;----------------------------------------------------------
; IndirectSort Routine
;----------------------------------------------------------
;
; Sorts the index table from Low to High
;
; (change the "bcc" commands to "bcs"
;  to sort from High to Low)
;
; USES:
;   IndexTable    An array of indexes. Indexes for the DataArray
;   DataTable     An array with 16 bit data. The index table has indexes to this array
;   ArrayLength   A variable filled with the number of elements (not bytes) in the data array.
;   DoMoreSort    A flag which is set to "true" if more sorting is needed
;
        
        ;init index table
        ldx #$00
        lda #$00
        clc
IS_nextIndexInit
        sta IS_IndexTable,x
        adc #$02
        inx
        cpx #IS_ArrayLength
        bne IS_nextIndexInit
        
IS_startOfSortPass
        ;init table index
        ldy #$00
        
        ;init DoMoreSort flag
        lda #false
        sta IS_DoMoreSort
        
IS_checkSwapOnMSB
        ;get y-pos (msb)
        ldx IS_IndexTable,y        ;index to y-pos-table
        lda IS_DataTable,x         ;load y pos (msb)
        
        ;compare element with next element (msb)
        ldx IS_IndexTable + 1,y    ;index to y-pos-table
        cmp IS_DataTable,x         ;compare y pos (msb)
        
        ;check which is higher
        beq IS_checkSwapOnLSB
        bcc IS_nextIndex           ;carry is clear when the second is higher then the first
        
        ;swap indexes in index table
        lda IS_IndexTable,y
        sta IS_IndexTable + 1,y
        stx IS_IndexTable,y

        ;set DoMoreSort flag
        lda #true
        sta IS_DoMoreSort
        
        ;jump to next index
        jmp IS_nextIndex
        
IS_checkSwapOnLSB
        ;get y-pos (lsb)
        ldx IS_IndexTable,y        ;index to y-pos-table
        lda IS_DataTable + 1,x     ;load y pos (lsb)
        
        ;compare element with next element (lsb)
        ldx IS_IndexTable + 1,y    ;index to y-pos-table
        cmp IS_DataTable + 1,x     ;compare y pos (lsb)
        
        ;check which is higher
        beq IS_nextIndex
        bcc IS_nextIndex           ;carry is clear when the second is higher then the first
        
        ;swap indexes in index table
        lda IS_IndexTable,y
        sta IS_IndexTable + 1,y
        stx IS_IndexTable,y
        
        ;set DoMoreSort flag
        lda #true
        sta IS_DoMoreSort
        
IS_nextIndex
        iny
        cpy #IS_ArrayLength - 1
        bne IS_checkSwapOnMSB
        
        ;check if sort is ready
        lda IS_DoMoreSort
        cmp #true
        beq IS_startOfSortPass
        
        ;done
        rts

lda msb
lsr
lda lsb
ror
sta smallYPos