im looking for a zoom in routine

[777]

nothing on google. so you can select an area of the screen and zoom into it. or something that could expand a udg. any ideas?

[Cheez26]

Can you repeat that question with a bit more detail? Because I'm confused by what you mean by "zoom-in routine". Which software are you even using? Forgive me if I'm being blunt.

[ParadigmShifter]

If you only have a few size possibilities use a lookup table mapping bits to double/triple/quadruple bits. Then if that also needs shifting, shift each row into a temp buffer. Then draw each line of the buffer for zoom amount of rows.

Slower way is shifting the data out of A register and building the graphics depending on which bit is shifted out into carry flag.

[777]

Can you repeat that question with a bit more detail? Because I'm confused by what you mean by "zoom-in routine". Which software are you even using? Forgive me if I'm being blunt.

i mean an assembly language routine

[Cheez26]

i mean an assembly language routine

Ah. I get it.

Unfortunately, Z80 assembly is not my strong suit unless if we're talking in-line of Boriel BASIC; even then, I'm still a noob at Boriel BASIC too. So, maybe take ParadigmShifter's advice instead.

[sn3j]

You could use the Plot routine to do that (mentioned a bit earlier here).
You just need to derive from it a new routine that checks the bit at position in DE.
Then you can do this:

Code: Select all

    ld de, 0x0000              ; pixel pos where to check: (0,0) = top-left corner
    ld hl, 0x0080              ; pixel pos where to draw: (0,128)
    ld c, 15                   ; #rows
NextRow:
    ld b, 11                   ; #bits per row
    ld a, e
    add b                      ; advance DE to end of row
    ld e, a
    ld a, l
    add b
    add b                      ; advance HL to end of row
    ld l, a
NextBit:
    dec e                      ; go 1 pixel to the left
    dec l
    dec l                      ; set Draw pos 2 pixels to the left
    push hl
    call CheckBitAtDE
    pop hl                     ; restore Draw position
    call nz PlotSquareAtHL     ; plot a 2x2 square if the bit was set
    djnz NextBit               ; for all bits in row
    inc d                      ; advance DE to next row
    inc h
    inc h                      ; advance HL to next row
    dec c                      ; decrease the row counter
    jr nz NextRow              ; for all rows

Code: Select all

PlotSquareAtHL:
    push de
    ex de hl
    inc e
    call PlotAtDE              ; plot at (y,x+1)
    inc d
    call PlotAtDE              ; plot at (y+1,x+1)
    dec e
    call PlotAtDE              ; plot at (y+1,x)
    dec d
    call PlotAtDE              ; plot at (y,x)
    ex de hl
    pop de                     ; restore DE
    ret

[Dr beep]

Like in this game?

https://spectrumcomputing.co.uk/entry/2 ... _Lost_Keys