Array storage in RAM

[FFMan]

Trying to work out an elegant way to shift my data one bit at a time to create a smooth scroll on my matrix display and I wondered if i could use BitCopy like so:-

Code: Select all

		for byChr=1 to byMaxDisplays
			for byRow=1 to Ubound(byMsgBuf,2)
				inBufRam=MemAddress(byMsgBuf(byChr,byRow))
				inTmpRam=MemAddress(byMsgTmp(byChr,byRow))
	
				Call BitCopy(inTmpRam,0,inBufRam,inScrollStep,32)
			next
		next

byMsgBuf(50,8 ) - storage of the required message bit patterns, 8 rows

byMsgTmp(4,8 ) - display buffer, 1 column per physical display (4) times number of rows.

the intention being to move the bits required into the displaybuffer but this relies upon my assumption that in ram an array is stored sequentially in column order. The code isn't producing the desired effect and i wonder if the ram storage order in not what I think

[dkinzer]

i wonder if the ram storage order in not what I think

Two dimensional RAM arrays are arranged in memory sequentially with the leftmost index varying the fastest. This is documented in the ZBasic Language Reference Manual:
http://www.zbasic.net/doc/ZBasicRef.php?page=90

You can verify that this is so using a simple test program like the one below. It superimposes a one dimensional array on top of a two dimensional array, initializes one and displays from the other.

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Dim a(1 to 4, 1 to 4) as Byte
Dim b(1 to 16) as Byte Based a.DataAddress

Sub Main()
    Dim i as Integer, j as Integer
    Dim bval as Byte

    bval = 1
    For i = 1 to 4
        For j = 1 to 4
            a(j, i) = bval
            bval = bval + 1
        Next j
    Next i

    For i = 1 to 16
        Debug.Print b(i); " ";
    Next i
    Debug.Print
End Sub