First day of advent of code

Signed-off-by: Miquel Sabaté Solà <msabate@suse.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/include/ppu.s b/include/ppu.s
new file mode 100644
index 0000000..23fd978
--- /dev/null
+++ b/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