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| author | Miquel Sabaté Solà <msabate@suse.com> | 2023-11-27 10:31:03 +0100 |
|---|---|---|
| committer | Miquel Sabaté Solà <mikisabate@gmail.com> | 2025-02-04 21:02:54 +0100 |
| commit | cee93625989b651cfe91387eabd0abd3f64a00df (patch) | |
| tree | d1525bd15c191c2926ea1166263b249a8bbeb79c /scroll/include/ppu.s | |
| parent | 0e1839f48ada69b81f5879449d0e0fe435f851c5 (diff) | |
| download | code.nes-cee93625989b651cfe91387eabd0abd3f64a00df.tar.gz code.nes-cee93625989b651cfe91387eabd0abd3f64a00df.zip | |
scroll: Start with the scrolling examples
This is still work in progress but at least there's some basic structure
to it.
Signed-off-by: Miquel Sabaté Solà <msabate@suse.com>
Diffstat (limited to 'scroll/include/ppu.s')
| -rw-r--r-- | scroll/include/ppu.s | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/scroll/include/ppu.s b/scroll/include/ppu.s new file mode 100644 index 0000000..23fd978 --- /dev/null +++ b/scroll/include/ppu.s @@ -0,0 +1,27 @@ +.segment "CODE" + +.scope PPU + CONTROL = $2000 + MASK = $2001 + STATUS = $2002 + SCROLL = $2005 + ADDRESS = $2006 + DATA = $2007 +.endscope + +.macro PPU_ADDR address + lda #.HIBYTE(address) + sta PPU::ADDRESS + lda #.LOBYTE(address) + sta PPU::ADDRESS +.endmacro + +;; WRITE_PPU_DATA is a macro that will write into PPU::ADDRESS the given address +;; and into PPU::DATA the given byte value. +.macro WRITE_PPU_DATA address, value + bit PPU::STATUS + + PPU_ADDR address + lda #value + sta PPU::DATA +.endmacro |