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Diffstat (limited to 'nes/dma.go')
-rw-r--r--nes/dma.go19
1 files changed, 19 insertions, 0 deletions
diff --git a/nes/dma.go b/nes/dma.go
new file mode 100644
index 0000000..ebdbcea
--- /dev/null
+++ b/nes/dma.go
@@ -0,0 +1,19 @@
+package nes
+
+// im too lazy to write an explanation so heres the nesdev page
+// https://www.nesdev.org/wiki/DMA#OAM_DMA
+func (n *Console) oamDMA(page uint8) {
+ base := uint16(page) << 8
+ for i := uint16(0); i < 256; i++ {
+ n.PPU.WriteRegister(0x2004, n.Read(base+i))
+ }
+ n.dmaPending = true
+}
+
+func (n *Console) dmaStallCycles() int {
+ stall := 513
+ if n.CPU.Cycles&1 == 1 {
+ stall++
+ }
+ return stall
+}