMap[j];
                     }
                     continue;
                 }
                 logicalStart=runs[i].logicalStart;
                 evenRun=IS_EVEN_RUN(logicalStart);
                 REMOVE_ODD_BIT(logicalStart);
                 logicalEnd=logicalStart+length-1;
                 for(j=0; j<length; j++) {
                     m= evenRun ? logicalStart+j : logicalEnd-j;
                     uchar=pBiDi->text[m];
                     if(!IS_BIDI_CONTROL_CHAR(uchar)) {
                         indexMap[k++]=m;
                     }
                 }
             }
         }
     }
 }
 U_CAPI void U_EXPORT2
 ubidi_invertMap(const int32_t *srcMap, int32_t *destMap, int32_t length) {
     if(srcMap!=NULL && destMap!=NULL && length>0) {
         const int32_t *pi;
         int32_t destLength=-1, count=0;
         /* find highest value and count positive indexes in srcMap */
         pi=srcMap+length;
         while(pi>srcMap) {
             if(*--pi>destLength) {
                 destLength=*pi;
             }
             if(*pi>=0) {
                 count++;
             }
         }
         destLength++;           /* add 1 for origin 0 */
         if(count<destLength) {
             /* we must fill unmatched destMap entries with -1 */
             uprv_memset(destMap, 0xFF, destLength*sizeof(int32_t));
         }
         pi=srcMap+length;
         while(length>0) {
             if(*--pi>=0) {
                 destMap[*pi]=--length;
             } else {
                 --length;
             }
         }
     }
 }

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intl/icu/source/common/ubidiln.c@129ffea94266 (annotated)

intl/icu/source/common/ubidiln.c