Check in the pristine copy of ICU 4.6...

icu46/source/common/ubidiln.c

+/*
+******************************************************************************
+*
+*   Copyright (C) 1999-2010, 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"
+
+/*
+ * 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 3.0 BiDi algorithm as defined in
+ * http://www.unicode.org/unicode/reports/tr9/ , version 13,
+ * also described in The Unicode Standard, Version 4.0.1 .
+ *
+ * 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(NO_CONTEXT_RTL(dirProps[start-1])==B) {
+        pBiDi->trailingWSStart=start;   /* currently == pBiDi->length */
+        return;
+    }
+    /* go backwards across all WS, BN, explicit codes */
+    while(start>0 && DIRPROP_FLAG_NC(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;
+            }
+        }
+    }
+}