Eskil

        return [expr {($n1 > $n2 ? $n1 : $n2) + 1}]
    } else {
        return [expr {-($n1 > $n2 ? $n1 : $n2)}]
    }
}

# Insert two blocks of lines in the compare windows.

# The return value is true if the block should not be considered a change
proc insertMatchingBlocks {top block1 block2 line1 line2 details} {
    global doingLine1 doingLine2

    # A large block may take time.  Give a small warning.
    set n1 [llength $block1]
    set n2 [llength $block2]
    if {$n1 * $n2 > 1000} {
        set ::widgets($top,eqLabel) "!"
        #puts "Eskil warning: Analyzing a large block. ($size1 $size2)"
        update idletasks
    }

    
    # Detect if only newlines has changed within the block, e.g.
    # when rearranging newlines.
    if {$::eskil(ignorenewline)} {
        set res [ParseBlocksAcrossNewline $top $block1 $block2]
        if {$res != 0} {
            # FIXA: move this to ParseBlocksAcrossNewline
            if {$res > 0 && $details} {
                addChange $top $res change $line1 $n1 $line2 $n2
            } else {
                addMapLines $top [expr {abs($res)}]
            }
            # Negative means considered not a change
            return [expr {$res < 0}]
        }
    }

    set apa [compareBlocks $block1 $block2]

    set t1 0
    set t2 0

                    "hl$::HighLightCount change"
            $::widgets($top,wDiff2) insert end "$bepa\n" new2
            emptyLine $top 1
            incr doingLine2
            incr t2
        }
    }
    if {$details} {
        addChange $top [llength $apa] change $line1 $n1 $line2 $n2
    } else {
        addMapLines $top [llength $apa]
    }
    return 0
}

# Process one of the change/add/delete blocks reported by diff.
#  ch1 is a file channel for the left file
#  ch2 is a file channel for the right file
#  n1/n2 is the number of lines involved
#  line1/line2 says on what lines this block starts
# If n1/n2 are both 0, it means that this is the last lines to be displayed.
#  In that case line1/line2, if non-zero says the last line to display.
# The return value is true if the block should not be considered a change
proc doText {top ch1 ch2 n1 n2 line1 line2} {
    global doingLine1 doingLine2 Pref

    if {$n1 == 0 && $n2 == 0} {
        # All blocks have been processed. Continue until end of file.
        # If "show all" is not on, just display a couple of context lines.
        set limit -1

        while {[gets $ch1 apa] != -1} {
            if {$line1 > 0 && $doingLine1 > $line1} break
            insertLine $top 1 $doingLine1 $apa
            incr doingLine1
            incr t
            if {$limit >= 0 && $t >= $limit} break
        }
        return 0
    }

    # Is this a change block, a delete block or a insert block?
    if {$n1 == 0} {set tag2 new2} else {set tag2 change}
    if {$n2 == 0} {set tag1 new1} else {set tag1 change}

    # Display all equal lines before next diff

            }
        }
        incr doingLine1
        incr doingLine2
        incr t
        if {$::diff($top,limitlines) && \
                ($::diff($top,mapMax) > $::diff($top,limitlines))} {
            return 0
        }
    }
    # This should not happen unless something is wrong...
    if {$doingLine2 != $line2} {
        disallowEdit $top
        $::widgets($top,wDiff1) insert end \
                "**Bad alignment here!! $doingLine2 $line2**\n"

                lappend block1 $apa
            }
            set block2 {}
            for {set t 0} {$t < $n2} {incr t} {
                gets $ch2 apa
                lappend block2 $apa
            }
            set apa [insertMatchingBlocks $top $block1 $block2 $line1 $line2 1]
            if {$apa < 0} {



                # In this case, a change is not visible
                return 1
            }
        } else {
            # No extra parsing at all.
            for {set t 0} {$t < $n1} {incr t} {
                gets $ch1 apa

                    emptyLine $top 2
                }
                addChange $top $n1 $tag1 $line1 $n1 $line2 $n2
            }
        }
    }
    # Empty return value
    return 0
}

proc enableRedo {top} {
    $top.m.mf entryconfigure "Redo Diff" -state normal
    $top.m.mt entryconfigure "Merge"     -state normal
}

            }
            continue
        }
        # No change block anymore. If one just ended, display it.
        if {[llength $lblock] > 0 || [llength $rblock] > 0} {
            set ::doingLine1 $lblockl
            set ::doingLine2 $rblockl
            insertMatchingBlocks $top $lblock $rblock $lblockl $rblockl 0
            set lblock {}
            set rblock {}
        }
        if {$lmode == "" && $rmode == ""} {
            insertLine $top 1 $lline $lstr
            insertLine $top 2 $rline $rstr
            incr leftc

            continue
        }
    }
    # If the patch ended with a change block, display it.
    if {[llength $lblock] > 0 || [llength $rblock] > 0} {
        set ::doingLine1 $lblockl
        set ::doingLine2 $rblockl
        insertMatchingBlocks $top $lblock $rblock $lblockl $rblockl 0
        set lblock {}
        set rblock {}
    }
}

# Read a patch file and display it
proc displayPatch {top} {